A systematic overview of the incidence of posterior capsule opacification

Contrast sensitivity evaluation of aspheric and spherical intraocular lenses 2 years after implantation

PURPOSE

To compare the quality of vision with aspheric and spherical intraocular lenses (IOLs) in pseudophakic patients after long-term follow-up.

METHODS

Two hundred eyes of 100 patients with bilateral cataracts were randomly assigned to receive spherical (Acrysof SN60AT [Alcon Laboratories Inc] or Sensar AR40e [Advanced Medical Optics Inc]) or aspheric IOLs (Acrysof SN60WF [Alcon] or Tecnis Z9000 [Advanced Medical Optics]). Ophthalmologic examination, including best spectacle-corrected visual acuity (BSCVA), pupil size, ocular dominance, contrast sensitivity under mesopic and photopic conditions, and wavefront analysis, was performed 2 months and 1 and 2 years after surgery.

RESULTS

No statistically significant differences among the four groups in terms of age, pupil diameter, postoperative BSCVA, comeal spherical aberration, and posterior capsular opacification were noted. At all followup examinations, contrast sensitivity results showed no significant differences between the two aspheric IOLs at all spatial frequencies. Under photopic conditions, significant differences (P<.05) between spherical and aspheric IOLs were detected for spatial frequencies of 12 and 18 cycles per degree (cpd) at 2 months and 2 years and 12 cpd at 1 year. Under mesopic conditions, significant differences (P<.05) were detected between spherical and aspheric IOLs for all spatial frequencies at 2 months; all spatial frequencies except 18 cpd at 1 year; and spatial frequencies of 3, 12, and 18 cpd at 2 years. In addition, aspheric IOLs had statistical reductions in total spherical aberration at all follow-up examinations (P<.01).

CONCLUSIONS

This study confirms that implantation of a modified aspheric IOL improves functional visual performance at 2 years postoperative.

The effects of posterior continuous curvilinear capsulorhexis on contrast sensitivity

PURPOSE

We aimed at evaluating the effects of posterior continuous curvilinear capsulorhexis (PCCC) on contrast sensitivity.

MATERIALS AND METHODS

In this prospective, randomized, bilateral clinical study, 40 eyes of 20 patients who underwent bilateral cataract surgery were included. The phacoemulsification machine, viscoelastic substances, surgical tools, and intraocular lenses (IOLs) were the same for both eyes. The only difference was that we conducted the PCCC procedure before IOL implantation to one of the eyes of the patients. The selection of the eye that underwent the PCCC procedure was decided randomly.

RESULTS

The mean photopic contrast sensitivity values at spatial frequencies of 1.5, 3, 6, 12, and 18 cpd (cycles per degree) were 41.55, 59.90, 61.25, 32.35, and 9.75, respectively, and for the control group these values were 39.05, 56.60, 57.95, 29.80, and 8.75, respectively. The mean mesopic contrast sensitivity values at special frequencies of 1.5, 3, 6, 12, and 18 cpd were 41.20, 54.75, 55.55, 31.70, and 9.00, respectively, and for the control group these values were 38.35, 51.70, 52.15, 30.05, and 8.00, respectively. The mean contrast sensitivity values of the eyes that underwent the PCCC procedure were slightly better than the fellow eyes at all spatial frequencies, but the difference was statistically insignificant (P>0.05).

CONCLUSIONS

In early post-operative period, the PCCC procedure exerts some positive effects on contrast sensitivity although these effects are statistically insignificant.

Nd: YAG capsulotomy for posterior capsule opacification after combined clear corneal phacoemulsification and vitrectomy

PURPOSE

To evaluate the efficacy and safety of Neodymium:YAG (Nd:YAG) laser capsulotomy for posterior capsule opacification (PCO) following combined phacoemulsification and vitrectomy for the treatment of cataract in association with macular hole (MH) or epiretinal membrane (ERM).

METHODS

Retrospective clinical study of 34 eyes of 34 patients who underwent combined cataract surgery and vitrectomy, developed PCO, and subsequently underwent Nd:YAG laser capsulotomy. Follow-up examinations included visual acuity measurement, evaluation of intraocular lens (IOL) centration, intraocular pressure (IOP) measurement, and dilated fundus examination.

RESULTS

Nd:YAG laser capsulotomy was performed in all 34 eyes. The mean age of the patients was 65.08 years (range 45-87) and the mean follow up period was 11.05 months (range 4-23). The mean time elapsed between the last intraocular operation and the development of PCO was 10.00 months for patients with previous ERM and 15.33 for those with MH (P = 0.001, t-test for equality of means). None of our patients developed recurrence of MH, retinal detachment, IOL dislocation, or permanent IOP elevation.

