Development, Mechanical Performance, and Ex Vivo Porcine Eye Biomechanical Validation of a 3D-Printed Schepens Scleral Depressor

Development, Mechanical Performance, and Ex Vivo Porcine Eye Biomechanical Validation of a 3D-Printed Schepens Scleral Depressor | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Development, Mechanical Performance, and Ex Vivo Porcine Eye Biomechanical Validation of a 3D-Printed Schepens Scleral Depressor Luís Expedito Sabage, Mariana Pasqualin Wojcikiewicz, Thiago Meister, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8242729/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose : To develop a low-cost, 3D-printed Schepens scleral depressor and evaluate its mechanical performance, safety, and ocular biomechanical effects. Methods: A Schepens-style depressor was developed and printed in PLA using a 3D-printer. Examiners performed two different tests: (1) the maximum simulated scleral depression force, using both the 3D-printed and a conventional steel depressor, and (2) a breakage test performed only on the 3D-printed device to determine its mechanical failure threshold. Peak forces were applied to porcine belly and recorded by a precision balance with a slow-motion video analysis. A third test - conduced exclusively with the 3D-printed depressor - was performed using one ex vivo porcine eye model to correlate applied force with induced intraocular pressure (IOP) elevation. Pressure–volume behavior was modeled using the Friedenwald rigidity coefficient. Results: One unit of the depressor prototype consumed 3.06g of PLA with an estimated cost and print time of U$0.06 and 22min. Simulated indentation produced forces of 21.21 ± 6.23N (3D-printed depressor) and 25.02 ± 4.64N (steel depressor), with no significant difference between devices. The 3D-printed instrument breakage point was 63.27 ± 10.72N, with a 2.98 Factor of Safety (FS) and 3.39 Reliability Index (b). In the porcine model, scleral depression produced 15.63 ± 8.13mmHg IOP elevation, requiring 0.191 ± 0.09N (FS = 331.2 and b = 5.88). Conclusion: The 3D-printed depressor demonstrates effective mechanical robustness, wide safety margins, and functional equivalence to steel instruments, supporting the use of customizable, low-cost 3D-printed depressors in training and clinical settings. scleral depression 3D printing medical device prototyping biomechanics intraocular pressure Schepens depressor instrument design Figures Figure 1 Figure 2 Figure 3 Figure 4 Key Messages What is known 3D printing is increasingly used in ophthalmology to enable fast, low-cost production of clinical and training tools. Scleral depression is essential for diagnosing peripheral retinal lesions, yet limited evidence exists regarding safety of devices, the forces applied during indentation and their ocular biomechanical effects. What is new A scleral depressor was successfully developed using 3D printing, enabling fast and low-cost production with commercially available PLA filament. Mechanical testing demonstrated robust structural performance and wide safety margins of 3D-printed scleral depressor. Ex vivo model showed that clinically effective scleral indentation requires only sub-Newton forces. INTRODUCTION The retinal periphery is characterized by distinct anatomical, functional, and molecular properties, the integrity of which exerts a substantial influence on the preservation of visual acuity [ 1 ]. Diseases affecting this region represent a severe and often silent threat [ 2 , 3 ]. The gold standard for the detailed assessment of the peripheral retina is Retinal Mapping performed using Indirect Binocular Ophthalmoscopy (IBO), which requires the use of the scleral depressor [ 4 ]. This approach provides stereoscopic and dynamic visualization, which is essential for determining the nature and elevation of lesions [ 4 , 5 ]. Although newer technologies, such as Ultra-Wide Field (UWF) photography, offer images of up to 200° retina coverage with greater patient comfort and documentation capability, they remain inherently static, high-cost, and, crucially, do not replace examination with scleral depression, which remains the first line for the definitive diagnosis of retinal tears [ 5 ]. The increasing technological innovation in the medical field has the potential to expand the accessibility of such devices and trials. In this context, additive manufacturing with 3D printers emerges as a transformative technology, already established in various areas of healthcare and with increasing applications in ophthalmology [ 6 – 9 ]. 3D printing facilitates the rapid and cost-effective production of customized devices, also enhancing the integration of the clinician into the creation and production process; thereby, establishing a direct connection between the professional, technology, and patient care [ 10 , 11 ]. Although the clinical technique is well established, remarkably little is known about the actual forces applied during scleral indentation or their biomechanical consequences. The literature demonstrates wide variability in IOP responses during forces directly applied to the eye [ 12 ] – yet almost no data exist on the amount of force required to produce these changes. Despite its relevance, the mechanical properties of scleral depressors themselves—particularly their loading capacity, failure thresholds, and the relationship between user-applied force and ocular biomechanical response—have not been systematically evaluated. Therefore, the present study aims to address those gaps by developing a low-cost 3D-printed Schepens scleral depressor and evaluating its mechanical performance, structural safety under breakage loading, and biomechanical effect using an ex vivo porcine model. Thus, enabling the application of innovative and low-cost solutions for well know daily problems. METHODS Step 1. Prototype Development In the first step, based on the original Schepens scleral depressor[ 13 , 14 ], two main pieces were designed using Autodesk Fusion 360 (Autodesk®, CA, USA), a 3D modeling software for engineering: The first piece was a cylinder for finger fitting with dimensions of 22.0 mm long and 16.0 mm diameter. The second piece was the stem for scleral depression, which included a 21.0 mm curved rod with a diameter of 5.00 mm and a small curved tip with dimensions of 10.5 mm long and 5.0 mm diameter (Fig. 1 ). The combined piece was then imported into Orca Slicer (SoftFever team, 2025, https://orca-slicer.com/ ) for printing preparation. The printing layers were set to 0.2 mm, with adaptive layers of 0.08 mm in transition areas and at the tip to achieve higher resolution in critical patient-contact areas. For strength, the sparse infill pattern was set to "cross-hatch" with 15% infill density, sparse infill anchor length of 400%, and the top surface pattern was "archimedean chords." The model was oriented vertically ("standing position") to eliminate the necessity for supports ( Supplemental Fig. 1 ). All prototypes were printed on an Ender 3 V3 KE 3D printer (Shenzhen Creality 3D Technology Co., Shenzhen, China) using a standard polylactic acid (PLA) filament of 1.75 mm (white Ender Fast, Shenzhen Creality 3D Technology Co., Shenzhen, China), due to its commercially availability, price, and sustainability properties. Other considered filaments were Thermoplastic Polyurethane (TPU) and Acrylonitrile Butadiene Styrene (ABS); however, TPU has very high flexibility, and ABS has high toxicity during the printing process for force safety [ 15 , 16 ]. Step 2. Mechanical Testing In the second step, the mechanical limits of the prototype were assessed through the implementation of two distinct tests. The initial test involved the measurement of the maximum force that could be applied realistically by an examiner in a standard scleral depression posture (simulated depression test) with both the developed 3D-printer and a commercially available steel scleral depressor, mean cost of U $ 18.00 (Qingshang Trading Co, China), Supplemental Fig. 2 . The second test focused on the identification of the maximum force required to induce mechanical failure (breakage test); this second test was only performed with the 3D-printed depressor. The objective of those tests was to ensure that the prototype could safely perform and efficient scleral depression without breaking during an examination. For this setup, a digital precision balance (OIH-3200, Oasis, China; 10 kg maximum capacity, 1 g precision) was positioned on the floor. A smartphone (iPhone 13, Apple, California, USA) was mounted on a tripod and positioned to record the balance. In order to guarantee stability, a water-filled glass bottle was anchored to the tripod ( Supplemental Fig. 2 ). The procedure was recorded using the smartphone's slow-motion function, set at 240 frames per second (FPS). A 4cm x 4cm x 5cm piece of fresh porcine belly, acquired from a local slaughterhouse, was centered on the balance to serve as a soft substrate. Substrate replacement was performed for each new test. The porcine belly was used to simulate tissue compliance and mitigate direct force concentration on the rigid surface of the balance. Porcine eyes were considered but not used due to their soft structure, which would likely be destroyed before the depressor's breaking point was reached. Prior to each test, the balance was tared with the porcine belly and the depressor gently in contact with its surface ( Supplemental Fig. 2 ). Subsequent analysis of the slow-motion recordings was conducted to identify the peak force achieved during the simulated depression test and the peak force at the precise moment of device breakage. For the simulated use (depression) test, the depressor was worn on the ring finger, as is most common in clinical practice. For the breakage test, the device was worn on the index finger with the intention of applying a greater and more stable force. The experimental protocol was executed by three different researchers, with each researcher conducting five trials. A new, separate 3D-printed depressor—fabricated using the identical printer, setup, and filament—was used for each trial to account for potential printing variability. The breakage position was also analyzed and measured in millimeters. The results were recorded in gram-force (gf), converted to Newtons (N = gf x 0.00981), and compiled into a single spreadsheet (Excel, Microsoft, Washington, USA). The evaluation of safety was conducted employing both deterministic and probabilistic methods to account for variability in manufacturing and clinical usage. A standard deterministic Factor of Safety (FS det ) was calculated as the ratio of mean strength to mean load. Additionally, a statistical Factor of Safety. (FS 2σ ) was calculated using a 95.4% confidence interval (2σ) to ensure that the minimum probable strength exceeds the maximum probable load under typical varying conditions. To quantify the overall probability of failure based on the combined variability of both parameters, a Reliability Index (β) was calculated, as previously described [ 17 ]. Step 3. Biomechanical analysis in an ex vivo porcine model Since the porcine belly is a solid piece and does not clearly