Differences in Corneal Biomechanical Parameters in Normal Tension Glaucoma versus Normotensive Glaucoma Suspect Eyes

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R. Garbeloti, Isabela C. T. Araujo, Jayter S. Paula, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8995481/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 10 You are reading this latest preprint version Abstract Multicenter retrospective study to evaluate differences in corneal biomechanical parameters provided by Corvis ST to segregate those with normal tension glaucoma (NTG) from glaucoma suspects. We included only newly diagnosed and treatment naïve glaucoma patients. Several corneal biomechanical parameters provided by Corvis ST were investigated. The discrimination ability of BGF was investigated through the area under the receiver operating characteristics curve (AUC). We included a total of 200 eyes from 100 patients with NTG and 200 eyes from 100 controls. We found statistical difference in Corneal velocity at second applanation (A2) with − 0.264 ± 0.061 m/s (OD) and − 0.270 ± 0.067 m/s (OS) in the control group, versus − 0.226 ± 0.084 m/s (OD, p = 0.0004) and − 0.223 ± 0.079 m/s (OS, p = 0.0001) in the NTG group. In addition, we found statistical difference in biomechanical glaucoma factor (BGF) between groups, with 0.568 ± 0.239 (OD) and 0.560 ± 0.229 (OS) in the control group, versus 0.674 ± 0.212 (OD, p = 0.001) and 0.659 ± 0.231 (OS, p = 0.056) in the NTG group. The AUC value was 0.63 BGF for discriminating NTG eyes from normal eyes. Both BGF and corneal velocity at second applanation were statistically different between groups. Using BGF parameter from Corvis ST can improve diagnostic accuracy when dealing with NTG. Health sciences/Diseases Health sciences/Medical research Normal Tension Corneal Biomechanics Glaucoma Corvis ST Figures Figure 1 INTRODUCTION Normal-tension glaucoma (NTG) is a progressive optic neuropathy like primary open-angle glaucoma (POAG); however, NTG does not present with intraocular pressure (IOP) outside the statistically normal range. 1 In addition, pathophysiology of NTG involves multiple non-pressure mechanisms, such as ocular perfusion dysfunction, impaired vascular autoregulation, obstructive sleep apnea, nocturnal hypotension, alterations in the extracellular matrix of the optic nerve head, and, more recently, ocular biomechanical alterations. 2,3 Previous studies have shown that corneal hysteresis was significantly lower in NTG patients compared with POAG patients. 4,5 The Corvis® ST (Corneal Visualization Scheimpflug Technology) is a non-contact tonometer that records cornea's response and deformation to an air pulse using a Scheimpflug camera that captures over 4,300 images/second, enabling IOP measurement and a detailed assessment of corneal biomechanical properties. Eyes with a more deformable cornea, less viscous damping, and lower corneal hysteresis could have optic discs more susceptible to glaucoma damage from increased IOP. 5 Studies have shown that eyes with NTG may have lower biomechanical stiffness and a greater range of corneal deformation compared to healthy eyes and those with ocular hypertension. 6–8 The proper diagnosis of NTG sometimes can be challenging. Additional information about new ocular parameters that could segregate those with real disease from glaucoma suspects could be helpful in clinical practice. Thus, the aim of the current study is to compare corneal biomechanical parameters provided by Corvis ST in patients with NTG versus a control group of glaucoma suspect eyes. RESULTS We included a total of 100 patients with NTG and 100 controls. Table 1 presents the clinical and demographic characteristics of the participants. The control group had an average age of 68.74 ± 8.33 years, compared to 70.47 ± 12.68 years for the NTG group (p = 0.255). Males made up 35% of the Control group and 46% of the NTG group (p = 0.113), whereas females were 65% of the Control group and 54% of the NTG group. Visual acuity (logMAR) was 0.052 ± 0.108 (right eye, OD) and 0.053 ± 0.090 (left eye, OS) in the Control group, versus 0.076 ± 0.191 (OD, p = 0.275) and 0.068 ± 0.138 (OS, p = 0.365) in the NTG group. Axial length was 23.83 ± 1.00 mm (OD) and 23.82 ± 1.04 mm (OS) in the Control group, versus 24.01 ± 1.04 mm (OD, p = 0.260) and 23.99 ± 1.04 mm (OS, p = 0.292) in the NTG group. Baseline intraocular pressure (IOP) was 14.25 ± 2.21 mmHg (OD) and 14.09 ± 2.24 mmHg (OS) in the Control group, versus 13.98 ± 1.99 mmHg (OD, p = 0.365) and 14.10 ± 2.31 mmHg (OS, p = 0.975) in the NTG group. Ultrasound pachymetry was 531.03 ± 32.73 µm (OD) and 530.43 ± 33.91 µm (OS) in the control group, versus 532.16 ± 35.24 µm (OD, p = 0.814) and 531.75 ± 33.85 µm (OS, p = 0.783) in the NTG group. Table 1 Clinical and Demographic Characteristics of Patients Included in the Study Variable Controls (n = 100) NTG (n = 100) P-value Age (years) 68.74 ± 8.33 70.47 ± 12.68 0.255 Gender (Male %) 35% 46% 0.113 Corrected Visual Acuity OD (logMAR) 0.052 ± 0.108 0.076 ± 0.191 0.275 Corrected Visual Acuity OE (logMAR) 0.053 ± 0.090 0.068 ± 0.138 0.365 Axial Length OD (mm) 23.83 ± 1.00 24.01 ± 1.04 0.260 Axial Length OE (mm) 23.82 ± 1.04 23.99 ± 1.04 0.292 Spherical Equivalent OD (D) -0.114 ± 1.210 -0.364 ± 1.479 0.191 Spherical Equivalent OE (D) -0.099 ± 1.281 -0.309 ± 1.355 0.263 Baseline IOP without Drops OD (mmHg) 14.25 ± 2.21 13.98 ± 1.99 0.365 Baseline IOP without Drops OE (mmHg) 14.09 ± 2.24 14.10 ± 2.31 0.975 Pachymetry OD (µm) 531.03 ± 32.73 532.16 ± 35.24 0.814 Pachymetry OE (µm) 530.43 ± 33.91 531.75 ± 33.85 0.783 MD OD (dB) -0.815 ± 2.432 -3.698 ± 4.791 < 0.0001 MD OE (dB) -0.900 ± 2.754 -3.954 ± 4.781 < 0.0001 Pseudophakic OD (%) 44% 40% 0.567 Pseudophakic OE (%) 44% 42% 0.775 Use of Prostaglandin Drops (%) 0% 36% < 0.0001 Values expressed as mean ± standard deviation (SD), except for categorical variables (percentages). OD: Right Eye; OE: Left Eye; IOP: Intraocular Pressure; MD: Mean Deviation. In Table 2 , we described the comparison of corneal biomechanical properties between the two groups. The bIOP was 15.31 ± 2.13 mmHg (OD) and 15.23 ± 2.48 mmHg (OS) in the Control group, versus 14.08 ± 2.17 mmHg (OD, p = 0.00011) and 14.66 ± 2.54 mmHg (OD, p = 0.108) in the NTG group. We found statistical difference in Corneal velocity at second applanation (A2) with − 0.264 ± 0.061 m/s (OD) and − 0.270 ± 0.067 m/s (OS) in the control group, versus − 0.226 ± 0.084 m/s (OD, p = 0.0004) and − 0.223 ± 0.079 m/s (OS, p = 0.0001) in the NTG group. In addition, we found statistical difference in BGF between groups, with 0.568 ± 0.239 (OD) and 0.560 ± 0.229 (OS) in the control group, versus 0.674 ± 0.212 (OD, p = 0.001) and 0.659 ± 0.231 (OS, p = 0.056) in the NTG group. Table 2 Corneal Biomechanics Properties from Controls and Normal Tension Glaucoma Patients. Variables Controls (n = 100) NTG (n = 100) P-value bIOP OD (mmHg) 15.31 ± 2.13 14.08 ± 2.17 0.110 bIOP OE (mmHg) 15.23 ± 2.48 14.66 ± 2.54 0.108 SPA1 OD 111.95 ± 19.93 111.12 ± 18.08 0.759 SPA1 OE 111.34 ± 20.68 114.18 ± 20.55 0.335 SSI OD 2.381 ± 12.187 1.121 ± 0.289 0.307 SSI OE 1.157 ± 0.217 1.123 ± 0.226 0.277 DA Ratio OD 4.507 ± 0.619 4.570 ± 0.775 0.528 DA Ratio OE 4.426 ± 0.665 4.719 ± 1.223 0.036 ARTh OD 644.70 ± 515.51 610.62 ± 252.67 0.557 ARTh OE 618.28 ± 302.40 588.04 ± 275.00 0.463 Corneal Velocity A1 OD (m/s) 0.128 ± 0.025 0.127 ± 0.026 0.836 Corneal Velocity A1 OE (m/s) 0.134 ± 0.071 0.124 ± 0.030 0.227 Corneal Velocity A2 OD (m/s) -0.264 ± 0.061 -0.226 ± 0.084 0.0004 Corneal Velocity A2 OE (m/s) -0.270 ± 0.067 -0.223 ± 0.079 0.0001 HC DA OD (mm) 3.343 ± 0.618 3.484 ± 0.746 0.149 HC DA OE (mm) 3.364 ± 0.708 3.436 ± 0.813 0.504 BGF OD 0.568 ± 0.239 0.674 ± 0.212 0.001 BGF OE 0.560 ± 0.229 0.659 ± 0.231 0.056 Values expressed as mean ± standard deviation (SD). Legends: Normal-Tension Glaucoma (NTG) group. OD: Right Eye; OE: Left Eye; bIOP: Biomechanically Corrected Intraocular Pressure; SPA1: Stiffness Parameter at First Applanation; SSI: Stress-Strain Index; DA Ratio: Deformation Amplitude Ratio; ARTh: Adjusted Radius of Highest Concavity Time (interpreted from ArtH); HC DA: Highest Concavity Deformation Amplitude. BGF: Biomechanical Glaucoma Factor The receiver operating characteristic curves of BGF for discriminating NTG eyes from normal eyes are shown in Fig. 1 . The area under the receiver operating characteristic curves (AUC) value was 0.63 for BGF, considering pooled eyes (any eye positive), with a cut-off value of 0.74 from BGF to discriminate healthy eyes from NTG ones (Table 3 ). Table 3 Cut-ff values for biomechanical glaucoma factor for discriminating suspects from glaucomatous eyes. Variable Cut-off Youden J Sensitivity Specificity AUC BGF OD 0.74 0.257 0.49 0.768 0.634 BGF OS 0.74 0.247 0.48 0.768 0.629 Mean (OD + OS) 0.78 0.267 0.398 0.869 0.645 Pooled eyes (any eye positive) 0.74 0.252 0.485 0.768 0.632 BGF: biomechanical glaucoma factor; OD: right eye; OS: left eye; AUC: area under the curve DISCUSSION Earlier studies have reported significant differences in corneal biomechanical properties between glaucoma and normal eyes. 5,7,9 Most studies have been performed by comparing corneal parameters between confirmed glaucomatous patients from healthy individuals with normal excavations in a cross-sectional design. However, clinicians are most interested in the ability of a new test to provide additional information that can be helpful in a patient who presents suspicious findings for the disease, such as apparent enlarged cupping. 