Effect of perfusion pressure sensors on posterior capsule elevation in the porcine eye model with eyelid speculums

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The mean intraocular pressure of the porcine eyes with the ES was significantly higher than that of without the ES (15.42 ± 4.10 mmHg vs. 21.86 ± 4.12 mmHg, P = 0.0003). Changes in the posterior capsule elevation were observed using the slit side view method in the following four groups: with an ES using AS [AS (ES+)], without an ES using AS [AS (ES−)], with an ES using the Ozil handpiece [OZ (ES+)], and without an ES using OZ [OZ (ES−)]. Eleven eyes in each group were tested. AS (ES+) and OZ (ES+) had a significantly higher rate of posterior capsule elevation than did AS (ES−) and OZ (ES−) (P = 0.135 and P = 0.010). AS (ES+) and AS (ES−) significantly suppressed posterior capsule elevation compared with OZ (ES+) and OZ (ES−) (P = 0.034 and P = 0.045). Porcine eyes with ES had increased IOP and greater posterior capsule elevation after occlusion break than did those without. AS effectively suppressed posterior capsule elevation better than did OZ. Health sciences/Medical research Health sciences/Risk factors Posterior capsule elevation Active Sentry Intraocular pressure Eyelid speculum Phacoemulsification and aspiration Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction With advances in ultrasonic cataract surgery devices developed by Kelman [ 1 ], cataract surgery has become minimally invasive and has doubled as refractive surgery. However, prevention of posterior capsule rupture is particularly important as current intraocular lenses are based on intracapsular fixation, and complications, such as posterior capsule rupture, can result in reduced quality of vision. One of the causes of posterior capsule rupture is an unstable anterior chamber and posterior capsule elevation caused by a surge after an occlusion break of the ultrasonic tip [ 2 , 3 ]. Whether this occlusion break surge causes the posterior capsule to move depends on the surgical case, and it is difficult to identify which cases are likely to experience posterior capsule movement before surgery. Movement of the posterior capsule is thought to be caused by several factors. One of these is anatomical changes in the posterior capsule and anterior vitreous, such as detachment of the posterior capsule and anterior vitreous [ 4 ]. The other is external pressure on the eye due to factors such as muscular force on the tissue and placement of an eyelid speculum (ES). Placing an ES, blinking, or opening the eyes wide can increase the intraocular pressure (IOP) [ 5 – 9 ]. However, no studies have examined how external pressures, such as that from an ES, affect the posterior capsule. We previously reported anterior chamber movements using the slit side view (SSV) method, which allows intraoperative observation of anterior chamber movements using a slit-lamp microscope [ 10 – 12 ]. Using this system, changes in the anterior chamber depth can be quantified. In this context, we evaluated the anterior chamber stability using Active Fluidics™ of the Centurion® Vision System (Centurion) (Alcon Vision LLC, Fort Worth, TX, USA), an active perfusion system, and an Active Sentry® handpiece (AS) (Alcon Vision LLC, Fort Worth, TX, USA), an ultrasound handpiece with an integrated perfusion pressure sensor, and found that these systems demonstrated high anterior chamber stability [ 11 ]. This is largely owing to the development of ultrasonic cataract surgery systems that actively supply Balanced Salt Solution® Plus (BSS) (Alcon Vision LLC, Fort Worth, TX, USA) into the eye. However, even with these systems, there are cases wherein the posterior capsule can become unstable during cataract surgery, even with an active supply of BSS to the anterior chamber of the eye. We hypothesized that external pressures, such as those from an ES, would result in greater posterior capsule elevation in a porcine eye model of an ES. We used the SSV method to experimentally investigate the extent to which the posterior capsule moved owing to IOP changes after an occlusion break. In addition, the effects of Centurion with AS on reducing posterior capsule elevations were examined. Results Porcine Eye with Simulated Eyelid Model The mean IOP of the porcine eyes with and without an ES is shown in Figure 1. The mean IOP was 15.42 ± 4.10 and 21.86 ± 4.12 mmHg in porcine eyes without and with an ES, respectively (P = 0.0003). Change Ratio in Posterior Capsule Elevation Posterior capsule elevation ratios in porcine eyes with and without an ES are shown in Fig. 2a and 2b. The posterior capsule elevation ratio in the AS (ES−) group (5.5 ± 2.3%) was significantly lower than that in the AS (ES+) group (18.0 ± 19.1%) (P = 0.0135). In addition, the posterior capsule elevation ratio was significantly lower in the OZ (ES−) group (21.2 ± 19.9%) than that in the OZ (ES+) group (46.2 ± 20.2%) (P = 0.010). Comparing posterior capsule elevation rates between phacoemulsification and aspirations (PEAs), AS showed significantly lower posterior capsule elevation rates than did OZ, regardless of ES attachment (Fig. 3a and 3b; P = 0.0034 and 0.0045, respectively). Effect of IOP Increases in Porcine Eyes With an ES The posterior capsule elevation ratio in the AS (ES+) group at IOPs of 20, 30, and 40 mmHg was 18.0 ± 19.1%, 13.4 ± 8.9%, and 7.5 ± 6.5%, respectively (Fig. 4a). There were significant differences in the ratio between 20 and 40 mmHg, and 30 and 40 mmHg (P = 0.0234 and 0.0135, respectively). The posterior capsule elevation ratio in the OZ (ES+) group at IOPs of 20, 30, and 40 mmHg was 46.2 ± 20.2%, 19.4 ± 16.3%, and 11.7 ± 9.0%, respectively (Fig. 4b). There were significant differences in the ratio between 20 and 30 mmHg, 20 and 40 mmHg, and 30 and 40 mmHg (P = 0.0135, 0.0135, and 0.0234, respectively). Discussion An ES is useful for maintaining the opening of an eyelid; however it not only causes tension in patient but may also interfere with the elasticity of the eyeball by touching the eyeball itself, which may increase pressure within the eye. We considered external pressures on the eye, such as ES placement, to be one of the factors causing elevation of the posterior capsule during cataract surgery. To intentionally create such an external pressure, we created a model in which porcine eyes were subjected to an ES to evaluate posterior capsule elevation. In this experimental model, the mere use of an ES significantly increased the IOP. An ES and artificial eyelids (rubber band) in contact with the outside of the porcine eyeball could reduce the elasticity of the eyeball against the force pushing it outwards in response to changes in the IOP, resulting in increased IOP. In our experiment, the