represent ocular properties, a third step was developed with an ex vivo porcine model. One fresh porcine eye was obtained from a local slaughterhouse, transported in DPBS in a waterproof bag, kept on a cooling aggregate in a closed temperature isolating box at 4ºC, and used within 24 hours postmortem [ 18 ]. The globe was inspected for structural integrity before usage. Intraocular pressure (IOP) was monitored through a single anterior chamber cannulation with a 27-gauge needle scalp (Anhui Easyway Medical Supplies Co, China) inserted through the corneal limbus and connected to a rigid, bubble-free fluid (0.9% saline solution) line attached to a 1-mL insulin syringe (Becton Dickinson Ind, Brazil) positioned vertically in a 3D-printed supporter as an open hydrostatic reservoir, an adapted model from what has being already described [ 19 ]. The surface of the fluid column served as the atmospheric reference (Fig. 2 ; Supplemental File 1 ). The reservoir height was adjusted to produce a baseline IOP of 20 mmHg, corresponding to a hydrostatic column height of 27.2 cm H₂O, measured from the fluid surface to the needle tip. The eye was allowed to stabilize for 2 minutes before testing. External indentation was performed using the developed scleral depressor with a contact area of 91.89 mm², measured in Autodesk Fusion 360 (Autodesk®, CA, USA). The depressor was applied manually to the equatorial sclera. Each indentation produced measurable displacement of the fluid within the anterior chamber–syringe system, representing an increase in the AC pressure. Ten indentation trials were performed on the eye by two researchers, five each. Because the syringe was open to the atmosphere and oriented vertically, indentation resulted in a net shift of fluid into or out of the syringe barrel. The movement of the plunger was recorded directly as a change in the syringe scale (ΔU), where 1 U = 0.01 mL = 10 µL. Intraocular pressure change (ΔP) was estimated using the Friedenwald exponential ocular rigidity model [ 20 ]. Published porcine rigidity coefficient ( K = 0.00878) was used to compute the pressure increase associated with each observed volume displacement [ 20 ]. Compliance (C) was derived analytically from the differential form of the Friedenwald equation \(\:C=\:\frac{1}{KP}\) , evaluated at the baseline intraocular pressure of 20 mmHg. This provided a model-based interpretation of how each indentation-induced ΔV translated into a physiologically meaningful ΔP. Force associated with each indentation was computed as: \(\:F=P\left(Pa\right)\:X\:A\) , where \(\:P\left(Pa\right)=P\left(mmHg\right)*133.322\) , and area as the contact tip of the depressor ( \(\:A=9.189\:x\:{10}^{-5}\) m 2 ). Statistical Analysis Statistical analysis was conducted using the IBM SPSS version 30.0 (IBM, Inc., Chicago, IL, USA). The variables were analyzed using descriptive statistics, forces and pressure were generally compared with Kruskal-Wallis test and individually compared with Mann Whitney U test. Bonferroni correction was used for p value (significant p < 0.017). RESULTS Device Manufacturing and Material Testing The described methodology resulted in a standardized Schepens scleral depressor prototype ( Supplemental Figure 1 ; Supplemental File 1 ). All printed units exhibited stable structures with no visible printing defects. The printing time per unit was 22 minutes and 20 seconds, consuming 3.06 g of PLA with an estimated material cost of U$0.06. Regarding the mechanical test, a total of 15 trials were performed for each test condition (simulated use and breakage, Supplemental Figure 3 ). In the simulated use position test, the mean maximum force applied by the researchers in the scleral depression position (simulated depression test) on the substrate was 21.21 ± 6.23 N (range 14.76 to 32.27 N, Table 1 ). In the breakage test, the prototypes demonstrated high mechanical resistance. Notably, one of the three researchers (Researcher 2) was unable to generate sufficient force to cause mechanical failure in any of their five trials. In the 10 trials where failure was reached, the mean force required to break the device was 63.27 ± 10.72 N (range 49.48 to 88.28 N, Table 1 ). The observed breaking point occurred at the junction between the finger supporter and the stem at a point of 0.55 ± 0.16 mm (range 0.40 to 0.80 mm). This location was identified as the weakest point of the design. In the simulated depression test, the force applied differed significantly among researchers both with the 3D-printed depressor (p = 0.006) and the steel depressor (p = 0.009). Pairwise comparisons revealed that, with the 3D-printed depressor, Researcher 3 applied substantially more force than Researchers 1 (p = 0.008) and 2 (p = 0.008); no significant difference was found between Researchers 1 and 2 (p = 0.151). With the steel depressor, Researcher 2 applied substantially lower forces than Researcher 1 and 3 (p = 0.016 and p = 0.008). The observed forces with the 3D-printed and steel depressor showed no difference (p = 0.106). In the breakage test, no statistically significant difference in the force required was observed between the two researchers who successfully completed the test (p = 0.310, Figure 3 ). Table 1. Results of the simulated depression test and breakage test. Researcher 1 (mean ± SD) Researcher 2 (mean ± SD) Researcher 3 (mean ± SD) Total (mean ± SD) 3D-Printed depressor Simulated depression force (N) 15.79 ± 1.05 18.83 ± 3.35 29.01 ± 1.93 21.21 ± 6.23 Steel depressor Simulated depression force (N) 26.29 ± 2.87 19.94 ± 1.93 28.84 ± 3.32 25.02 ± 4.64 3D-Printed depressor Breakage force (N) 58.72 ± 6.39 No breakage 67.82 ± 12.88 63.27 ± 10.72 N: Newtons; SD: Standard deviation. A comparison of the mechanical limits to the operational requirements indicated a substantial safety margin. The FS det was 2.98, indicating substantial average reserve strength. When accounting for variability within a 95.4% confidence interval, the statistical analysis yielded a FS 2 s of 1.24, confirming the device maintains a positive safety margin even under varying conditions. The calculated Reliability Index (b) was 3.39, corresponding to a theoretical reliability of approximately 99.96%. Ex Vivo Porcine Model In the ex vivo porcine model, scleral indentation produced clear and measurable shifts in the syringe reservoir volume connected to the anterior chamber. Across all trials (n = 10), the recorded volume displacements (ΔV) were 89.0 ± 46.3 (range 40–160 µL). Individual ΔV values for each indentation are presented in Table 2 . No leakage, plunger recoil, or unstable fluid motion was observed during recording, and all measurements displayed consistent monotonic displacement in response to indentation depth. No systematic differences in ΔV were detected between researchers (p = 0.610), and therefore all indentation trials were pooled for subsequent analyses. Table 2. Results of individual trials in the porcine ex vivo model for scleral depression. Trial ∆V (µL) ∆P (mmHg) IOP (mmHg) Force (N) 1 40.0 7.02 27.02 0.086 2 60.0 10.54 30.54 0.129 3 80.0 14.05 34.05 0.172 4 140 24.58 44.58 0.301 5 140 24.58 44.58 0.301 6 160 28.10 48.10 0.344 7 40 7.02 27.02 0.086 8 50 8.78 28.78 0.108 9 60 10.54 30.54 0.129 10 120 21.07 41.07 0.258 Total 89.0 ± 46.3 15.63 ± 8.13 35.63 ± 8.13 0.191 ± 0.09 IOP: intraocular pressure; N: Newtons; P: pressure; V: volume. Across the observed ΔV values, the estimated pressure elevation was 15.63 ± 8.13 (range 7.0 to 28.1 mmHg) above the 20-mmHg baseline, with a potential IOP of 35.63 ± 8.13 ( Table 2 ). These values represent the expected intraocular pressure response of a porcine globe experiencing indentation-induced volume disturbances. The predicted force was 0.191 ± 0.09 (range 0.086 to 0.340 N) across the measured ΔV. These values represent the force required to generate the observed volume displacements in a porcine ex vivo eye and provide a biomechanical context for comparing the magnitude of pressure and force produced by the depressor ( Figure 4 ). The mechanical limits to the operational requirements were recalculated with the force results of the ex vivo porcine model, yielding extremely high safety margins: FS det of 331.2, FS 2 s of 112.7, and b = 5.88. DISCUSSION This study demonstrates the feasibility, mechanical reliability, and potential clinical applicability of a low-cost, 3D-printed Schepens scleral depressor. The findings of this study demonstrate that standard PLA filament, when printed with the described optimized settings, is capable of producing a device with a low supply manufacturing cost, approximately 300 times cheaper compared to steel scleral depressor minimum price. Beyond its economic advantage, the device exhibited a high safety profile, suggesting its mechanical suitability for clinical use with a high degree of safety. The simulated depression tests showed that examiners were capable of generating high mean peak forces when using the 3D-printed depressor. These values were statistically indistinguishable from those achieved using a conventional steel depressor, indicating that material composition (PLA vs. stainless steel) did not meaningfully limit operator-applied force. However, both tests highlighted significant inter-operator variability, a finding consistent with the subjective and experience-dependent nature of scleral indentation, reinforcing that this exam technique is a highly subjective maneuver. The mechanical testing revealed a significant margin between operational forces and failure limits, three times higher. The fact that the device remained safe even for the researcher who consistently applied significantly higher forces (Researcher 3) further validates its robustness for a wide range of clinical users. Notably, the robustness of the design was evidenced by one researcher's inability to break the device manually during testing, suggesting that for some users, the device's mechanical limits exceed the standard manual force capabilities. The identified failure point at the junction of the finger supporter and stem is a possible target for future designs. Reinforcement could be done to enhance strength and durability, without greatly increasing material use and print time, although standard usage forces are unlikely to reach this threshold. In this study, the mean operational force measured during simulated scleral depression represents the maximum macroscopic load an examiner could generate in the scleral-indentation posture, establishing a practical upper bound of user-applied effort with this tool. When interpreted in accordance with the intended purpose, the test demonstrates that the 3D-printed depressor has the capacity to reproduce the forces necessary to achieve clinical indentation. The failure load and safety factors indicate a significant mechanical reserve that can accommodate inter-operator variability without compromising integrity or safety [12]. While simulated macroscopic forces are relevant for validating robustness, they do not reflect the actual forces transmitted to the eye. For this reason, we incorporated an ex vivo porcine eye experiment to quantify indentation-induced intraocular pressure changes and the