10 Thus, the current study used corneal biomechanical parameters from Corvis ST and has focused on treatment naïve newly diagnosed NTG patients versus a control group of glaucoma suspect eyes. We have found statistical differences in corneal velocity at second applanation and BGF values between both groups. Moreover, the AUC from BGF parameter for discriminating NTG from normal eyes was 0.63. The biomechanical environment of the eye is increasingly recognized as a determinant of glaucoma susceptibility. Although IOP is the most important modifiable risk factor, the way tissues respond to this load is highly individualized. 11 Factors such as tissue stiffness, viscoelasticity, collagen microarchitecture, and extracellular matrix remodeling dictate how forces are absorbed and transmitted throughout the eye. 12,13 Thus, two patients with identical IOP values may experience profoundly different levels of strain at the lamina cribrosa (LC) and optic nerve head (ONH), explaining interindividual variability in glaucoma progression 14 , 15 . The cornea provides a practical and accessible window to study ocular biomechanics. Unlike static measures such as central corneal thickness, the Corvis-ST derived parameters capture the cornea’s real-time viscoelastic response, offering richer information about ocular biomechanical properties. Importantly, these responses are not isolated to the cornea itself but are believed to reflect the integrated biomechanical phenotype of the entire globe. A key concept underpinning this interpretation is the notion of structural continuity between the cornea, sclera, and LC. 13 These tissues form a continuous fibrous shell, dominated by type I collagen fibrils that are organized differently but connected in function. While the cornea exhibits highly ordered lamellae optimized for transparency, the sclera has a more irregular and interwoven collagen arrangement that provides mechanical strength, and the LC contains a cribriform plate structure through which retinal ganglion cell axons pass. 16 Despite regional differences, this shell acts as a single biomechanical unit: loads applied at one point are distributed and absorbed across the system. 17,18 Clinical and experimental evidence supports this continuity. 19–22 Studies using ocular response analyzers and in vivo imaging have demonstrated that lower corneal hysteresis (CH) is associated with deeper and more compliant ONHs, and with measurable LC displacement after surgical IOP reduction. 23–25 These findings highlight that corneal biomechanical properties are not mere epiphenomena but rather biomarkers of how the posterior segment will react under stress. 26 Reduced CH and CRF suggest a structurally “softer” ocular wall, transmitting higher levels of strain to axons even at normal IOP values. This biomechanical vulnerability is particularly relevant in NTG. 27 In these patients, the absolute level of IOP may not exceed the statistical cutoff of 21 mmHg, but the effective stress reaching the LC may still be pathological if the supporting tissues are less capable of absorbing load. In other words, NTG eyes may operate with a lower threshold of biomechanical tolerance. 28 The BGF was developed based on dynamic corneal response deformation and corneal thickness parameters, to discriminate between healthy and NTG patients. 29 The BGF included deformation amplitude ratio progression (DARatioProg), which describes the increase of the ratio between the deformation amplitude measured in the centre compared to the periphery. HCTime, which measures the time until maximum deformation after application of the air pulse is reached. Pachymetry slope, which describes the difference in corneal thickness from the centre towards the periphery. bIOP, which is a measure of intraocular pressure that corrects for corneal thickness, corneal response parameters and age and pachymetry, derived from the Scheimpflug imaging of the Corvis ST. 30 We found statistical difference in BGF between groups, with 0.568 ± 0.239 (OD) and 0.560 ± 0.229 (OS) in the control group, versus 0.674 ± 0.212 (OD, p = 0.001) and 0.659 ± 0.231 (OS, p = 0.056) in the NTG group. In clinical practice, the proper diagnosis of NTG can be challenging. The current study tried to replicate the clinical dilemma that we face when dealing with glaucoma suspect eyes and IOP below 21mmHg. In these cases, any additional parameter that could discriminate a healthy from a glaucomatous patients can be helpful. We found an AUC of 0.63 when considering BGF from pooled eyes (Fig. 1 ). BGF is a relatively novel Corvis ST index that was devloped to distinguish eyes with NTG from normal eyes. 29 Pillunat et al have reported an AUC of 0.814 to distinguish glaucoma eyes from normal eyes. However, Aoki et al have reported lower AUC value (0.61). 9 It is important to highlight that Aoki et al have included a broader spectrum of POAG patients in contrast to the original study from Pillunat in which BGF was developed, that included only NTG patients. In addition, Aoki et al have included patients under hypotensive treatment which could have led to changes in other biomechanical measures such as DARatioProg and HCtime. This IOP reduction could have weakened the potential relationship between BGF and POAG in their findings. In contrast, our study have included only treatment naive NTG patients, eliminating the bias of possible changes in corneal biomechanics from IOP reduction. The Corvis ST automatically calculates the time and length of the cornea deformations and the instantaneous speed of corneal movement at the two applanation states (during inward and outward). The applanation times, lengths, and velocities are recorded during the inward (first applanation, designated and outward (second applanation, designated #2) phases of corneal applanation. 31 The corneal velocity #2 is the outward applanation velocity. (the instantaneous speed of the cornea as it returns to its original, undisturbed state) 32 We found statistical difference in corneal velocity at second applanation (A2) with − 0.264 ± 0.061 m/s (OD) and − 0.270 ± 0.067 m/s (OS) in the control group, versus − 0.226 ± 0.084 m/s (OD, p = 0.0004) and − 0.223 ± 0.079 m/s (OS, p = 0.0001) in the NTG group. A less deformable cornea is thought to reach inward applanation slower and reach outward applanation faster, with higher outward velocity. 33 We did not find statistical differences regarding other parameters such as: bIOP, SPA1, SSI, DA ratio, ARTh, corneal velocity at first applanation and HC DA. The Corvis ST device can measure up to 37 different parameters. Unfortunately, across several studies evaluating corneal biomechanical properties in glaucoma, some parameters present with statistical difference, whereas other do not. 31 This disagreement between different studies can be explained by several factors. Most of the studies are limited by the inclusion of glaucoma subjects under hypotensive treatment, which may alter corneal biomechanics and contribute to contradicting results. Lack of proper stratification of patients (high versus normal tension glaucoma) can lead to misinterpretation of the results based on factors that are confounded by intraocular pressure changes. Finally, it is important to note that corneal biomechanical properties are dynamic metrics and can change over time with age, corneal trauma, or surgery. 