Corticocapsular cleavage during phacoemulsification: Viscodissection versus hydrodissection

LABORATORY SCIENCE

Corticocapsular cleavage during phacoemulsification: Viscodissection versus hydrodissection Miyake–Apple view analysis Vaishali Vasavada, MS, Viraj A. Vasavada, MS, Liliana Werner, MD, PhD, Nick Mamalis, MD, Abhay R. Vasavada, MS, FRCS, Alan S. Crandall, MD

PURPOSE: To compare the corticocapsular separation created by viscodissection and by hydrodissection using Miyake–Apple video-photographic analysis. SETTING: University-based center. METHODS: Fourteen cadaver eyes were randomized to hydrodissection (Group 1, n Z 7) or viscodissection (Group 2, n Z 7). Twelve eyes were prepared for Miyake–Apple viewing. One eye in each group was prepared to simulate a closed chamber. On Miyake–Apple viewing, corticocapsular separation was graded from 0 to 3 after hydrodissection/viscodissection and at the sculpting, nuclear division, and early and late fragment removal stages. The surgeon’s subjective impression of the mechanical cushion effect was noted. Histopathology of the capsular bag was performed in 4 eyes in each group to determine the amount of residual lens epithelial cells (LECs). RESULTS: More space was created and maintained between the capsule and cortex in Group 2 than in Group 1. The mean scores in Groups 1 and 2 were endpoint of hydrodissection/viscodissection 1.92 G 0.38 and 2.58 G 0.38, respectively (P Z .05); sculpting, 1.6 G 0.42 and 2.3 G 0.45, respectively (P Z .05); nuclear division, 0.9 G 0.42 and 1.5 G 0.35, respectively (P Z .13); early fragment removal, 0.6 G 0.22 and 1.0 G 0, respectively (P Z .04); and late fragment removal, 0.1 G 0.22 and 0.4 G 0.22, respectively (P Z .17). Although only early fragment removal achieved statistical significance, the surgeon’s impression confirmed greater cushion effect with viscodissection. Residual LECs in the 2 groups were comparable. CONCLUSION: Viscodissection as an adjunct to hydrodissection created and maintained greater corticocapsular separation than hydrodissection alone during phacoemulsification. J Cataract Refract Surg 2008; 34:1173–1180 Q 2008 ASCRS and ESCRS

Cortical-cleaving hydrodissection1 has significantly increased the safety and efficacy of cataract surgery2 by creating a plane of cleavage between the cortex and the capsule and may have reduced the rates of posterior capsule opacification (PCO) after cataract surgery with intraocular lens (IOL) implantation.3 However, in the presence of a weakened or deficient posterior capsule or zonules, cortical-cleaving hydrodissection is unsafe and can lead to blowout of the posterior capsule.2 Viscodissection (injection of an ophthalmic viscosurgical device [OVD] between the capsule and the cortex) has been recommended in eyes with posterior polar cataract2,4 to protect the posterior capsule and tamponade the vitreous. Q 2008 ASCRS and ESCRS Published by Elsevier Inc.

Viscodissection as an adjunct to phacoemulsification has also been found to be useful in cases of zonular and capsular bag weakness, such as in eyes with subluxated or traumatic cataract.5,6 Recently, in a clinical setting,7 a lower posterior capsule rupture rate was found with viscodissection than with hydrodissection, even in uncomplicated cases. It is believed that viscodissection might provide additional safety during phacoemulsification by creating a barrier and providing a cushion of OVD that protects the posterior capsule and maintains space for in-the-bag manipulation. A recently introduced OVD, DisCoVisc (hyaluronic acid 1.6%–chondroitin sulfate 4%), has both viscous and dispersive properties. Thus, it is proposed that 0886-3350/08/$dsee front matter doi:10.1016/j.jcrs.2008.03.026