corresponding biomechanical force. The porcine model revealed that clinically relevant scleral indentation requires remarkably small force magnitudes. This supports the conclusion that the 3D-printed device is mechanically over-engineered relative to actual clinical force requirements, providing a wide functional margin without risk of unintended deformation or failure during use. After a concise literature review, the optimal force required for scleral depression has not yet been standardized, only a minority of reports have quantified the applied force during scleral indentation. Among those that did, the forces between 0.64 and 0.9 N, applied with a calibrated ophthalmodynamometer, were sufficient to double intraocular pressure relative to baseline in healthy and glaucomatous eyes [12]. In this study, it is shown a direct influence on IOP variations during scleral depression, which could vary from 7.02 to 28.10 mmHg, fact that could be of importance for glaucoma patients, which neural and connective tissue are more susceptible to acute IOP changes [12]. The majority of studies have focused on IOP-induced changes for exam techniques and glaucoma analysis rather than on scleral depression and its required force [21, 22]. This discrepancy renders a direct comparison with our results difficult. A single study in the literature has successfully developed a 3D-printed scleral depressor, demonstrating a necessary force for depression of 0.71 ± 0.06 lbf (3.16 ± 0.37 N) and a maximum achieved force of 6.021 ± 0.06 lbf (26.78 ± 0.27 N) [23], analogous to the results of the present study in both sub-Newton necessary force and maximum force capability. However, this study is a conference abstract, and the full data set could not be retrieved. The economic implications of this device are substantial. The material cost of this 3D-printed alternative was estimated to be U$0.06 per unit, which indicates that it is more economical than conventional stainless-steel depressors. PLA was selected as it is capable of fast, affordable, and reproducible production, while maintaining adequate strength for clinical application. Additionally, 3D printing allows for efficient production of multiple devices with minimal waste and the ability to standardize production variables to assure consistent quality [24]. Thus, for a production on a mass scale, parallel printing or batching methods could enhance the number of devices produced without substantial costs, while quality assurance and inspection strategies/design plans could ensure reliable devices [25]. This reduction in cost has the potential to democratize access to essential ophthalmological tools in low-resource settings and facilitate production for training purposes [26, 27]. This approach is projected to enhance accessibility, thereby facilitating the diagnosis of retinal diseases and contributing to a reduction in the global burden of blindness due to undiagnosed peripheral retinal diseases [28]. Our contribution thus fills a notable gap by presenting, for the first time, validated force thresholds, material-specific failure profiles, and IOP responses during indentation, all supported by statistical safety metrics in different models. However, the present study is subject to certain inherent limitations due to its ex vivo design. While fresh porcine belly and eyes were used to simulate tissue compliance, it does not perfectly replicate the complex biomechanics of a living human eye, not accounting for blood flow, neural and extraocular muscle tone, and normal IOP autoregulation. We also used only one porcine eye specimen, which does not account for inter-eye variability, age effects, or disease-related differences in ocular rigidity—factors shown in the literature to significantly alter IOP recovery, tissue compliance, and susceptibility to IOP spikes [29, 30]. The ex vivo design also does not permit testing for patient comfort, physician usability, and real-life clinical practice testing. Furthermore, only three researchers participated in simulated testing with manually applied forces; the study did not evaluate the influence of examiner experience and indentation technique. The present study focused exclusively on the performance of a single PLA filament brand. Despite its affordability and accessibility, PLA exhibits a low transition temperature (~60°C), and it is incapable of undergoing autoclaving [31]. Additionally, materials such as polyethylene terephthalate glycol (PETG) or medical-grade nylons could be chosen in future iterations because these materials offer enhanced thermal stability and chemical resistance while maintaining mechanical and structural performance [32, 33]. At the moment, if sterilization is required, alternative methodologies such as ethylene oxide must be employed [34–36]; however, no tests were conducted for post sterilization safety. Thus, at the moment, this prototype is recommended for single-use and not to be sterilized. CONCLUSION The present study demonstrates that a low-cost, rapidly manufactured 3D-printed Schepens scleral depressor can safely and effectively withstand the forces typically applied during scleral indentation. The methodology presented enables fast production with minimal material costs, offering significant potential for easy worldwide replicability. Mechanical testing confirmed that the printed instrument tolerates examiner-generated loads far exceeding those required for clinical use, while the breakage test showed failure thresholds well above simulated operational demands. The ex vivo porcine biomechanical model further revealed that only sub-Newton forces are needed to reproduce scleral depression and induce meaningful intraocular pressure elevations, highlighting a wide safety margin between the device’s structural strength and the physiologic forces transmitted to the eye. These findings indicate that standard PLA filament, when printed with optimized settings, is a suitable, economical, and reliable alternative to conventional tools. This work furnishes a foundation for democratizing access to essential ophthalmological instruments, particularly for training purposes and in settings with limited resources. Future work should prioritize in vivo validation for teaching and clinical practice, evaluation aand optimization of sterilizable materials, evaluation of performance across multiple printers and users, and extension of this approach to additional 3D-printed ophthalmic instruments. Declarations Funding: This work was supported by São Paulo Research Foundation (grant number #2024/16042-9). Competing Interests: The authors have no relevant financial or non-financial interests to disclose. Author Contributions LES: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Resources, Software, Validation, Visualization, Writing – original draft, Writing – review and editing. MPW: Conceptualization, Data curation, Investigation, Methodology, Resources, Validation, Writing – original draft. TM: Conceptualization, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review and editing. JPVNM: Data curation, Formal analysis, Investigation, Writing – review and editing. GTM: Formal analysis, Visualization, Writing – original draft, Writing – review and editing. JMSO: Conceptualization, Methodology, Resources, Validation, Writing – review and editing. JS: Conceptualization, Investigation, Methodology, Resources, Validation, Writing – review and editing. CAMN: Conceptualization, Methodology, Project administration, Resources, Supervision, Validation, Writing – review and editing. AM: Conceptualization, Funding acquisition, Methodology, Project administration, Resources, Supervision, Validation, Writing – review and editing. All authors read and approved the final manuscript. References Quinn N, Csincsik L, Flynn E, et al (2019) The clinical relevance of visualising the peripheral retina. 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Invest Ophthalmol Vis Sci 60:6594 Kantaros A, Drosos C, Papoutsidakis M, et al (2025) The Role of 3D Printing in Advancing Automated Manufacturing Systems: Opportunities and Challenges. Automation 6:21. https://doi.org/10.3390/automation6020021 Chitnis K, Lu Y, Rhoads B, et al (2025) Optimization of print parameters for batch and continuous manufacturing of three-dimensional (3D) printed dosage forms using artificial intelligence and machine learning. Drug Deliv Transl Res. https://doi.org/10.1007/s13346-025-02006-4 Sommer AC, Blumenthal EZ (2019) Implementations of 3D printing in ophthalmology. Graefes Arch Clin Exp Ophthalmol 257:1815–1822. https://doi.org/10.1007/s00417-019-04312-3 DesLauriers AC, Ackah PF, Skidd PM (2024) The Versatile Teaching Eye: an affordable, 3D-printed model eye for simulating ophthalmic examination. Digit J Ophthalmol 30:22–26. https://doi.org/10.5693/djo.01.2024.02.001 Sabage J, Sabage LE, Mota Lanzarin JV, et al (2025) Application of Smartphone-Based Fundus Cameras and Telemedicine in the Brazilian Amazon Forest. Journal of Clinical & Translational Ophthalmology 3:23. https://doi.org/10.3390/jcto3040023 Ma Y, Moroi SE, Roberts CJ (2021) Non-invasive Clinical Measurement of Ocular Rigidity and Comparison to Biomechanical and Morphological Parameters in Glaucomatous and Healthy Subjects. Front Med (Lausanne) 8:. https://doi.org/10.3389/fmed.2021.701997 Sayah DN, Medina-Cornejo J, Adel Y, et al (2025) Interocular differences in ocular rigidity in healthy subjects with isometropia. Invest Ophthalmol Vis Sci 66:2141 Suder J, Bobovsky Z, Mlotek J, et al (2021) EXPERIMENTAL ANALYSIS OF TEMPERATURE RESISTANCE OF 3D PRINTED PLA COMPONENTS. MM Science Journal 2021:4322–4327. https://doi.org/10.17973/MMSJ.2021_03_2021004 Yan C, Kleiner C, Tabigue A, et al (2024) PETG: Applications in Modern Medicine. Engineered Regeneration 5:45–55. https://doi.org/10.1016/j.engreg.2023.11.001 Shakiba M, Rezvani Ghomi E, Khosravi F, et al (2021) Nylon—A material introduction and overview for biomedical applications. Polym Adv Technol 32:3368–3383. https://doi.org/10.1002/pat.5372 Mendes GCC, Brandão TRS, Silva CLM (2007) Ethylene oxide sterilization of medical devices: A review. Am J Infect Control 35:574–581. https://doi.org/10.1016/j.ajic.2006.10.014 Pérez Davila S, González Rodríguez L, Chiussi S, et al (2021) How to Sterilize Polylactic Acid Based Medical Devices? Polymers (Basel) 13:. https://doi.org/10.3390/polym13132115 Neijhoft J, Henrich D, Kammerer A, et al (2023) Sterilization of PLA after Fused Filament Fabrication 3D Printing: Evaluation on Inherent Sterility and the Impossibility of Autoclavation. Polymers (Basel) 15:369. https://doi.org/10.3390/polym15020369 Additional Declarations No competing interests reported. Supplementary Files SupplementalFigure1.tiff SupplementalFigure2.tiff SupplementalFigure3.tiff Supplementalfile1.