31 The current study has several strengths as both NTG and controls had no statistical differences in IOP, age, corneal thickness, and axial length. In addition, we have excluded patients who underwent corneal surgeries and all Corvis ST measurement were taken in newly diagnosed treatment naïve patients, which minimize any bias from artificial IOP reduction. However, we acknowledge several limitations. First, the cross-sectional nature of our study design did not allow assessment of causation or prospective prediction of glaucoma risk but rather only established a difference in corneal biomechanical parameters between NTG and control group. Second, as glaucoma is in general an aging disease some subjects in the control group can develop glaucoma in the future, even though, we have monitored those patients for at least two years with normal visual fields and normal retinal nerve fiber layer thickness from OCT. Third, we only found differences in BGF and corneal velocity and further investigation with a larger sample size may increase the power of the study to detect differences in other parameters. In conclusion, we identified corneal biomechanical differences between NTG and a group of glaucoma suspect eyes. Clinically, these findings underscore the value of integrating corneal biomechanical assessment when diagnosing NTG. Parameters such as BGF and corneal velocity at second applanation should not be interpreted as stand-alone diagnostic criteria, but rather as biomechanical risk biomarkers. Their value lies in refining risk stratification, identifying patients who may progress despite apparently controlled IOP, and informing individualized follow-up protocols. METHODS Participants This was a multicenter retrospective study carried out in 2 different eye centers in Brazil. Hospital Oftalmológico de Brasília in Brasília and Hospital de Medicina dos Olhos in Osasco, São Paulo. Eligible patients had newly diagnosed, untreated glaucoma in both eyes identified at two different eye centers across Brazil between January 2024 and January 2025. We included only treatment naïve, newly diagnosed glaucoma patients aged over 18 years old. Patients with previous diagnosis of glaucoma performed in other centers or already under treatment were not included in this protocol. We also excluded patients with previous corneal and glaucoma surgeries, retinal diseases, corneal opacity, or any other opacity disease that could significantly affect visual field outcomes. The study protocol was revised and approved by the Institutional Review Board from the Hospital Oftalmológico de Brasília (IRB number: 75438823.1.0000.5667). All study methods complied with the Declaration of Helsinki guidelines for human subject research. Informed consent from each patient was not required due to the retrospective nature of the study being waived by the Institutional Review Board from the Hospital Oftalmológico de Brasília. We collected data from electronic charts regarding ophthalmologic examinations including review of medical history, visual acuity, slit-lamp biomicroscopy, intraocular pressure (IOP) measurement (Goldmann tonometer), gonioscopy (Posner goniolens), ocular biometry (IOL Master, Carl Zeiss Meditec, Inc, Dublin, CA), ultrasound pachymetry, dilated fundoscopic examination with 78 diopters lens, and optic disc photography. Subjects underwent standard automated perimetry (SAP) using the 24 − 2 Swedish interactive threshold algorithm (Humphrey Field Analyzer 3, 840; Carl Zeiss Meditec, Inc, Dublin, CA). The diagnosis of NTG was based on the presence of repeatable (at least two consecutive) abnormal SAP results with corresponding evidence of glaucomatous optic neuropathy in at both eyes and at least 3 IOP measurements < 21mmHg, without any hypotensive medication (as patients were newly diagnosed). An abnormal SAP result was defined as a pattern standard deviation with P < 0.05, and/or glaucoma hemifield test results outside normal limits. 34 We evaluated more than one visual field per patient if the first exam was not reliable to minimize learning effects. We applied a cutoff of 20% of false-positives or negatives and a cutoff of 20% for fixation losses to define an exam as unreliable. 35 We accepted a cutoff of 33% for false negatives in cases of advanced disease confirmed with retinography and extensive loss of retinal nerve fiber layer (RNFL) on optical coherence tomography (OCT) evaluation. 36 We used measurement of RNFL (using superior temporal, global and inferior temporal RNFL thickness and assessing correlation with optic nerve and visual field findings) from OCT to confirm glaucoma diagnosis (Avantis, Optovue, Fremont, CA). 10,37 According to Hodapp-Parrish-Anderson criteria, glaucoma patients were categorized as mild [mean deviation (MD): ≥ −6 dB], moderate (-12dB < MD <-6dB) and advanced (MD 0.6, but normal IOP (below 21mmHg), normal visual field and normal OCT RNFL thickness, without family history of glaucoma, followed for at least two years, without changes in the exams. Corvis ST Measurements The principles of Corvis ST have been described in detail elsewhere. 29 Briefly, the tonometer’s camera records a sequence of images of corneal deformation, capturing 4330 images per second. All study subjects had measurements collected by the same operator, and without dilation. Only exams with adequate quality score were included. After each Corvis measurement, the data output was confirmed by reviewing the film to ensure that numbers for instantaneous velocities, applanation lengths, and times corresponded to true values. 32 Corvis measurements that failed to correspond to true applanation states and highest concavity time points were considered unreliable, and were not used in this study. We used the Corvis ST software version 1.3r1538 and the following parameters were recorded: biomechanically compensated IOP (bIOP), stiffness parameter at first applanation (SPA1), stress-strain index (SSI), deformation amplitude ratio (DA Ratio), adjusted radius of highest concavity time (ARTh), corneal velocity at first applanation (A1), corneal velocity at second applanation (A2), highest concavity deformation amplitude (HC DA) and biomechanical glaucoma factor (BGF). Statistical Analysis For continuous variables with normal distribution, the Student’s t test was used, and the Wilcoxon signed rank test was employed for continuous variables that were not normally distributed. Categorical variables were analyzed using with the Chi-square or Fischer exact tests. The discrimination ability of BGF was investigated through the area under the receiver operating characteristics curve (AUC). 38 Statistical analysis and artwork were performed using Stata, version 13 (StataCorp LP, College Station, Texas, USA). The alpha level (type I error) was set at 0.05. Declarations Acknowledgments Financial Support None. Authors Contributions Statement EJRG and RYA have made substantial contributions to the conception and design of the work. EJRG, ICTA, JSP, MM, WTH, TP and RYA have made substantial contributions to the acquisition, analysis, and interpretation of data. EJRG, ICTA, JSP, MM, WTH, TP and RYA have drafted the work or substantively revised it. Data availability The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. References Esporcatte, B. L. & Tavares, I. M. Normal-tension glaucoma: an update. Arq. Bras. 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Corneal Hysteresis for the Diagnosis of Glaucoma and Assessment of Progression Risk: A Report by the American Academy of Ophthalmology. Ophthalmology 130 , 433–442. https://doi.org:10.1016/j.ophtha.2022.11.009 (2023). Zhang, C. et al. Corneal Hysteresis and Progressive Retinal Nerve Fiber Layer Loss in Glaucoma. Am. J. Ophthalmol. 166 , 29–36. https://doi.org:10.1016/j.ajo.2016.02.034 (2016). Takeda, Y. et al. Relationship between corneal hysteresis and the site of damage to peripapillary retinal nerve fibre layer thickness in open-angle glaucoma. Sci. Rep. 14 , 26329. https://doi.org:10.1038/s41598-024-76187-2 (2024). Morita, T., Shoji, N., Kamiya, K., Fujimura, F. & Shimizu, K. Corneal biomechanical properties in normal-tension glaucoma. Acta Ophthalmol. 90 , e48–53. https://doi.org:10.1111/j.1755-3768.2011.02242.x (2012). Xu, Y. et al. Corneal Stiffness and Modulus of Normal-Tension Glaucoma in Chinese. Am. J. 