Lens capsule opacification in aphakic and pseudophakic eyes

Posterior capsular opacification and YAG laser capsulotomy in uveitis patients following cataract surgery

OBJECTIVE

To evaluate the incidence of visually significant posterior capsule opacification (PCO with visual acuity ≤20/50) and the incidence of Nd:YAG laser capsulotomy in the year following cataract surgery for uveitic eyes.

METHOD

Patients were identified from the Systemic Immunosuppressive Therapy for Eye Diseases (SITE) Cohort Study using a standardized chart review process.

RESULTS

Among 1,855 uveitic eyes of 1,370 patients who had undergone cataract surgery, visually significant PCO occurred in 297 eyes (16%), and YAG laser capsulotomy was done in 407 eyes (22%) within the first year following surgery. Higher odds of developing 20/50 visual acuity attributed to PCO were noted in children and young adults compared with adults older than 65 years of age (overall p = 0.03). Poorer preoperative visual acuity (overall p = 0.0069) and postoperative inflammation (odds ratio [OR] = 1.83; 95% CI, 1.37-2.45; p < 0.0001) were associated with PCO incidence. In multivariable analysis, risk factors for YAG laser capsulotomy were younger age groups compared with those older than 65 years of age at the time of surgery (adjusted OR [aOR] = 1.90-2.24; 95% CI, 1.90-2.24; overall p = 0.0007), female sex (aOR = 1.37; 95% CI, 1.03-1.82; p = 0.03), postoperative active inflammation (aOR = 165; 95% CI, 1.27-2.16; overall p < 0.0001), extracapsular cataract extraction compared with phacoemulsification (aOR = 1.70; 95% CI, 1.17-2.47; overall p < 0.0001), and insertion of an intraocular lens (aOR = 4.60; 95% CI, -2.29-9.25; p < 0.0001). Black race was associated with lower YAG laser capsulotomy incidence than Whites (aOR = 0.36; 95% CI, 0.24-0.52; overall p < 0.0001).

CONCLUSIONS

Vision-reducing (≤20/50) PCO is common, occurring in about one sixth of uveitic eyes within 1 year of cataract surgery; a higher number (22%) of eyes underwent YAG laser capsulotomy within the first year. Age and postoperative inflammation following cataract surgery are the variables most associated with the incidence of visually significant PCO and YAG laser capsulotomy.

Cataract surgeon viewpoints on the need for novel preventative anti-inflammatory and anti-posterior capsular opacification therapies

Purpose: To determine cataract surgeon viewpoints on the efficacy of available therapies/preventatives for two common sequelae of cataract surgery: inflammation and posterior capsular opacification (PCO). Methods: Cataract surgeons practicing worldwide specializing in adult, pediatric and veterinary patients were interviewed between March and August 2018. Results: Ocular inflammation following cataract surgery is treated by either corticosteroids and/or nonsteroidal anti-inflammatories (NSAIDs). Adult and pediatric cataract surgeons are satisfied with current treatments whereas this inflammation is still considered a problem by some in veterinary practice due to its slow resolution. Yttrium-aluminum-garnet (YAG) laser therapy is the PCO treatment of choice for adult cataract surgeons and they are generally pleased with its outcome. However, pediatric cataract surgeons find YAG problematic, especially in patients under 6 years of age, and invasive surgery is often needed to correct PCO/visual axis opacification (VAO). Veterinary ophthalmologists report that YAG is not effective for PCO in animals, especially dogs, due to the density of the fibrotic plaques; 86% of adult and 100% of veterinary and pediatric cataract surgeons surveyed agree that effective anti-PCO therapeutics would improve clinical care. Conclusions: Surgeons treating human patients are pleased with the available treatments for ocular inflammation following cataract surgery, although some veterinary ophthalmologists disagree. The surgeons surveyed agree that PCO/VAO remains an unsolved problem in pediatric and veterinary cataract surgery while the long-term outcome of adult cataract surgery could be improved by additional attention to this issue.

Efficacy of COX-2 inhibitors in controlling inflammation and capsular opacification after phacoemulsification cataract removal

OBJECTIVE

To evaluate the efficacy of 0.9% bromfenac (Xibrom™) or a celecoxib-impregnated intraocular lens (celecoxib-IOL) compared with 1% prednisolone acetate (PA) in controlling postoperative inflammation and posterior capsule opacification (PCO).

ANIMAL STUDIED

Fifty-nine dogs undergoing cataract extraction by phacoemulsification.

