A systematic overview of the incidence of posterior capsule opacification

Predicting posterior capsule opacification: value of early retroillumination imaging

PURPOSE

To investigate the value of early retroillumination imaging of the posterior capsule in predicting the eventual development of posterior capsule opacification (PCO).

SETTING

Ophthalmology Department, St. Thomas' Hospital, and Department of Physics, King's College, London, United Kingdom.

METHODS

All patients with retroillumination images of the posterior capsule taken 6 months and 2 years after uneventful phacoemulsification with in-the-bag intraocular lens (IOL) implantation were selected. The images were taken using the same hardware and analyzed with the same software to calculate the percentage area of the posterior capsule covered by lens epithelial cells. The percentage area of PCO with all IOL types 6 months postoperatively was correlated with that at 2 years.

RESULTS

One hundred forty patients had analyzable images at 6 months and 2 years. Of these, 63 had a poly(methyl methacrylate) (PMMA) IOL (Pharmacia 812A or Storz P497UV), 33 an acrylic (Alcon AcrySof MA30 or SA30), 22 a silicone (Allergan SI-30), and 22 a hydrophilic acrylic (Bausch & Lomb Hydroview H60). The correlation of the percentage area of PCO at 6 months with that at 2 years resulted in an r value of 0.71 (P <.0001) in the entire group. The r value was 0.48 in the PMMA group and 0.86 in the foldable IOL group (P <.0001) (r value: AcrySof, 0.66; silicone, 0.82; Hydroview, 0.75).

CONCLUSIONS

Retroillumination imaging of the posterior capsule 6 months after cataract surgery predicted the PCO outcome at 2 years in eyes with foldable IOLs.

Comparison of 4 methods for quantifying posterior capsule opacification

PURPOSE

To compare the results of posterior capsule opacification (PCO) quantification and the repeatability of a fully automated analysis system (Automated Quantification of After-Cataract [AQUA]) with that of 2 other quantification methods and subjective grading of PCO. A test set of digital retroillumination images of 100 eyes with PCO of varying degrees was used.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

One hundred digital retroillumination images of eyes (100 patients) with PCO were selected to attain an even distribution from mild to severe cases. The images were evaluated by 4 methods: subjective grading by 4 experienced and 4 inexperienced examiners, the subjective Evaluation of Posterior Capsular Opacification (EPCO) system, posterior capsule opacification (POCO) software, and the AQUA system. Ten images were presented twice to assess the reproducibility of the analysis systems.

RESULTS

Subjective grading correlated best with the subjective EPCO system and the objective AQUA system (r = 0.94 and r = 0.93, respectively). The POCO system showed very early saturation and therefore a much weaker correlation (r = 0.73). The POCO scores reached the maximum of 100% in several minimal to mild PCO cases. The reproducibility of the AQUA software was perfect and that of the other analysis systems, comparably satisfactory.

CONCLUSION

The objective AQUA score correlated well with subjective methods including the EPCO system. The POCO system, which assesses PCO area, did not adequately describe PCO intensity and includes a subjective step in the analysis process. The AQUA system could become an important tool for randomized masked trials of PCO inhibition.

Mathematical modeling of the forces between an intraocular lens and the capsule

PURPOSE

To model the pressure relationship between an intraocular lens (IOL) and the capsular bag.

SETTING

Department of Physics, Kings' College, London University, London, United Kingdom.

METHODS

A mathematical model was made of the forces between the capsule and IOL showing that the pressure related to the local radius of curvature of the IOL at any given point. The local radius of curvature for round-edged and square-edged IOLs was measured from electron micrographs of the IOL profiles, and the corresponding pressure profiles were calculated and compared.

RESULTS

The pressure between an IOL and the capsular bag was proportional to the quotient of the tension in the capsule divided by the local radius of curvature of the IOL, with a constant of proportionality that depended on the coefficient of friction between the capsule and IOL. Measuring the local radius of curvature of the 2 IOL types suggested a pressure increase of at least 69% +/- 6% at the optic edge with the square-edged IOL.

CONCLUSIONS

The mathematical model predicted that IOLs with square-edged optic profiles exerts higher pressure on the posterior capsule than IOLs with round-edged optic profiles. The higher pressure may form a physical barrier to lens epithelial cell migration onto the posterior capsule.

Evaluation of neodymium:yttrium-aluminum-garnet capsulotomies in eyes implanted with AcrySof intraocular lenses

PURPOSE

As of December 31, 2000, the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy rate for the Alcon AcrySof intraocular lens (IOL) as measured in our database was 3.3%. This was the lowest of any IOL model used in the United States. Only 12 of 361 cases required treatment. We analyzed possible surgical reasons that may have been responsible for the posterior capsule opacification (PCO) in this small group. Special attention was given to the three surgical factors that we had previously identified as being important for PCO reduction: (1) quality of cortical clean up, (2) type of haptic fixation, and (3) continuous curvilinear capsulorhexis (CCC) size and shape.

DESIGN

Comparative autopsy tissue analysis.

PARTICIPANTS

Three hundred sixty-one human eyes obtained postmortem with Alcon AcrySof IOLs, accessioned between January 1995 and December 2000 from Lions Eye Banks.

METHODS

The eyes were evaluated by the Miyake-Apple posterior photographic technique.

MAIN OUTCOME MEASURES

The area and intensity of Soemmering's ring and type of fixation were studied in 361 eyes. The size and shape of the CCC and relation of the CCC edge to the IOL's optic rim were analyzed in 168 eyes.

RESULTS

The amount of Soemmering's ring formation was significantly larger in the group of IOLs requiring Nd:YAG capsulotomy (Nd:YAG group). The not in-the-bag fixated IOLs required more Nd:YAG capsulotomies. Although the trend was clear, the number of specimens was not large enough to acquire statistical significance. The Nd:YAG group showed a highly significant difference compared with the No Nd:YAG group with regard to the amount of clock hours of the CCC edge on the optic rim's surface (P < 0.001). Mean CCC diameters were significantly larger in the Nd:YAG group (P < 0.05).

CONCLUSIONS

The amount of Soemmering's ring correlates with the quality of cortical clean up. Cells within the Soemmering's ring are the direct precursors of PCO. This study confirms our previous laboratory studies and the clinical assumption that the incidence of PCO and thus the need for Nd:YAG capsulotomy is correlated with the cortical clean up. A second clinical assumption, that poor IOL fixation increases the risk of PCO, is also strongly suggested in this study. This study also verifies the relation of the CCC to PCO and the Nd:YAG laser, namely that a relatively small CCC without tears is best to prevent this complication. Use of a high-quality IOL combined with diligent attention to these three surgical factors should lower further the incidence of PCO.

Functional and anatomic outcome of retinal detachment surgery in pseudophakic eyes

PURPOSE

To determine the long-term anatomic and functional visual outcome of retinal detachment (RD) surgery in pseudophakic eyes after uncomplicated cataract surgery.

DESIGN

An interventional, retrospective noncomparative case series

PARTICIPANTS

One hundred thirty-eight consecutive patients who had undergone uncomplicated extracapsular cataract extraction and intraocular lens implantation followed by rhegmatogenous RD between 1990 and 1995.

METHODS

One hundred one eligible patients were examined (inclusion ratio, 73%) a median of 4.3 years after last RD surgery. The best-corrected visual acuity (BCVA), visual fields, retinal status, and patient-rated visual outcome were recorded, the latter by a questionnaire that included self-reported satisfaction, trouble with vision, a modified Cataract Symptom Score, and the VF-14 Visual Functioning Index.

MAIN OUTCOME MEASURES

BCVA, retinal attachment, diameter of visual field, modified Cataract Symptom Score, VF-14 score.

RESULTS

Baseline characteristics of enrolled and nonenrolled patients were comparable, except that nonenrolled patients were older. When RD developed, 55 eyes had an intact posterior capsule, and 46 had a laser posterior capsulotomy (LCT). The BCVAs before (median, logarithm of the minimum angle of resolution [-logMAR] 1.2 versus 1.1, Snellen equivalent 0.063 versus 0.08) and after retinal surgery (median, -logMAR 0.46 versus 0.4, Snellen equivalent 0.35 versus 0.4) were comparable for eyes with and without LCT (P = 0.86). The retina was reattached with one procedure in 75 eyes (74%), with two procedures in 98 eyes (97%), and with three to five procedures in all eyes. The retina remained attached long term in 92 eyes (91%). Redetachment rate (9% versus 9%, P = 1.0) and visual field diameters were comparable for eyes with and without LCT. Overall, 80% of patients were satisfied or very satisfied with their binocular vision, and 62% had no or only a little trouble with binocular vision. Visual performance was similar regardless of presence or absence of LCT (median Cataract Symptom Score, 3.0 versus 3.0, P = 0.76; and median VF-14 score, 87.5 versus 87.5, P = 0.81).