IOP of the porcine eye model before applying an ES was 15.42 ± 4.10 mmHg and 21.86 ± 4.12 mmHg after applying an ES, resulting in an IOP increase of approximately 6 mmHg. Considering that previous clinical reports have reported IOP differences of 1.9 to 7.71 mmHg before and after ES placement [ 6 – 8 ], it can be said that we successfully reproduced the condition of the eye with a clinical ES in the porcine eye. We then quantitatively measured the elevation of the posterior capsule after occlusion break in porcine eyes with and without an ES. We found that the rate of posterior capsule elevation after occlusion break was significantly greater in porcine eyes with an ES than in those without an ES, regardless of the PEA type. When an occlusion break surge occurs, the IOP of the anterior chamber is lowered; difference in the IOP between the anterior chamber and vitreous is large; and elastic force pushes the posterior capsule upward. The reason the posterior capsule elevation rate was higher in porcine eyes with an ES than in those without may be the increased elasticity of the vitreous side following an increase in the IOP in the anterior segment due to ES placement. During cataract surgery, the posterior capsule may be elevated for unknown reasons. Based on the results in the current study, an increase in IOP due to external factors such as ES is thought to be involved. In addition, we increased the anterior chamber IOP from 20 to 30 and 40 mmHg to confirm how the IOP setting could affect posterior capsule elevation after occlusion break. The rate of posterior capsule elevation decreased in both PEA types as the IOP increased. We attribute this to the fact that by increasing the IOP in the anterior chamber, the difference in the IOP after occlusion break between the anterior and vitreous sides became smaller, which suppressed posterior capsule elevation. Of note, the standard deviation was higher at a lower IOP. This is because the compliance of the eye was reported to be hyperbolic in nature; the lower the IOP was, the higher the compliance of the eye was [ 13 ]. A comparison of posterior capsule elevation rates after occlusion break between the AS and OZ groups showed that the posterior capsule elevation rate was smaller in the AS than that in the OZ group, regardless of ES attachment. This indicated that AS provided better posterior capsule stability than did the conventional handpiece, even when affected by external pressure. In addition, the posterior capsule elevation rate for AS being less than half that of OZ would allow the surgeon to manage the surgery safely and efficiently. In this study, to evaluate the effect of the AS sensor alone, we adjusted for confounding factors such as leakage from incision. However, in clinical practice, there is a leakage from incision wound, which may increase the amplitude of post-occlusion surge, and posterior capsule elevation of AS should be clinically evaluated. We previously reported that the change in anterior chamber depth after occlusion breaks in porcine eyes was smaller in the AS than that in the OZ groups [ 11 ]. Vasavada et al. also showed that the rate of IOP recovery after an occlusion break was faster with Centurion with AS than without AS [ 14 ]. The reason for the smaller posterior capsule elevation as well as the change in anterior chamber depth may be that the perfusion pressure sensor in the AS handpiece instantly detected IOP fluctuations and actively reduced the post-occlusion surge using an active surge mitigation mechanism. In other words, this feature instantly compensates for the IOP difference between the anterior chamber and vitreous side, contributing to the reduction in posterior capsule elevation. When pressure from the vitreous side is high, increasing pressure from the anterior chamber side to some extent is necessary; the results of this study showed that increasing the IOP could also reduce posterior capsule elevation. However, it has been previously reported that the intraoperative IOP should be low for minimally invasive ocular tissues [ 15 – 20 ]. Wenzel et al. found that intermittent irrigation and aspiration without phacoemulsification in porcine eyes at different bottle height (BH) resulted in greater relative corneal endothelial cell loss at higher BH [ 21 ]. Liu et al and our previous study have also shown that lower IOP and BH during cataract surgery result in less loss of corneal endothelial cell density [ 15 , 16 ]. These reports indicate that corneal endothelial cells may be more susceptible to damage in association with high IOP. The author of the present study usually recommends cataract surgery with a low IOP setting. However, but if the posterior capsule movement is judged to be unstable when the number of nuclei in the lens capsule decreases during cataract surgery with a low IOP setting, the author suggests that temporarily increasing the IOP could be effective in suppressing posterior capsule elevation and preventing posterior capsule breakage. Since the present study had a bit small sample size and used an experimental model using porcine eyes and simulated eyelids, which is also different from that of the actual human eye in the orbit, whether the artificial eyelids with rubber bands reproduced the actual clinical situation remains unclear. Since facial morphology differs according to race, the condition of the ES touching the eye is also likely to vary according to the shape of the face and eyelid and the effects of local anesthesia are not taken into account. Furthermore, since the extracted porcine eye was postmortem eyes that lacked dynamic responses of living tissues, the posterior capsules might behave differently in clinical cases. Future studies using human eyes to further evaluate posterior capsule movement are necessary. In addition, there are reports indicating that the IOP varies depending on the form of the ES, whether it is a screw or spring type [ 8 ]; it will be necessary to examine intraoperative IOP variation depending on the form of the eyelid speculum and the width of the speculum in the future. Anatomical changes between the vitreous and posterior capsules within the eye are also thought to alter the movement of the posterior capsule; therefore, the presence or absence of the vitreous must also have been considered. In conclusion, this study experimentally investigated the movement of the posterior capsule after an occlusion break using an ES. After occlusion break, the posterior capsule was more elevated in porcine eyes that were intentionally pressured with an ES than in porcine eyes without ES placement. In addition, AS was able to suppress the movement of the posterior capsule after occlusion break, even when the anterior IOP was increased by