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Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 10 Apr, 2026 Reviews received at journal 07 Apr, 2026 Reviews received at journal 20 Mar, 2026 Reviewers agreed at journal 16 Mar, 2026 Reviewers agreed at journal 10 Mar, 2026 Reviewers invited by journal 09 Mar, 2026 Editor assigned by journal 09 Mar, 2026 Editor invited by journal 09 Mar, 2026 Submission checks completed at journal 07 Mar, 2026 First submitted to journal 07 Mar, 2026 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-8995481","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":604811805,"identity":"4c1fc331-7fa6-4c3b-82cf-bac0a526dcf5","order_by":0,"name":"Eduardo J. R. Garbeloti","email":"","orcid":"","institution":"Hospital Oftalmológico de Brasília","correspondingAuthor":false,"prefix":"","firstName":"Eduardo","middleName":"J. R.","lastName":"Garbeloti","suffix":""},{"id":604811806,"identity":"7d3215ab-2975-45b0-9773-9f433eef2195","order_by":1,"name":"Isabela C. T. Araujo","email":"","orcid":"","institution":"Hospital Oftalmológico de Brasília","correspondingAuthor":false,"prefix":"","firstName":"Isabela","middleName":"C. T.","lastName":"Araujo","suffix":""},{"id":604811807,"identity":"728a8237-4f1b-49cf-9035-710088270ac7","order_by":2,"name":"Jayter S. Paula","email":"","orcid":"","institution":"Universidade de São Paulo","correspondingAuthor":false,"prefix":"","firstName":"Jayter","middleName":"S.","lastName":"Paula","suffix":""},{"id":604811808,"identity":"68cc4d0a-bc99-433d-8585-70640e454e33","order_by":3,"name":"Marcelo Macedo","email":"","orcid":"","institution":"Universidade de São Paulo","correspondingAuthor":false,"prefix":"","firstName":"Marcelo","middleName":"","lastName":"Macedo","suffix":""},{"id":604811809,"identity":"2aaed880-2e0d-461f-90df-446d1fd43035","order_by":4,"name":"Wilson T. Hida","email":"","orcid":"","institution":"Hospital Oftalmológico de Brasília","correspondingAuthor":false,"prefix":"","firstName":"Wilson","middleName":"T.","lastName":"Hida","suffix":""},{"id":604811810,"identity":"a22b493d-5c46-45ec-b802-88a09ec8fa3c","order_by":5,"name":"Tiago S. Prata","email":"","orcid":"","institution":"Hospital Medicina dos Olhos","correspondingAuthor":false,"prefix":"","firstName":"Tiago","middleName":"S.","lastName":"Prata","suffix":""},{"id":604811811,"identity":"84b9b285-dd13-4480-8a2d-03be7a49a53d","order_by":6,"name":"Ricardo Y. Abe","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYDACZhDBxsBgwMB8/MMHBoYEmEQCLh1IWtjSGGcQpYUBroXHjJmHGC3m7cwPP1eU2cibs7elPbZts8vjZ29g/PAxhyHPvAG7FpnDbMaSZ86lGe7sOXzcOLctuViy5wCz5MxtDMUyB7BrkQA6RrKx7TDjhhtpCdK5bcyJG24ksDHzbmNInIHDYUAtzD+BWuw33H9jIG3ZVk+UFjaQLUCVPGbSjGAGQS1sZpYN59KSd/akJRv2nDueOLPnYDPQLxLFEri08B9+fLOhzMZ2O/vhgw9+lFUn9rM3H/zwcZtNHi4tqICRDUw2gMwiSgMQ/CFW4SgYBaNgFIwkAAAgD1kob6sLvwAAAABJRU5ErkJggg==","orcid":"","institution":"Hospital Oftalmológico de Brasília","correspondingAuthor":true,"prefix":"","firstName":"Ricardo","middleName":"Y.","lastName":"Abe","suffix":""}],"badges":[],"createdAt":"2026-02-28 12:54:38","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8995481/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8995481/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104667883,"identity":"9636c008-e21a-4827-ae98-fbadda78506e","added_by":"auto","created_at":"2026-03-15 16:50:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":740562,"visible":true,"origin":"","legend":"\u003cp\u003eThe receiver operating characteristic curves of biomechanical glaucoma factor (BGF) for discriminating normal tension glaucoma (NTG) eyes from normal eyes. The area under the receiver operating characteristic curves (AUC) value was 0.63 for BGF.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-8995481/v1/9088a9d30723b865b131cd05.png"},{"id":104667896,"identity":"ae6523d5-1085-4391-a1d8-8b32bc2267b8","added_by":"auto","created_at":"2026-03-15 16:50:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2174234,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8995481/v1/899c2320-acc6-47be-8e29-a87abc87d3aa.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Differences in Corneal Biomechanical Parameters in Normal Tension Glaucoma versus Normotensive Glaucoma Suspect Eyes","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eNormal-tension glaucoma (NTG) is a progressive optic neuropathy like primary open-angle glaucoma (POAG); however, NTG does not present with intraocular pressure (IOP) outside the statistically normal range. \u003csup\u003e1\u003c/sup\u003e In addition, pathophysiology of NTG involves multiple non-pressure mechanisms, such as ocular perfusion dysfunction, impaired vascular autoregulation, obstructive sleep apnea, nocturnal hypotension, alterations in the extracellular matrix of the optic nerve head, and, more recently, ocular biomechanical alterations. \u003csup\u003e2,3\u003c/sup\u003e Previous studies have shown that corneal hysteresis was significantly lower in NTG patients compared with POAG patients. \u003csup\u003e4,5\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe Corvis\u0026reg; ST (Corneal Visualization Scheimpflug Technology) is a non-contact tonometer that records cornea's response and deformation to an air pulse using a Scheimpflug camera that captures over 4,300 images/second, enabling IOP measurement and a detailed assessment of corneal biomechanical properties. Eyes with a more deformable cornea, less viscous damping, and lower corneal hysteresis could have optic discs more susceptible to glaucoma damage from increased IOP. \u003csup\u003e5\u003c/sup\u003e Studies have shown that eyes with NTG may have lower biomechanical stiffness and a greater range of corneal deformation compared to healthy eyes and those with ocular hypertension. \u003csup\u003e6\u0026ndash;8\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe proper diagnosis of NTG sometimes can be challenging. Additional information about new ocular parameters that could segregate those with real disease from glaucoma suspects could be helpful in clinical practice. Thus, the aim of the current study is to compare corneal biomechanical parameters provided by Corvis ST in patients with NTG versus a control group of glaucoma suspect eyes.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eWe included a total of 100 patients with NTG and 100 controls. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the clinical and demographic characteristics of the participants. The control group had an average age of 68.74\u0026thinsp;\u0026plusmn;\u0026thinsp;8.33 years, compared to 70.47\u0026thinsp;\u0026plusmn;\u0026thinsp;12.68 years for the NTG group (p\u0026thinsp;=\u0026thinsp;0.255). Males made up 35% of the Control group and 46% of the NTG group (p\u0026thinsp;=\u0026thinsp;0.113), whereas females were 65% of the Control group and 54% of the NTG group. Visual acuity (logMAR) was 0.052\u0026thinsp;\u0026plusmn;\u0026thinsp;0.108 (right eye, OD) and 0.053\u0026thinsp;\u0026plusmn;\u0026thinsp;0.090 (left eye, OS) in the Control group, versus 0.076\u0026thinsp;\u0026plusmn;\u0026thinsp;0.191 (OD, p\u0026thinsp;=\u0026thinsp;0.275) and 0.068\u0026thinsp;\u0026plusmn;\u0026thinsp;0.138 (OS, p\u0026thinsp;=\u0026thinsp;0.365) in the NTG group. Axial length was 23.83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.00 mm (OD) and 23.82\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04 mm (OS) in the Control group, versus 24.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04 mm (OD, p\u0026thinsp;=\u0026thinsp;0.260) and 23.99\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04 mm (OS, p\u0026thinsp;=\u0026thinsp;0.292) in the NTG group. Baseline intraocular pressure (IOP) was 14.25\u0026thinsp;\u0026plusmn;\u0026thinsp;2.21 mmHg (OD) and 14.09\u0026thinsp;\u0026plusmn;\u0026thinsp;2.24 mmHg (OS) in the Control group, versus 13.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99 mmHg (OD, p\u0026thinsp;=\u0026thinsp;0.365) and 14.10\u0026thinsp;\u0026plusmn;\u0026thinsp;2.31 mmHg (OS, p\u0026thinsp;=\u0026thinsp;0.975) in the NTG group. Ultrasound pachymetry was 531.03\u0026thinsp;\u0026plusmn;\u0026thinsp;32.73 \u0026micro;m (OD) and 530.43\u0026thinsp;\u0026plusmn;\u0026thinsp;33.91 \u0026micro;m (OS) in the control group, versus 532.16\u0026thinsp;\u0026plusmn;\u0026thinsp;35.24 \u0026micro;m (OD, p\u0026thinsp;=\u0026thinsp;0.814) and 531.75\u0026thinsp;\u0026plusmn;\u0026thinsp;33.85 \u0026micro;m (OS, p\u0026thinsp;=\u0026thinsp;0.783) in the NTG group.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical and Demographic Characteristics of Patients Included in the Study\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eControls (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNTG (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.74\u0026thinsp;\u0026plusmn;\u0026thinsp;8.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70.47\u0026thinsp;\u0026plusmn;\u0026thinsp;12.