CONCLUSION

In our study, the most remarkable observation is that no complication occurred after the YAG capsulotomy, possibly because the eyes were vitrectomized and vitreous seems to play an important role in the occurrence of post-Nd:YAG complications. In addition we noted that PCO seems to occur earlier in the eyes undergoing combined surgery for cataract and ERM when compared with those where combined phacoemulsification and vitrectomy are performed for cataract and MH.

Small incision cataract surgery: Complications and mini-review

This article reviews the literature on manual small incision cataract surgery (MSICS) and its complications. Various articles on MSICS published in indexed journals were reviewed, as well as the sections on complications of MSICS. The Pubmed search engine on the Internet was used to find out articles published since 1985 on MSICS in any language in indexed journals. Books published by Indian authors and the website of Indian Journal of Ophthalmology were also referred to. MSICS has become very popular technique of cataract surgery in India, and it is often used as an alternative to phacoemulsification. Studies on its efficacy and safety for cataract surgery show that, being a variant of extracapsular cataract surgery, MSICS also has similar intraoperative and postoperative complications. The considerable handling inside the anterior chamber during nucleus delivery increase the chances of iris injury, striate keratitis, and posterior capsular rupture. The surgeon has to be extra careful in the construction of the scleral tunnel and to achieve a good capsulorrhexis. Postoperative inflammation and corneal edema are rare if surgeons have the expertise and patience. The final astigmatism is less than that in the extracapsular cataract surgery and almost comparable to that in phacoemulsification. There is, however, a concern of posterior capsular opacification in the long term, which needs to be addressed. Although MSICS demands skill and patience from the cataract surgeon, it is a safe, effective, and economical alternative to competing techniques and can be the answer to tackle the large backlog of blindness due to cataract.

Effect of intraocular lens design on posterior capsule opacification

Posterior capsule opacification (PCO) remains the most common long-term complication after cataract surgery. Many studies have attempted to identify factors that influence the development of PCO. The aim of this systematic review based on Cochrane methodology was to summarize the effects of intraocular lens (IOL) geometry, including modifications of the IOL optic (especially optic edge design) and haptics, on the development of PCO. Twenty-six prospective randomized controlled trials with a follow-up of at least 12 months were included. In 5 of 7 studies, visual acuity was better in sharp-edged IOLs than in round-edged IOL. The PCO score was significantly lower with sharp-edged IOLs but did not differ significantly between 1-piece and 3-piece open-loop IOLs. Because of the significant difference in the PCO score, sharp-edged IOL optics should be preferred to round-edged IOL optics.

Polylactide-glycoli acid and rapamycin coating intraocular lens prevent posterior capsular opacification in rabbit eyes

OBJECTIVES

Posterior capsular opacification (PCO) is caused by the proliferation and migration of residual lens epithelium cells (LECs) after extracapsular cataract extraction (ECCE). Rapamcin (RAPA) is known to be a potent immunosuppressive drug with anti-inflammatory and anti-proliferative effects. The aim of this study was to investigate the safety and efficacy of rapamycin sustained release from modified intraocular lens (IOLs) in the prevention of PCO in rabbits.

METHODS

Three types of IOLs were used, including the original IOL without modification, IOL with polylactide-glycoli acid (PLGA) coating (PLGA-IOL), and RAPA-loaded PLGA-IOL (RAPA-PLGA-IOL). Sixty New Zealand albino rabbits undergoing phacoemulsification in left eyes were randomly and equally divided into three groups. Group A was implanted with the original IOLs, group B was implanted with the PLGA-IOLs, and group C was implanted with the RAPA-PLGA-IOLs. All of the 60 treated left eyes were examined by a slit-lamp microscope. The concentrations of RAPA in the aqueous humor and blood were determined by high-performance liquid chromatography (HPLC), indicating an vivo release of drug from the polymer carrier. Anterior segment tissue was histologically examined, and wet posterior capsules were weighed. Six months after intervention the PCO was graded.