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this OVD maintains space, affords excellent tissue protection, and is easy to remove.8,9 We designed this cadaver eye study to evaluate and compare the corticocapsular separation created by viscodissection with a viscous–dispersive OVD as opposed to hydrodissection with balanced salt solution (BSS) during phacoemulsification. MATERIALS AND METHODS This experimental study was performed at the John A. Moran Eye Center, University of Utah, Utah. Seven pairs of fresh human cadaver phakic eyes were obtained within 72 hours of enucleation from eye banks throughout the United States. Six pairs of eyes were prepared according to the standard Miyake–Apple technique for posterior viewing and imaging, which has been described.10 In 1 pair of eyes, the corneal epithelium was debrided. Subsequently, these eyes were immersed in dextran solution for 30 minutes and prepared according to the technique of Auffarth et al.11 to simulate a closed-chamber setting. One eye of each pair was randomly selected to receive hydrodissection with BSS (Group 1, n Z 7) or hydrodissection followed by viscodissection with DisCoVisc (Group 2, n Z 7). A computer-generated random-numbers table was used to make this selection. The other eye of the pair was automatically allotted to the other group. In the eyes prepared according to the Miyake–Apple technique, a continuous curvilinear capsulorhexis of approximately 4.5 mm was created. In both groups, multiquadrant cortical-cleaving hydrodissection with BSS was performed by tenting the anterior capsule. The endpoint of hydrodissection was the passage of a fluid wave across the posterior capsule, confirming the creation of a plane of cleavage between the capsule and cortex. In Group 2, this was followed by viscodissection with DisCoVisc.

Viscodissection Technique Viscodissection began at the point of completion of hydrodissection. The OVD cannula was directed along the cleavage plane created by hydrodissection. Small quantities of DisCoVisc were injected in multiple quadrants by a swiping motion of the cannula. The surgeon injected enough OVD to

Accepted for publication March 26, 2008. From the John A. Moran Eye Center (V. Vasavada, V.A. Vasavada, Werner, Mamalis, Crandall), University of Utah School of Medicine, Salt Lake City, Utah, USA, and the Iladevi Cataract & IOL Research Centre (A.R. Vasavada), Ahmedabad, India. No author has a financial or proprietary interest in any material or method mentioned. Supported in part by a Research Grant from Alcon Laboratories and by a Funding Incentive Seed Grant of the University of Utah Research Foundation (Dr. Werner). Corresponding author: Vaishali Vasavada, MS, Iladevi Cataract & IOL Research Centre, Raghudeep Eye Clinic, Gurukul Road, Memnagar, Ahmedabad - 380052. India. E-mail: vvasavada@hotmail. com.