applying an ES. However, it was suggested that the IOP setting itself was also a factor that caused the posterior capsule to move intensely, suggesting that it is necessary in the future to develop a device that can respond realistically to fluctuations in the IOP during actual surgery to avoid posterior capsule elevation. Methods Ethical Considerations Since this study used enucleated porcine eyeballs obtained from a local slaughterhouse, the ARVO Statement for the Use of Animals in Ophthalmology and Vision was not required. The Ethics Committee (Zegyo Suzuki Eye Clinic ethics committee) ruled that approval was not required for this study. Preparation and Evaluation of the Porcine Eye Model of an ES Freshly extracted whole porcine eyes were obtained from a local slaughterhouse (Tokyo Shibaura Organ Corporation, Tokyo, Japan) and stored in a controlled laboratory. The whole eyes used in this study were shipped to the laboratory within 1 day of storage. Porcine eyes without obvious ocular damage, corneal opacities, or vitreous leakage were selected for this study. To create a porcine eye model of an ES, a rubber band with a diameter of 26 mm was used as the simulated eyelid. The rubber band was stretched horizontally by 35 mm, centered on the porcine corneal apex, and both ends of the rubber band were fixed to a porcine eye folder. A screw-type ES was then hooked to a rubber band, and the rubber band was vertically extended 18 mm, which is the maximum eyelid opening width of the ES, to create a porcine eye model of an ES (Fig. 5a). To confirm that the porcine eye with an ES had an increased IOP compared with the porcine eye before ES placement, as clinically reported, changes in the IOP were tested in five porcine eyes before and after ES application. Under an ophthalmic microscope (LuxOR Revalia; Alcon Vision LLC, Fort Worth, TX, USA), a 2.4-mm corneal incision was first created in the porcine eye before an ES was attached, and the crystalline lens was removed using the PEA technique with Centurion with AS. Hydration was ensured to prevent leakage from incision. A 25-gauge sharp needle was inserted into the cornea of the porcine eye, and BSS was injected into the anterior chamber to inflate it. A pressure transducer (IX-TA-220 Recorder with Integrated Sensors: iWorx, Dover, NH, USA) was used to measure the IOP in the porcine eye without ES attachment, according to a previously reported procedure [11] . The IOP was then measured and recorded in the same manner as when the ES was attached to the porcine eye. Phacoemulsification Systems Used for Evaluating Posterior Capsule Elevation Two different PEA systems were used: Centurion with Active Fluidics TM and AS, and Centurion with Active Fluidics TM and an Ozil handpiece (OZ) (Alcon Vision LLC, Fort Worth, TX, USA). The Active Fluidics TM technology in the Centurion compresses the BSS bag with two plates, and the more fluid the surgeon removes from the anterior chamber, the more it compresses the bag, replenishes the removed volume, and compensates for flow losses. Thus, irrigation adapts to aspiration at each step of cataract surgery, and the pressure in the anterior chamber is maintained consistently. AS has an integrated pressure sensor that responds in real time. When the onset of occlusion is detected, the AS system vents the aspiration line without affecting the holding power of the lens material at the distal end of the tip, thereby reducing the post-occlusion surge because less fluid is pulled from the eye owing to the reduced vacuum demand during automated surge mitigation. Therefore, AS technology allows for faster mitigation of the surge response and ensures stability of the anterior chamber [22,23]. Evaluation of Posterior Capsule Elevation In this experimental study, to evaluate posterior capsule elevation, 4 groups were tested with 11 porcine eyes per group. The porcine eye model groups were as follows: with an ES tested using AS [AS (ES+)], without an ES tested using AS [AS (ES–)], with an ES tested using OZ [OZ (ES+)], and without an ES tested using OZ [OZ (ES–)]. A 2.4-mm corneal incision was first created in the porcine eye, and the crystalline lens was removed using the PEA technique with Centurion with AS under a microscope. After injecting a cohesive ophthalmic viscosurgical device (OVD) (Provisc; Alcon Vision LLC, Fort Worth, TX, USA) into the anterior chamber, the porcine eye was moved onto a slit-lamp microscope stand and fixed. A phaco tip was inserted through a corneal incision and stabilized over the iris surface, and PEA was performed in each group. To minimize variations between PEA systems, a 0.9-mm mini-flared 45° Kelman aspiration bypass system phaco tip and UltraSleeve (Alcon Vision LLC, Fort Worth, TX, USA) were used for both PEA systems. To minimize incision leakage and ensure that it did not affect the movement of the posterior capsule, we vertically fixed the PEA handpiece and porcine eyes on a fixed table. Both PEA systems were used in my daily clinical setting with a target IOP setting of 20 mmHg, aspiration rate of 22 mL/min, vacuum limit of 320 mmHg, and ultrasonic oscillation setting of 0%. After pressing on a foot pedal to replace the OVD in the anterior chamber with BSS, the aspiration tube was pinched with pliers, occluded for 3 seconds, and then released for 3 seconds. This procedure was repeated three times. To ensure reproducibility, these procedures were performed by the same surgeon. Posterior capsule elevations were observed during the occlusion break using the SSV method and continuously recorded. These methods were performed according to the established procedure described in our previous reports [10,11]. In porcine eyes with an ES, after testing for posterior capsule elevation at an IOP of 20 mmHg, posterior capsule elevation was also evaluated at IOPs of 30 and 40 mmHg (parameters other than IOP were not changed) to assess whether the elevation of the posterior capsule was affected by an increase in the IOP. Examination Changes in the posterior capsule during the occlusion break test were observed and recorded using the SSV method. The distance between the apex of corneal endothelium and posterior capsule located vertically just below the apex of the corneal endothelium was measured from recorded SSV images using the image analysis software from DITECT Image Processing Products (DITECT, Tokyo, Japan; Fig. 5b). The elevation ratio in the posterior capsule was calculated as the ratio of the distance from the corneal apex to the posterior capsule before and immediately after the occlusion break surge. Statistical Analysis Descriptive statistics (means and standard deviations) were calculated for each test group. Wilcoxon’s t-test was used for comparison between two groups, and the chi-square test was used for comparison within each group. Statistical significance was set at P < 0.05. Data were analyzed using Excel 2019 software (Microsoft Corp., WA, USA). Declarations Conflict of Interest Disclosure: The author has received lecture fees and grants from Alcon Japan Ltd. outside of the submitted work. Financial Support: No funding was received for this study. Author Contribution H.S. is the sole author of this manuscript. The author confirms that he/ she has made the following contributions: conceptualization, data collection, formal analysis, validation, visualization, writing and approved the final manuscript. Data Availability The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request. References Kelman, C. D. 