RESULTS

The mean concentrations of RAPA in the aqueous humor from group C at 2 h, 1 days, 3 days, and 7 days after operation were 12.81 +/- 1.27 microg/ml, 14.57 +/- 0.99 microg/ml, 6.39 +/- 0.95 microg/ml, and 1.10 +/- 0.32 microg /ml respectively. The concentrations of RAPA in blood were undetectable. During the early days after the operation, the reactions of the anterior chamber from groups A and B were more severe than from group C. Our findings showed that the initial appearance of PCO in group C was much later than in the other two groups. The wet posterior capsules were weighed to be 0.3735 +/- 0.0943 g (group A), 0.3754 +/- 0.1093 g (group B), and 0.0432 +/- 0.0089 g (group C). Histological observation showed a similar phenomenon, that there was remarkably less accumulation of lens materials on the posterior capsules in group C than in the other two groups.

CONCLUSION

Our findings suggest that the designed RAPA-PLGA-IOL effectively prevented formation and development of PCO for a relatively long duration.

Effect of posterior capsular opacification removal on macular optical coherence tomography

PURPOSE

To evaluate the influence of posterior capsular opacification (PCO) on macular optical coherence tomography (OCT) imaging quality and measurements of macular retinal thickness.

METHODS

In this prospective interventional case series, 32 eyes of 23 patients with PCO were recruited. Best-corrected visual acuity (BCVA), a complete ophthalmologic assessment, and macular OCT scans (OCT Stratus 3000) before and after Nd:YAG capsulotomy were performed. Two parameters for image quality (signal strength (SS) and number of tomographic messages) and 10 macular retinal thickness measurements were compared. Spearman correlations between BCVA and SS and macular retinal thickness measurements before and after capsulotomy were also performed.

RESULTS

PCO removal was associated with an increase of best-corrected visual acuity (p<0.0001). The mean SS (n=32) went from 3.34+/-2.31 to 6.38+/-1.93 (p<0.0001) after Nd:YAG capsulotomy. The SS improved in 26 of 32 eyes. No significant difference between mean preoperative and postoperative macular retinal thickness measurements was observed (p<0.05) in valuable scans. Before capsulotomy, a correlation existed between BCVA and SS. After capsulotomy this correlation was no longer found.

CONCLUSIONS

OCT image quality is influenced by PCO. Nd:YAG capsulotomy results in a measurable improvement in SS and improvement in the number of valuable examinations. Valuable OCT scans in patients with PCO seem to yield reliable measurements of macular retinal thickness even in the presence of severe PCO. The correlation between BCVA and SS before capsulotomy suggests that the SS could be considered an objective indicator of the degree of PCO.

Cataract surgery in previously vitrectomized eyes

PURPOSE

To evaluate the results of extracapsular cataract extraction (ECCE) and phacoemulsification (PHACO) performed in previously vitrectomized eyes.

MATERIAL AND METHOD

In this retrospective study, 56 vitrectomized eyes that had ECCE and 60 vitrectomized eyes that had PHACO were included in the study group while 65 eyes that had PHACO in the control group. The evaluated parameters were the incidence of intra-operative and postoperative complications (IPC) and visual outcomes. Chi-squared, independent samples and paired samples tests were used for comparing the results.

RESULTS

Deep anterior chamber (AC) was significantly more common in the PHACO group of vitrectomized eyes (PGVE) and observed in eyes that had undergone extensive vitreous removal (p < 0.05). Except for this there were no significant differences in the rate of IPC between the ECCE group and the PGVE (p > 0.05). Some of the intra-operative conditions such as posterior synechiae, primary posterior capsular opacification (PCO) and postoperative complications such as retinal detachment (RD), PCO were significantly more common in vitrectomized eyes than the controls (p < 0.05). There was no significant difference in the visual acuity gain between the ECCE group and the PGVE (p > 0.05).

CONCLUSION

Deep AC is more common in eyes with extensive vitreous removal during PHACO than ECCE. Decreasing the bottle height is advised in this case. Except for this, the results of ECCE and PHACO are similar in previously vitrectomized eyes. Posterior synechiaes, primary and postoperative PCO and RD are more common in vitrectomized eyes than the controls.

Statistical problems caused by missing data resulting from neodymium:YAG laser capsulotomies in long-term posterior capsule opacification studies: problem identification and possible solutions

PURPOSE

To describe a way to eliminate the problem caused by missing data due to neodymium:YAG (Nd:YAG) laser capsulotomies before statistical analysis, which leads to incomplete data in long-term studies of posterior capsule opacification (PCO).

SETTING

Medical University of Vienna, Vienna, Austria.

METHODS

To demonstrate the problem, an existing long-term study comparing PCO development in eyes with round-edged and sharp-edged intraocular lenses (IOLs) was analyzed. In the study, several Nd:YAG capsulotomies led to dropouts in the round-edged IOL group. To solve the resulting missing value problem, the missing values were replaced by estimated PCO values in various scenarios; that is, different assumptions were made of how PCO would have developed without a capsulotomy. Standard statistical analyses that included the estimated PCO values rather than excluding the incomplete cases were then performed.