CONCLUSIONS

Nine in 10 pseudophakic retinal detachments remain attached long term, and 8 in 10 patients are satisfied with their binocular vision after surgery. Even though secondary cataract and posterior capsulotomy can cause problems for the retinal surgeon, the anatomic and functional outcomes of pseudophakic RD are not influenced by capsulotomy.

Posterior capsule opacification after cataract surgery in remote Australian Aboriginal patients

PURPOSE

The aim of this retrospective study was to determine the rate of visually significant posterior capsular opacification formation after cataract surgery for Australian Aborigines living in rural or remote areas in the 'Top End' of the Northern Territory, Australia, and then to assess these patients' outcomes after capsulotomy.

METHODS

Aboriginal patients living in remote areas of the Top End of the Northern Territory who underwent cataract surgery between 1994 and 1999 were identified from records at the three major hospitals in the region. The presence of posterior capsular opacification (PCO) was determined by clinical examination. The primary endpoint for this study was the presence of axial opacification of the posterior capsule and the need for subsequent Nd:YAG posterior capsulotomy to improve sight. Linear regression analysis of the time from surgery to follow up and the number of eyes requiring Nd:YAG capsulotomy was performed. Operated eyes were grouped according to the interval between surgery and follow up (Group 1: follow up within 1 year of surgery, n= 25; Group 2: follow up 1-3 years after surgery, n= 42; Group 3: follow up 3-5 years after surgery, n= 51).

RESULTS

One hundred and eighteen operated eyes were examined. Eyes in Group 3 were found to have the highest incidence of visually significant PCO (27.5%). There were more eyes requiring capsulotomy after 3 years than after 1 year following surgery. Linear regression analysis revealed an odds ratio of 1.4 (P = 0.07). All nine eyes in the 1-3 year group that had developed visually significant PCO had undergone extra-capsular cataract extraction.

CONCLUSIONS

For the remote Aboriginal patient who has undergone cataract surgery, there is a relatively minor chance of developing PCO within the first postoperative year regardless of the type of surgery undertaken. This study illustrates that the longer the time after surgery the greater the chance of developing visually significant PCO. For the remote Aboriginal patient there is a high chance (approximately 28%) of developing visually significant PCO within 5 years after cataract surgery. These figures are lower than those reported from other parts of Australia.

Performance of a truncated-edged silicone foldable intraocular lens in Indian eyes

PURPOSE

To study the role of truncated-edged silicone foldable intraocular lenses (IOLs) in preventing posterior capsule opacification (PCO) in Indian eyes.

SETTING

Cornea and Anterior Segment Service, L.V. Prasad Eye Institute, Hyderabad, India.

METHODS

This prospective study evaluated 39 Indian patients (39 eyes) with a mean age of 55.4 years who had uneventful implantation of the CeeOn Edge 911A IOL (Pharmacia). All IOLs were placed in the bag. Except in 4 patients, the capsulorhexis margin overlapped 360 degrees on the IOL optic periphery. The mean follow-up was 10.9 months (range 6.5 to 13.0 months); 32 patients were followed for 1 year.

RESULTS

Intraoperatively, posterior capsule fibrosis was noted in 7 patients. Diffuse haze was noted in the IOL optic in 1 patient. Clinically significant PCO did not occur in any case. One patient had clinically nonsignificant (grade 1) PCO at the 6- and 12-month follow-up visits. Although epithelial pearl accumulation (Soemmering's ring) was seen beyond the edge of the IOL in the 32 patients followed for 1 year, the epithelial pearls were central only in the patient with grade 1 PCO. Significant cell deposits were noted in 1 patient who had fibrinous uveitis at the 1-week postoperative visit; both resolved by 1 month. All eyes achieved a best corrected visual acuity of 20/30 or better.

CONCLUSIONS

The CeeOn Edge 911A IOL was well tolerated in Indian eyes, and the posterior capsule remained clear. Larger patient groups with a longer follow-up will provide more useful information.

Failure of a discontinuous bend to prevent lens epithelial cell migration in vitro

PURPOSE

To assess the effect of substrate geometry (discontinuous bend) on lens epithelial cell (LEC) growth in vitro.

SETTING

Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

METHODS

Culture wells with central depths of 0.4 mm, 1.0 mm, or 3.0 mm and a sharp square-edged profile (discontinuous bend) or a round-edged profile (continuous bend) were produced from a block of poly(methyl methacrylate). Freshly harvested bovine LECs were attached to the center of each well and cultured using standard techniques. Observations were made of whether LECs grew out of the wells and of the time required to do so.

RESULTS

Lens epithelial cells migrated out of all the wells. There was no significant difference in the rate at which they migrated out of round-edged and square-edged wells.

CONCLUSIONS

In vitro, a sharp discontinuous bend did not appear to induce contact inhibition of migrating LECs nor did it significantly hinder the rate at which LECs migrated. Therefore, a discontinuous bend in the lens capsule in isolation is unlikely to be responsible for the observed reduction in posterior capsule opacification associated with the use of square-edged IOLs.

Effect of an acrylic intraocular lens with a sharp posterior optic edge on posterior capsule opacification

PURPOSE

To compare the posterior capsule opacification (PCO) inhibiting effect of the sharp posterior optic edge design of the Sensar OptiEdge AR40e intraocular lens (IOL) (Allergan Surgical) with that of the round-edged design of the Sensar AR40 IOL. Setting Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective randomized patient- and examiner-masked study comprised 106 eyes of 53 patients with bilateral age-related cataract. Each patient had cataract surgery in both eyes and received an AR40 IOL in 1 eye and an AR40e IOL in the other eye. Postoperative examinations were at 1 week, 2 and 6 months, and 1 year. Digital slitlamp and digital retroillumination images of each eye were taken. The amount of PCO was assessed subjectively at the slitlamp and objectively using automated image-analysis software.

RESULTS

The AR40e group had significantly less regeneratory and fibrotic PCO 1 year after surgery. The mean automated image-analysis software PCO score (scale 0 to 10) was 2.19 in the AR40 group and 1.10 in the AR40e group (P <.001). The AR40e group had less peripheral fibrotic PCO. There was no significant difference in patient-reported edge glare between the 2 IOL groups.

CONCLUSIONS

The sharp-edged design of the Sensar OptiEdge AR40e IOL led to significantly less PCO than the round-edged AR40 IOL 1 year postoperatively.

Use of bipolar diathermy to prevent posterior capsule opacification(1)

PURPOSE

To determine the feasibility of using directed bipolar diathermy to eliminate or reduce the formation of new cortical lens material following phacoemulsification in a rabbit model.

SETTING

Department of Research & Development, Bausch & Lomb Surgical, and Department of Ophthalmology, St. Louis University, St. Louis, Missouri, USA.

METHODS

A rabbit model for posterior capsule opacification (PCO) was used. A continuous curvilinear capsulorhexis was performed followed by phacoemulsification to remove cortical lens material. In 2 experimental groups, modified bipolar instruments were used to apply diathermy to residual lens epithelial cells using an intracapsular or extracapsular method of application. Postoperative clinical examinations were at 1, 3, and 7 days and then weekly up to 60 days. Selected animals were followed for a longer period. Capsule integrity was evaluated by measuring the pressure required to rupture the capsule in similarly treated porcine eyes.

RESULTS

Diathermy prevented PCO in 4 of 4 eyes in the intracapsular treatment group and 4 of 5 in the extracapsular group. Eyes remained free of new lens cortex for the life of the animal, which was as long as 18 months. New cortical material was detected after 35 days in 1 animal in the extracapsular group. Mean time for the formation of observable cortical material was 29 days +/- 5 (SD) in the control animals. Physical measurements did not detect a reduction in capsule integrity with diathermy treatment. The extracapsular treatment method resulted in fewer iris complications.

CONCLUSIONS

Directed diathermy has the potential to eliminate secondary cataract formation with minimal damage to collateral tissues.

Outcome of phacoemulsification after pars plana vitrectomy

PURPOSE

To compare the outcome of phacoemulsification surgery in patients with and without prior vitrectomy, adjusted for confounding factors.

DESIGN

Retrospective cohort study.

PARTICIPANTS AND CONTROLS

Thirty-one consecutive eyes undergoing phacoemulsification after pars plana vitrectomy (PPV) and 116 consecutive eyes undergoing phacoemulsification without previous PPV.