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8242729","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":555345984,"identity":"c03f56aa-d693-4d2a-ace2-1e33991b703d","order_by":0,"name":"Luís Expedito Sabage","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA00lEQVRIiWNgGAWjYBACPgbGBhCdAMSMD0AsA0Ja2JC0MBsQqQUCQFrYJIjTIpHc/IHhj10ef//iY9U8f+4wmEsfIKQlsU2CsS25WOLGs7TbvG3PGCz7EghrAXqHObHhxhmz27wNhxkMzhB0WCLIYfWJ82+c/1bM84c4LQ0SDGyHEzec72Fj5mEjRgvPwzag244XG95gM5ac2/aMx7KHgBZ+9vTHHz78qc6TO3/44Yc3f+7ImfMQ0AIGCSBCAkweIEoDzL4DYC0k6BgFo2AUjIKRAgDV5EP+hqHyJQAAAABJRU5ErkJggg==","orcid":"","institution":"Hospital de Reabilitações em Anomalias Craniofaciais da Universidade de São Paulo","correspondingAuthor":true,"prefix":"","firstName":"Luís","middleName":"Expedito","lastName":"Sabage","suffix":""},{"id":555345985,"identity":"a1ca52aa-c3cf-4bed-811d-ffb667c882b2","order_by":1,"name":"Mariana Pasqualin Wojcikiewicz","email":"","orcid":"","institution":"Faculdade Evangélica do Paraná","correspondingAuthor":false,"prefix":"","firstName":"Mariana","middleName":"Pasqualin","lastName":"Wojcikiewicz","suffix":""},{"id":555345986,"identity":"001bf728-40cd-4ca0-82b7-ebe5fdd1d9e8","order_by":2,"name":"Thiago Meister","email":"","orcid":"","institution":"Hospital de Olhos do Paraná – Instituto Professor Moreira","correspondingAuthor":false,"prefix":"","firstName":"Thiago","middleName":"","lastName":"Meister","suffix":""},{"id":555345987,"identity":"bea56128-58df-4f47-8755-8b62ea539675","order_by":3,"name":"João Pedro Vieira Neto Murta","email":"","orcid":"","institution":"Hospital de Olhos do Paraná","correspondingAuthor":false,"prefix":"","firstName":"João","middleName":"Pedro Vieira Neto","lastName":"Murta","suffix":""},{"id":555345988,"identity":"0d32da0a-023e-405b-ac4e-579f65a0d001","order_by":4,"name":"Gustavo Túlio Manfredini","email":"","orcid":"","institution":"University of Central Florida","correspondingAuthor":false,"prefix":"","firstName":"Gustavo","middleName":"Túlio","lastName":"Manfredini","suffix":""},{"id":555345989,"identity":"bcb71d61-ce95-4835-8801-1ee3c124940c","order_by":5,"name":"Jair Marcelo Saad Ortega","email":"","orcid":"","institution":"Tecnoprom Engenharia e Automação","correspondingAuthor":false,"prefix":"","firstName":"Jair","middleName":"Marcelo Saad","lastName":"Ortega","suffix":""},{"id":555345990,"identity":"7d658740-5e69-496d-8e76-8e659bb82bce","order_by":6,"name":"Josmar Sabage","email":"","orcid":"","institution":"Universidade de São Paulo","correspondingAuthor":false,"prefix":"","firstName":"Josmar","middleName":"","lastName":"Sabage","suffix":""},{"id":555345991,"identity":"1505353e-0dd2-4fb5-a343-d7870b782757","order_by":7,"name":"Carlos Augusto Moreira-Neto","email":"","orcid":"","institution":"Hospital de Olhos do Paraná – Instituto Professor Moreira","correspondingAuthor":false,"prefix":"","firstName":"Carlos","middleName":"Augusto","lastName":"Moreira-Neto","suffix":""},{"id":555345992,"identity":"ce934983-5dd7-4f59-af65-6cde2b2d95b0","order_by":8,"name":"Alessandra Mazzo","email":"","orcid":"","institution":"Hospital de Reabilitações em Anomalias Craniofaciais da Universidade de São Paulo","correspondingAuthor":false,"prefix":"","firstName":"Alessandra","middleName":"","lastName":"Mazzo","suffix":""}],"badges":[],"createdAt":"2025-11-30 14:38:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8242729/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8242729/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97504488,"identity":"b6827f49-3190-4df6-ad76-7a9c91c53d3d","added_by":"auto","created_at":"2025-12-05 07:28:30","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":11202043,"visible":true,"origin":"","legend":"\u003cp\u003eIsometric view of the piece, Autodesk Fusion 360 screenshot (Autodesk Inc®, CA, USA). (\u003cstrong\u003eA\u003c/strong\u003e) Inferior posterior view illustrating finger fitting diameter. (\u003cstrong\u003eB\u003c/strong\u003e) Posterior view illustrating finger fitting height. (\u003cstrong\u003eC\u003c/strong\u003e) Superior side view illustrating stem size. (\u003cstrong\u003eD\u003c/strong\u003e) Superior view illustrating indentation cylinder.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/9f1ef70f47b028dca035fd3e.png"},{"id":97504491,"identity":"5a7237bf-85a6-4a24-b86d-95b4f15e0ac8","added_by":"auto","created_at":"2025-12-05 07:28:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":27063383,"visible":true,"origin":"","legend":"\u003cp\u003eIllustration of the ex vivo porcine model for intraocular pressure change (∆P). (\u003cstrong\u003eA\u003c/strong\u003e) System setup with open vertical syringe at a high of 27.2cm connected to the needle (\u003cstrong\u003eB\u003c/strong\u003e) 27-gauge needle inserted in the anterior chamber by the limbus.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/cd419a7ced98fcbcc30e6ea2.png"},{"id":97504485,"identity":"0604a6c4-f0f5-4c73-8241-2f8229468c3f","added_by":"auto","created_at":"2025-12-05 07:28:30","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":166109,"visible":true,"origin":"","legend":"\u003cp\u003eComparison between researchers’ maximum force across all three tests.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/486fcbeecde79236ee540732.png"},{"id":97671930,"identity":"6c203a97-1358-401c-9b0e-3f4b34fd6159","added_by":"auto","created_at":"2025-12-08 09:33:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":5660325,"visible":true,"origin":"","legend":"\u003cp\u003eBiomechanical results of the ex vivo porcine eye model. (\u003cstrong\u003eA\u003c/strong\u003e) Comparison between ∆Volume and ∆Pressure, each triangle represents one trial. (\u003cstrong\u003eB\u003c/strong\u003e) Comparison between ∆Volume and force, each square represents one trial.\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/0d91d53446fc646ee19979df.png"},{"id":97678021,"identity":"72526b03-5d2b-4c20-88c6-32d569a5230d","added_by":"auto","created_at":"2025-12-08 09:55:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":44359459,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/7b910d77-4b90-4683-8968-d0012f3a5858.pdf"},{"id":97504489,"identity":"6ddd96af-4d8a-495c-b47d-0fb87c735f09","added_by":"auto","created_at":"2025-12-05 07:28:30","extension":"tiff","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":6085560,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalFigure1.tiff","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/c9079ee4f9529b60298ebf59.tiff"},{"id":97671309,"identity":"69c889c0-d605-43f0-acbb-0ddd90d98e8f","added_by":"auto","created_at":"2025-12-08 09:32:25","extension":"tiff","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":6973548,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalFigure2.tiff","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/726d856b979ecd532b75aa68.tiff"},{"id":97504492,"identity":"1d887778-f5bf-45b9-8cac-5812841a4410","added_by":"auto","created_at":"2025-12-05 07:28:30","extension":"tiff","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":16108320,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementalFigure3.tiff","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/10618846c534d9eceabe1b46.tiff"},{"id":97504486,"identity":"585e04a1-25b6-41b7-be85-ede7cf8d57a9","added_by":"auto","created_at":"2025-12-05 07:28:30","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":15638,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementalfile1.docx","url":"https://assets-eu.researchsquare.com/files/rs-8242729/v1/76a4ea081333985d08602441.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Development, Mechanical Performance, and Ex Vivo Porcine Eye Biomechanical Validation of a 3D-Printed Schepens Scleral Depressor","fulltext":[{"header":"Key Messages","content":"\u003cp\u003e\u003cstrong\u003eWhat is known\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e3D printing is increasingly used in ophthalmology to enable fast, low-cost production of clinical and training tools.\u003c/li\u003e\n \u003cli\u003eScleral depression is essential for diagnosing peripheral retinal lesions, yet limited evidence exists regarding safety of devices, the forces applied during indentation and their ocular biomechanical effects.\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is new\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eA scleral depressor was successfully developed using 3D printing, enabling fast and low-cost production with commercially available PLA filament.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eMechanical testing demonstrated robust structural performance and wide safety margins of 3D-printed scleral depressor.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eEx vivo model showed that clinically effective scleral indentation requires only sub-Newton forces.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"INTRODUCTION","content":"\u003cp\u003eThe retinal periphery is characterized by distinct anatomical, functional, and molecular properties, the integrity of which exerts a substantial influence on the preservation of visual acuity [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Diseases affecting this region represent a severe and often silent threat [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The gold standard for the detailed assessment of the peripheral retina is Retinal Mapping performed using Indirect Binocular Ophthalmoscopy (IBO), which requires the use of the scleral depressor [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. This approach provides stereoscopic and dynamic visualization, which is essential for determining the nature and elevation of lesions [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Although newer technologies, such as Ultra-Wide Field (UWF) photography, offer images of up to 200\u0026deg; retina coverage with greater patient comfort and documentation capability, they remain inherently static, high-cost, and, crucially, do not replace examination with scleral depression, which remains the first line for the definitive diagnosis of retinal tears [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe increasing technological innovation in the medical field has the potential to expand the accessibility of such devices and trials. In this context, additive manufacturing with 3D printers emerges as a transformative technology, already established in various areas of healthcare and with increasing applications in ophthalmology [\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. 3D printing facilitates the rapid and cost-effective production of customized devices, also enhancing the integration of the clinician into the creation and production process; thereby, establishing a direct connection between the professional, technology, and patient care [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAlthough the clinical technique is well established, remarkably little is known about the actual forces applied during scleral indentation or their biomechanical consequences. The literature demonstrates wide variability in IOP responses during forces directly applied to the eye [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] \u0026ndash; yet almost no data exist on the amount of force required to produce these changes. Despite its relevance, the mechanical properties of scleral depressors themselves\u0026mdash;particularly their loading capacity, failure thresholds, and the relationship between user-applied force and ocular biomechanical response\u0026mdash;have not been systematically evaluated. Therefore, the present study aims to address those gaps by developing a low-cost 3D-printed Schepens scleral depressor and evaluating its mechanical performance, structural safety under breakage loading, and biomechanical effect using an ex vivo porcine model. Thus, enabling the application of innovative and low-cost solutions for well know daily problems.