PROCEDURE

Bilateral patients received bromfenac or celecoxib-IOL plus PA in one eye, and PA in the contralateral eye. Unilateral patients received bromfenac or PA. Complete ophthalmic examination including tonometry, slit-lamp grading of flare and PCO, and digital image acquisition for masked PCO evaluation was performed within 24 h and 1, 4, 12, 24, and 56 weeks following surgery.

RESULTS

Celecoxib-IOL/PA-treated eyes had significantly less flare than PA-treated eyes, which had significantly less flare than bromfenac-treated eyes 24 h postoperatively. There was no significant difference in intraocular pressure (IOP) postoperatively, or at 1, 24, or 56 weeks. Celecoxib-IOL/PA-treated eyes had significantly lower IOP measurements than bromfenac and PA-treated eyes at 4 and 12 weeks. There was no significant difference in PCO level between groups using slit-lamp biomicroscopy at any time point. Masked evaluation of digital images revealed significantly less PCO in celecoxib-IOL/PA- vs. bromfenac-treated eyes at 4 weeks, and in bromfenac- vs. PA-treated eyes at 56 weeks.

CONCLUSIONS

Eyes receiving celecoxib-IOL/PA had better initial control of inflammation. Bromfenac was equally effective compared with PA in controlling inflammation. There was no association between COX-2 inhibitor administration and ocular hypertension. Celecoxib-IOL/PA-treated eyes showed better initial control of PCO (up to 12 weeks), while eyes receiving bromfenac had better long-term control of PCO (56 weeks).

Phacoemulsification and acryl foldable intraocular lens implantation in dogs: 32 cases

This study evaluated the surgical outcome and complications of phacoemulsification and the implantation of an acryl foldable intraocular lens (IOL) with a squared edge in dogs with cataracts. Thirty-two eyes from 26 dogs were examined. The mean follow up period was 75.9 days ranging from 23 to 226 days. The complications after phacoemulsification were posterior capsular opacity (PCO) around the IOL (n = 11), ocular hypertension (n = 4), focal posterior synechia (n = 4), hyphema (n = 3) and corneal ulcer (n = 2). The complications associated with the IOL were decenteration of the optic (n = 2) and ventral haptic displacement (n = 1). Most cases of PCO were found only around the margin of the IOL, and all eyes had vision during the observation period. In conclusion, the implantation of an acryl-foldable lens with a squared edge at the time of phacoemulsification is an effective method for preserving the central visual field of dogs with cataract.

Effect of ophthalmic Nd:YAG laser energy on intraocular lenses after posterior capsulotomy in normal dog eyes

OBJECTIVE

To determine Nd:YAG laser energy requirements for posterior capsulotomy and intraocular lens (IOL) damage threshold for foldable acrylic IOLs as compared to traditional polymethylmethacrylate (PMMA). MATERIALS AND PROCEDURES: Four groups of five-six fresh canine cadaver eyes were used in this study. The groups included (1) unaltered eyes (2) aphakic eyes (3) eyes implanted with PMMA IOLs, and (4) eyes implanted with acrylic IOLs. Laser energy was delivered to the posterior capsule in grid fashion for 10 sites each of five levels of laser energy ranging from 0.5 mJ to 9 mJ. Number of successful capsulotomy sites was recorded based on slit-lamp observation. Sites of IOL damage were evaluated using scanning electron microscopy (SEM). Statistical analysis of number of capsulotomies and IOL defects per laser energy level was conducted among and between groups using anova with Tukey's HSD test.

RESULTS

When comparing groups (a) including all energy levels (n = 25) and (b) by specific energy levels (n = 5), there was no significant difference (P < 0.05) in number of successful capsulotomy sites between IOL types. The 50% incidence threshold for successful capsulotomy was 2.74 mJ for acrylic IOLs and 2.64 mJ for PMMA IOLs. Energy-dependent damage to both types of IOL was detected for medium, high-medium, and high laser energy. Calculated 50% damage threshold was 4.9 mJ for acrylic IOL and 5.7 mJ for PMMA IOL. Damage to the IOL varied subjectively between IOL type, but there was no significant difference in number of defects caused, with the exception of high-medium energy.

CONCLUSIONS

Both posterior lens capsules and IOLs were disrupted in an energy-dependent manner with minimal difference in number of capsulotomy sites or damage to the IOL between acrylic and PMMA IOLs. A therapeutic margin between capsulotomy threshold (2.6-2.7 mJ) and IOL damage threshold (4.9-5.7 mJ) was determined to reliably achieve capsulotomies with minimal IOL damage for both acrylic and PMMA IOLs in normal canine cadaver eyes.