METHODS

Office records of the operating surgeons were reviewed for age, gender, type of cataract, vitrectomy status, best-corrected visual acuity (BCVA) before and after phacoemulsification, intraoperative difficulties, and postoperative complications. Bivariate analyses between these predictors and the main outcome, BCVA of 20/40 or better after phacoemulsification, were performed using Pearson's chi-square tests. An adjusted analysis of the relationship between outcome and vitrectomy status was performed with logistic regression. Pearson's chi-square tests were used to compare type of cataract, intraoperative difficulties, and postoperative complications in study and control eyes.

MAIN OUTCOME MEASURES

BCVA of 20/40 or better after phacoemulsification, rates of intraoperative difficulties, and postoperative complications.

RESULTS

The most common indication for PPV was macular hole. The average interval from PPV to phacoemulsification was 15.4 months. Study eyes were followed for an average of 10 months compared with 6.6 months for controls. Study eyes were more likely than controls to have predominantly nuclear sclerotic cataracts (P = 0.002). After cataract extraction, 24 of 31 study eyes (77.4%) and 110 of 116 control eyes (94.8%), had BCVAs of 20/40 or better. After adjusting for confounders, eyes without previous vitrectomy were 3.44 times more likely to obtain a BCVA of 20/40 or better than eyes with prior PPV, but this difference was not statistically significant (95% CI, 0.72-16.67). Only 3 of 31 (9.7%) study and 11 of 116 (9.4%) control eyes had intraoperative difficulties (P = 0.47). Posterior capsule plaque was the most common intraoperative difficulty in study eyes; small pupil requiring stretching or iris hooks was most common in controls. Only 1 of 31 (3.2%) study eyes had a postoperative complication other than posterior capsule opacification compared with 18 of 116 (15.5%) controls (P = 0.07).

CONCLUSIONS

A large proportion of patients with prior PPV obtain good visual acuity after phacoemulsification. We did not find significantly higher rates of intraoperative difficulties or postoperative complications compared with controls. The benefits of phacoemulsification seem to be limited only by retinal comorbidity.

Post cataract-intraocular lens (IOL) surgery opacification

Intraocular lens (IOL) implantation has no doubt been one of the most satisfying advances of medicine. Millions of individuals with visual disability or frank blindness from cataracts had and continue to have benefit from this procedure. It has been reported by ophthalmologists that the modern cataract-intraocular lens (IOL) surgery is safe and complication-free most of the time. This makes the watchword for any cataract surgeon to be 'implantation,' 'implantation,' 'implantation.' In the mid-1980s, as IOLs were evolving rapidly, the watchword of the implant surgeon was 'fixation,' 'fixation,' 'fixation.' Most techniques, lenses and surgical adjuncts now allow us to achieve the basic requirement for successful IOL implantation, namely long-term stable IOL fixation in the capsular bag. However despite this advancement some items 'slipped through cracks.' In this article, we would like to alert the reader to a new watchword, namely 'opacification,' 'opacification,' 'opacification.' Here we will be talking about the good, the bad, and the ugly. Examples of the 'good' include the recent successes now being achieved in reducing the incidence of posterior capsule opacification. Examples of the 'bad' include various proliferations of anterior capsule cells, problems caused by silicone oil adherence to IOLs and problems with piggyback IOLs. The 'ugly' include the sometimes striking and often visually disabling opacifications occurring on and within IOL optics, both on some modern foldable IOLs as well as a poly(methyl methacrylate) (PMMA) optic degradation occurring with some models a decade or more after implantation.

Relationship of AcrySof acrylic and PhacoFlex silicone intraocular lenses to visual acuity and posterior capsule opacification

PURPOSE

To compare the changes in visual acuity and the development of posterior capsule opacification (PCO) with AcrySof acrylic intraocular lenses (IOLs) (Alcon Laboratories) and second-generation PhacoFlex silicone IOLs (Allergan ).

SETTING

Eye Associates of New Mexico and Southwest Colorado, Albuquerque, New Mexico, USA.

METHODS

Medical charts of patients having cataract extraction with implantation of an AcrySof MA30BA or MA60BM (MA30/60) or PhacoFlex SI-30NB or SI-40NB (SI-30/40) IOL between January 1995 and June 1997 were abstracted. Analyzed were the changes in visual acuity and development of PCO 1 month postoperatively and at the last available ophthalmologist visit or the visit before neodymium:YAG (Nd:YAG) capsulotomy.

RESULTS

Patients with MA30/60 acrylic IOLs were significantly older, had a worse preoperative best corrected visual acuity (BCVA), and had more concomitant ocular diseases than those with SI-30/40 silicone IOLs. The change in BCVA from preoperatively to 1 month postoperatively was equivalent in the 2 lens groups. The BCVA declined from 1 month postoperatively to the last recorded or pre-Nd:YAG visit. This decline was greater in eyes with SI-30/40 silicone IOLs than in those with MA30/60 acrylic IOLs. Although the decrease in BCVA between IOL types was not significantly different, eyes with a SI-30/40 silicone IOL were significantly more likely to develop PCO and have Nd:YAG capsulotomy. Eyes developing PCO had a statistically significant decline in BCVA from 1 month postoperatively to the last/pre-Nd:YAG visit.

CONCLUSIONS

The MA30/60 acrylic lenses were associated with lower PCO and Nd:YAG capsulotomy rates than second-generation SI-30/40 silicone IOLs. Patients with MA30/60 IOLs also tended to have less of a decrease in visual acuity than patients with SI-30/40 silicone lenses, probably as a result of the difference in PCO rates between groups.

Incremental cost-effectiveness of initial cataract surgery

PURPOSE

The purpose of this study was to perform a reference case, cost-utility analysis of initial cataract surgery using the current literature on cataract outcomes and complications.

DESIGN

Computer-based econometric modeling.

METHODS

Visual acuity data of patients treated and observed over a 4-month postoperative period was obtained from the US National Cataract Patient Outcomes Research Team (PORT). The results from this prospective study were combined with other studies that investigated the complication rates of cataract surgery to complete the cohort of patients and outcomes. These synthesized data were incorporated with time-tradeoff utility values, decision analysis, and econometric modeling to account for the time value of money.

MAIN OUTCOME MEASURES

The number of quality-adjusted life-years (QALYs) gained was calculated for the study group undergoing cataract extraction in the first eye when the vision was the same in both eyes. This was divided into the cost of the procedure to find the year 2000 nominal US dollars spent per quality-adjusted life-year ($/QALY) gained.

RESULTS

Initial cataract surgery, compared with observation, resulted in a mean gain of 1.776 QALYs per patient treated. A 3% annual discount rate was used to account for the benefit over time, yielding 1.25 QALYs gained. The mean cost of treatment (also discounted at a 3% annual rate) of each patient totaled 2525 US dollars. The cost divided by the discounted benefit resulted in $2020/QALY gained for this procedure.

CONCLUSIONS

Initial cataract surgery seems to be highly cost-effective compared with procedures across multiple medical specialties. This information, incorporating patient preferences into evidenced-based medicine, will play an increasingly important role in the evaluation of health care in the future.

Reproducibility of standardized retroillumination photography for quantification of posterior capsule opacification

PURPOSE

To determine the short-term reproducibility of standardized digital retroillumination images of regeneratory posterior capsule opacification (PCO) using the photographic setup at 1 institution.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

In this prospective study, 60 retroillumination images of 30 eyes with varying degrees of PCO and different types of intraocular lenses were acquired with a standardized digital coaxial retroillumination system. Two images were taken per eye with a 1-minute interval between images. Ten other eyes were photographed in the same way but with a 5-day interval between the 2 images. All images were evaluated with a fully automated, objective PCO analysis software in which the PCO score was from 0 to 100. The 2 results (A, B) in each eye were compared, and the differences were calculated.

RESULTS

There was a high correlation between the A and B results (r = 0.99). The mean absolute difference was 3.7%. The repeatability coefficient was 8.8%.

CONCLUSION

Digital coaxial retroillumination photography provided quick acquisition of regeneratory PCO images. It provided excellent image quality and high reproducibility. The technique forms a good basis for automated quantification of PCO with new software systems.

Comparison of long-term incidence of posterior capsular opacification between phacoemulsification and phacotrabeculectomy

PURPOSE

To investigate the long-term incidence of posterior capsular opacification after phacoemulsification compared with phacotrabeculectomy with or without adjunctive subconjunctival mitomycin C.