visualize its passage beyond the equator in all quadrants. The endpoint of viscodissection was the passage of OVD beyond the equator. A total of 0.15 to 0.2 mL of OVD was injected in each eye. At this point, with the crystalline lens in situ, 1 eye in each group was fixed in 10% neutral buffered formalin, sectioned, and subjected to histopathological evaluation. In the remaining 10 eyes, phacoemulsification was performed using the Alcon Legacy system with the following parameters: ultrasound energy up to 60%, vacuum up to 250 mm Hg, and aspiration flow rate up to 25 cc/min. A central groove was sculpted, and the nucleus was cracked into halves. Subsequently, the nucleus was chopped into smaller fragments and in-the-bag emulsification was performed. All surgeries were performed by the same surgeon (V.A.V.). The 2 eyes prepared for the closed-chamber setting were fixed to a training head, and a self-sealing clear corneal incision of 2.8 mm was made. The iris was pulled from its attachment to allow better visualization. The subsequent steps were the same as described above. Surgical manipulations in the closed-system eyes were performed by the same surgeon (N.M.). The surgeries were recorded on videotape using digital and analog cameras and subsequently captured onto a computer hard drive using commercially available video-editing hardware and software. To compare the 2 techniques, 2 independent observers (L.W., V.V.) evaluated the space created and maintained between the capsule and cortex using the Miyake–Apple viewing technique. Attention was also paid to visible signs of capsular distortion or zonular stress. At each subsequent stage of the surgery (ie, after hydrodissection; after viscodissection; and during the sculpting, early fragment removal, and late fragment removal stages), a semiquantitative scale was devised to grade the space from 0 to 3 (0 Z no space/ space equal to that before the start of surgery; 3 Z maximum space detectable). Values were reported as mean G standard deviation. Statistical analysis was performed using the Wilcoxon matched-pairs signed ranks test; a P value greater than 0.05 was considered statistically significant. The surgeon was also asked to subjectively evaluate the space maintained at each of the above-mentioned stages of surgery as well as the ease of OVD injection. In 2 eyes in which surgery was performed through a closed-globe system, objective scoring was not possible. The surgeon’s subjective impression of the cushion effect created and maintained between the capsule and cortex at each stage was recorded. A limitation of the Miyake–Apple preparation is that it requires open-sky surgery. The closed-system surgery was done to rule out bias due to the open-sky approach and to more closely mimic the clinical scenario. Six of the 12 eyes prepared according to the Miyake–Apple technique were fixed in formalin after the capsular bag was evacuated. Eight eyes were subjected to histopathological evaluation. The anterior segments of these eyes were processed for standard light microscopy and stained with periodic acid-Schiff (PAS) and Masson trichrome. Care was taken to orient the specimens in such a way as to ensure that the histologic cuts would include the entire capsular bag. Multiple sections for each specimen were examined under a light microscope, and photomicrographs were taken for documentation. The amount of residual cortical material and lens epithelial cells (LECs) at the level of the residual anterior capsule, equatorial region of the capsular bag, and posterior capsule was noted.

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Figure 1. Miyake–Apple view showing corticocapsular separation during sculpting. A: Hydrodissection alone. B: Viscodissection with hydrodissection.

RESULTS On Miyake–Apple viewing, a plane of cleavage was visible in all eyes when a wave of BSS passed between the capsule and the cortex. Some space could also be seen separating the capsule and cortex, but it was not uniform around the entire equator. In Group 1, as sculpting and nuclear division were performed, much of the fluid egressed, leaving only a small amount of space in 1 or 2 quadrants. During fragment removal, a minimal cushion effect of the fluid was seen. In contrast, upon DisCoVisc injection, a larger corticocapsular separation was uniformly created (Figure 1). This space was maintained in almost all eyes throughout sculpting and nuclear division (Figure 2). During the early part of fragment removal, Group 2 continued to have significantly greater separation between the capsule and cortex (Figure 3). Although the space reduced considerably, some could still be seen until the removal of the last few fragments in the viscodissection group. Table 1 shows the semiquantitative grading of the corticocapsular space created in both groups based on the Miyake–Apple posterior imaging. The mean score of the 2 independent observers for the space created was comparable between the 2 groups at the end of hydrodissection (P Z .32). The space created after

viscodissection (Group 2) was greater than the space at the end of hydrodissection (Group 1); the difference achieved borderline statistical significance (P Z .05). Similarly, during sculpting, Group 2 had a greater mean score (P Z .05). During early nuclear fragment removal, Group 2 had a statistically significantly greater mean score (1.0 G 0.0) than Group 1 (0.6 G 0.22) (P Z .04). During the later phases of fragment removal, the amount of corticocapsular separation in both groups was reduced; although no statistical significance was achieved, some cushion effect was detected in Group 2 compared with Group 1 (P Z .17). Although Miyake–Apple viewing showed greater space at all stages of phacoemulsification in Group 2, statistical significance was achieved only during early nuclear fragment removal. The subjective impressions of the surgeons confirmed the Miyake–Apple view findings. In eyes that received viscodissection in addition to hydrodissection, the surgeons perceived a greater mechanical cushion effect during phacoemulsification. Even in the 2 eyes operated on under the closed-chamber setting, although objective scoring was not possible, the surgeon noticed a greater cushion effect during phacoemulsification after viscodissection than after hydrodissection.