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStep 1. Prototype Development\u003c/h2\u003e\u003cp\u003eIn the first step, based on the original Schepens scleral depressor[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], two main pieces were designed using Autodesk Fusion 360 (Autodesk\u0026reg;, CA, USA), a 3D modeling software for engineering: The first piece was a cylinder for finger fitting with dimensions of 22.0 mm long and 16.0 mm diameter. The second piece was the stem for scleral depression, which included a 21.0 mm curved rod with a diameter of 5.00 mm and a small curved tip with dimensions of 10.5 mm long and 5.0 mm diameter (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The combined piece was then imported into Orca Slicer (SoftFever team, 2025, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://orca-slicer.com/\u003c/span\u003e\u003cspan address=\"https://orca-slicer.com/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) for printing preparation. The printing layers were set to 0.2 mm, with adaptive layers of 0.08 mm in transition areas and at the tip to achieve higher resolution in critical patient-contact areas. For strength, the sparse infill pattern was set to \"cross-hatch\" with 15% infill density, sparse infill anchor length of 400%, and the top surface pattern was \"archimedean chords.\" The model was oriented vertically (\"standing position\") to eliminate the necessity for supports (\u003cb\u003eSupplemental Fig.\u0026nbsp;1\u003c/b\u003e). All prototypes were printed on an Ender 3 V3 KE 3D printer (Shenzhen Creality 3D Technology Co., Shenzhen, China) using a standard polylactic acid (PLA) filament of 1.75 mm (white Ender Fast, Shenzhen Creality 3D Technology Co., Shenzhen, China), due to its commercially availability, price, and sustainability properties. Other considered filaments were Thermoplastic Polyurethane (TPU) and Acrylonitrile Butadiene Styrene (ABS); however, TPU has very high flexibility, and ABS has high toxicity during the printing process for force safety [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eStep 2. Mechanical Testing\u003c/h3\u003e\n\u003cp\u003eIn the second step, the mechanical limits of the prototype were assessed through the implementation of two distinct tests. The initial test involved the measurement of the maximum force that could be applied realistically by an examiner in a standard scleral depression posture (simulated depression test) with both the developed 3D-printer and a commercially available steel scleral depressor, mean cost of U\u003cspan\u003e$\u003c/span\u003e18.00 (Qingshang Trading Co, China), \u003cb\u003eSupplemental Fig.\u0026nbsp;2\u003c/b\u003e. The second test focused on the identification of the maximum force required to induce mechanical failure (breakage test); this second test was only performed with the 3D-printed depressor. The objective of those tests was to ensure that the prototype could safely perform and efficient scleral depression without breaking during an examination. For this setup, a digital precision balance (OIH-3200, Oasis, China; 10 kg maximum capacity, 1 g precision) was positioned on the floor. A smartphone (iPhone 13, Apple, California, USA) was mounted on a tripod and positioned to record the balance. In order to guarantee stability, a water-filled glass bottle was anchored to the tripod (\u003cb\u003eSupplemental Fig.\u0026nbsp;2\u003c/b\u003e).\u003c/p\u003e\u003cp\u003eThe procedure was recorded using the smartphone's slow-motion function, set at 240 frames per second (FPS). A 4cm x 4cm x 5cm piece of fresh porcine belly, acquired from a local slaughterhouse, was centered on the balance to serve as a soft substrate. Substrate replacement was performed for each new test. The porcine belly was used to simulate tissue compliance and mitigate direct force concentration on the rigid surface of the balance. Porcine eyes were considered but not used due to their soft structure, which would likely be destroyed before the depressor's breaking point was reached. Prior to each test, the balance was tared with the porcine belly and the depressor gently in contact with its surface (\u003cb\u003eSupplemental Fig.\u0026nbsp;2\u003c/b\u003e). Subsequent analysis of the slow-motion recordings was conducted to identify the peak force achieved during the simulated depression test and the peak force at the precise moment of device breakage.\u003c/p\u003e\u003cp\u003eFor the simulated use (depression) test, the depressor was worn on the ring finger, as is most common in clinical practice. For the breakage test, the device was worn on the index finger with the intention of applying a greater and more stable force. The experimental protocol was executed by three different researchers, with each researcher conducting five trials. A new, separate 3D-printed depressor\u0026mdash;fabricated using the identical printer, setup, and filament\u0026mdash;was used for each trial to account for potential printing variability. The breakage position was also analyzed and measured in millimeters. The results were recorded in gram-force (gf), converted to Newtons (N\u0026thinsp;=\u0026thinsp;gf x 0.00981), and compiled into a single spreadsheet (Excel, Microsoft, Washington, USA).\u003c/p\u003e\u003cp\u003eThe evaluation of safety was conducted employing both deterministic and probabilistic methods to account for variability in manufacturing and clinical usage. A standard deterministic Factor of Safety (FS\u003csub\u003edet\u003c/sub\u003e) was calculated as the ratio of mean strength to mean load. Additionally, a statistical Factor of Safety. (FS\u003csub\u003e2σ\u003c/sub\u003e) was calculated using a 95.4% confidence interval (2σ) to ensure that the minimum probable strength exceeds the maximum probable load under typical varying conditions. To quantify the overall probability of failure based on the combined variability of both parameters, a Reliability Index (β) was calculated, as previously described [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eStep 3. Biomechanical analysis in an ex vivo porcine model\u003c/h3\u003e\n\u003cp\u003eSince the porcine belly is a solid piece and does not clearly represent ocular properties, a third step was developed with an ex vivo porcine model. One fresh porcine eye was obtained from a local slaughterhouse, transported in DPBS in a waterproof bag, kept on a cooling aggregate in a closed temperature isolating box at 4\u0026ordm;C, and used within 24 hours postmortem [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The globe was inspected for structural integrity before usage. Intraocular pressure (IOP) was monitored through a single anterior chamber cannulation with a 27-gauge needle scalp (Anhui Easyway Medical Supplies Co, China) inserted through the corneal limbus and connected to a rigid, bubble-free fluid (0.9% saline solution) line attached to a 1-mL insulin syringe (Becton Dickinson Ind, Brazil) positioned vertically in a 3D-printed supporter as an open hydrostatic reservoir, an adapted model from what has being already described [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The surface of the fluid column served as the atmospheric reference (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; \u003cb\u003eSupplemental File 1\u003c/b\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe reservoir height was adjusted to produce a baseline IOP of 20 mmHg, corresponding to a hydrostatic column height of 27.2 cm H₂O, measured from the fluid surface to the needle tip. The eye was allowed to stabilize for 2 minutes before testing. External indentation was performed using the developed scleral depressor with a contact area of 91.89 mm\u0026sup2;, measured in Autodesk Fusion 360 (Autodesk\u0026reg;, CA, USA). The depressor was applied manually to the equatorial sclera. Each indentation produced measurable displacement of the fluid within the anterior chamber\u0026ndash;syringe system, representing an increase in the AC pressure. Ten indentation trials were performed on the eye by two researchers, five each.\u003c/p\u003e\u003cp\u003eBecause the syringe was open to the atmosphere and oriented vertically, indentation resulted in a net shift of fluid into or out of the syringe barrel. The movement of the plunger was recorded directly as a change in the syringe scale (ΔU), where 1 U\u0026thinsp;=\u0026thinsp;0.01 mL\u0026thinsp;=\u0026thinsp;10 \u0026micro;L. Intraocular pressure change (ΔP) was estimated using the Friedenwald exponential ocular rigidity model [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Published porcine rigidity coefficient (\u003cem\u003eK\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00878) was used to compute the pressure increase associated with each observed volume displacement [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Compliance (C) was derived analytically from the differential form of the Friedenwald equation \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:C=\\:\\frac{1}{KP}\\)\u003c/span\u003e\u003c/span\u003e, evaluated at the baseline intraocular pressure of 20 mmHg. This provided a model-based interpretation of how each indentation-induced ΔV translated into a physiologically meaningful ΔP.\u003c/p\u003e\u003cp\u003eForce associated with each indentation was computed as: \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:F=P\\left(Pa\\right)\\:X\\:A\\)\u003c/span\u003e\u003c/span\u003e, where \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:P\\left(Pa\\right)=P\\left(mmHg\\right)*133.322\\)\u003c/span\u003e\u003c/span\u003e, and area as the contact tip of the depressor (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:A=9.189\\:x\\:{10}^{-5}\\)\u003c/span\u003e\u003c/span\u003em\u003csup\u003e2\u003c/sup\u003e).\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eStatistical analysis was conducted using the IBM SPSS version 30.0 (IBM, Inc., Chicago, IL, USA). The variables were analyzed using descriptive statistics, forces and pressure were generally compared with Kruskal-Wallis test and individually compared with Mann Whitney U test. Bonferroni correction was used for p value (significant p\u0026thinsp;\u0026lt;\u0026thinsp;0.017).