METHODS

This was a retrospectively conducted long-term, observational, case-control study. One hundred eyes of 100 cataract patients who underwent phacoemulsification and posterior chamber intraocular lens implantation and 100 eyes of 100 primary open-angle glaucoma patients with cataract that underwent phacotrabeculectomy and posterior chamber intraocular lens implantation, matched with respect to age, intraocular lens type, prevalence of diabetes mellitus, and length of follow-up. The main outcome measure was the rate of clinically significant posterior capsular opacification as determined by slit-lamp biomicroscopy and necessity to perform neodynium:yttrium aluminum garnet (Nd:YAG) capsulotomy and as calculated by Kaplan-Meier survival analysis. Postoperative visual acuity and maintenance of intraocular pressure control were also measured.

RESULTS

There was no significant difference in the rate of posterior capsular opacification requiring Nd:YAG capsulotomy between the phacoemulsification and phacotrabeculectomy groups (P =.77). However, a significant difference in the rate of posterior capsular opacification was found between those patients without diabetes mellitus and those with a preoperative diagnosis of diabetes mellitus (P =.016). Also, survival analysis comparing use of mitomycin C with no use of mitomycin C in the phacotrabeculectomy group showed a higher survival in the mitomycin C subgroup (P =.03).

CONCLUSION

There was no significant difference in long-term posterior capsular opacification between phacoemulsification and phacotrabeculectomy in the study population. Intraoperative, adjunctive use of mitomycin C in the phacotrabeculectomy group and the presence of diabetes mellitus in the overall patients were beneficial (protective) factors against posterior capsular opacification.

Intracapsular ring sustained 5-fluorouracil delivery system for the prevention of posterior capsule opacification in rabbits: a histological study

PURPOSE

To evaluate the efficacy of an intracapsular ring releasing 5-fluorouracil (5-FU) in preventing posterior capsule opacification (PCO) in rabbit eyes.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA, and Chu Morvan, Department d'Ophtalmologie, University of Brest, France.

METHODS

Seventeen rabbits were divided into 3 groups: Group 1, 6 rabbits (6 eyes), had phacoemulsification only (control group); Group 2, 6 rabbits (6 eyes), had phacoemulsification with implantation of an open-loop hydrogel intracapsular ring; Group 3, 5 rabbits (5 eyes), had phacoemulsification with implantation of a ring with sustained release of 0.25 microg/h of 5-FU for 9 days. All eyes were followed for 8 weeks before enucleation. Capsular bag shrinkage and the position of the intracapsular ring were assessed, and central and peripheral PCO was evaluated for intensity and area by stereomicroscopy from a posterior (Miyake-Apple) view. The residual equatorial lens epithelial cells (LECs) were counted by the same observer in histological sections. Transmission electron microscopy (TEM) of the cornea, capsular bag, and retina was done to evaluate the toxicity of 5-FU.

RESULTS

No significant difference was seen in the degree of capsular bag shrinkage in the 3 groups. The intracapsular ring was decentered in 2 eyes (1 each in Groups 2 and 3). There was a statistically significant difference (P <.05, Student t test) between Group 1 and Groups 2 and 3 in the area and intensity of central PCO. There was no difference between Groups 2 and 3 in the intensity of central PCO. No evidence of 5-FU toxicity to intraocular structures (cornea, capsular bag, and retina) was demonstrated on TEM analysis.

CONCLUSION

Implantation of an intracapsular ring may prevent central PCO after cataract surgery by mechanically blocking LEC migration toward the central visual axis. The potential pharmacological effect of 5-FU in PCO prevention was not demonstrated.

Extracellular matrix and Na+,K+-ATPase in human corneas following cataract surgery: comparison with bullous keratopathy and Fuchs' dystrophy corneas

PURPOSE

To examine the distribution of extracellular matrix (ECM) and basement membrane (BM) components and of Na+,K+-ATPase in postcataract surgery (PCS) corneas. These corneas were from patients who never developed pseudophakic or aphakic bullous keratopathy (PBK/ABK) after cataract surgery. PCS corneas were compared with PBK/ABK and Fuchs' dystrophy corneas.

METHODS

The distribution of PBKIABK ECM and BM markers and of all three Na+,K+-ATPase alpha subunits was studied by immunofluorescence in 10 healthy, 11 PCS, 16 PBK/ABK, and 12 Fuchs' dystrophy corneas.

RESULTS

Fibrotic ECM proteins, tenascin-C and fibrillin-1, were found in only 1 of 10 healthy and in 2 of 11 PCS corneas. In contrast, these proteins were expressed in all PBK/ABK and more than half of the Fuchs' dystrophy corneas. BM components in PCS corneas were altered to a greater extent (40-60%), especially fibronectin and laminin-10. A decreased epithelial immunostaining for Na+,K+-ATPase alpha subunits was seen in approximately 40% of PCS corneas and in approximately two thirds of PBK/ABK and Fuchs' dystrophy corneas. However, the endothelial staining was normal in all groups.

CONCLUSIONS

Because tenascin-C and fibrillin-1 were mostly found in diseased but not in PCS corneas, their expression may be related to later, clinical stages of corneal edema development. However, BM components abnormal in PBK/ABK and Fuchs' dystrophy corneas were also altered in PCS corneas without clinical evidence of ocular disease. This may result from subclinical corneal changes resulting from cataract surgery, lens removal, exposure to the intraocular lens, or endothelial cell damage. Alterations of epithelial Na+,K+-ATPase point to the importance of epithelial changes in the development of corneal edematous diseases.

Inhibition of lens epithelial cell growth by induction of apoptosis: potential for prevention of posterior capsule opacification

As a model of the cell proliferation occurring in posterior capsule opacification (PCO), lens epithelial cells (LEC) from human and rabbit capsulotomies, and a rabbit LEC line (N/N1003A) were grown in Dulbecco's Minimal Essential Media (MEM) with 10% fetal calf serum. LEC were exposed to the calcium ionophore, calcimycin, and viability was assessed by trypan blue staining, growth by 3H-thymidine incorporation and apoptosis by annexin/propidium iodide staining, calcein AM/ethidium bromide staining and DNA laddering. Human capsulotomy samples were similarly exposed to calcimycin, and apoptosis assayed by calcein AM/ethidium bromide staining. Calcimycin exposure induced apoptosis in both rabbit LEC cultures and human LEC, and changes leading to apoptosis could be detected within 30 minutes of calcimycin treatment. The decrease in viability and growth in human and rabbit LEC was dose-dependent. These data support the further evaluation of apoptosis induction as a possible treatment mechanism to prevent development of PCO following primary cataract surgery in humans.

Posterior capsule opacification with AcrySof and poly(methyl methacrylate) intraocular lenses. Comparative study with a 3-year follow-up

PURPOSE

To evaluate whether reports of reduced posterior capsule opacification (PCO) rates with AcrySof intraocular lenses (IOLs) are applicable to a mixed group of cataract patients in everyday surgical practice.

SETTING

Department of Ophthalmology, Kärnsjukhuset, Skövde, Sweden.

METHODS

A retrospective study comparing a study group receiving an AcrySof IOL (n = 145) and a group receiving a poly(methyl methacrylate) (PMMA) IOL (n = 153) was performed. The follow-up was 3 years in both groups. The performance of a neodymium:YAG laser capsulotomy was used as the end point for clinically significant PCO.

RESULTS

Nine capsulotomies (6.2%) were performed in the AcrySof group and 34 (22.2%) in the PMMA group. The difference in the capsulotomy rate between the 2 groups was highly significant (P <.001). The relative risk was 3.6 times higher in the PMMA group.

CONCLUSIONS

There was a significant difference in the frequency of capsulotomy between AcrySof and PMMA IOLs in a mixed group of cataract patients in everyday clinical practice. This finding indicates the importance of the IOL type in PCO formation.

Clinical features of 46 eyes with calcified hydrogel intraocular lenses

PURPOSE

To clarify the clinical features of delayed calcification of hydrogel intraocular lenses (IOLs) based on observation of a large case series.

SETTING

Ophthalmology department of 2 university teaching hospitals, Hong Kong, China.

METHODS

The first 44 patients with a known diagnosis of calcified IOL were recruited. Medical and ophthalmic histories were obtained. Surgical details, surgical complications, and visual acuity before and after IOL implantation were also retrieved. Patients then had a visual acuity test, a slitlamp examination of the features of the IOL calcification, and a fundus examination for clarity of view.

RESULTS

Forty-six eyes of 44 patients had IOL calcification. All had a Hydroview IOL. The onset was from 4 to 26 months after surgery. Ninety-three percent of eyes had generalized IOL calcification, and 96% had forceps marks on the IOL. Mean visual acuity deteriorated from 0.4 at 3 months to 0.13 at 19 months. Visual loss was more severe in patients with diabetes mellitus or ischemic heart disease and in those in which the IOL calcified earlier after implantation.