Figure 2. Miyake–Apple view showing the corticocapsular separation during sculpting. A: Hydrodissection alone. B: Viscodissection with hydrodissection.

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Figure 3. Miyake–Apple view showing the sustained corticocapsular separation during early fragment removal. A: Hydrodissection alone. B: Viscodissection with hydrodissection.

Injecting DisCoVisc was found to be easy; no resistance to the injection was encountered in any eye. It could be clearly observed passing beyond the equator and creating a space between the capsule and the cortex, both by the surgeon while injecting and by the independent observers on Miyake–Apple viewing (Figure 4). There was no evidence of overdistension of the capsular bag, prolapse of the nucleus through the anterior capsulorhexis margins, or visible zonular stress in any eye. No adverse intraoperative events occurred in either group. Histopathological examination of the 2 eyes with the lens in situ showed significantly greater separation of the posterior capsule and cortex in the eyes in which DisCoVisc was injected than in eyes in which only

BSS was injected (Figure 5). Histopathological evaluation of the capsular bags in 3 eyes in each group showed that in both groups, no residual cortex was visible and the central posterior capsule was clear. However, residual LECs were found lining the undersurface of the anterior capsule and in the area of the equator and the capsular fornix. The number and distribution of these residual cells in the 2 groups did not differ (Figure 6). DISCUSSION Since the introduction of cortical-cleaving hydrodissection,1 phacoemulsification has become safer and more efficient. Creating a cleavage between the cortex and capsule allows more thorough cortical cleanup

Table 1. Objective (semiquantitative) scoring of capsular–cortical space in the 2 groups of eyes* prepared according to the Miyake–Apple technique (n Z 12).

Group/Eye Group 1 Eye 1 Eye 2 Eye 3 Eye 4 Eye 5 Eye 6 Mean G SD Group 2 Eye 1 Eye 2 Eye 3 Eye 4 Eye 5 Eye 6 Mean G SD P valuez

After Hydrodissection

After Viscodissection

Sculpting

Nuclear Division

Early Fragment Removal

Late Fragment Removal

2.0 1.5 2.5 1.5† 2.0 2.0 1.92 G 0.38

d d d d d d d

2.0 1.5 2.0 1.0 1.5 d 1.60 G 0.42

1.5 1.0 1.0 0.5 0.5 d 0.90 G 0.42

1.0 0.5 0.5 0.5 0.5 d 0.60 G 0.22

0.5 0.0 0.0 0.0 0.0 d 0.10 G 0.22

1.5 1.5 2.0 2.0† 1.5 2.0 1.58 G 0.38 .32

2.0 2.5 2.5 3.0 2.5 3.0 2.58 G 0.38 .05

2.0 2.0 2.5 3.0 2.0 d 2.30 G 0.45 .05

1.0 1.5 1.5 2.0 1.5 d 1.50 G 0.35 .13

1.0 1.0 1.0 1.0 1.0 d 1.00 G 0.0 .04

0.0 0.5 0.5 0.5 0.5 d 0.40 G 0.22 .17

*

One eye in each group subjected to histopathologic analysis immediately after hydrodissection/viscodissection In 1 quadrant z Wilcoxon matched-pairs signed ranks test †

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Figure 4. Visible passage of DisCoVisc between the lens cortex and capsule during viscodissection. A: Anterior view showing the passage of DisCoVisc between the lens capsule and cortex. B: Miyake–Apple view showing the passage of DisCoVisc between the lens capsule and cortex.