Anterior lens capsule disruption and suspected malignant glaucoma in a dog

A Boston Terrier puppy presented with a full-thickness peripheral corneal defect, iris prolapse and anterior lens capsule tear in the left eye (OS). Phacofragmentation and primary repair of the corneal laceration was performed. At surgery, subluxation of the lens was also apparent. One day postoperative, there was severe corneal edema, diffuse hyphema, an intraocular pressure (IOP) of 65 mmHg and a small amount of vitreous that protruded from the corneal incision OS. Malignant glaucoma or pupillary block glaucoma were suspected. Intravenous mannitol was administered preoperatively and had no effect. An anterior vitrectomy was performed on the vitreous within the anterior chamber and pupil. One day postoperative the IOP was 16 mmHg in the right eye (OD) and 20 mmHg OS. Postoperative iridocyclitis was managed medically, and additional elevations in IOP were not recorded. Resolution of the elevated IOP following anterior vitrectomy was supportive of pupillary block or malignant glaucoma. Vision returned 3 weeks after the initial surgery. Two years after the initial injury, the eye is visual and comfortable with infrequent topical anti-inflammatory therapy.

Immunohistochemical analysis of lens epithelial-derived membranes following cataract extraction in the dog

The objective of the study was to characterize the morphologic and immunohistochemical features of lens epithelial-derived proliferative membranes from the anterior segment of canine globes. These features were correlated with those previously identified for diseases resulting from lens epithelial cell (LEC) proliferation including posterior capsular opacification, traumatic subcapsular cataract, and subcapsular plaques associated with hypermature cataracts. Sixteen canine globes were removed as a result of glaucoma or other complications following cataract extraction. Light microscopic and immunohistochemical analysis was performed on sections from formalin-fixed, paraffin-embedded globes. The tissues were stained with a variety of antibodies for cellular markers for LECs, growth factors or other cellular constituents relevant to cellular metaplasia and proliferation. The membranes were composed of monolayers or multilayers of spindle-shaped cells on the external surfaces of the anterior and posterior lens capsule, ciliary processes, iris leaflets, and iridocorneal angle, and they could be seen extending from an obvious monolayer of LEC within the capsular sac. Variably, scattered pigment cells, presumably of uveal origin, were concurrently present. Cellular components of the membranes stained positive for vimentin, transforming growth factor-beta, basic fibroblast growth factor, and smooth muscle actin. An amorphous eosinophilic extracellular matrix consisting predominately of collagen was associated with the membranes. Proliferative anterior segment membranes following cataract surgery were morphologically and immunohistochemically similar to cellular and matrix components of posterior capsular opacification and capsular plaques seen with hypermature cataracts, both of which result from metaplasia and proliferation of LEC. The presence of these LEC-derived membranes in association with secondary glaucoma suggests that exuberant proliferation of LEC outside the confines of the lens capsular sac may cause pathologic alterations in the eye following cataract surgery in the dog.

Morphologic alterations in the anterior lens capsule of canine eyes with cataracts

OBJECTIVE

To examine the morphologic changes in the anterior lens capsule and lens epithelium of canine eyes with cataracts.

SAMPLE POPULATION

Anterior lens capsules from the eyes of 25 dogs with cataracts and from an additional 10 canine globes with lenses subjectively assessed to be normal.

PROCEDURE

Thickness of each anterior lens capsule was measured by use of a digital microscopic camera and imaging software. All 25 capsules from eyes with cataracts were submitted for light microscopy; 4 were also submitted for electron microscopy.

RESULTS

Thickness of the anterior lens capsule increased with age for the normal lenses and the lenses with cataracts; the change with age was similar for both groups. Light microscopy revealed fibrous metaplasia of lens epithelial cells in 7 of 25 anterior lens capsules with focal thickenings of the posterior aspect of the capsule. Electron microscopy revealed deposition of collagen and basement membrane-like material by fibroblast-like cells.

CONCLUSIONS

Results indicate that thickness of the anterior lens capsule in dogs increases with age and that this increase in thickness is not significantly different between normal lenses and lenses with cataracts. In addition, epithelial cells from lenses with cataracts may undergo metaplasia to form plaques composed of fibrous tissue and ectopic basement membrane produced by epithelial cells.