CONCLUSION

All cases of IOL calcification were delayed in onset. The presence of forceps marks may provide a clue to the pathogenesis. Bilateral but asymmetric involvement in 2 patients suggests that the IOL was involved in the pathogenesis. Affected patients lost an average of 2.8 Snellen lines of visual acuity. Some eyes progressed more rapidly; however, the modulating factors remain unknown.

Phacoemulsification in patients after allogeneic bone marrow transplantation

OBJECTIVE

To study the outcomes of phacoemulsification in allogeneic bone marrow transplant (allo-BMT) recipients.

DESIGN

Retrospective, noncomparative, interventional case series.

METHODS

Retrospective study of 34 eyes of 19 consecutive patients who had visually significant cataracts after allo-BMT and subsequently underwent phacoemulsification.

MAIN OUTCOME MEASURES

Best-corrected vision at the last follow-up visit and development of postoperative complications.

RESULTS

Surgery was done at a mean interval of 37 months after BMT, and the mean postoperative follow-up was 13 months. Twenty-one eyes (62%) had subnormal Schirmer I scores as a result of graft-versus-host disease (GVHD) involving the lacrimal gland. Of these, 71% (15 eyes) additionally had significant ocular surface epitheliopathy because of conjunctival GVHD. Frequent lubrication (95%), punctal occlusion (76%), topical steroids (33%), and other topical immunosuppressive therapies (14%) were used to manage GVHD-induced ocular surface disease before cataract surgery. Twelve patients (63%) also received systemic steroids and immunosuppressives. Patients proceeded to surgery only after their ocular surface disease was well controlled. Early postoperative complications included intraocular pressure elevation (three eyes), worsening of dry eye syndrome (two eyes), and corneal thinning (one eye). Posterior capsular opacification (PCO) requiring laser capsulotomy occurred in 44% of eyes. In eyes with preoperative conjunctival GVHD, 47% had recurrence with cessation of immunosuppressive therapy after surgery. Visual acuity at last follow-up visit was 20/30 or better in 33 (97%) eyes.

CONCLUSIONS

Phacoemulsification is an effective procedure in restoring vision in patients who have cataracts develop after BMT. However, coexisting ocular disease must be recognized and aggressively treated both before and after surgery to ensure good visual outcomes.

Capsular bending ring to prevent posterior capsule opacification: 2 year follow-up

PURPOSE

To evaluate the preventive effect of a capsular bending ring on anterior and posterior capsule (PCO) opacification in a 2 year clinical study.

SETTING

Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan.

METHODS

This study comprised 60 patients with senile cataract (35 women, 25 men) with a mean age of 69 years. An open poly(methyl methacrylate) capsular bending ring with a truncated edge profile designed to create a sharp bend in the equatorial capsule was implanted in 1 eye of patients with a hydroxyethyl methacrylate intraocular lens (IOL). The contralateral eye, which acted as a control, received an IOL but no ring. Patients were examined 6 months (n = 52), 1 year (n = 48), and 2 years (n = 42) postoperatively. Anterior capsule opacification was determined by slitlamp evaluation. Anterior capsule shrinkage (area within the capsulorhexis) and PCO were evaluated and scored using a computer software package for image analysis. Posterior capsule opacification was also measured by the rate of neodymium:YAG (Nd:YAG) capsulotomies.

RESULTS

Anterior capsule opacification and shrinkage were significantly less in eyes with the ring. The mean PCO score was 0.235 +/- 0.215 (SD), 0.287 +/- 0.200, and 0.398 +/- 0.248 with the ring and 0.530 +/- 0.190, 0.670 +/- 0.225, and 1.111 +/- 0.298 without the ring at 6 months, 1 year, and 2 years, respectively (P <.01 at each follow-up). An Nd:YAG laser capsulotomy was performed in 4 eyes with and 17 eyes without the ring after 2 years (P <.01).

CONCLUSIONS

The capsular bending ring significantly reduced anterior capsule fibrosis and shrinkage as well as PCO. The ring may be useful in patients who are at high risk of developing eye complications from capsule opacification that require Nd:YAG laser capsulotomy, in those expected to have vitreoretinal surgery and photocoagulation, and in cases of pediatric cataract.

Anterior capsule opacification: correlation of pathologic findings with clinical sequelae

OBJECTIVE

To evaluate the degree of anterior capsule opacification (ACO) in human eyes obtained postmortem containing various rigid and foldable posterior chamber intraocular lens (PC-IOL) designs and compare the findings with clinical sequelae of capsular shrinkage.

DESIGN

Comparative autopsy tissue study with clinicopathologic correlations.

MATERIALS

Three hundred formalin-fixed human eyes containing the following PC-IOL styles were analyzed: (1) one-piece polymethyl methacrylate (PMMA) optic-PMMA haptic (n = 50), one-piece silicone-plate IOL, with large (2) or small (3) fixation holes (n = 35), (4) three-piece PMMA optic-Prolene haptic (n = 50), (5) three-piece acrylic optic-PMMA haptic (n = 55), three-piece silicone optic with PMMA (6) or polyimide (7) haptics (n = 30), and (8) three-piece silicone optic-Prolene haptic (n = 80) lenses.

TESTING

The eyes were sectioned in the equatorial plane for gross examination of the capsular bag from a posterior view. The cornea and iris were then excised for evaluation from an anterior view.

MAIN OUTCOME MEASURES

ACO was scored in each eye from 0 to IV, according to the degree/area of capsule opacification. Capsulorrhexis size and IOL decentration were measured with calipers.

RESULTS

The overall differences among the IOL groups regarding the three parameters were significant (ACO score: P < 0.001; capsulorrhexis diameter: P = 0.036; IOL decentration: P = 0.012). Mean ACO scores were highest with the large- and small-hole one-piece silicone-plate lenses (2.543 +/- 0.950) and lowest with the three-piece acrylic optic-PMMA haptic lenses (0.600 +/- 0.710). Of 10 cases of capsulorrhexis phimosis observed in the study, 7 cases were associated with three-piece silicone optic-Prolene haptic lenses, which also presented the highest mean decentration (0.375 +/- 0.601 mm).

CONCLUSIONS

Our results confirm previous histopathologic observations that the rate of ACO is the lowest with acrylic lenses and higher with plate-haptic silicone IOLs. Nevertheless, clinical sequelae of capsular shrinkage are also very important with three-piece silicone optic-Prolene haptic designs. Thus, IOL material and design are significant factors in the development of ACO, but they ultimately also influence the clinical presentation of capsular shrinkage.

Posterior capsule opacification and lens epithelial cell layer formation: Hydroview hydrogel versus AcrySof acrylic intraocular lenses

PURPOSE

To quantitatively compare the incidence of visually significant posterior capsule opacification (PCO) and lens epithelial cell (LEC) layer formation on the anterior surface of Hydroview hydrogel and AcrySof acrylic foldable intraocular lenses (IOLs) after implantation.

SETTING

Single-surgeon ophthalmology practice, Orange Base Hospital, and Dudley Private Hospital, Orange, New South Wales, Australia.

METHODS

This retrospective study comprised 166 eyes of 150 patients (after exclusions) who had cataract extraction and insertion of a foldable IOL in the capsular bag by a single surgeon using a standardized phacoemulsification technique from December 1997 to September 1998. The mean follow-up was 13.1 months (range 6.0 to 23.6 months). The eyes were divided into 2 groups based on the type of IOL implanted: Storz Hydroview H60M (81 eyes) or Alcon AcrySof MA30BA (85 eyes). A neodymium:YAG posterior capsule laser capsulotomy (PC YAG) was performed for an objective decrease in Snellen best corrected visual acuity (BCVA) of more than 1 line, significant visual symptoms, or both. This was used as a measure of visually significant PCO. An Nd:YAG anterior surface clearance (ASC YAG) was done for LEC layer formation anterior to the IOL to better visualize or facilitate treatment of PCO. The rates of PC YAG and ASC YAG after Hydroview and AcrySof IOL implantation were statistically compared.

RESULTS

Forty-five eyes (55.6%) in the Hydroview IOL group and 3 eyes (3.5%) in the AcrySof IOL group required a PC YAG; the risk difference was 52.0% (P <.001). An ASC YAG was required in 27 eyes (33.3%) in the Hydroview group and 1 eye (1.2%) in the AcrySof group; the risk difference was 32.2% (P <.001). Survival analysis demonstrated that the only independent predictor of the incidence of PC YAG and ASC YAG over time was IOL type, with the Hydroview IOL group having a statistically significantly higher incidence of both procedures.