while reducing stress on the capsule and zonules.2 This is thought to have had an influence on the gradual reduction in PCO rates over the past several years.3 In addition, a judicious combination of multiquadrant and focal hydrodissection is a useful tool to cleave dense corticocapsular adhesions and remove a major obstacle during phacoemulsification.12 However, this technique can be hazardous in cases with preexisting capsule tears, capsule weakness, or zonule weakness. The technique of viscodissection (injecting OVD between the lens capsule and cortex) was popularized by Krag et al.13 and Burton and Pickering14 as an adjunct during extracapsular cataract extraction. Viscodissection has been shown to be invaluable in complicated cases with capsulozonular complex instability, such as eyes with posterior polar cataract, subluxated cataract, traumatic cataract, or similar surgically induced problems arising perioperatively.2,4 It is believed that the OVD fills the capsular bag, supports the capsule, tamponades the vitreous, stabilizes the nucleus, and helps peel the cortex from the capsule. Recently, Mackool et al.7 described the use of a dispersive OVD (Viscoat [sodium hyaluronate 3.0%–chondroitin sulfate 4.0%]) for viscodissection during phacoemulsification, even in a standard cataract scenario. The authors retrospectively reviewed the

posterior capsule rupture rates with hydrodissection and compared them with the rates in a series of cases in which viscodissection in addition to hydrodissection was performed prospectively. They found a reduction in posterior capsule rupture rates in the viscodissection group. We believe that viscodissection, although underused, is a useful technique as an adjunct to phacoemulsification in various cataract scenarios. One benefit of viscodissection is that it creates a physical barrier or a buffer between the cortex and the posterior capsule, thus providing greater space for intraoperative in-thebag manipulation and preventing movement of the capsule toward the phaco tip. However, to our knowledge, no published report has documented this barrier effect of OVD in viscodissection and its advantage over hydrodissection with BSS. With hydrodissection (Group 1), a plane of cleavage was created between the capsule and the cortex. Although some space was created between the capsule and cortex, it was not uniform around the entire equator. Furthermore, it gradually decreased as sculpting and nuclear division progressed due to the egress of fluid. During fragment removal, a negligible barrier between the capsule and the lens fragments could be detected. On the other hand, during viscodissection

Figure 5. Histopathological section of the capsular bag with lens in-situ. A: Hydrodissection alone. B: Viscodissection with hydrodissection.

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Figure 6. Residual LECs lining the anterior capsule and capsular bag fornix (PAS stain), A: Hydrodissection group, low magnification. B: Hydrodissection group, high magnification. C: Viscodissection group, low magnification. D: Viscodissection group, high magnification.

(Group 2), the plane of cleavage created during hydrodissection was expanded and a significant space was created, partitioning the capsule and cortex all around. As sculpting and nuclear division progressed, the barrier effect was maintained to a large extent. Although this space decreased during fragment removal, a cushion effect could be detected even during the later stages of fragment removal. On videographic documentation, although the space created between the capsule and cortex was much greater with viscodissection than with hydrodissection, statistical significance was achieved only during early fragment removal. We attribute this to the presence of a very small sample size. Furthermore, we strongly believe that clinically, even a small increase in the mechanical cushion effect would translate into a significant benefit in terms of protection of the posterior capsule. The surgeon’s subjective impression was similar to that documented on posterior viewing. Even in whole globes with an intact cornea, viscodissection was superior to hydrodissection in terms of allowing the surgeon to perform posterior plane emulsification with greater comfort without causing an undue rise in capsule pressure. On histopathological examination, the number of residual LECs in the capsular bag did not differ in the 2 groups. At this point, it is uncertain whether performing viscodissection would affect the incidence of PCO. Viscodissection has been described with various OVDs including Healon (sodium hyaluronate 1.0%), Healon5 (sodium hyaluronate 2.3%), and Viscoat. In