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.255\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender (Male %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.113\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorrected Visual Acuity OD (logMAR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.052\u0026thinsp;\u0026plusmn;\u0026thinsp;0.108\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.076\u0026thinsp;\u0026plusmn;\u0026thinsp;0.191\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.275\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorrected Visual Acuity OE (logMAR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.053\u0026thinsp;\u0026plusmn;\u0026thinsp;0.090\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.068\u0026thinsp;\u0026plusmn;\u0026thinsp;0.138\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.365\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAxial Length OD (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.260\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAxial Length OE (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.82\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.99\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.292\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpherical Equivalent OD (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.114\u0026thinsp;\u0026plusmn;\u0026thinsp;1.210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.364\u0026thinsp;\u0026plusmn;\u0026thinsp;1.479\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.191\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpherical Equivalent OE (D)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.099\u0026thinsp;\u0026plusmn;\u0026thinsp;1.281\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.309\u0026thinsp;\u0026plusmn;\u0026thinsp;1.355\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.263\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline IOP without Drops OD (mmHg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.25\u0026thinsp;\u0026plusmn;\u0026thinsp;2.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.365\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline IOP without Drops OE (mmHg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.09\u0026thinsp;\u0026plusmn;\u0026thinsp;2.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.10\u0026thinsp;\u0026plusmn;\u0026thinsp;2.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.975\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePachymetry OD (\u0026micro;m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e531.03\u0026thinsp;\u0026plusmn;\u0026thinsp;32.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e532.16\u0026thinsp;\u0026plusmn;\u0026thinsp;35.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.814\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePachymetry OE (\u0026micro;m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e530.43\u0026thinsp;\u0026plusmn;\u0026thinsp;33.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e531.75\u0026thinsp;\u0026plusmn;\u0026thinsp;33.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.783\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMD OD (dB)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.815\u0026thinsp;\u0026plusmn;\u0026thinsp;2.432\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-3.698\u0026thinsp;\u0026plusmn;\u0026thinsp;4.791\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMD OE (dB)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.900\u0026thinsp;\u0026plusmn;\u0026thinsp;2.754\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-3.954\u0026thinsp;\u0026plusmn;\u0026thinsp;4.781\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePseudophakic OD (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.567\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePseudophakic OE (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.775\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUse of Prostaglandin Drops (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD), except for categorical variables (percentages). OD: Right Eye; OE: Left Eye; IOP: Intraocular Pressure; MD: Mean Deviation.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, we described the comparison of corneal biomechanical properties between the two groups. The bIOP was 15.31\u0026thinsp;\u0026plusmn;\u0026thinsp;2.13 mmHg (OD) and 15.23\u0026thinsp;\u0026plusmn;\u0026thinsp;2.48 mmHg (OS) in the Control group, versus 14.08\u0026thinsp;\u0026plusmn;\u0026thinsp;2.17 mmHg (OD, p\u0026thinsp;=\u0026thinsp;0.00011) and 14.66\u0026thinsp;\u0026plusmn;\u0026thinsp;2.54 mmHg (OD, p\u0026thinsp;=\u0026thinsp;0.108) in the NTG group. We found statistical difference in Corneal velocity at second applanation (A2) with \u0026minus;\u0026thinsp;0.264\u0026thinsp;\u0026plusmn;\u0026thinsp;0.061 m/s (OD) and \u0026minus;\u0026thinsp;0.270\u0026thinsp;\u0026plusmn;\u0026thinsp;0.067 m/s (OS) in the control group, versus \u0026minus;\u0026thinsp;0.226\u0026thinsp;\u0026plusmn;\u0026thinsp;0.084 m/s (OD, p\u0026thinsp;=\u0026thinsp;0.0004) and \u0026minus;\u0026thinsp;0.223\u0026thinsp;\u0026plusmn;\u0026thinsp;0.079 m/s (OS, p\u0026thinsp;=\u0026thinsp;0.0001) in the NTG group. In addition, we found statistical difference in BGF between groups, with 0.568\u0026thinsp;\u0026plusmn;\u0026thinsp;0.239 (OD) and 0.560\u0026thinsp;\u0026plusmn;\u0026thinsp;0.229 (OS) in the control group, versus 0.674\u0026thinsp;\u0026plusmn;\u0026thinsp;0.212 (OD, p\u0026thinsp;=\u0026thinsp;0.001) and 0.659\u0026thinsp;\u0026plusmn;\u0026thinsp;0.231 (OS, p\u0026thinsp;=\u0026thinsp;0.056) in the NTG group.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorneal Biomechanics Properties from Controls and Normal Tension Glaucoma Patients.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eControls (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNTG (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ebIOP OD (mmHg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e15.31\u0026thinsp;\u0026plusmn;\u0026thinsp;2.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e14.08\u0026thinsp;\u0026plusmn;\u0026thinsp;2.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.110\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ebIOP OE (mmHg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e15.23\u0026thinsp;\u0026plusmn;\u0026thinsp;2.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e14.66\u0026thinsp;\u0026plusmn;\u0026thinsp;2.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.108\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSPA1 OD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e111.95\u0026thinsp;\u0026plusmn;\u0026thinsp;19.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e111.12\u0026thinsp;\u0026plusmn;\u0026thinsp;18.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.759\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSPA1 OE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e111.34\u0026thinsp;\u0026plusmn;\u0026thinsp;20.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e114.18\u0026thinsp;\u0026plusmn;\u0026thinsp;20.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.335\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSSI OD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.381\u0026thinsp;\u0026plusmn;\u0026thinsp;12.187\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.121\u0026thinsp;\u0026plusmn;\u0026thinsp;0.289\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.307\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSSI OE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.157\u0026thinsp;\u0026plusmn;\u0026thinsp;0.217\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.123\u0026thinsp;\u0026plusmn;\u0026thinsp;0.226\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.277\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDA Ratio OD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.507\u0026thinsp;\u0026plusmn;\u0026thinsp;0.619\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.570\u0026thinsp;\u0026plusmn;\u0026thinsp;0.775\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.528\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDA Ratio OE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.426\u0026thinsp;\u0026plusmn;\u0026thinsp;0.665\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.719\u0026thinsp;\u0026plusmn;\u0026thinsp;1.223\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.036\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eARTh OD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e644.70\u0026thinsp;\u0026plusmn;\u0026thinsp;515.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e610.62\u0026thinsp;\u0026plusmn;\u0026thinsp;252.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.557\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eARTh OE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e618.28\u0026thinsp;\u0026plusmn;\u0026thinsp;302.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e588.04\u0026thinsp;\u0026plusmn;\u0026thinsp;275.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.463\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorneal Velocity A1 OD (m/s)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.128\u0026thinsp;\u0026plusmn;\u0026thinsp;0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.127\u0026thinsp;\u0026plusmn;\u0026thinsp;0.