CONCLUSION

There was a greater incidence of visually significant PCO and LEC layer formation on the anterior surface of Hydroview IOLs than of AcrySof IOLs.

Prevention of posterior capsule opacification by intraoperative single-dose pharmacologic agents

PURPOSE

To determine whether an intraoperative single dose of dexamethasone, diclofenac, ethylenediaminetetraacetic acid (EDTA), a combination of EDTA and RGD peptide (arginine-glycin-aspartic acid sequence), or mitomycin-C (MMC) is a pharmacological means of preventing or reducing the development of posterior capsule opacification (PCO).

SETTING

Department of Ophthalmology, Celal Bayar University, School of Medicine, Manisa, and Department of Pathology, Dokur Eylül University, School of Medicine, Izmir, Turkey.

METHODS

Fifty-four rabbits were randomly divided into 6 groups. Dexamethasone (4 mg/cc), diclofenac (2.5 mg/cc), EDTA (8 mg/cc), a combination of EDTA and RGD peptide (2.5 mg/cc), or MMC (0.04 mg/cc) was given, 0.1 cc by hydrodissection and 0.9 cc into the capsular bag after phacoemulsification. The sixth group served as a control group. After 3 months, the PCO was graded clinically and the proliferation of lens epithelial cells (LECs) was evaluated histologically.

RESULTS

The drugs were significantly effective in preventing PCO compared with the control (P <.005). Dexamethasone had a weaker effect than the other drugs. In histological analysis, although monolayer LECs in the dexamethasone and diclofenac groups were observed, there was no proliferative activity on the posterior capsules in the EDTA, EDTA+RGD, and MMC groups in contrast to the multilayer cells in the control.

CONCLUSIONS

Intraoperative single-dose application of EDTA, EDTA+RGD peptide combination, and MMC significantly prevented the development of PCO in rabbit eyes. Diclofenac was less effective but also reduced PCO. Although dexamethasone did not prevent the proliferation of LECs, it decreased PCO clinically.

Effect of in-the-bag intraocular lens fixation on the prevention of posterior capsule opacification

PURPOSE

To compare the incidence of posterior capsule opacification (PCO) after extracapsular cataract extraction (ECCE) and phacoemulsification and to evaluate the role of posterior chamber intraocular lens (PC IOL) haptic fixation and biomaterial/design in reducing the incidence.

SETTING

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

METHODS

This study comprised 278 eyes of 263 patients having ECCE and 318 eyes of 297 patients having phacoemulsification with PC IOL implantation. Posterior capsule opacification leading to a decrease in Snellen visual acuity of 2 or more lines was considered visually significant. The presence of PCO and IOL haptic fixation were evaluated postoperatively using slitlamp biomicroscopy. Haptic position was noted as in-the-bag (B-B), 1 haptic in the bag and 1 in the sulcus (bag-sulcus [B-S]), or both haptics out of the bag (sulcus-sulcus [S-S]). In addition, the rate of visually significant PCO was compared among 3 IOL biomaterials: poly(methyl methacrylate), silicone, and hydrophobic acrylic.

RESULTS

Visually significant PCO occurred in 42.45% of eyes having ECCE and 19.18% of eyes having phacoemulsification (P <.001, chi-square test) after a mean follow-up of 2.4 years +/- 0.7 (SD). In both groups, visually significant PCO was significantly less in eyes with B-B fixation than in those with B-S or S-S fixation (P <.001). The rate of visually significant PCO in all eyes in the phacoemulsification group with B-B fixation was low (11.90%) and was significantly lower in eyes with a hydrophobic acrylic IOL (2.22%; P <.05, chi-square test).

CONCLUSIONS

In-the-bag PC IOL fixation is required to consistently reduce the incidence of PCO. Thorough removal of lens substance, including hydrodissection-assisted cortical cleanup, and in-the-bag PC IOL fixation seem to be the most important factors in reducing PCO, regardless of surgical procedure or IOL type used. Intraocular lens biomaterial and design also help prevent PCO.

Visual acuity and contrast sensitivity in different types of posterior capsule opacification

PURPOSE

To compare the visual acuity (VA) and contrast sensitivity in 2 types of posterior capsule opacification (PCO) in pseudophakic eyes before and after neodymium:YAG (Nd:YAG) capsulotomy and to evaluate vision test results after Nd:YAG capsulotomy.

SETTING

Department of Ophthalmology, Taipei Veterans General Hospital, National Yang-Ming University, Taipei, Taiwan.

METHODS

Fourteen eyes with fibrosis-type PCO and 15 eyes with Elschnig-pearl-type PCO were enrolled prospectively. Before and 1 week after Nd:YAG capsulotomy, VA and contrast sensitivity were assessed using the illiterate E version of the Bailey-Lovie chart and the Vistech VCTS 6000 chart, respectively.

RESULTS

Before capsulotomy, the mean logMAR acuity in the group with Elschnig-pearl-type PCO was 0.47 +/- 0.32 (SD) and in the group with fibrosis-type PCO, 0.17 +/- 0.07. The difference between the 2 groups was significant (P =.002). After capsulotomy, there was no significant between-group difference (P >.05). Before capsulotomy, the contrast sensitivity was significantly worse (P <.01) at all spatial frequencies in the group with pearl-type PCO, especially at 6 cycles per degree. After capsulotomy, there was no significant between-group difference (P >.05) at any spatial frequency.

CONCLUSIONS

After cataract surgery, patients with pearl-type PCO had lower VA and contrast sensitivity than those with fibrosis-type PCO. An Nd:YAG capsulotomy improved the VA and contrast sensitivity in patients with both types of PCO.

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

OBJECTIVE

(1) To report the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy rate (%) of eight rigid and foldable intraocular lens (IOL) designs in a series of 5416 pseudophakic human eyes obtained postmortem, accessioned in our center between January 1988 and January 2000. (2) To identify factors that are instrumental in reducing the incidence of posterior capsule opacification, (PCO, secondary cataract) and hence the need for Nd:YAG laser posterior capsulotomy.

DESIGN

Comparative autopsy tissue analysis.

PARTICIPANTS

A total of 5416 globes with posterior chamber intraocular lens (PC-IOLs) obtained postmortem received from Lions Eye Banks between 1988 and 2000.

METHODS

Miyake-Apple posterior photographic technique. Special reference was given to the presence or absence of Nd:YAG laser posterior capsulotomy orifice on the posterior capsule of each eye.

MAIN OUTCOME MEASURES

The Nd:YAG laser posterior capsulotomy rate (%) as of January 2000 was documented. In addition, the Nd:YAG laser posterior capsulotomy rate for each lens was plotted on a monthly basis for the same period, creating a computerized trend or "timeline" for each IOL style.

RESULTS

Relatively high Nd:YAG laser posterior capsulotomy rates ranging from 20.3% to 33.4% were noted with four relatively older designs (high incidence of implantation between 1988 and the early 1990s). Four modern foldable IOLs manufactured from silicone and acrylic materials had significantly lower Nd:YAG laser posterior capsulotomy rates ranging from 0.9% (Alcon Acrysof) to 17.1%. The difference in Nd:YAG rates among the eight IOL designs was found to be significant (P < 0.0001, chi-square test). Comparing foldable versus rigid designs, the foldable IOLs were associated with a much lower Nd:YAG laser posterior capsulotomy rate (14.1% vs. 31.1%).

CONCLUSIONS

By use of the six factors regarding surgical technique and IOL choice described in this article, we strongly believe that the overall incidence of PCO and hence the incidence of Nd:YAG laser posterior capsulotomy is now rapidly decreasing from rates as high as 50% in the 1980s to early 1990s. Surgical tools and IOLs are now available to bring these rates down to single digits. Careful application and use of these tools by surgeons can genuinely lead in the direction of virtual eradication of secondary cataract, the second most common cause of visual loss worldwide.

Capsulotomy

Research is continually seeking to better describe the relationship between pseudophakic capsular opacification and underlying cell biology, surgical technique, and intra-ocular lens biomaterial and design. Outcomes are reviewed from prospective, randomized studies that investigate the importance of capsulorhexis size, pharmacological treatment, and lens material in influencing capsular opacification and the need for capsulotomy. The results of several studies support the role of lens edge profile in inhibiting lens epithelial cell migration. A large post-mortem study also examines how lens type may affect anterior capsular opacification formation. Of particular interest is a histological report that sheds additional light on understanding cellular processes in posterior capsu-lar opacification.