\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eDevice Manufacturing and Material Testing\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe described methodology resulted in a standardized Schepens scleral depressor prototype (\u003cstrong\u003eSupplemental\u003c/strong\u003e \u003cstrong\u003eFigure 1\u003c/strong\u003e;\u003cstrong\u003e\u0026nbsp;Supplemental File 1\u003c/strong\u003e). All printed units exhibited stable structures with no visible printing defects. The printing time per unit was 22 minutes and 20 seconds, consuming 3.06 g of PLA with an estimated material cost of U$0.06. Regarding the mechanical test, a total of 15 trials were performed for each test condition (simulated use and breakage, \u003cstrong\u003eSupplemental\u003c/strong\u003e \u003cstrong\u003eFigure 3\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eIn the simulated use position test, the mean maximum force applied by the researchers in the scleral depression position (simulated depression test) on the substrate was 21.21 \u0026plusmn; 6.23 N (range 14.76 to 32.27 N, \u003cstrong\u003eTable 1\u003c/strong\u003e). In the breakage test, the prototypes demonstrated high mechanical resistance. Notably, one of the three researchers (Researcher 2) was unable to generate sufficient force to cause mechanical failure in any of their five trials. In the 10 trials where failure was reached, the mean force required to break the device was 63.27 \u0026plusmn; 10.72 N (range 49.48 to 88.28 N, \u003cstrong\u003eTable 1\u003c/strong\u003e). The observed breaking point occurred at the junction between the finger supporter and the stem at a point of 0.55 \u0026plusmn; 0.16 mm (range 0.40 to 0.80 mm). This location was identified as the weakest point of the design. In the simulated depression test, the force applied differed significantly among researchers both with the 3D-printed depressor (p = 0.006) and the steel depressor (p = 0.009). Pairwise comparisons revealed that, with the 3D-printed depressor, Researcher 3 applied substantially more force than Researchers 1 (p = 0.008) and 2 (p = 0.008); no significant difference was found between Researchers 1 and 2 (p = 0.151). With the steel depressor, Researcher 2 applied substantially lower forces than Researcher 1 and 3 (p = 0.016 and p = 0.008). The observed forces with the 3D-printed and steel depressor showed no difference (p = 0.106). In the breakage test, no statistically significant difference in the force required was observed between the two researchers who successfully completed the test (p = 0.310, \u003cstrong\u003eFigure 3\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Results of the simulated depression test and breakage test. \u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eResearcher 1\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mean\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026plusmn;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eResearcher 2\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mean\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026plusmn;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eResearcher 3\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mean\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026plusmn;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mean\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026plusmn;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e3D-Printed depressor\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eSimulated depression force (N)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e15.79\u0026nbsp;\u0026plusmn;\u0026nbsp;1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e18.83\u0026nbsp;\u0026plusmn;\u0026nbsp;3.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e29.01\u0026nbsp;\u0026plusmn;\u0026nbsp;1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e21.21\u0026nbsp;\u0026plusmn;\u0026nbsp;6.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSteel depressor\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eSimulated depression force (N)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e26.29\u0026nbsp;\u0026plusmn;\u0026nbsp;2.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e19.94\u0026nbsp;\u0026plusmn;\u0026nbsp;1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e28.84\u0026nbsp;\u0026plusmn;\u0026nbsp;3.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e25.02\u0026nbsp;\u0026plusmn;\u0026nbsp;4.64\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 189px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e3D-Printed depressor\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eBreakage force (N)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e58.72\u0026nbsp;\u0026plusmn;\u0026nbsp;6.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003eNo breakage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e67.82\u0026nbsp;\u0026plusmn;\u0026nbsp;12.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 115px;\"\u003e\n \u003cp\u003e63.27\u0026nbsp;\u0026plusmn;\u0026nbsp;10.72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eN: Newtons; SD: Standard deviation.\u003c/p\u003e\n\u003cp\u003eA comparison of the mechanical limits to the operational requirements indicated a substantial safety margin. The FS\u003csub\u003edet\u003c/sub\u003e was 2.98, indicating substantial average reserve strength. When accounting for variability within a 95.4% confidence interval, the statistical analysis yielded a FS\u003csub\u003e2\u003c/sub\u003e\u003csub\u003es\u003c/sub\u003e of 1.24, confirming the device maintains a positive safety margin even under varying conditions. The calculated Reliability Index (b) was 3.39, corresponding to a theoretical reliability of approximately 99.96%.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEx Vivo Porcine Model\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the ex vivo porcine model, scleral indentation produced clear and measurable shifts in the syringe reservoir volume connected to the anterior chamber. Across all trials (n = 10), the recorded volume displacements (\u0026Delta;V) were 89.0 \u0026plusmn; 46.3 (range 40\u0026ndash;160 \u0026micro;L). Individual \u0026Delta;V values for each indentation are presented in \u003cstrong\u003eTable 2\u003c/strong\u003e. No leakage, plunger recoil, or unstable fluid motion was observed during recording, and all measurements displayed consistent monotonic displacement in response to indentation depth. No systematic differences in \u0026Delta;V were detected between researchers (p = 0.610), and therefore all indentation trials were pooled for subsequent analyses.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Results of individual trials in the porcine ex vivo model for scleral depression.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrial\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e∆V (\u0026micro;L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e∆P (mmHg)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIOP (mmHg)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eForce (N)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e40.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e7.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e27.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.086\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e60.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e10.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e30.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.129\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e80.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e14.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e34.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.172\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e24.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e44.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.301\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e24.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e44.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.301\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e160\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e28.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e48.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.344\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e7.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e27.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.086\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e8.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e28.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.108\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e10.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e30.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.129\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e120\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e21.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e41.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.258\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e89.0\u0026nbsp;\u0026plusmn;\u0026nbsp;46.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e15.63\u0026nbsp;\u0026plusmn;\u0026nbsp;8.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e35.63\u0026nbsp;\u0026plusmn;\u0026nbsp;8.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 130px;\"\u003e\n \u003cp\u003e0.191\u0026nbsp;\u0026plusmn;\u0026nbsp;0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIOP: intraocular pressure; N: Newtons; P: pressure; V: volume.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAcross the observed \u0026Delta;V values, the estimated pressure elevation was 15.63\u0026nbsp;\u0026plusmn;\u0026nbsp;8.13 (range 7.0 to 28.1 mmHg) above the 20-mmHg baseline, with a potential IOP of 35.63\u0026nbsp;\u0026plusmn;\u0026nbsp;8.13 (\u003cstrong\u003eTable 2\u003c/strong\u003e). These values represent the expected intraocular pressure response of a porcine globe experiencing indentation-induced volume disturbances. The predicted force was 0.191\u0026nbsp;\u0026plusmn;\u0026nbsp;0.09 (range 0.086 to 0.340 N) across the measured \u0026Delta;V. These values represent the force required to generate the observed volume displacements in a porcine ex vivo eye and provide a biomechanical context for comparing the magnitude of pressure and force produced by the depressor (\u003cstrong\u003eFigure 4\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eThe mechanical limits to the operational requirements were recalculated with the force results of the ex vivo porcine model, yielding extremely high safety margins: FS\u003csub\u003edet\u003c/sub\u003e of 331.2, FS\u003csub\u003e2\u003c/sub\u003e\u003csub\u003es\u003c/sub\u003e of 112.7, and b = 5.88.\u0026nbsp;\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study demonstrates the feasibility, mechanical reliability, and potential clinical applicability of a low-cost, 3D-printed Schepens scleral depressor. The findings of this study demonstrate that standard PLA filament, when printed with the described optimized settings, is capable of producing a device with a low supply manufacturing cost, approximately 300 times cheaper compared to steel scleral depressor minimum price. Beyond its economic advantage, the device exhibited a high safety profile, suggesting its mechanical suitability for clinical use with a high degree of safety.\u003c/p\u003e\n\u003cp\u003eThe simulated depression tests showed that examiners were capable of generating high mean peak forces when using the 3D-printed depressor. These values were statistically indistinguishable from those achieved using a conventional steel depressor, indicating that material composition (PLA vs. stainless steel) did not meaningfully limit operator-applied force. However, both tests highlighted significant inter-operator variability, a finding consistent with the subjective and experience-dependent nature of scleral indentation, reinforcing that this exam technique is a highly subjective maneuver.