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.836\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorneal Velocity A1 OE (m/s)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.134\u0026thinsp;\u0026plusmn;\u0026thinsp;0.071\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.124\u0026thinsp;\u0026plusmn;\u0026thinsp;0.030\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.227\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorneal Velocity A2 OD (m/s)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e-0.264\u0026thinsp;\u0026plusmn;\u0026thinsp;0.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e-0.226\u0026thinsp;\u0026plusmn;\u0026thinsp;0.084\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCorneal Velocity A2 OE (m/s)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e-0.270\u0026thinsp;\u0026plusmn;\u0026thinsp;0.067\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e-0.223\u0026thinsp;\u0026plusmn;\u0026thinsp;0.079\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHC DA OD (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e3.343\u0026thinsp;\u0026plusmn;\u0026thinsp;0.618\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.484\u0026thinsp;\u0026plusmn;\u0026thinsp;0.746\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.149\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHC DA OE (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e3.364\u0026thinsp;\u0026plusmn;\u0026thinsp;0.708\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.436\u0026thinsp;\u0026plusmn;\u0026thinsp;0.813\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.504\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBGF OD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.568\u0026thinsp;\u0026plusmn;\u0026thinsp;0.239\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.674\u0026thinsp;\u0026plusmn;\u0026thinsp;0.212\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBGF OE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.560\u0026thinsp;\u0026plusmn;\u0026thinsp;0.229\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.659\u0026thinsp;\u0026plusmn;\u0026thinsp;0.231\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.056\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). Legends: Normal-Tension Glaucoma (NTG) group. OD: Right Eye; OE: Left Eye; bIOP: Biomechanically Corrected Intraocular Pressure; SPA1: Stiffness Parameter at First Applanation; SSI: Stress-Strain Index; DA Ratio: Deformation Amplitude Ratio; ARTh: Adjusted Radius of Highest Concavity Time (interpreted from ArtH); HC DA: Highest Concavity Deformation Amplitude. BGF: Biomechanical Glaucoma Factor\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe receiver operating characteristic curves of BGF for discriminating NTG eyes from normal eyes are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The area under the receiver operating characteristic curves (AUC) value was 0.63 for BGF, considering pooled eyes (any eye positive), with a cut-off value of 0.74 from BGF to discriminate healthy eyes from NTG ones (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCut-ff values for biomechanical glaucoma factor for discriminating suspects from glaucomatous eyes.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCut-off\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eYouden J\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAUC\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBGF OD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.257\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.634\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBGF OS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.247\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.629\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean (OD\u0026thinsp;+\u0026thinsp;OS)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.267\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.398\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.869\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.645\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePooled eyes (any eye positive)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.252\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.485\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.632\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eBGF: biomechanical glaucoma factor; OD: right eye; OS: left eye; AUC: area under the curve\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eEarlier studies have reported significant differences in corneal biomechanical properties between glaucoma and normal eyes. \u003csup\u003e5,7,9\u003c/sup\u003e Most studies have been performed by comparing corneal parameters between confirmed glaucomatous patients from healthy individuals with normal excavations in a cross-sectional design. However, clinicians are most interested in the ability of a new test to provide additional information that can be helpful in a patient who presents suspicious findings for the disease, such as apparent enlarged cupping. \u003csup\u003e10\u003c/sup\u003e Thus, the current study used corneal biomechanical parameters from Corvis ST and has focused on treatment na\u0026iuml;ve newly diagnosed NTG patients versus a control group of glaucoma suspect eyes. We have found statistical differences in corneal velocity at second applanation and BGF values between both groups. Moreover, the AUC from BGF parameter for discriminating NTG from normal eyes was 0.63.\u003c/p\u003e \u003cp\u003eThe biomechanical environment of the eye is increasingly recognized as a determinant of glaucoma susceptibility. Although IOP is the most important modifiable risk factor, the way tissues respond to this load is highly individualized. \u003csup\u003e11\u003c/sup\u003e Factors such as tissue stiffness, viscoelasticity, collagen microarchitecture, and extracellular matrix remodeling dictate how forces are absorbed and transmitted throughout the eye. \u003csup\u003e12,13\u003c/sup\u003e Thus, two patients with identical IOP values may experience profoundly different levels of strain at the lamina cribrosa (LC) and optic nerve head (ONH), explaining interindividual variability in glaucoma progression\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. The cornea provides a practical and accessible window to study ocular biomechanics. Unlike static measures such as central corneal thickness, the Corvis-ST derived parameters capture the cornea\u0026rsquo;s real-time viscoelastic response, offering richer information about ocular biomechanical properties. Importantly, these responses are not isolated to the cornea itself but are believed to reflect the integrated biomechanical phenotype of the entire globe. A key concept underpinning this interpretation is the notion of structural continuity between the cornea, sclera, and LC. \u003csup\u003e13\u003c/sup\u003e These tissues form a continuous fibrous shell, dominated by type I collagen fibrils that are organized differently but connected in function. While the cornea exhibits highly ordered lamellae optimized for transparency, the sclera has a more irregular and interwoven collagen arrangement that provides mechanical strength, and the LC contains a cribriform plate structure through which retinal ganglion cell axons pass. \u003csup\u003e16\u003c/sup\u003e Despite regional differences, this shell acts as a single biomechanical unit: loads applied at one point are distributed and absorbed across the system. \u003csup\u003e17,18\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eClinical and experimental evidence supports this continuity. \u003csup\u003e19\u0026ndash;22\u003c/sup\u003e Studies using ocular response analyzers and in vivo imaging have demonstrated that lower corneal hysteresis (CH) is associated with deeper and more compliant ONHs, and with measurable LC displacement after surgical IOP reduction. \u003csup\u003e23\u0026ndash;25\u003c/sup\u003e These findings highlight that corneal biomechanical properties are not mere epiphenomena but rather biomarkers of how the posterior segment will react under stress. \u003csup\u003e26\u003c/sup\u003e Reduced CH and CRF suggest a structurally \u0026ldquo;softer\u0026rdquo; ocular wall, transmitting higher levels of strain to axons even at normal IOP values. This biomechanical vulnerability is particularly relevant in NTG. \u003csup\u003e27\u003c/sup\u003e In these patients, the absolute level of IOP may not exceed the statistical cutoff of 21 mmHg, but the effective stress reaching the LC may still be pathological if the supporting tissues are less capable of absorbing load. In other words, NTG eyes may operate with a lower threshold of biomechanical tolerance. \u003csup\u003e28\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe BGF was developed based on dynamic corneal response deformation and corneal thickness parameters, to discriminate between healthy and NTG patients. \u003csup\u003e29\u003c/sup\u003e The BGF included deformation amplitude ratio progression (DARatioProg), which describes the increase of the ratio between the deformation amplitude measured in the centre compared to the periphery. HCTime, which measures the time until maximum deformation after application of the air pulse is reached. Pachymetry slope, which describes the difference in corneal thickness from the centre towards the periphery. bIOP, which is a measure of intraocular pressure that corrects for corneal thickness, corneal response parameters and age and pachymetry, derived from the Scheimpflug imaging of the Corvis ST. \u003csup\u003e30\u003c/sup\u003e We found statistical difference in BGF between groups, with 0.568\u0026thinsp;\u0026plusmn;\u0026thinsp;0.239 (OD) and 0.560\u0026thinsp;\u0026plusmn;\u0026thinsp;0.229 (OS) in the control group, versus 0.674\u0026thinsp;\u0026plusmn;\u0026thinsp;0.212 (OD, p\u0026thinsp;=\u0026thinsp;0.001) and 0.659\u0026thinsp;\u0026plusmn;\u0026thinsp;0.231 (OS, p\u0026thinsp;=\u0026thinsp;0.056) in the NTG group.