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Cite Share Download PDF Status: Published Journal Publication published 01 Jul, 2025 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 13 May, 2025 Reviews received at journal 09 May, 2025 Reviewers agreed at journal 28 Apr, 2025 Reviews received at journal 21 Apr, 2025 Reviewers agreed at journal 27 Mar, 2025 Reviewers invited by journal 27 Mar, 2025 Submission checks completed at journal 25 Mar, 2025 First submitted to journal 20 Mar, 2025 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. 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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-5235231","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":434715279,"identity":"36213ba4-0f25-48b0-bdac-3009483369b1","order_by":0,"name":"Hisaharu Suzuki","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvUlEQVRIiWNgGAWjYDAC+YPtHyQqYDweYrRIMB9jsDhDmha2NIbKNpLcNbvH7MHNeXei5RuYH35gkLlDWIvBnTPmhjO3PcvdcIDNWIKB5xkRWhhyDKQltx3O3cDAYAb0y2EiHNYA1PJ3zuHc+Q3s34jTwnAjLU1CsuFwbsMBHiJtMThz+LCBxDGgww7zFEskEOMX+fbGxgcSNUCHtbdv/PCxh4gQQwBmIE7sOUCKFjD4QbqWUTAKRsEoGP4AAB5EPWSgQofMAAAAAElFTkSuQmCC","orcid":"","institution":"Zengyo Suzuki Eye Clinic","correspondingAuthor":true,"prefix":"","firstName":"Hisaharu","middleName":"","lastName":"Suzuki","suffix":""}],"badges":[],"createdAt":"2024-10-09 22:53:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5235231/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5235231/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-08134-8","type":"published","date":"2025-07-01T15:57:49+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79435300,"identity":"e99fa349-48c7-4caf-9dc2-9620d355cdff","added_by":"auto","created_at":"2025-03-28 11:50:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3110860,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in intraocular pressure in porcine eyes with and without eyelid speculum.\u003c/p\u003e\n\u003cp\u003eP \u0026lt; 0.05, Wilcoxon’s t-test\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-5235231/v1/5a2d2a23b45cb46165e263b0.png"},{"id":79435302,"identity":"5ffd0b9c-15ba-4388-9aed-b4d64e9a92fc","added_by":"auto","created_at":"2025-03-28 11:50:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2322822,"visible":true,"origin":"","legend":"\u003cp\u003eChange ratio in the distance between the apex of the corneal endothelium and posterior lens capsule at an intraocular pressure of 20 mmHg. The x-axis denotes the test group, and the Y-axis denotes the % of elevation of the posterior capsule.\u003cbr\u003e\na. Porcine eyes with ES (ES+, right) and without ES (ES-, left) when AS was used\u003c/p\u003e\n\u003cp\u003eb. Porcine eyes with ES (ES+, right) and without ES (ES-, left) when OZ was used\u003c/p\u003e\n\u003cp\u003eP \u0026lt; 0.05, Wilcoxon’s t-test\u003c/p\u003e\n\u003cp\u003e(AS = Active Sentry; ES = eyelid speculum; OZ = Ozil )\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-5235231/v1/361bbb850eea7992b616d907.png"},{"id":79435301,"identity":"96598a8b-75c0-44df-85ec-191ecac31c89","added_by":"auto","created_at":"2025-03-28 11:50:50","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2303671,"visible":true,"origin":"","legend":"\u003cp\u003eChange ratio in the distance between the apex of the corneal endothelium and posterior lens capsule at an intraocular pressure of 20 mmHg. The x-axis denotes the test group, and the Y-axis denotes the % of elevation of the posterior capsule.\u003cbr\u003e\na. Porcine eyes without ES (ES-) when AS (left) and OZ (right) were used\u003c/p\u003e\n\u003cp\u003eb.\u003cstrong\u003e \u003c/strong\u003ePorcine eyes with ES (ES+) when AS (left) and OZ (right) were used\u003c/p\u003e\n\u003cp\u003eP \u0026lt; 0.05, Wilcoxon’s t-test\u003c/p\u003e\n\u003cp\u003e(AS = Active Sentry; ES = eyelid speculum; OZ = Ozil)\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-5235231/v1/952d23a43121733883d4f477.png"},{"id":79435990,"identity":"f316f0a5-09ec-44e5-96af-333a72ab15b2","added_by":"auto","created_at":"2025-03-28 11:58:50","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2992691,"visible":true,"origin":"","legend":"\u003cp\u003eChange ratio in the distance between the apex of the corneal endothelium and posterior lens capsule at intraocular pressures of 20, 30, and 40 mmHg. The x-axis denotes the intraocular pressure, and the Y-axis denotes the % of elevation of the posterior capsule.\u003c/p\u003e\n\u003cp\u003ea. Porcine eyes with ES when AS was used\u003c/p\u003e\n\u003cp\u003eb. Porcine eyes with ES when the Ozil was used\u003c/p\u003e\n\u003cp\u003eP \u0026lt; 0.05, chi-square t-test\u003c/p\u003e\n\u003cp\u003e(AS = Active Sentry; ES = eyelid speculum; OZ = Ozil)\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-5235231/v1/a59d5235a75cba1f5a195671.png"},{"id":79435303,"identity":"714dab02-7623-496f-99d6-3ebf172ab1de","added_by":"auto","created_at":"2025-03-28 11:50:50","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":13871654,"visible":true,"origin":"","legend":"\u003cp\u003eThe components of the porcine eye with eyelid speculum and the distance calculated for posterior capsule movement\u003c/p\u003e\n\u003cp\u003ea. Porcine eye with eyelid speculum\u003c/p\u003e\n\u003cp\u003eb. Distance between the apex of the corneal endothelium and posterior lens capsule\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-5235231/v1/01225461ccb59b99be345931.png"},{"id":86179095,"identity":"a640a29b-3142-4ab0-9f2a-adbb6644bfb6","added_by":"auto","created_at":"2025-07-07 16:15:38","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":22091423,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5235231/v1/cf724752-d6b4-48fc-96d6-8ee45bf44653.pdf"}],"financialInterests":"Competing interest reported. The author has received lecture fees and grants from Alcon Japan Ltd. outside of the submitted work.","formattedTitle":"Effect of perfusion pressure sensors on posterior capsule elevation in the porcine eye model with eyelid