Probability of Nd:YAG laser capsulotomy after cataract surgery in Olmsted County, Minnesota

PURPOSE

To estimate the cumulative probability of Nd:YAG laser posterior capsulotomy after cataract extraction in a geographically defined population.

METHODS

Rochester Epidemiology Project databases were used to identify retrospectively all Nd:YAG laser posterior capsulotomies performed on Olmsted County, Minnesota, residents who had previously undergone cataract extraction between 1988 and 1996, inclusive. Demographic data and potential risk factors for laser, including age, sex, surgical technique, year of surgery, and intraocular lens material, were obtained by chart review or by retrieval from computer databases. The cumulative probability of Nd:YAG laser posterior capsulotomy was calculated by Kaplan-Meier estimates, and risk factors were analyzed using the Cox proportional hazards model.

RESULTS

A total of 925 Nd:YAG laser posterior capsulotomies were identified after 3541 cataract extractions in 2718 patients. The cumulative probability of Nd:YAG laser posterior capsulotomy after cataract surgery was 6% (95% confidence interval = 5% to 7%) at 1 year, increasing to 38% (35% to 40%) at 9 years. Young age at the time of surgery (P =.02), polymethylmethacrylate intraocular lens material (P <.001), earlier year of surgery (P <.001), and extracapsular extraction (in comparison with phacoemulsification, P <.001) were found to increase significantly the risk of subsequent Nd:YAG laser posterior capsulotomy. Women tended to have a greater probability of Nd:YAG laser posterior capsulotomy (P =.17), but this difference was not statistically significant.

CONCLUSIONS

Nd:YAG laser posterior capsulotomy was common after cataract surgery but infrequent during the first postoperative year. Prolonged follow-up is necessary in investigations of the effects of new cataract surgery technologies on the probability of capsulotomy.

Posterior capsule opacification and anterior capsule opacification

Posterior capsule opacification (PCO) is still the most frequent complication of cataract surgery. A variety of studies has led to a better understanding of the pathogenesis of PCO, and strategies of molecular biology have produced new therapeutic options, such as immunological techniques or gene therapeutic approaches. Surgical strategies and intra-ocular lens-dependent factors also are capable to reduce the rate of PCO. In-the-bag implantation of intra-ocular lenses with a sharp optic edge seems to be effective in inhibiting equatorial lens epithelial cell migration to the center of the posterior capsule. Several PCO documentation systems have been developed that will lead to more exact and better comparable recording of PCO rates. In the year 2000, PCO or secondary cataract is still the most frequent complication after extracapsular cataract surgery. In a 1998 meta-analysis, PCO rates of 11.8% 1 year after extracapsular cataract surgery with intraocular lens implantation, 20.7% after 3 years, and 28.4 % after 5 years have been reported. For the United States, it has been estimated that the overall expenses for treatment of PCO are only exceeded by the costs for cataract treatment itself. In the past decade, a lot of experimental and clinical studies have been performed on this topic. They have led to 1) to a better understanding of the pathogenesis of the development of anterior and posterior capsule opacification; 2) more objective and better comparable systems of documentation and analysis of PCO; and a number of 3) surgical and 4) pharmaceutical strategies to prevent PCO.

The madurai intraocular lens study IV: posterior capsule opacification

PURPOSE

To estimate the cumulative incidence of posterior capsule opacification 4 years after surgery in patients who participated in the Madurai Intraocular Lens Study and had extracapsular cataract extraction with posterior chamber intraocular lens implantation.

METHODS

In the Madurai Intraocular Lens Study, 1,700 patients with best-corrected visual acuity 20/120 or worse in the better eye had extracapsular cataract extraction with posterior chamber intraocular lens implantation, and 1,474 (86.7%) of these completed the 1-year follow-up examination. From this group of 1,474 pseudophakic patients, 400 were randomly selected for reexamination 4 years after the original surgery. The eye that was operated on was examined by an ophthalmologist who was involved in the 1-year follow-up examinations and posterior capsule opacification grading. A grading of I to III was used to reflect the degree of opacification. With grades II and III, posterior capsule opacification detectable with an undilated pupil was present in the central axis.

RESULTS

Three hundred twenty-seven (81.8%) of the selected population were examined between October 1997 and December 1998. Thirty-four (8.5%) were confirmed as being deceased, and 39 (9.8%) were unavailable for follow-up. The median age was 60 years, and 57.2% were women. The 4-year incidence of grade II or III posterior capsule opacification, including eyes already treated with laser capsulotomy, was 13.1% (95% confidence interval [CI], 9.7% to 17.3%). Each year of increased age was associated with a decreased risk of posterior capsule opacification (odds ratio, 0.96; 95% CI, 0.92 to 1.00). Based on best-corrected visual acuity of 20/40 or worse without co-existing pathology, the 4-year incidence of posterior capsule opacification was 13.5%.

CONCLUSION

Because patients with relatively mature cataracts routinely receive extracapsular cataract extraction with posterior chamber intraocular lens implantation instead of the traditional intracapsular extraction, the subsequent need for laser capsulotomy may be less than that anticipated, based on previous reports.

Posterior capsule opacification 3 years after implantation of an AcrySof and a MemoryLens in fellow eyes

PURPOSE

To compare the rates of lens epithelial cell (LEC) migration and posterior capsule opacification (PCO) 1 and 3 years after sutureless small incision phacoemulsification and in-the-bag implantation of 2 acrylic polymer intraocular lenses (IOLs)-the AcrySof and MemoryLens-in fellow eyes of patients.

SETTING

Eye Clinic, Beyoğlu Education and Research Hospital, Istanbul, Turkey.

METHODS

Fifty patients with no systemic or ocular problems that would interfere with postoperative visual acuity were included in this prospective study. Each patient had in-the-bag implantation of an AcrySof IOL in 1 eye and a MemoryLens in the fellow eye in a randomized fashion after uneventful phacoemulsification through a sutureless clear corneal incision.

RESULTS

At 1 year (n = 32 patients), there was no significant difference between fellow eyes in postoperative best corrected visual acuity (BCVA) and contrast sensitivity. In the MemoryLens group, 10 eyes (31.3%) had PCO and 9 (28.1%), LEC migration. In the AcrySof group, no eye had PCO and 2 eyes (6.3%) had LEC migration (P <.001). At 3 years (n = 21 patients), 1 eye (4.7%) in the AcrySof group had PCO and 3 eyes (14.4%) had LEC migration without PCO. In the MemoryLens group, 1 eye (4.7%) had a clear posterior capsule, 11 eyes (52.4%) had LEC migration, and 9 eyes (42.9%) had PCO (P <.001). A neodymium:YAG capsulotomy was required in 4 eyes (19.0%) in the MemoryLens group but no eye in the AcrySof group. At 3 years, BCVA was lower in the MemoryLens group than in the AcrySof group (P <.05).

CONCLUSION

The 3 year clinical data of fellow eyes indicate that the AcrySof IOL causes less PCO than the MemoryLens.

Posterior capsule opacification after phacoemulsification: foldable acrylic versus poly(methyl methacrylate) intraocular lenses

PURPOSE

To study the effects of foldable acrylic and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation on posterior capsule opacification (PCO).

SETTING

Department of Ophthalmology, Dokuz Eylül University School of Medicine, Izmir, Turkey.

METHODS

This consecutive series comprised 157 eyes having phacoemulsification with implantation of a foldable acrylic IOL with rectangular optic edges and a 5.5 mm optic (AcrySof) (n = 80 eyes) or a PMMA IOL with rounded optic edges and 5.5 mm optic (n = 77). Evaluated were incidence, location, and degree of PCO. Mean postoperative follow-up was 17.8 months +/- 1.7 (SD) (range 16 to 22 months).

RESULTS

Posterior capsule opacification occurred in 8.7% of eyes in the foldable acrylic IOL group and in 24.7% of eyes in the PMMA IOL group. The difference between the 2 groups was statistically significant (P < .01). Centrally located PCO was significantly lower in the acrylic group (P < .01). There were 3 eyes with severe PCO in the PMMA group and none in the acrylic group. Anterior capsule contraction and fibrosis were present in 4 eyes in the PMMA group but none in the acrylic group. Soemmering's ring cataract formation was detected in 3 eyes, all with the AcrySof IOL.

CONCLUSION

In addition to its optic material and rectangular optic edges, the AcrySof IOL provides additional advantages in lowering the incidence of PCO compared with rounded-edge PMMA IOLs.

Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial

PURPOSE

To compare the visual outcome, percentage of posterior capsular opacification, and laser capsulotomy rates with polymethylmethacrylate, silicone, and hydrogel intraocular lens implants at 1 and 2 years postoperatively.

METHODS

Ninety-three eyes of 93 patients were randomized to receive a polymethylmethacrylate, silicone, or hydrogel intraocular lens implant. A standardized surgical protocol was followed by a single surgeon using phacoemulsification with capsulorhexis; any patients with surgical complications were excluded, and all patients received standardized medication and follow-up. Patients were examined at days 1 and 7, months 1, 3, and 6, and years 1 and 2 after surgery. At each assessment, best-corrected logMAR visual acuity and Pelli-Robson contrast sensitivity were measured. Posterior capsular opacification was objectively assessed by digital retroillumination imaging with the use of a dedicated software program and calculated as the percentage area of opacified capsule. Laser capsulotomy was performed if the eye had lost 2 lines of visual acuity with a clinically opaque capsule.

RESULTS

At 2 years postoperatively, the mean percentage area of posterior capsular opacification for hydrogel lenses was 63%; for polymethylmethacrylate, 46%; and for silicone, 17%. Hydrogel intraocular lenses were associated with 17% more posterior capsule opacification than were polymethylmethacrylate lenses (95% confidence interval, 1-33; P =. 037) and 45% more than were silicone lenses (95% confidence interval, 33-58; P <.0001) at 2 years. Polymethylmethacrylate lenses had 28% more posterior capsule opacification than silicone lenses (95% confidence interval, 13-43; P <.0001) at 2 years. Twenty-eight percent of patients with hydrogel intraocular lenses required an Nd:YAG laser posterior capsulotomy at 2 years, compared with 14% with polymethylmethacrylate, whereas no patients with silicone lenses needed a capsulotomy (P =.014). Visual acuity was not significantly different among the three groups, but patients with silicone intraocular lenses had significantly better contrast sensitivity than those with hydrogel lenses (P =.046).

CONCLUSIONS

Intraocular lenses made of this specific hydrogel were associated with a significantly higher degree of posterior capsular opacification and more laser capsulotomies than polymethylmethacrylate and silicone intraocular lenses.

Operated and unoperated cataract in Australia

PURPOSE

To quantify the prevalence of cataract, the outcomes of cataract surgery and the factors related to unoperated cataract in Australia.

METHODS

Participants were recruited from the Visual Impairment Project: a cluster, stratified sample of more than 5,000 Victorians aged 40 years and over. At examination sites interviews, clinical examinations and lens photography were performed. Cataract was defined in participants who had: had previous cataract surgery, cortical cataract greater than 4/16, nuclear greater than Wilmer standard 2, or posterior subcapsular greater than 1 mm2.

RESULTS

The participant group comprised 3,271 Melbourne residents, 403 Melbourne nursing home residents and 1,473 rural residents. The weighted rate of any cataract in Victoria was 21.5%. The overall weighted rate of prior cataract surgery was 3.79%. Two hundred and forty-nine eyes had had prior cataract surgery. Of these 249 procedures, 49 (20%) were aphakic, 6 (2.4%) had anterior chamber intraocular lenses and 194 (78%) had posterior chamber intraocular lenses. Two hundred and eleven of these operated eyes (85%) had best-corrected visual acuity of 6/12 or better, the legal requirement for a driver's license. Twenty-seven (11%) had visual acuity of less than 6/18 (moderate vision impairment). Complications of cataract surgery caused reduced vision in four of the 27 eyes (15%), or 1.9% of operated eyes. Three of these four eyes had undergone intracapsular cataract extraction and the fourth eye had an opaque posterior capsule. No one had bilateral vision impairment as a result of cataract surgery. Surprisingly, no particular demographic factors (such as age, gender, rural residence, occupation, employment status, health insurance status, ethnicity) were related to the presence of unoperated cataract.

CONCLUSIONS

Although the overall prevalence of cataract is quite high, no particular subgroup is systematically underserviced in terms of cataract surgery. Overall, the results of cataract surgery are very good, with the majority of eyes achieving driving vision following cataract extraction.

Neodymium:YAG laser posterior capsulotomies performed by residents at a Veterans Administration Hospital

PURPOSE

To assess the initial efficacy of neodymium:YAG (Nd:YAG) laser posterior capsulotomies performed by residents at a teaching institution and to evaluate the associated complications over an extended follow-up.

SETTING

Department of Ophthalmology, Edward Hines, Jr. Veterans Administration Hospital, Hines, Illinois, USA.

METHODS

This retrospective noncomparative case review comprised 212 pseudophakic eyes having Nd:YAG laser posterior capsulotomies from April 1992 through March 1995. Evaluated were postoperative changes in best corrected visual acuity (BCVA), intraocular pressure (IOP) elevations, and complications related to the procedure.

RESULTS

In all 212 eyes, Snellen visual acuity was obtained at least 1 week after the capsulotomy. The BCVA in 96 eyes (45.3%) improved by 3 or more lines, in 43 (20.3%) by 2 lines, and in 51 (24.1%) by 1 line. Nineteen eyes (9.0%) did not improve by 1 or more lines, and 3 eyes (1.4%) had decreased Snellen acuity. All but 4 eyes with less than 1 line of improvement had underlying ocular pathology or a previous incomplete capsulotomy. For evaluation of postoperative complications, long-term follow-up was available for 133 of 212 eyes (62.7%). The mean follow-up for this group was 3.18 years. Postoperative complications were found in 14 of these eyes (10.5%). Nine (6.8%) had a rise in IOP greater than 10 mm Hg after the capsulotomy. One eye (0.8%) developed a persistent iritis, 2 (1.5%) had vitreous prolapse into the anterior chamber, and 2 (1.5%) developed rhegmatogenous retinal detachments.

CONCLUSION

Postoperative Snellen acuity results and complication rates compare favorably with those in previous studies. The results indicate that Nd:YAG laser posterior capsulotomies performed by residents with attending supervision are safe, effective, and carry a low associated complication rate over a long follow-up.

Interlenticular opacification: clinicopathological correlation of a complication of posterior chamber piggyback intraocular lenses

PURPOSE

To present a clinicopathological correlation of 2 pairs of piggyback posterior chamber intraocular lenses (PC IOLs) explanted because of opacification between the lens optics.

SETTING

Gayton Health Center, Eyesight Associates of Middle Georgia, Warner Robins, Georgia, and Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Two pairs of piggyback AcrySof lenses were explanted from 2 patients with significant visual loss related to opacification between the optics. They were submitted for pathological analysis. Gross and histopathological examinations were performed, and photomicroscopy was used to document the results.

RESULTS

Gross examination showed accumulation of a membrane-like white material between the lenses. Histopathological examination revealed that the tissue consisted of retained/proliferative lens epithelial cells (bladder cells or pearls) mixed with lens cortical material.

CONCLUSION

Piggyback PC IOLs were explanted in 2 cases because of a newly described complication, interlenticular opacification. Three surgical means may help prevent this complication: meticulous cortical cleanup, especially in the equatorial region; creation of a relatively large continuous curvilinear capsulorhexis to sequester retained cells peripheral to the IOL optic within the equatorial fornix; insertion of the posterior IOL in the capsular bag and the anterior IOL in the ciliary sulcus to isolate retained cells from the interlenticular space.

Surgical prevention of posterior capsule opacification. Part 2: Enhancement of cortical cleanup by focusing on hydrodissection

PURPOSE

To experimentally analyze the role and efficacy of hydrodissection in achieving maximal cortical cleanup.

SETTING

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

METHODS

Phacoemulsification and irrigation/aspiration were performed in 10 pairs of human eyes (20 eyes) obtained postmortem. Ten eyes had previous hydrodissection and 10 eyes, no hydrodissection. The time (seconds) required for complete lens substance removal in each procedure was measured. In addition, a qualitative evaluation of difficulty of surgery was noted.

RESULTS

Phacoemulsification required 28.6% less time in eyes with previous hydrodissection than in those without. Irrigation/aspiration time was reduced by 50.9% when hydrodissection was performed. The total time of each procedure required for complete evacuation of the capsular bag was reduced by an average of 37.7% in eyes with hydrodissection. Furthermore, qualitatively the procedure was far easier, less stressful, and caused less posterior capsule stress or rupture when copious hydrodissection was performed.

CONCLUSIONS

Hydrodissection enhances the general safety and efficiency of cortical cleanup, especially at 12 o'clock. Hydrodissection is the best available, practical, immediately implementable, and inexpensive means to help remove equatorial E-cells and thus alleviate the incidence of posterior capsule opacification.