\u003c/p\u003e \u003cp\u003eIn clinical practice, the proper diagnosis of NTG can be challenging. The current study tried to replicate the clinical dilemma that we face when dealing with glaucoma suspect eyes and IOP below 21mmHg. In these cases, any additional parameter that could discriminate a healthy from a glaucomatous patients can be helpful. We found an AUC of 0.63 when considering BGF from pooled eyes (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). BGF is a relatively novel Corvis ST index that was devloped to distinguish eyes with NTG from normal eyes. \u003csup\u003e29\u003c/sup\u003e Pillunat et al have reported an AUC of 0.814 to distinguish glaucoma eyes from normal eyes. However, Aoki et al have reported lower AUC value (0.61). \u003csup\u003e9\u003c/sup\u003e It is important to highlight that Aoki et al have included a broader spectrum of POAG patients in contrast to the original study from Pillunat in which BGF was developed, that included only NTG patients. In addition, Aoki et al have included patients under hypotensive treatment which could have led to changes in other biomechanical measures such as DARatioProg and HCtime. This IOP reduction could have weakened the potential relationship between BGF and POAG in their findings. In contrast, our study have included only treatment naive NTG patients, eliminating the bias of possible changes in corneal biomechanics from IOP reduction.\u003c/p\u003e \u003cp\u003eThe Corvis ST automatically calculates the time and length of the cornea deformations and the instantaneous speed of corneal movement at the two applanation states (during inward and outward). The applanation times, lengths, and velocities are recorded during the inward (first applanation, designated and outward (second applanation, designated #2) phases of corneal applanation. \u003csup\u003e31\u003c/sup\u003e The corneal velocity #2 is the outward applanation velocity. (the instantaneous speed of the cornea as it returns to its original, undisturbed state) \u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e We found statistical difference in corneal velocity at second applanation (A2) with \u0026minus;\u0026thinsp;0.264\u0026thinsp;\u0026plusmn;\u0026thinsp;0.061 m/s (OD) and \u0026minus;\u0026thinsp;0.270\u0026thinsp;\u0026plusmn;\u0026thinsp;0.067 m/s (OS) in the control group, versus \u0026minus;\u0026thinsp;0.226\u0026thinsp;\u0026plusmn;\u0026thinsp;0.084 m/s (OD, p\u0026thinsp;=\u0026thinsp;0.0004) and \u0026minus;\u0026thinsp;0.223\u0026thinsp;\u0026plusmn;\u0026thinsp;0.079 m/s (OS, p\u0026thinsp;=\u0026thinsp;0.0001) in the NTG group. A less deformable cornea is thought to reach inward applanation slower and reach outward applanation faster, with higher outward velocity. \u003csup\u003e33\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eWe did not find statistical differences regarding other parameters such as: bIOP, SPA1, SSI, DA ratio, ARTh, corneal velocity at first applanation and HC DA. The Corvis ST device can measure up to 37 different parameters. Unfortunately, across several studies evaluating corneal biomechanical properties in glaucoma, some parameters present with statistical difference, whereas other do not. \u003csup\u003e31\u003c/sup\u003e This disagreement between different studies can be explained by several factors. Most of the studies are limited by the inclusion of glaucoma subjects under hypotensive treatment, which may alter corneal biomechanics and contribute to contradicting results. Lack of proper stratification of patients (high versus normal tension glaucoma) can lead to misinterpretation of the results based on factors that are confounded by intraocular pressure changes. Finally, it is important to note that corneal biomechanical properties are dynamic metrics and can change over time with age, corneal trauma, or surgery. \u003csup\u003e31\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe current study has several strengths as both NTG and controls had no statistical differences in IOP, age, corneal thickness, and axial length. In addition, we have excluded patients who underwent corneal surgeries and all Corvis ST measurement were taken in newly diagnosed treatment na\u0026iuml;ve patients, which minimize any bias from artificial IOP reduction. However, we acknowledge several limitations. First, the cross-sectional nature of our study design did not allow assessment of causation or prospective prediction of glaucoma risk but rather only established a difference in corneal biomechanical parameters between NTG and control group. Second, as glaucoma is in general an aging disease some subjects in the control group can develop glaucoma in the future, even though, we have monitored those patients for at least two years with normal visual fields and normal retinal nerve fiber layer thickness from OCT. Third, we only found differences in BGF and corneal velocity and further investigation with a larger sample size may increase the power of the study to detect differences in other parameters.\u003c/p\u003e \u003cp\u003eIn conclusion, we identified corneal biomechanical differences between NTG and a group of glaucoma suspect eyes. Clinically, these findings underscore the value of integrating corneal biomechanical assessment when diagnosing NTG. Parameters such as BGF and corneal velocity at second applanation should not be interpreted as stand-alone diagnostic criteria, but rather as biomechanical risk biomarkers. Their value lies in refining risk stratification, identifying patients who may progress despite apparently controlled IOP, and informing individualized follow-up protocols.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003eThis was a multicenter retrospective study carried out in 2 different eye centers in Brazil. Hospital Oftalmol\u0026oacute;gico de Bras\u0026iacute;lia in Bras\u0026iacute;lia and Hospital de Medicina dos Olhos in Osasco, S\u0026atilde;o Paulo. Eligible patients had newly diagnosed, untreated glaucoma in both eyes identified at two different eye centers across Brazil between January 2024 and January 2025. We included only treatment na\u0026iuml;ve, newly diagnosed glaucoma patients aged over 18 years old. Patients with previous diagnosis of glaucoma performed in other centers or already under treatment were not included in this protocol. We also excluded patients with previous corneal and glaucoma surgeries, retinal diseases, corneal opacity, or any other opacity disease that could significantly affect visual field outcomes.\u003c/p\u003e \u003cp\u003e The study protocol was revised and approved by the Institutional Review Board from the Hospital Oftalmol\u0026oacute;gico de Bras\u0026iacute;lia (IRB number: 75438823.1.0000.5667). All study methods complied with the Declaration of Helsinki guidelines for human subject research. Informed consent from each patient was not required due to the retrospective nature of the study being waived by the Institutional Review Board from the Hospital Oftalmol\u0026oacute;gico de Bras\u0026iacute;lia. We collected data from electronic charts regarding ophthalmologic examinations including review of medical history, visual acuity, slit-lamp biomicroscopy, intraocular pressure (IOP) measurement (Goldmann tonometer), gonioscopy (Posner goniolens), ocular biometry (IOL Master, Carl Zeiss Meditec, Inc, Dublin, CA), ultrasound pachymetry, dilated fundoscopic examination with 78 diopters lens, and optic disc photography.