speculums","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWith advances in ultrasonic cataract surgery devices developed by Kelman [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], cataract surgery has become minimally invasive and has doubled as refractive surgery. However, prevention of posterior capsule rupture is particularly important as current intraocular lenses are based on intracapsular fixation, and complications, such as posterior capsule rupture, can result in reduced quality of vision. One of the causes of posterior capsule rupture is an unstable anterior chamber and posterior capsule elevation caused by a surge after an occlusion break of the ultrasonic tip [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Whether this occlusion break surge causes the posterior capsule to move depends on the surgical case, and it is difficult to identify which cases are likely to experience posterior capsule movement before surgery. Movement of the posterior capsule is thought to be caused by several factors. One of these is anatomical changes in the posterior capsule and anterior vitreous, such as detachment of the posterior capsule and anterior vitreous [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The other is external pressure on the eye due to factors such as muscular force on the tissue and placement of an eyelid speculum (ES). Placing an ES, blinking, or opening the eyes wide can increase the intraocular pressure (IOP) [\u003cspan additionalcitationids=\"CR6 CR7 CR8\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, no studies have examined how external pressures, such as that from an ES, affect the posterior capsule.\u003c/p\u003e \u003cp\u003eWe previously reported anterior chamber movements using the slit side view (SSV) method, which allows intraoperative observation of anterior chamber movements using a slit-lamp microscope [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Using this system, changes in the anterior chamber depth can be quantified. In this context, we evaluated the anterior chamber stability using Active Fluidics\u0026trade; of the Centurion\u0026reg; Vision System (Centurion) (Alcon Vision LLC, Fort Worth, TX, USA), an active perfusion system, and an Active Sentry\u0026reg; handpiece (AS) (Alcon Vision LLC, Fort Worth, TX, USA), an ultrasound handpiece with an integrated perfusion pressure sensor, and found that these systems demonstrated high anterior chamber stability [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. This is largely owing to the development of ultrasonic cataract surgery systems that actively supply Balanced Salt Solution\u0026reg; Plus (BSS) (Alcon Vision LLC, Fort Worth, TX, USA) into the eye. However, even with these systems, there are cases wherein the posterior capsule can become unstable during cataract surgery, even with an active supply of BSS to the anterior chamber of the eye.\u003c/p\u003e \u003cp\u003eWe hypothesized that external pressures, such as those from an ES, would result in greater posterior capsule elevation in a porcine eye model of an ES. We used the SSV method to experimentally investigate the extent to which the posterior capsule moved owing to IOP changes after an occlusion break. In addition, the effects of Centurion with AS on reducing posterior capsule elevations were examined.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003ePorcine Eye with Simulated Eyelid Model\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe mean IOP of the porcine eyes with and without an ES is shown in Figure 1. The mean IOP was 15.42 \u0026plusmn; 4.10 and 21.86 \u0026plusmn; 4.12 mmHg in porcine eyes without and with an ES, respectively (P = 0.0003).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eChange Ratio in Posterior Capsule Elevation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePosterior capsule elevation ratios in porcine eyes with and without an ES are shown in Fig.\u0026nbsp;2a and\u0026nbsp;2b. The posterior capsule elevation ratio in the AS (ES\u0026minus;) group (5.5 \u0026plusmn; 2.3%) was significantly lower than that in the AS (ES+) group (18.0 \u0026plusmn; 19.1%) (P = 0.0135). In addition, the posterior capsule elevation ratio was significantly lower in the OZ (ES\u0026minus;) group (21.2 \u0026plusmn; 19.9%) than that in the OZ (ES+) group (46.2 \u0026plusmn; 20.2%) (P = 0.010).\u003c/p\u003e\n\u003cp\u003eComparing posterior capsule elevation rates between phacoemulsification and aspirations (PEAs), AS showed significantly lower posterior capsule elevation rates than did OZ, regardless of ES attachment (Fig.\u0026nbsp;3a and\u0026nbsp;3b; P = 0.0034 and 0.0045, respectively).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEffect of IOP Increases in Porcine Eyes With an ES\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe posterior capsule elevation ratio in the AS (ES+) group at IOPs of 20, 30, and 40 mmHg was 18.0 \u0026plusmn; 19.1%, 13.4 \u0026plusmn; 8.9%, and 7.5 \u0026plusmn; 6.5%, respectively (Fig. 4a). There were significant differences in the ratio between 20 and 40 mmHg, and 30 and 40 mmHg (P = 0.0234 and 0.0135, respectively). The posterior capsule elevation ratio in the OZ (ES+) group at IOPs of 20, 30, and 40 mmHg was 46.2 \u0026plusmn; 20.2%, 19.4 \u0026plusmn; 16.3%, and 11.7 \u0026plusmn; 9.0%, respectively (Fig. 4b). There were significant differences in the ratio between 20 and 30 mmHg, 20 and 40 mmHg, and 30 and 40 mmHg (P = 0.0135, 0.0135, and 0.0234, respectively).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAn ES is useful for maintaining the opening of an eyelid; however it not only causes tension in patient but may also interfere with the elasticity of the eyeball by touching the eyeball itself, which may increase pressure within the eye. We considered external pressures on the eye, such as ES placement, to be one of the factors causing elevation of the posterior capsule during cataract surgery. To intentionally create such an external pressure, we created a model in which porcine eyes were subjected to an ES to evaluate posterior capsule elevation. In this experimental model, the mere use of an ES significantly increased the IOP. An ES and artificial eyelids (rubber band) in contact with the outside of the porcine eyeball could reduce the elasticity of the eyeball against the force pushing it outwards in response to changes in the IOP, resulting in increased IOP.\u003c/p\u003e \u003cp\u003eIn our experiment, the IOP of the porcine eye model before applying an ES was 15.42\u0026thinsp;\u0026plusmn;\u0026thinsp;4.10 mmHg and 21.86\u0026thinsp;\u0026plusmn;\u0026thinsp;4.12 mmHg after applying an ES, resulting in an IOP increase of approximately 6 mmHg. Considering that previous clinical reports have reported IOP differences of 1.9 to 7.71 mmHg before and after ES placement [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], it can be said that we successfully reproduced the condition of the eye with a clinical ES in the porcine eye.