Postoperative opacification of the capsular bag remains the most common complication following pediatric and adult cataract and lens implant surgery.1-3 It occurs from the proliferation and migration of the lens epithelial cells present on the anterior and equatorial inner surfaces of the capsular bag and within the residual cortex and/or cortical fibers. The complication can be subclassified as anterior, equatorial, or posterior capsular opacification.1,2
It is possible to obtain a 360º view of the peripheral capsular bag (capsular fornices) in postmortem eyes using an oblique or side view by creating a uveoscleral window4 or using the Miyake-Apple posterior video/photographic technique.5,6 In living eyes, however, it is impossible to visualize the peripheral capsular bag, which is hidden by the iris root. As a result, it is difficult to remove the residual cortex, cortical fibers, and cells within the capsular fornices under direct visualization with a surgical microscope (Figure 1).
We conducted a two-part study intended to highlight surgical strategies for achieving complete cortical cleanup and the removal of lens epithelial cells. In the first part, we proposed a novel technique that uses a fiber-optic endoscope for intraoperatively visualizing the capsular fornices for the presence or absence of residual cortex/cortical fibers during cataract surgery. In the second part, we presented an experimental study evaluating the effect of distilled water for irrigation on the lens epithelial cells present on the anterior-capsulectomy (capsulorhexis) specimens.
Part 1: The intraoperative
visualization of THE capsular fornices
Materials and Methods
Six eyes with age-related cataract (without any ocular and/or systemic pathology) underwent routine phaco surgery. We used a standard surgical technique (capsulorhexis creation, hydrodissection, hydrodelineation, nuclear rotation and emulsification, I/A, and lens implantation) in all cases. Immediately after concluding I/A and prior to implanting the IOL, we inserted a fiber-optic endoscope (Endo Optiks, Little Silver, NJ) into the anterior chamber and capsular bag in order to examine the capsular fornices for the presence or absence of residual cortex/cortical fibers (Figure 2).
Part 2: distilled water for irrigation
We obtained the anterior-capsulotomy specimens (approximately 4.5 to 5.0mm) from six routine cataract surgeries. After completing the capsulorhexis, we placed the excised anterior capsules on the anterior surface of the cornea and gently rinsed them with BSS (Alcon Laboratories, Inc., Fort Worth, TX) to remove any residual viscoelastic. We then transferred the capsules to plastic vials (BD Ophthalmic Systems, Franklin Lakes, NJ) containing minimal essential media (M-199) for culture. Then, we transferred the plastic vials containing the specimens from the OR to the laboratory. We placed the capsulorhexis specimens within a culture plate containing minimal essential media (M-199) and fixated them to the plate using metallic pins to avoid their displacement during irrigation with distilled water. We oriented the specimens in the culture plate such that the posterior surface of the anterior capsule containing lens epithelial cells faced anteriorly.
We placed the culture plate on the phase-contrast microscope and selected an area containing viable lens epithelial cells. We used a digital timer to note the time of the cells' treatment with distilled water. We used approximately 30mL of distilled water (Baxter Healthcare Pty. Ltd., Old Toongabbie, New South Wales, Australia) to irrigate the lens epithelial cells present on the fixated anterior capsule. During the initial experiments, we performed irrigation for a maximum of 2 minutes. We also stained the cultures with 0.001% trypan blue solution in order to confirm that the cells were not viable.
Examination of the Capsular Fornices
No intraoperative complications occurred. The capsular bag appeared to be clean when viewed through the surgical microscope (Figure 2). Endoscope-assisted visualization of the capsular fornices, however, suggested a varying degree of residual cortex/fibers/lens epithelial cells in all cases (Figure 3).
We were able to remove the residual cortex and cortical fibers using bimanual and/or coaxial I/A with or without the capsular vacuum setting (Legacy phacoemulsification system; Alcon Laboratories, Inc.). We could also see the anterior capsulorhexis through the endoscope. The anterior capsule and capsular bag had a slight blue tinge, probably due to the presence of lens epithelial cells. Figure 2 illustrates the absence of residual cortex/cortical fibers when viewed through the surgical microscope after we performed cortical cleanup using automated I/A. Endoscopic-assisted visualization of the capsular fornices of the same specimen, however, revealed the presence of residual cortex and cortical fibers in the inferonasal quadrant of the capsular bag (Figure 3).
Using automated I/A with and without the capsular vacuum setting, we carefully attempted to clean the residual cortical material and cortical strands from the inferonasal quadrant of the capsular fornices. We then re-inserted the endoscope to confirm the presence or absence of residual cortex. We were able to clean the residual cortical material and cortical strands from the capsular fornices (Figure 4).