\u003c/p\u003e \u003cp\u003eSubjects underwent standard automated perimetry (SAP) using the 24\u0026thinsp;\u0026minus;\u0026thinsp;2 Swedish interactive threshold algorithm (Humphrey Field Analyzer 3, 840; Carl Zeiss Meditec, Inc, Dublin, CA). The diagnosis of NTG was based on the presence of repeatable (at least two consecutive) abnormal SAP results with corresponding evidence of glaucomatous optic neuropathy in at both eyes and at least 3 IOP measurements \u0026lt;\u0026thinsp;21mmHg, without any hypotensive medication (as patients were newly diagnosed). An abnormal SAP result was defined as a pattern standard deviation with P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, and/or glaucoma hemifield test results outside normal limits. \u003csup\u003e34\u003c/sup\u003e We evaluated more than one visual field per patient if the first exam was not reliable to minimize learning effects. We applied a cutoff of 20% of false-positives or negatives and a cutoff of 20% for fixation losses to define an exam as unreliable. \u003csup\u003e35\u003c/sup\u003e We accepted a cutoff of 33% for false negatives in cases of advanced disease confirmed with retinography and extensive loss of retinal nerve fiber layer (RNFL) on optical coherence tomography (OCT) evaluation. \u003csup\u003e36\u003c/sup\u003e We used measurement of RNFL (using superior temporal, global and inferior temporal RNFL thickness and assessing correlation with optic nerve and visual field findings) from OCT to confirm glaucoma diagnosis (Avantis, Optovue, Fremont, CA). \u003csup\u003e10,37\u003c/sup\u003e According to Hodapp-Parrish-Anderson criteria, glaucoma patients were categorized as mild [mean deviation (MD): \u0026ge; \u0026minus;6 dB], moderate (-12dB\u0026thinsp;\u0026lt;\u0026thinsp;MD \u0026lt;-6dB) and advanced (MD\u0026lt;-12dB). \u003csup\u003e34\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe control group was defined as: subjects with excavation\u0026thinsp;\u0026gt;\u0026thinsp;0.6, but normal IOP (below 21mmHg), normal visual field and normal OCT RNFL thickness, without family history of glaucoma, followed for at least two years, without changes in the exams.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCorvis ST Measurements\u003c/h3\u003e\n\u003cp\u003eThe principles of Corvis ST have been described in detail elsewhere. \u003csup\u003e29\u003c/sup\u003e Briefly, the tonometer\u0026rsquo;s camera records a sequence of images of corneal deformation, capturing 4330 images per second. All study subjects had measurements collected by the same operator, and without dilation. Only exams with adequate quality score were included. After each Corvis measurement, the data output was confirmed by reviewing the film to ensure that numbers for instantaneous velocities, applanation lengths, and times corresponded to true values. \u003csup\u003e32\u003c/sup\u003e Corvis measurements that failed to correspond to true applanation states and highest concavity time points were considered unreliable, and were not used in this study. We used the Corvis ST software version 1.3r1538 and the following parameters were recorded: biomechanically compensated IOP (bIOP), stiffness parameter at first applanation (SPA1), stress-strain index (SSI), deformation amplitude ratio (DA Ratio), adjusted radius of highest concavity time (ARTh), corneal velocity at first applanation (A1), corneal velocity at second applanation (A2), highest concavity deformation amplitude (HC DA) and biomechanical glaucoma factor (BGF).\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eFor continuous variables with normal distribution, the Student\u0026rsquo;s \u003cem\u003et\u003c/em\u003e test was used, and the Wilcoxon signed rank test was employed for continuous variables that were not normally distributed. Categorical variables were analyzed using with the Chi-square or Fischer exact tests. The discrimination ability of BGF was investigated through the area under the receiver operating characteristics curve (AUC). \u003csup\u003e38\u003c/sup\u003e Statistical analysis and artwork were performed using Stata, version 13 (StataCorp LP, College Station, Texas, USA). The alpha level (type I error) was set at 0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFinancial Support\u003c/p\u003e\n\u003cp\u003eNone.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors Contributions Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eEJRG and RYA have made substantial contributions to the conception and design of the work.\u003c/p\u003e\n\u003cp\u003eEJRG, ICTA, JSP, MM, WTH, TP and RYA have made substantial contributions to the acquisition, analysis, and interpretation of data.\u003c/p\u003e\n\u003cp\u003eEJRG, ICTA, JSP, MM, WTH, TP and RYA have drafted the work or substantively revised it.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eData availability\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eEsporcatte, B. 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Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. \u003cem\u003eBiometrics\u003c/em\u003e \u003cb\u003e44\u003c/b\u003e, 837\u0026ndash;845 (1988).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Normal Tension, Corneal Biomechanics, Glaucoma, Corvis ST","lastPublishedDoi":"10.21203/rs.3.rs-8995481/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8995481/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMulticenter retrospective study to evaluate differences in corneal biomechanical parameters provided by Corvis ST to segregate those with normal tension glaucoma (NTG) from glaucoma suspects. We included only newly diagnosed and treatment na\u0026iuml;ve glaucoma patients. Several corneal biomechanical parameters provided by Corvis ST were investigated. The discrimination ability of BGF was investigated through the area under the receiver operating characteristics curve (AUC). We included a total of 200 eyes from 100 patients with NTG and 200 eyes from 100 controls. We found statistical difference in Corneal velocity at second applanation (A2) with \u0026minus;\u0026thinsp;0.264\u0026thinsp;\u0026plusmn;\u0026thinsp;0.061 m/s (OD) and \u0026minus;\u0026thinsp;0.270\u0026thinsp;\u0026plusmn;\u0026thinsp;0.067 m/s (OS) in the control group, versus \u0026minus;\u0026thinsp;0.226\u0026thinsp;\u0026plusmn;\u0026thinsp;0.084 m/s (OD, p\u0026thinsp;=\u0026thinsp;0.0004) and \u0026minus;\u0026thinsp;0.223\u0026thinsp;\u0026plusmn;\u0026thinsp;0.079 m/s (OS, p\u0026thinsp;=\u0026thinsp;0.0001) in the NTG group. In addition, we found statistical difference in biomechanical glaucoma factor (BGF) between groups, with 0.568\u0026thinsp;\u0026plusmn;\u0026thinsp;0.239 (OD) and 0.560\u0026thinsp;\u0026plusmn;\u0026thinsp;0.229 (OS) in the control group, versus 0.674\u0026thinsp;\u0026plusmn;\u0026thinsp;0.212 (OD, p\u0026thinsp;=\u0026thinsp;0.001) and 0.659\u0026thinsp;\u0026plusmn;\u0026thinsp;0.231 (OS, p\u0026thinsp;=\u0026thinsp;0.056) in the NTG group. The AUC value was 0.63 BGF for discriminating NTG eyes from normal eyes. Both BGF and corneal velocity at second applanation were statistically different between groups. Using BGF parameter from Corvis ST can improve diagnostic accuracy when dealing with NTG.\u003c/p\u003e","manuscriptTitle":"Differences in Corneal Biomechanical Parameters in Normal Tension Glaucoma versus Normotensive Glaucoma Suspect Eyes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-15 16:50:02","doi":"10.21203/rs.3.rs-8995481/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-10T05:38:40+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-07T13:05:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-21T03:05:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"146582868409527787186569643983217548438","date":"2026-03-17T01:06:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"210985989365339868236175514741780175055","date":"2026-03-10T13:56:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-10T03:57:39+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-10T03:43:01+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-09T16:41:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-07T11:30:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-03-07T11:25:24+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9bfa1738-50c4-48d8-a558-4c2b16c55a7f","owner":[],"postedDate":"March 15th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[{"id":64364174,"name":"Health sciences/Diseases"},{"id":64364175,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2026-04-10T05:54:44+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-15 16:50:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8995481","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8995481","identity":"rs-8995481","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}