\u003c/p\u003e \u003cp\u003eWe then quantitatively measured the elevation of the posterior capsule after occlusion break in porcine eyes with and without an ES. We found that the rate of posterior capsule elevation after occlusion break was significantly greater in porcine eyes with an ES than in those without an ES, regardless of the PEA type. When an occlusion break surge occurs, the IOP of the anterior chamber is lowered; difference in the IOP between the anterior chamber and vitreous is large; and elastic force pushes the posterior capsule upward. The reason the posterior capsule elevation rate was higher in porcine eyes with an ES than in those without may be the increased elasticity of the vitreous side following an increase in the IOP in the anterior segment due to ES placement. During cataract surgery, the posterior capsule may be elevated for unknown reasons. Based on the results in the current study, an increase in IOP due to external factors such as ES is thought to be involved. In addition, we increased the anterior chamber IOP from 20 to 30 and 40 mmHg to confirm how the IOP setting could affect posterior capsule elevation after occlusion break. The rate of posterior capsule elevation decreased in both PEA types as the IOP increased. We attribute this to the fact that by increasing the IOP in the anterior chamber, the difference in the IOP after occlusion break between the anterior and vitreous sides became smaller, which suppressed posterior capsule elevation. Of note, the standard deviation was higher at a lower IOP. This is because the compliance of the eye was reported to be hyperbolic in nature; the lower the IOP was, the higher the compliance of the eye was [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA comparison of posterior capsule elevation rates after occlusion break between the AS and OZ groups showed that the posterior capsule elevation rate was smaller in the AS than that in the OZ group, regardless of ES attachment. This indicated that AS provided better posterior capsule stability than did the conventional handpiece, even when affected by external pressure. In addition, the posterior capsule elevation rate for AS being less than half that of OZ would allow the surgeon to manage the surgery safely and efficiently. In this study, to evaluate the effect of the AS sensor alone, we adjusted for confounding factors such as leakage from incision. However, in clinical practice, there is a leakage from incision wound, which may increase the amplitude of post-occlusion surge, and posterior capsule elevation of AS should be clinically evaluated.\u003c/p\u003e \u003cp\u003eWe previously reported that the change in anterior chamber depth after occlusion breaks in porcine eyes was smaller in the AS than that in the OZ groups [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Vasavada et al. also showed that the rate of IOP recovery after an occlusion break was faster with Centurion with AS than without AS [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The reason for the smaller posterior capsule elevation as well as the change in anterior chamber depth may be that the perfusion pressure sensor in the AS handpiece instantly detected IOP fluctuations and actively reduced the post-occlusion surge using an active surge mitigation mechanism. In other words, this feature instantly compensates for the IOP difference between the anterior chamber and vitreous side, contributing to the reduction in posterior capsule elevation.\u003c/p\u003e \u003cp\u003eWhen pressure from the vitreous side is high, increasing pressure from the anterior chamber side to some extent is necessary; the results of this study showed that increasing the IOP could also reduce posterior capsule elevation. However, it has been previously reported that the intraoperative IOP should be low for minimally invasive ocular tissues [\u003cspan additionalcitationids=\"CR16 CR17 CR18 CR19\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Wenzel et al. found that intermittent irrigation and aspiration without phacoemulsification in porcine eyes at different bottle height (BH) resulted in greater relative corneal endothelial cell loss at higher BH [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Liu et al and our previous study have also shown that lower IOP and BH during cataract surgery result in less loss of corneal endothelial cell density [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. These reports indicate that corneal endothelial cells may be more susceptible to damage in association with high IOP. The author of the present study usually recommends cataract surgery with a low IOP setting. However, but if the posterior capsule movement is judged to be unstable when the number of nuclei in the lens capsule decreases during cataract surgery with a low IOP setting, the author suggests that temporarily increasing the IOP could be effective in suppressing posterior capsule elevation and preventing posterior capsule breakage.\u003c/p\u003e \u003cp\u003eSince the present study had a bit small sample size and used an experimental model using porcine eyes and simulated eyelids, which is also different from that of the actual human eye in the orbit, whether the artificial eyelids with rubber bands reproduced the actual clinical situation remains unclear. Since facial morphology differs according to race, the condition of the ES touching the eye is also likely to vary according to the shape of the face and eyelid and the effects of local anesthesia are not taken into account. Furthermore, since the extracted porcine eye was postmortem eyes that lacked dynamic responses of living tissues, the posterior capsules might behave differently in clinical cases. Future studies using human eyes to further evaluate posterior capsule movement are necessary. In addition, there are reports indicating that the IOP varies depending on the form of the ES, whether it is a screw or spring type [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]; it will be necessary to examine intraoperative IOP variation depending on the form of the eyelid speculum and the width of the speculum in the future. Anatomical changes between the vitreous and posterior capsules within the eye are also thought to alter the movement of the posterior capsule; therefore, the presence or absence of the vitreous must also have been considered.