Effect of Irrigation
The lens epithelial cells had been completely lysed in five cases after being exposed to distilled water for irrigation for 120 seconds. The lysis of lens epithelial cells was incomplete in one specimen in which few cortical fibers were present. We saw the earliest microscopic evidence of cellular lysis after 30 seconds of exposure to irrigation with distilled water. At this stage, we had stained the cell nuclei with trypan blue, which was suggestive of a cell that was not viable. The nucleus became swollen and stained densely with trypan blue as time progressed to 120 seconds (Figure 5).
Owing to the localization deep in the fornix of the capsular bag, the residual cortex and germinative lens epithelial cells may escape complete removal during I/A. Thorough cleanup of cortical fibers and the successful removal of potent pre-equatorial germinative cells in significant quantities remain the basis for reducing capsular bag opacification.
Endoscopic-assisted visualization of the capsular fornices suggested the presence of varying amounts of residual cortex/fibers/lens epithelial cells within the capsular fornices during routine cataract surgery, even in cases handled by an experienced surgeon. Experimental studies in rabbit and human eyes have suggested that the retained residual cortex in the capsular bag can harbor mitotically active lens epithelial cells.7-9
Lens cortex may also act as a barrier against the osmotic effect of irrigation with distilled water on the lens epithelial cells, as observed in one capsulectomy specimen in our in vitro study. The presence of residual cortex and fibers may be attributed to the incomplete lysis of the lens epithelial cells in the clinical setting when using a sealed-capsule irrigation technique (Perfectcapsule; Milvella Pty. Ltd., Sydney, Australia).10 Studies have also suggested that the presence of residual cortex may lead to the breach of the capsular bend's formation with time.11 This phenomenon may result in visually significant posterior capsular opacification, even after the implantation of a square-edged lens.11
The selective irrigation of distilled water into the human capsular bag is now possible using the Perfectcapsule Sealed Capsule Irrigation (Milvella Pty. Ltd.) device, which allows the isolation of lens epithelial cells and positive pressure inflation of the capsular bag intraoperatively.10 We have demonstrated the lysis of the lens epithelial cells using distilled-water irrigation in a laboratory setting. In spite of complete lysis of the lens epithelial cells in an in vitro setting, there can be some variation in the clinical settings during the use of distilled water with the Perfectcapsule device—differences that may influence the efficacy of irrigation. These variations are (1) the presence of residual cortex within the capsular fornices, (2) the presence of viscoelastic in the capsular bag, and (3) the role of the inflammatory mediators secondary to disruption of the blood-aqueous barrier during cataract surgery.
In summary, endoscopic-assisted visualization of the capsular bag suggests the presence of residual cortex/fibers within the capsular fornices, despite a clean appearance of the capsular bag under the operating microscope. Our in vitro study demonstrated the complete lysis of residual lens epithelial cells present on the anterior lens capsule using irrigation with distilled water. The capsular bag's opacification is a multifactorial process. Thorough cortical cleanup and removal of lens epithelial cells are critical for maintaining the capsular bag's transparency, which is important for a long-term, successful visual outcome with injectable, accommodative, refractive, and new-technology lens implants.
Anthony J. Maloof, MBBS, MBiomedE, FRANZCO, FRACS, is a member of the Intraocular Implant Unit, Sydney Eye Hospital, and Director of Ophthalmic Surgery at the Western Sydney Eye Hospital in Westmead, New South Wales, Australia. He holds a financial interest in the Perfectcapsule. Dr. Maloof may be reached at +61 2 9845 6972; firstname.lastname@example.org.
John E. Milverton, MBBS, DO, FRANZCO, FRCOphth, is Chairman of the Intraocular Implant Unit, Sydney Eye Hospital. He holds a financial interest in the Perfectcapsule. Dr. Milverton may be reached at +61 2 9382 7433; email@example.com.
Suresh K. Pandey, MD, is Assistant Professor for the John A. Moran Eye Center at University of Utah Health Sciences in Salt Lake City and is affiliated with the Intraocular Implant Unit, Sydney Eye Hospital, Save Sight Institute, University of Sydney. He states that he holds no financial interest in the products or companies mentioned herein. Dr. Pandey may be reached at +61 2 9382 7111; firstname.lastname@example.org or email@example.com.
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9. Maloof A, Pandey SK, Neilson G, et al. Selective death of lens epithelial cells using demineralized water and Triton X-100 with PerfectCapsule™ sealed capsule irrigation: a histological study in rabbit eyes. Arch Ophthalmol. In press.
10. Maloof AJ, Neilson G, Milverton EJ, Pandey SK. Selective and specific targeting of lens epithelial cells during cataract surgery using sealed-capsule irrigation. J Cataract Refract Surg. 2003;29:1566-1568.
11. Dewey SH, Werner L, Apple DJ, et al. Cellular proliferation and Soemmering's ring: the long-term threat to capsule clarity. Video presented at: The ASCRS/ASOA Symposium on Cataract, IOL, and Refractive Surgery; May 2-3, 2004; San Diego, CA.