\u003c/p\u003e\n\u003cp\u003eThe mechanical testing revealed a significant margin between operational forces and failure limits, three times higher. The fact that the device remained safe even for the researcher who consistently applied significantly higher forces (Researcher 3) further validates its robustness for a wide range of clinical users. Notably, the robustness of the design was evidenced by one researcher\u0026apos;s inability to break the device manually during testing, suggesting that for some users, the device\u0026apos;s mechanical limits exceed the standard manual force capabilities. The identified failure point at the junction of the finger supporter and stem is a possible target for future designs. Reinforcement could be done to enhance strength and durability, without greatly increasing material use and print time, although standard usage forces are unlikely to reach this threshold.\u003c/p\u003e\n\u003cp\u003eIn this study, the mean operational force measured during simulated scleral depression represents the maximum macroscopic load an examiner could generate in the scleral-indentation posture, establishing a practical upper bound of user-applied effort with this tool. When interpreted in accordance with the intended purpose, the test demonstrates that the 3D-printed depressor has the capacity to reproduce the forces necessary to achieve clinical indentation. The failure load and safety factors indicate a significant mechanical reserve that can accommodate inter-operator variability without compromising integrity or safety [12].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWhile simulated macroscopic forces are relevant for validating robustness, they do not reflect the actual forces transmitted to the eye. For this reason, we incorporated an ex vivo porcine eye experiment to quantify indentation-induced intraocular pressure changes and the corresponding biomechanical force. The porcine model revealed that clinically relevant scleral indentation requires remarkably small force magnitudes. This supports the conclusion that the 3D-printed device is mechanically over-engineered relative to actual clinical force requirements, providing a wide functional margin without risk of unintended deformation or failure during use.\u003c/p\u003e\n\u003cp\u003eAfter a concise literature review, the optimal force required for scleral depression has not yet been standardized, only a minority of reports have quantified the applied force during scleral indentation. Among those that did, the forces between 0.64 and 0.9 N, applied with a calibrated ophthalmodynamometer, were sufficient to double intraocular pressure relative to baseline in healthy and glaucomatous eyes [12]. In this study, it is shown a direct influence on IOP variations during scleral depression, which could vary from 7.02 to 28.10 mmHg, fact that could be of importance for glaucoma patients, which neural and connective tissue are more susceptible to acute IOP changes [12].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe majority of studies have focused on IOP-induced changes for exam techniques and glaucoma analysis rather than on scleral depression and its required force [21, 22]. This discrepancy renders a direct comparison with our results difficult. A single study in the literature has successfully developed a 3D-printed scleral depressor, demonstrating a necessary force for depression of 0.71 \u0026plusmn; 0.06 lbf (3.16 \u0026plusmn; 0.37 N) and a maximum achieved force of 6.021 \u0026plusmn; 0.06 lbf (26.78 \u0026plusmn; 0.27 N) [23], analogous to the results of the present study in both sub-Newton necessary force and maximum force capability. However, this study is a conference abstract, and the full data set could not be retrieved.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe economic implications of this device are substantial. The material cost of this 3D-printed alternative was estimated to be U$0.06 per unit, which indicates that it is more economical than conventional stainless-steel depressors. PLA was selected as it is capable of fast, affordable, and reproducible production, while maintaining adequate strength for clinical application. Additionally, 3D printing allows for efficient production of multiple devices with minimal waste and the ability to standardize production variables to assure consistent quality [24]. Thus, for a production on a mass scale, parallel printing or batching methods could enhance the number of devices produced without substantial costs, while quality assurance and inspection strategies/design plans could ensure reliable devices [25].\u003c/p\u003e\n\u003cp\u003eThis reduction in cost has the potential to democratize access to essential ophthalmological tools in low-resource settings and facilitate production for training purposes [26, 27]. This approach is projected to enhance accessibility, thereby facilitating the diagnosis of retinal diseases and contributing to a reduction in the global burden of blindness due to undiagnosed peripheral retinal diseases [28].\u003c/p\u003e\n\u003cp\u003eOur contribution thus fills a notable gap by presenting, for the first time, validated force thresholds, material-specific failure profiles, and IOP responses during indentation, all supported by statistical safety metrics in different models. However, the present study is subject to certain inherent limitations due to its ex vivo design. While fresh porcine belly and eyes were used to simulate tissue compliance, it does not perfectly replicate the complex biomechanics of a living human eye, not accounting for blood flow, neural and extraocular muscle tone, and normal IOP autoregulation. We also used only one porcine eye specimen, which does not account for inter-eye variability, age effects, or disease-related differences in ocular rigidity\u0026mdash;factors shown in the literature to significantly alter IOP recovery, tissue compliance, and susceptibility to IOP spikes [29, 30]. The ex vivo design also does not permit testing for patient comfort, physician usability, and real-life clinical practice testing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFurthermore, only three researchers participated in simulated testing with manually applied forces; the study did not evaluate the influence of examiner experience and indentation technique. The present study focused exclusively on the performance of a single PLA filament brand. Despite its affordability and accessibility, PLA exhibits a low transition temperature (~60\u0026deg;C), and it is incapable of undergoing autoclaving [31]. Additionally, materials such as polyethylene terephthalate glycol (PETG) or medical-grade nylons could be chosen in future iterations because these materials offer enhanced thermal stability and chemical resistance while maintaining mechanical and structural performance [32, 33]. At the moment, if sterilization is required, alternative methodologies such as ethylene oxide must be employed [34\u0026ndash;36]; however, no tests were conducted for post sterilization safety. Thus, at the moment, this prototype is recommended for single-use and not to be sterilized.\u0026nbsp;\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe present study demonstrates that a low-cost, rapidly manufactured 3D-printed Schepens scleral depressor can safely and effectively withstand the forces typically applied during scleral indentation. The methodology presented enables fast production with minimal material costs, offering significant potential for easy worldwide replicability.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMechanical testing confirmed that the printed instrument tolerates examiner-generated loads far exceeding those required for clinical use, while the breakage test showed failure thresholds well above simulated operational demands. The ex vivo porcine biomechanical model further revealed that only sub-Newton forces are needed to reproduce scleral depression and induce meaningful intraocular pressure elevations, highlighting a wide safety margin between the device\u0026rsquo;s structural strength and the physiologic forces transmitted to the eye.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThese findings indicate that standard PLA filament, when printed with optimized settings, is a suitable, economical, and reliable alternative to conventional tools. This work furnishes a foundation for democratizing access to essential ophthalmological instruments, particularly for training purposes and in settings with limited resources.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFuture work should prioritize in vivo validation for teaching and clinical practice, evaluation aand optimization of sterilizable materials, evaluation of performance across multiple printers and users, and extension of this approach to additional 3D-printed ophthalmic instruments.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eThis work was supported by São Paulo Research Foundation (grant number #2024/16042-9).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests:\u0026nbsp;\u003c/strong\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLES: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Resources, Software, Validation, Visualization, Writing – original draft, Writing – review and editing. MPW: Conceptualization, Data curation, Investigation, Methodology, Resources, Validation, Writing – original draft. TM: Conceptualization, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review and editing. JPVNM: Data curation, Formal analysis, Investigation, Writing – review and editing. GTM: Formal analysis, Visualization, Writing – original draft, Writing – review and editing. JMSO: Conceptualization, Methodology, Resources, Validation, Writing – review and editing. JS: Conceptualization, Investigation, Methodology, Resources, Validation, Writing – review and editing. CAMN: Conceptualization, Methodology, Project administration, Resources, Supervision, Validation, Writing – review and editing. AM: Conceptualization, Funding acquisition, Methodology, Project administration, Resources, Supervision, Validation, Writing – review and editing. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eQuinn N, Csincsik L, Flynn E, et al (2019) The clinical relevance of visualising the peripheral retina. Prog Retin Eye Res 68:83\u0026ndash;109. https://doi.org/10.1016/j.preteyeres.2018.10.001\u003c/li\u003e\n\u003cli\u003eZheng W, Huang Y, Qian S, et al (2025) Classification of peripheral vitreoretinal interface lesions using spectral-domain optical coherence tomography with guidance of ultrawide field imaging. Front Neurosci 19:. https://doi.org/10.3389/fnins.2025.1516919\u003c/li\u003e\n\u003cli\u003eFlaxel CJ, Adelman RA, Bailey ST, et al (2020) Posterior Vitreous Detachment, Retinal Breaks, and Lattice Degeneration Preferred Practice Pattern\u0026reg;. Ophthalmology 127:P146\u0026ndash;P181. https://doi.org/10.1016/j.ophtha.2019.09.027\u003c/li\u003e\n\u003cli\u003eNatkunarajah M, Goldsmith C, Goble R (2003) Diagnostic effectiveness of noncontact slitlamp examination in the identification of retinal tears. Eye (Lond) 17:607\u0026ndash;9. https://doi.org/10.1038/sj.eye.6700456\u003c/li\u003e\n\u003cli\u003eLin AC, Kalaw FGP, Sch\u0026ouml;nbach EM, et al (2023) The Sensitivity of Ultra-Widefield Fundus Photography Versus Scleral Depressed Examination for Detection of Retinal Horseshoe Tears. Am J Ophthalmol 255:155\u0026ndash;160. https://doi.org/10.1016/j.ajo.2023.07.010\u003c/li\u003e\n\u003cli\u003eLin N, Gagnon M, Wu KY (2024) The Third Dimension of Eye Care: A Comprehensive Review of 3D Printing in Ophthalmology. Hardware 2:1\u0026ndash;32. https://doi.org/10.3390/hardware2010001\u003c/li\u003e\n\u003cli\u003eGroot ALW, Remmers JS, Lissenberg-Witte BI, et al (2023) Workflow and treatment results for computer-aided design and 3D-printed conformer therapy of congenital anophthalmia and microphthalmia. British Journal of Ophthalmology 107:1239\u0026ndash;1245. https://doi.org/10.1136/bjophthalmol-2021-320882\u003c/li\u003e\n\u003cli\u003eWeisson EH, Fittipaldi M, Concepcion CA, et al (2020) Automated Noncontact Facial Topography Mapping, 3-Dimensional Printing, and Silicone Casting of Orbital Prosthesis. Am J Ophthalmol 220:27\u0026ndash;36. https://doi.org/10.1016/j.ajo.2020.06.032\u003c/li\u003e\n\u003cli\u003eFang Y, Chen F, Wu H, Chen B (2023) Progress in the application of 3D printing technology in ophthalmology. Graefe\u0026rsquo;s Archive for Clinical and Experimental Ophthalmology 261:903\u0026ndash;912. https://doi.org/10.1007/s00417-022-05908-y\u003c/li\u003e\n\u003cli\u003eSanchez AU, Silva AM de S, Heilmann RM, et al (2024) Impress\u0026atilde;o 3D na rela\u0026ccedil;\u0026atilde;o m\u0026eacute;dico-paciente, relato de experi\u0026ecirc;ncia da integra\u0026ccedil;\u0026atilde;o entre ensino, inova\u0026ccedil;\u0026atilde;o e assist\u0026ecirc;ncia. Rev Bras Educ Med 48:. https://doi.org/10.1590/1981-5271v48.3-2023-0012\u003c/li\u003e\n\u003cli\u003eGanapathy A, Chen D, Elumalai A, et al (2022) Guide for starting or optimizing a 3D printing clinical service. Methods 206:41\u0026ndash;52. https://doi.org/10.1016/j.ymeth.2022.08.003\u003c/li\u003e\n\u003cli\u003eSharma S, Tun TA, Baskaran M, et al (2018) Effect of acute intraocular pressure elevation on the minimum rim width in normal, ocular hypertensive and glaucoma eyes. British Journal of Ophthalmology 102:131\u0026ndash;135. https://doi.org/10.1136/bjophthalmol-2017-310232\u003c/li\u003e\n\u003cli\u003eHAVENER WH (1958) Schepens\u0026rsquo; binocular indirect ophthalmoscope. Am J Ophthalmol 45:915\u0026ndash;8. https://doi.org/10.1016/0002-9394(58)90408-2\u003c/li\u003e\n\u003cli\u003eHovland KR, Tanenbaum HL, Schepens CL (1968) New scleral depressor. Am J Ophthalmol 66:117\u0026ndash;8. https://doi.org/10.1016/0002-9394(68)91802-3\u003c/li\u003e\n\u003cli\u003eFarcas MT, McKinney W, Qi C, et al (2020) Pulmonary and systemic toxicity in rats following inhalation exposure of 3-D printer emissions from acrylonitrile butadiene styrene (ABS) filament. Inhal Toxicol 32:403\u0026ndash;418. https://doi.org/10.1080/08958378.2020.1834034\u003c/li\u003e\n\u003cli\u003eOjima T, Tsuchiya T, Kitade N, et al (2025) Low-cost and bendable patient-specific three-dimensional pulmonary vessel models for lung segmentectomy. The Surgeon. https://doi.org/10.1016/j.surge.2025.11.005\u003c/li\u003e\n\u003cli\u003eBensoussan A (2005) Reliability Index. In: Deissenberg C, Hartl RF (eds) Optimal Control and Dynamic Games: Applications in Finance, Management Science and Economics. Springer US, Boston, MA, pp 311\u0026ndash;317\u003c/li\u003e\n\u003cli\u003eWolf J, Sabage LE, Sun YJ, Mahajan VB (2022) Protocol to quantify enzymatic effects on vitreous liquefaction in porcine eyes using a transwell-plate system. STAR Protoc 3:101754. https://doi.org/10.1016/j.xpro.2022.101754\u003c/li\u003e\n\u003cli\u003ePallikaris IG, Kymionis GD, Ginis HS, et al (2005) Ocular Rigidity in Living Human Eyes. Investigative Opthalmology \u0026amp; Visual Science 46:409. https://doi.org/10.1167/iovs.04-0162\u003c/li\u003e\n\u003cli\u003eFriedenwald JS (1937) Contribution to the Theory and Practice of Tonometry. Am J Ophthalmol 20:985\u0026ndash;1024. https://doi.org/10.1016/S0002-9394(37)90425-2\u003c/li\u003e\n\u003cli\u003eKimura Y, Izumi I, Kaneko M, et al (2012) Deformation of macula area under compulsory increase of eye pressure. In: 2012 IEEE International Conference on Mechatronics and Automation. IEEE, pp 980\u0026ndash;985\u003c/li\u003e\n\u003cli\u003eMcMonnies CW, Boneham GC (2007) Experimentally Increased Intraocular Pressure Using Digital Forces. Eye \u0026amp; Contact Lens: Science \u0026amp; Clinical Practice 33:124\u0026ndash;129. https://doi.org/10.1097/01.icl.0000247637.71618.26\u003c/li\u003e\n\u003cli\u003eMallory P, Najafi M, Koozekanani DD (2019) Utilizing three-dimensional printing for the production of a scleral depressor: a technical assessment and primer for clinical integration. Invest Ophthalmol Vis Sci 60:6594\u003c/li\u003e\n\u003cli\u003eKantaros A, Drosos C, Papoutsidakis M, et al (2025) The Role of 3D Printing in Advancing Automated Manufacturing Systems: Opportunities and Challenges. Automation 6:21. https://doi.org/10.3390/automation6020021\u003c/li\u003e\n\u003cli\u003eChitnis K, Lu Y, Rhoads B, et al (2025) Optimization of print parameters for batch and continuous manufacturing of three-dimensional (3D) printed dosage forms using artificial intelligence and machine learning. Drug Deliv Transl Res. https://doi.org/10.1007/s13346-025-02006-4\u003c/li\u003e\n\u003cli\u003eSommer AC, Blumenthal EZ (2019) Implementations of 3D printing in ophthalmology. Graefes Arch Clin Exp Ophthalmol 257:1815\u0026ndash;1822. https://doi.org/10.1007/s00417-019-04312-3\u003c/li\u003e\n\u003cli\u003eDesLauriers AC, Ackah PF, Skidd PM (2024) The Versatile Teaching Eye: an affordable, 3D-printed model eye for simulating ophthalmic examination. Digit J Ophthalmol 30:22\u0026ndash;26. https://doi.org/10.5693/djo.01.2024.02.001\u003c/li\u003e\n\u003cli\u003eSabage J, Sabage LE, Mota Lanzarin JV, et al (2025) Application of Smartphone-Based Fundus Cameras and Telemedicine in the Brazilian Amazon Forest. Journal of Clinical \u0026amp; Translational Ophthalmology 3:23. https://doi.org/10.3390/jcto3040023\u003c/li\u003e\n\u003cli\u003eMa Y, Moroi SE, Roberts CJ (2021) Non-invasive Clinical Measurement of Ocular Rigidity and Comparison to Biomechanical and Morphological Parameters in Glaucomatous and Healthy Subjects. Front Med (Lausanne) 8:. https://doi.org/10.3389/fmed.2021.701997\u003c/li\u003e\n\u003cli\u003eSayah DN, Medina-Cornejo J, Adel Y, et al (2025) Interocular differences in ocular rigidity in healthy subjects with isometropia. Invest Ophthalmol Vis Sci 66:2141\u003c/li\u003e\n\u003cli\u003eSuder J, Bobovsky Z, Mlotek J, et al (2021) EXPERIMENTAL ANALYSIS OF TEMPERATURE RESISTANCE OF 3D PRINTED PLA COMPONENTS. MM Science Journal 2021:4322\u0026ndash;4327. https://doi.org/10.17973/MMSJ.2021_03_2021004\u003c/li\u003e\n\u003cli\u003eYan C, Kleiner C, Tabigue A, et al (2024) PETG: Applications in Modern Medicine. Engineered Regeneration 5:45\u0026ndash;55. https://doi.org/10.1016/j.engreg.2023.11.001\u003c/li\u003e\n\u003cli\u003eShakiba M, Rezvani Ghomi E, Khosravi F, et al (2021) Nylon\u0026mdash;A material introduction and overview for biomedical applications. Polym Adv Technol 32:3368\u0026ndash;3383. https://doi.org/10.1002/pat.5372\u003c/li\u003e\n\u003cli\u003eMendes GCC, Brand\u0026atilde;o TRS, Silva CLM (2007) Ethylene oxide sterilization of medical devices: A review. Am J Infect Control 35:574\u0026ndash;581. https://doi.org/10.1016/j.ajic.2006.10.014\u003c/li\u003e\n\u003cli\u003eP\u0026eacute;rez Davila S, Gonz\u0026aacute;lez Rodr\u0026iacute;guez L, Chiussi S, et al (2021) How to Sterilize Polylactic Acid Based Medical Devices? Polymers (Basel) 13:. https://doi.org/10.3390/polym13132115\u003c/li\u003e\n\u003cli\u003eNeijhoft J, Henrich D, Kammerer A, et al (2023) Sterilization of PLA after Fused Filament Fabrication 3D Printing: Evaluation on Inherent Sterility and the Impossibility of Autoclavation. Polymers (Basel) 15:369. https://doi.org/10.3390/polym15020369\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"scleral depression, 3D printing, medical device prototyping, biomechanics, intraocular pressure, Schepens depressor, instrument design","lastPublishedDoi":"10.21203/rs.3.rs-8242729/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8242729/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e: To develop a low-cost, 3D-printed Schepens scleral depressor and evaluate its mechanical performance, safety, and ocular biomechanical effects.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e A Schepens-style depressor was developed and printed in PLA using a 3D-printer. Examiners performed two different tests: (1) the maximum simulated scleral depression force, using both the 3D-printed and a conventional steel depressor, and (2) a breakage test performed only on the 3D-printed device to determine its mechanical failure threshold. Peak forces were applied to porcine belly and recorded by a precision balance with a slow-motion video analysis. A third test - conduced exclusively with the 3D-printed depressor - was performed using one ex vivo porcine eye model to correlate applied force with induced intraocular pressure (IOP) elevation. Pressure–volume behavior was modeled using the Friedenwald rigidity coefficient.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e One unit of the depressor prototype consumed 3.06g of PLA with an estimated cost and print time of U$0.06 and 22min. Simulated indentation produced forces of 21.21 ± 6.23N (3D-printed depressor) and 25.02 ± 4.64N (steel depressor), with no significant difference between devices. The 3D-printed instrument breakage point was 63.27 ± 10.72N, with a 2.98 Factor of Safety (FS) and 3.39 Reliability Index (b). In the porcine model, scleral depression produced 15.63 ± 8.13mmHg IOP elevation, requiring 0.191 ± 0.09N (FS = 331.2 and b = 5.88).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e The 3D-printed depressor demonstrates effective mechanical robustness, wide safety margins, and functional equivalence to steel instruments, supporting the use of customizable, low-cost 3D-printed depressors in training and clinical settings.\u003c/p\u003e","manuscriptTitle":"Development, Mechanical Performance, and Ex Vivo Porcine Eye Biomechanical Validation of a 3D-Printed Schepens Scleral Depressor","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-05 07:28:25","doi":"10.21203/rs.3.rs-8242729/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9629db1c-00e1-4567-ae4b-ba03003b4bbd","owner":[],"postedDate":"December 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-05T07:28:25+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-05 07:28:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8242729","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8242729","identity":"rs-8242729","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}