Surgical prevention of posterior capsule opacification. Part 3: Intraocular lens optic barrier effect as a second line of defense

PURPOSE

To emphasize an important aspect of preventing posterior capsule opacification (PCO), the barrier effect established by the optic of a posterior chamber intraocular lens (PC IOL), and present a new classification regarding capsular bag status after extra-capsular cataract extraction, including phacoemulsification.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

This analysis included 150 consecutive eyes obtained postmortem with United States-manufactured PC IOLs including (1) poly(methyl methacrylate), (2) silicone, and (3) hydrophobic acrylic designs that were accessioned in the Center from September 1995 to January 1, 1998. Gross photographs from behind (Miyake-Apple views) were taken and serial histologic sections prepared.

RESULTS

Microscopic analysis of the 150 eyes showed that the morphologic appearance of the capsular bag could be grouped into 2 categories: (1) those with little or no evidence of retained cortical material and cells, and (2) those with retained cortical material and cells in which a Soemmering's ring formed. With the latter, when a distinct barricade to cellular migration created by the IOL optic was noted, 2 discrete configurations occurred, depending on the different geometries of the optic components. With a classic biconvex optic with a curved and tapered edge, in many instances some ingrowth of cells proceeded posteriorly around the edge of the IOL optic in the direction of the central axis. With a lens optic that had a squared, truncated, and relatively thick edge, there was often abrupt termination of cells at the peripheral edge of the optic. The posterior capsule subtending the entire optic zone was therefore relatively or totally cell free.

CONCLUSIONS

The barrier effect of the IOL optic appears to be of critical importance in retarding ingrowth of cells, functioning as a second line of defense when cortical cleanup is incomplete. Analysis of PC IOLs obtained postmortem showed that a square, truncated optic edge seemed to provide the maximum impediment to cell growth behind the IOL optic.

Posterior capsule opacification. Part 2: Clinical findings

The incidence of posterior capsule opacification (PCO), the most common complication of modern cataract surgery with intraocular lens implantation, seems to have decreased slightly as a result of improved surgical and cortical cleanup techniques. However, the reported incidence is still significant. The diverse findings on PCO are the result in part of studies using different criteria to clinically judge and quantify the condition. In addition, the influence of intraocular and systemic factors are only now being identified. This second of a 2-part review of PCO focuses on (1) less subjective morphological and patient-dependent means to evaluate and quantify PCO; (2) the influence of ocular factors on PCO; (3) the influence of systemic factors on PCO; (4) available means and approaches to prevent or delay PCO.

Update on fixation of rigid and foldable posterior chamber intraocular lenses. Part II: Choosing the correct haptic fixation and intraocular lens design to help eradicate posterior capsule opacification

PURPOSE

Posterior capsule opacification (PCO) is one of the most common complications of cataract surgery, and there is an urgent need to reduce its incidence. Its main treatment, neodymium:YAG (Nd:YAG) laser posterior capsulotomy, may be associated with significant morbidity and is expensive. In this study, the authors ascertain the effect of posterior chamber intraocular lens (PC-IOL) fixation and various IOL designs (rigid polymethyl methacrylate [PMMA] optic and small-incision foldable designs) on the pathogenesis of PCO.

DESIGN

Prospective analysis of pseudophakic eyes obtained postmortem.

PARTICIPANTS

A total of 3493 eyes with PC-IOLs obtained postmortem and received between 1984 and 1998.

METHODS

Miyake-Apple posterior photographic technique.

MAIN OUTCOME MEASURES

Peripheral Soemmering's ring, central PCO in the visual axis, and eyes that have had Nd:YAG laser posterior capsulotomy were analyzed and scored, and these findings were correlated with the type of fixation and IOL design.

RESULTS

The degree of formation of peripheral Soemmering's ring was not influenced by IOL fixation. The acrylic design revealed relatively low Soemmering's ring scores. In contrast, central PCO and Nd:YAG laser capsulotomy scores were consistently influenced by fixation. The scores were significantly lower in eyes with in-the-bag fixation. The bag-bag fixated acrylic-PMMA design and the three modern silicone IOL designs analyzed in this study had less central PCO and lower posterior capsulotomy scores than did the PMMA IOLs.

CONCLUSIONS

The formation of peripheral PCO (the Soemmering's ring), the precursor of clinically significant, vision-threatening PCO, is not significantly influenced by the haptic fixation pattern. It is much more dependent on the quality and thoroughness of surgical cortical cleanup. Reduction of Soemmering's ring is an important goal because the retained regenerative cortical cells within this lesion are the cells of origin of PCO. The acrylic IOL design was associated with a lessor amount of peripheral Soemmering's ring as compared with all other designs. In sharp contrast to peripheral PCO, fixation of the IOL was a highly significant factor affecting the formation and quantity of central PCO-the clinically significant opacity behind the IOL optic, measured in this series either by scoring an intact retro-optical membrane or by documenting the presence of a Nd:YAG laser posterior capsulotomy orifice. The quantity of central PCO was consistently much lower in eyes with in-the-bag fixated IOLs compared with lenses with one or both haptics out of the bag. This is best explained by the fact that secure in-the-bag fixation positions the IOL optic in the best possible position to create a barrier effect. The lowest PCO rates were generally noted with the acrylic and modern silicone IOL designs.