our study, we chose to use DisCoVisc because it is a viscous–dispersive OVD.15 It has been demonstrated on confocal microscopy8 and Scheimpflug photography9 that DisCoVisc shows more retention than Viscoat and Healon5. However, compared with both these OVDs, DisCoVisc has a significantly shorter removal time. It also offers excellent intraoperative visibility, as opposed to Viscoat. In addition, after IOL implantation, it does not require special techniques to remove it from behind the lens. In a prospective case series, we found that DisCoVisc, although viscous similar to a cohesive OVD, has the protective properties of a dispersive OVD. It affords excellent space maintenance with superior visualization and can be easily removed at the end of surgery (M.R. Praveen, MD, A.R. Vasavada, MD, ‘‘Surgical Performance of DisCoVisc in Complicated Cataract Cases,’’ presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, San Francisco, California, USA, March 2006). The Miyake–Apple eye preparation provides a unique posterior view of the anterior segment during intraocular manipulations and is particularly useful in evaluating capsular bag dynamics and zonular stress.16 Two independent observers graded the corticocapsular cushion effect created by hydrodissection and viscodissection to avoid bias. However, one limitation of the Miyake–Apple preparation is the requirement of an open-sky system. In a clinical scenario, a concern with injecting OVD in the capsular bag could be overdistension of the bag and a rise in intracapsular pressure. This may be overlooked in an open-

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sky setting. To overcome this limitation and to more closely create a clinical situation, we decided to confirm our findings in a closed-globe setting. In our study, the passage of OVD beyond the equator could be easily visualized. It is important to keep in mind that the technique of injecting OVD differs from that of injecting BSS. In hydrodissection, a single-site, multiquadrant forceful injection of BSS produces a fluid wave. In viscodissection, small amounts of OVD are slowly and gently injected accompanied by a 360-degree swiping motion of the cannula. The cannula may have to be reinserted in different quadrants. Unlike hydrodissection, in which a fluid wave is typically seen, no wave is seen in viscodissection. The endpoint of viscodissection is visualization of OVD beyond the equator in all quadrants. A total of 0.1 to 0.2 mL of the OVD is injected during viscodissection. We found that injecting DisCoVisc was easy. However, the amount of OVD injected should be carefully monitored to avoid over-injection. As OVD disperses more slowly under the nucleus than BSS, it allows the capsular bag to gradually stretch without leading to a sudden increase in fluid pressure. It also allows the surgeon to titrate and control the amount of injection. In contrast, it is not always possible during hydrodissection to control the buildup of hydraulic pressure within the capsular bag. Sudden rapid injection of large amounts of fluid has been associated with intraoperative capsular block17 and hydrorupture of the posterior capsule, or pseudoexpulsive hemorrhage.18 The implication of these results is that viscodissection creates and maintains a safety zone, partitioning the posterior capsule from the activity inside the capsular bag. With various horizontal and vertical chopping techniques, particularly when the chopper is introduced beyond the capsulorhexis margin in the region of the equator, there is often a risk for the chopping instrument to come in contact with the posterior capsule. The barrier effect provided by the OVD might minimize the risk for posterior capsule injury. A crucial factor that helps in consistently achieving clear corneas is performing a posterior-plane emulsification. The OVD between the capsule and cortex mechanically stabilizes the capsule and prevents it from coming toward the phaco tip. This enables the surgeon to safely and efficiently perform posterior-plane emulsification without endangering the integrity of the posterior capsule until the very end of phacoemulsification. This may be of particular advantage to novice surgeons as it provides an added safety zone in cases with weak corneas such as in Fuchs dystrophy. A potential limitation of performing viscodissection is that in hyperopic or microphthalmic eyes with large, bulky, brunescent nuclei; intumescent cataracts; and