\u003c/p\u003e \u003cp\u003eIn conclusion, this study experimentally investigated the movement of the posterior capsule after an occlusion break using an ES. After occlusion break, the posterior capsule was more elevated in porcine eyes that were intentionally pressured with an ES than in porcine eyes without ES placement. In addition, AS was able to suppress the movement of the posterior capsule after occlusion break, even when the anterior IOP was increased by applying an ES. However, it was suggested that the IOP setting itself was also a factor that caused the posterior capsule to move intensely, suggesting that it is necessary in the future to develop a device that can respond realistically to fluctuations in the IOP during actual surgery to avoid posterior capsule elevation.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eEthical Considerations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSince this study used enucleated porcine eyeballs obtained from a local slaughterhouse, the ARVO Statement for the Use of Animals in Ophthalmology and Vision was not required. The Ethics Committee (Zegyo Suzuki Eye Clinic ethics committee) ruled that approval was not required for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation and Evaluation of the Porcine Eye Model of an ES\u003c/strong\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFreshly extracted whole porcine eyes were obtained from a local slaughterhouse (Tokyo Shibaura Organ Corporation, Tokyo, Japan) and stored in a controlled laboratory. The whole eyes used in this study were shipped to the laboratory within 1 day of storage. Porcine eyes without obvious ocular damage, corneal opacities, or vitreous leakage were selected for this study.\u003c/p\u003e\n\u003cp\u003eTo create a porcine eye model of an ES, a rubber band with a diameter of 26 mm was used as the simulated eyelid. The rubber band was stretched horizontally by 35 mm, centered on the porcine corneal apex, and both ends of the rubber band were fixed to a porcine eye folder.\u0026nbsp;A screw-type ES was then hooked to a rubber band, and the rubber band was vertically extended 18 mm,\u0026nbsp;which is the maximum eyelid opening width of the ES, to create a porcine eye model of an ES (Fig.\u0026nbsp;5a).\u003c/p\u003e\n\u003cp\u003eTo confirm that the porcine eye with an ES had an increased IOP compared with the porcine eye before ES placement, as clinically reported, changes in the IOP were tested in five porcine eyes before and after ES application.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnder an ophthalmic microscope (LuxOR Revalia; Alcon Vision LLC, Fort Worth, TX, USA), a 2.4-mm corneal incision was first created in the porcine eye before an ES was attached, and the crystalline lens was removed using the PEA technique with Centurion with AS. Hydration was ensured to prevent leakage from incision. A 25-gauge sharp needle was inserted into the cornea of the porcine eye, and BSS was injected into the anterior chamber to inflate it. A pressure transducer (IX-TA-220 Recorder with Integrated Sensors: iWorx, Dover, NH, USA) was used to measure the IOP in the porcine eye without ES attachment, according to a previously reported procedure\u0026nbsp;[11]\u003csup\u003e.\u003c/sup\u003e The IOP was then measured and recorded in the same manner as when the ES was attached to the porcine eye.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePhacoemulsification Systems Used for Evaluating Posterior Capsule Elevation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTwo different PEA systems were used: Centurion with Active Fluidics\u003csup\u003eTM\u003c/sup\u003e and AS, and Centurion with Active Fluidics\u003csup\u003eTM\u003c/sup\u003e and an Ozil handpiece (OZ) (Alcon Vision LLC, Fort Worth, TX, USA). The Active Fluidics\u003csup\u003eTM\u003c/sup\u003e technology in the Centurion compresses the BSS bag with two plates, and the more fluid the surgeon removes from the anterior chamber, the more it compresses the bag, replenishes the removed volume, and compensates for flow losses. Thus, irrigation adapts to aspiration at each step of cataract surgery, and the pressure in the anterior chamber is maintained consistently. AS has an integrated pressure sensor that responds in real time. When the onset of occlusion is detected, the AS system vents the aspiration line without affecting the holding power of the lens material at the distal end of the tip, thereby reducing the post-occlusion surge because less fluid is pulled from the eye owing to the reduced vacuum demand during automated surge mitigation. Therefore, AS technology allows for faster mitigation of the surge response and ensures stability of the anterior chamber [22,23].\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEvaluation of Posterior Capsule Elevation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this experimental study, to evaluate posterior capsule elevation, 4 groups were tested with 11 porcine eyes per group. The porcine eye model groups were as follows: with an ES tested using AS [AS (ES+)], without an ES tested using AS [AS (ES\u0026ndash;)], with an ES tested using OZ [OZ (ES+)], and without an ES tested using OZ [OZ (ES\u0026ndash;)].\u003c/p\u003e\n\u003cp\u003eA 2.4-mm corneal incision was first created in the porcine eye, and the crystalline lens was removed using the PEA technique with Centurion with AS under a microscope. After injecting a cohesive ophthalmic viscosurgical device (OVD) (Provisc; Alcon Vision LLC, Fort Worth, TX, USA) into the anterior chamber, the porcine eye was moved onto a slit-lamp microscope stand and fixed. A phaco tip was inserted through a corneal incision and stabilized over the iris surface, and PEA was performed in each group. To minimize variations between PEA systems, a 0.9-mm mini-flared 45\u0026deg; Kelman aspiration bypass system phaco tip and UltraSleeve (Alcon Vision LLC, Fort Worth, TX, USA) were used for both PEA systems. To minimize incision leakage and ensure that it did not affect the movement of the posterior capsule, we vertically fixed the PEA handpiece and porcine eyes on a fixed table. Both PEA systems were used in my daily clinical setting with a target IOP setting of 20 mmHg, aspiration rate of 22 mL/min, vacuum limit of 320 mmHg, and ultrasonic oscillation setting of 0%.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAfter pressing on a foot pedal to replace the OVD in the anterior chamber with BSS, the aspiration tube was pinched with pliers, occluded for 3 seconds, and then released for 3 seconds. This procedure was repeated three times. To ensure reproducibility, these procedures were performed by the same surgeon. Posterior capsule elevations were observed during the occlusion break using the SSV method and continuously recorded. These methods were performed according to the established procedure described in our previous reports [10,11]. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn porcine eyes with an ES, after testing for posterior capsule elevation at an IOP of 20 mmHg, posterior capsule elevation was also evaluated at IOPs of 30 and 40 mmHg (parameters other than IOP were not changed) to assess whether the elevation of the posterior capsule was affected by an increase in the IOP.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eExamination\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChanges in the posterior capsule during the occlusion break test were observed and recorded using the SSV method. The distance between the apex of corneal endothelium and posterior capsule located vertically just below the apex of the corneal endothelium was measured from recorded SSV images using the image analysis software from DITECT Image Processing Products (DITECT, Tokyo, Japan; Fig. 5b). The elevation ratio in the posterior capsule was calculated as the ratio of the distance from the corneal apex to the posterior capsule before and immediately after the occlusion break surge. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDescriptive statistics (means and standard deviations) were calculated for each test group. Wilcoxon\u0026rsquo;s t-test was used for comparison between two groups, and the chi-square test was used for comparison within each group. Statistical significance was set at P \u0026lt; 0.05. Data were analyzed using Excel 2019 software (Microsoft Corp., WA, USA).\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of Interest Disclosure:\u003c/h2\u003e\n\u003cp\u003eThe author has received lecture fees and grants from Alcon Japan Ltd. outside of the submitted work.\u003c/p\u003e\n\u003ch2\u003eFinancial Support:\u003c/h2\u003e\n\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eH.S. is the sole author of this manuscript. The author confirms that he/ she has made the following contributions: conceptualization, data collection, formal analysis, validation, visualization, writing and approved the final manuscript.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKelman, C. D. Phacoemulsification and aspiration: A new technique of cataract removal. A preliminary report. \u003cem\u003eAm. J. Ophthalmol.\u003c/em\u003e \u003cstrong\u003e46\u003c/strong\u003e, 23\u0026ndash;35 (1967).\u003c/li\u003e\n\u003cli\u003ePolat, A. Importance of anterior chamber stability in phaco surgery. \u003cem\u003eJ. Cataract Refract. Surg.\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 1397 (2014). 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Phacoemulsifier occlusion break surge volume reduction. \u003cem\u003eJ. Cataract Refract. Surg.\u003c/em\u003e \u003cstrong\u003e44\u003c/strong\u003e, 1491\u0026ndash;1496 (2018). (DOI 10.1016/j.jcrs.2018.01.032) (Pubmed:30473080)\u003c/li\u003e\n\u003cli\u003eMiller, K. M., Dyk, D. W. \u0026amp; Yalamanchili, S. Experimental study of occlusion break surge volume in 3 different phacoemulsification systems. \u003cem\u003eJ. Cataract Refract. Surg.\u003c/em\u003e \u003cstrong\u003e47\u003c/strong\u003e, 1466\u0026ndash;1472 (2021). (DOI 10.1097/j.jcrs.0000000000000651) (Pubmed:34675153)\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"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":"Posterior capsule elevation, Active Sentry, Intraocular pressure, Eyelid speculum, Phacoemulsification and aspiration","lastPublishedDoi":"10.21203/rs.3.rs-5235231/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5235231/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study evaluated the posterior capsule elevation ratio after occlusion break in a porcine eye model of an eyelid speculum (ES) using Centurion Vision System with Active Sentry handpiece (AS). The mean intraocular pressure of the porcine eyes with the ES was significantly higher than that of without the ES (15.42\u0026thinsp;\u0026plusmn;\u0026thinsp;4.10 mmHg vs. 21.86\u0026thinsp;\u0026plusmn;\u0026thinsp;4.12 mmHg, P\u0026thinsp;=\u0026thinsp;0.0003). Changes in the posterior capsule elevation were observed using the slit side view method in the following four groups: with an ES using AS [AS (ES+)], without an ES using AS [AS (ES\u0026minus;)], with an ES using the Ozil handpiece [OZ (ES+)], and without an ES using OZ [OZ (ES\u0026minus;)]. Eleven eyes in each group were tested. AS (ES+) and OZ (ES+) had a significantly higher rate of posterior capsule elevation than did AS (ES\u0026minus;) and OZ (ES\u0026minus;) (P\u0026thinsp;=\u0026thinsp;0.135 and P\u0026thinsp;=\u0026thinsp;0.010). AS (ES+) and AS (ES\u0026minus;) significantly suppressed posterior capsule elevation compared with OZ (ES+) and OZ (ES\u0026minus;) (P\u0026thinsp;=\u0026thinsp;0.034 and P\u0026thinsp;=\u0026thinsp;0.045). Porcine eyes with ES had increased IOP and greater posterior capsule elevation after occlusion break than did those without. AS effectively suppressed posterior capsule elevation better than did OZ.\u003c/p\u003e","manuscriptTitle":"Effect of perfusion pressure sensors on posterior capsule elevation in the porcine eye model with eyelid speculums","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-28 11:50:44","doi":"10.21203/rs.3.rs-5235231/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-13T11:35:10+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-09T16:21:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"156836815850756443032539844066983506343","date":"2025-04-29T00:14:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-21T04:15:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"111438243499330614001637109188235942799","date":"2025-03-27T08:54:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-27T08:14:14+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-25T11:08:26+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-03-20T15:29:57+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":"0fd9a546-e938-4c2f-a68d-a4a760741af9","owner":[],"postedDate":"March 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":46287004,"name":"Health sciences/Medical research"},{"id":46287005,"name":"Health sciences/Risk factors"}],"tags":[],"updatedAt":"2025-07-07T16:03:39+00:00","versionOfRecord":{"articleIdentity":"rs-5235231","link":"https://doi.org/10.1038/s41598-025-08134-8","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-07-01 15:57:49","publishedOnDateReadable":"July 1st, 2025"},"versionCreatedAt":"2025-03-28 11:50:44","video":"","vorDoi":"10.1038/s41598-025-08134-8","vorDoiUrl":"https://doi.org/10.1038/s41598-025-08134-8","workflowStages":[]},"version":"v1","identity":"rs-5235231","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5235231","identity":"rs-5235231","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}