Adhesion of lens capsule to intraocular lenses of polymethylmethacrylate, silicone, and acrylic foldable materials: an experimental study

AIMS

To investigate the adhesion characteristics of several intraocular lenses (IOLs) to the simulated and rabbit lens capsule.

METHODS

Adhesive force to bovine collagen sheets was measured in water with polymethylmethacrylate (PMMA), three piece silicone, and acrylic foldable IOLs. In rabbit eyes, phacoemulsification and IOL implantation were performed. Three weeks later, adhesion between the anterior/posterior capsules and IOL optic was tested, and the capsule was examined histologically.

RESULTS

The mean adhesive force to the collagen sheet was 1697 (SD 286) mg for acrylic foldable, 583 (49) mg for PMMA, and 0 mg for silicone IOLs (p = 0.0003, Kruskal-Wallis test). Scores (0-5) of adhesion between rabbit anterior capsule and IOL optic were 4.50 (0.55) for acrylic foldable, 3.20 (0.84) for PMMA, and 0.40 (0.55) for silicone IOLs (p = 0.004). Scores between rabbit posterior capsule and IOL optic displayed a similar tendency; 4.50 (0.84) for acrylic foldable, 3.00 (1.00) for PMMA, and 0.40 (0.55) for silicone IOLs (p = 0.021). Histological observation indicated that the edge of IOL optic suppressed the migration of lens epithelial cells towards the centre of the posterior capsule. This inhibitory effect was most pronounced with acrylic foldable IOL and least with silicone IOL.

CONCLUSIONS

The acrylic foldable IOL adhered to the lens capsule more than the PMMA IOL, and the silicone IOL showed no adhesiveness. These differences seem to play a role in preventing lens epithelial cells from migrating and forming posterior capsule opacification.

Presence of alpha smooth muscle actin in lens epithelial cells of aphakic rabbit eyes

AIMS

To determine whether alpha smooth muscle actin (alpha-SMA), a marker for myofibroblastic cells, is present in lens epithelial cells (LECs) in rabbit aphakic eyes.

METHODS

Phacoemulsification was performed in rabbit eyes, which were enucleated after surgery. Immunohistochemical methods were used to detect alpha-SMA in LECs.

RESULTS

Five days after surgery, the presence of alpha-SMA positive LECs was observed mainly around the adhesive portion of the anterior capsule margin and the posterior capsule. The posterior capsule was wrinkled at the adhesive portion. The alpha-SMA positive LECs were flattened with spindle-shaped cross sections. Seven days after surgery, the alpha-SMA positive LECs covered most of the central posterior capsule. They disappeared 10 days after surgery. On the other hand, the cuboidal LECs in the capsular bag were negative for alpha-SMA.

CONCLUSION

The flattened LECs with spindle-shaped cross sections observed 5 days after cataract surgery contained alpha-SMA. Such LECs were distinguished biochemically from the cuboidal LECs, which lacked alpha-SMA.

Lens epithelial cell outgrowth and matrix formation on intraocular lenses in rabbit eyes

PURPOSE

To evaluate the presence and distribution of lens epithelial cells (LECs) and extracellular matrix on intraocular lenses (IOLs) implanted in the capsular bag in rabbit eyes.

SETTING

Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan.

METHODS

Five adult albino rabbits had phacoemulsification and IOL implantation in both eyes. Two or 11 months later, the animals were killed by intravenous pentobarbital. The IOLs were removed and observed under scanning and transmission electron microscopy.

RESULTS

In addition to the macrophages and giant cells on the IOLs, all eyes had a monolayer of flattened cells growing out from the residual anterior lens capsule and a fibrous meshwork of extracellular matrix. Unlike those of a macrophagic origin, these cells had no central cytoplasmic elevation of nuclei and few cell surface microvilli and were considered to be proliferating LECs.

CONCLUSION

Lens epithelial cells are involved in the eye's cellular reaction to IOLs and in the formation of extracellular matrix on IOLs. Further study of LEC behavior on IOLs should be done to improve IOL biocompatibility.