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shallow anterior chambers, injection of even a small amount of OVD may cause a rise in the intracapsular pressure and shallowing of the anterior chamber. On the other hand, in these cases, it is even more crucial to perform safe posterior-plane emulsification and keep the nuclear fragments as far as possible from the corneal endothelium. In such situations, we suggest that focal viscodissection be performed initially with injection of very small amounts of OVD, which can be supplemented later as more and more nuclear fragments are removed. This would help keep the posterior capsule away from the fragments continuously during posterior-plane phacoemulsification. To summarize, viscodissection with a viscous– dispersive OVD is a useful adjunct during phacoemulsification. Not only is it useful in cases with a compromised capsulozonular complex, it is also an invaluable tool in a surgeon’s armamentarium to consistently and safely perform in-the-bag phacoemulsification irrespective of the type of cataract. In conclusion, in this cadaver eye study, viscodissection with DisCoVisc created a greater mechanical cushion between the lens and the capsular bag than hydrodissection alone without causing undue zonular stress or capsular bag distension. However, it had no effect on residual LECs remaining in the bag. The technique is easy to perform and may be incorporated more widely as an adjunct to hydrodissection. These findings must be further validated by a randomized clinical trial. REFERENCES 1. Fine IH. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508–512 2. Allen D, Wood C. Minimizing risk to the capsule during surgery for posterior polar cataract. J Cataract Refract Surg 2002; 28:742–744 3. Apple DJ, Peng Q, Visessook N, Werner L, Pandey SK, Escobar-Gomez M, Ram J, Auffarth GU. Eradication of posterior capsule opacification; documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem. Ophthalmology 2001; 108:505–518 4. Fine IH, Packer M, Hoffman RS. Management of posterior polar cataract. J Cataract Refract Surg 2003; 29:16–19 5. Cionni RJ, Osher RH. Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg 1998; 24:1299–1306 6. Cionni RJ, Osher RH, Marques DMV, Marques FF, Snyder ME, Shapiro S. Modified capsular tension ring for patients with congenital loss of zonular support. J Cataract Refract Surg 2003; 29:1668–1673 7. Mackool RJ, Nicolich S, Mackool R Jr. Effect of viscodissection on posterior capsule rupture during phacoemulsification. J Cataract Refract Surg 2007; 33:553 8. Petroll WM, Jafari M, Lane SS, Jester JV, Cavanagh HD. Quantitative assessment of ophthalmic viscosurgical device retention using in vivo confocal microscopy. J Cataract Refract Surg 2005; 31:2363–2368

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9. Bissen-Miyajima H. In vitro behavior of ophthalmic viscosurgical devices during phacoemulsification. J Cataract Refract Surg 2006; 32:1026–1031 10. Apple DJ, Lim ES, Morgan RC, Tsai JC, Gwin TD, Brown SJ, Carlson AN. Preparation and study of human eyes obtained postmortem with the Miyake posterior photographic technique. Ophthalmology 1990; 97:810–816 11. Auffarth GU, Wesendahl TA, Solomon K, Brown SJ, Apple DJ. A modified preparation technique for closed-system ocular surgery of human eyes obtained postmortem; an improved teaching tool. Ophthalmology 1996; 103:977–982 12. Vasavada AR, Goyal D, Shastri L, Singh R. Corticocapsular adhesions and their effect during cataract surgery. J Cataract Refract Surg 2003; 29:309–314 13. Krag S, Thim K, Corydon L. Strength of the lens capsule during hydroexpression of the nucleus. J Cataract Refract Surg 1993; 19:205–208 14. Burton RL, Pickering S. Extracapsular cataract surgery using capsulorhexis with viscoexpression via a limbal section. J Cataract Refract Surg 1995; 21:297–301

15. Arshinoff SA, Jafari M. New classification of ophthalmic viscosurgical devicesd2005. J Cataract Refract Surg; 31: 2167–2171 16. Miyake K, Miyake C. Intraoperative posterior chamber lens haptic fixation in the human cadaver eye. Ophthalmic Surg 1985; 16:230–236 17. Miyake K, Ota I, Ichihashi S, Miyake S, Tanaka Y, Terasaki H. New classification of capsular block syndrome. J Cataract Refract Surg 1998; 24:1230–1234 18. Yeoh R, Theng J. Capsular block syndrome and pseudoexpulsive hemorrhage. J Cataract Refract Surg 2000; 26:1082–1084

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First author: Vaishali Vasavada, MS Iladevi Cataract & IOL Research Centre, Ahmedabad, India