RESULTS

The analysis of all cases (including the estimated PCO scores) showed a highly significant difference between the round-edged group and the sharp-edged group. Sensitivity analyses confirmed that the difference between the 2 groups remained significant up to highly implausible values chosen for the missing PCO scores, thus proving the correctness of the analysis.

CONCLUSIONS

This study showed it is possible to perform statistical analyses without excluding incomplete cases. This approach is recommended for all studies with Nd:YAG dropouts as it increases the statistical power. Excluding incomplete cases may lead to biased or wrong study conclusions.

Effect of posterior capsule opacification on macular sensitivity

PURPOSE

To evaluate the effect of posterior capsule opacification (PCO) on macular sensitivity.

SETTING

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

METHODS

Macular sensitivity, best corrected visual acuity (BCVA), and PCO intensity were evaluated before and after neodymium:YAG (Nd:YAG) laser capsulotomy in pseudophakic eyes with clinically significant PCO that had a healthy macula or dry age-related macular degeneration (ARMD). Macular sensitivity was determined using the fundus-related Microperimeter 1 (Nidek) in a central field of 10 degrees. The intensity of the PCO was assessed objectively in the central 3.0 mm area (score 0 to 10) using quantification software.

RESULTS

After Nd:YAG capsulotomy, both groups had a significant improvement in BCVA and mean macular sensitivity; the change in the mean logMAR value was -0.26 in the healthy macula group and -0.23 in the dry ARMD group and the change in mean macular sensitivity, 2.5 dB and 2.0 dB, respectively. Before Nd:YAG capsulotomy, significant correlations were observed between PCO values, BCVA, and macular sensitivity in the healthy macula group only (P<.01).

CONCLUSIONS

Neodymium:YAG laser capsulotomy improved BCVA and macular sensitivity. The PCO scores correlated well with the PCO-induced decrease in BCVA and with PCO-induced loss of macular sensitivity. Functional macular mapping indicated an overall loss of macular sensitivity in patients with dry ARMD. There was no significant association between PCO values and macular sensitivity in eyes with dry ARMD.

Intraocular pressure rise after primary posterior continuous curvilinear capsulorhexis with a fixed dorzolamide–timolol combination

PURPOSE

To assess the safety, in terms of the intraocular pressure (IOP), of cataract surgery with primary posterior continuous curvilinear capsulorhexis (PPCCC) and a postoperative dose of a fixed dorzolamide-timolol combination and evaluate the effect of intraocular lens (IOL) haptic angulation.

SETTING

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

METHODS

In this prospective randomized double-masked bilateral study, 88 eyes of 44 consecutive patients with age-related cataract were included in an intraindividual comparison study. All patients had standardized cataract surgery with PPCCC and IOL implantation in the capsular bag followed by a postoperative dose of a fixed dorzolamide-timolol combination. Patients were randomly assigned to receive an ACR6D SE IOL (Laboratoires Cornéal) in 1 eye and a Centerflex (C-flex) 570C IOL (Rayner Surgical GmbH) in the contralateral eye. The IOP was measured at baseline and postoperatively at 6 and 24 hours as well as 1 week.

RESULTS

Intraindividual comparison showed statistically significantly higher IOP measurements in the C-flex 570C nonangulated IOL group than in the ACR6D SE angulated IOL group at 24 hours (P = .003) and 1 week (P = .043). The highest IOP spikes (34 mm Hg) were at 6 hours in 2 eyes with a C-flex 570C IOL. The ACR6D SE group had statistically significant changes in IOP between preoperative and all postoperative time points. In the C-flex 570C group, the only statistically significant change in IOP was between preoperatively and 6 hours postoperatively.

CONCLUSIONS

Cataract surgery with PPCCC was safe in terms of the postoperative IOP course. Haptic angulation slightly decreased the overall IOP rise and the incidence of IOP rises above 30 mm Hg.

Misdiagnosis of Hydrophilic Acrylic Intraocular Lens Optic Opacification

PURPOSE

To report 8 patients with misdiagnosis of MemoryLens intraocular lens (IOL) late postoperative calcification and the resulting potentially avoidable procedures leading to secondary complications.

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Eight patients with an opacified hydrophilic acrylic MemoryLens.

METHODS

Eight cases of MemoryLens IOL opacification that were originally misdiagnosed were reviewed. The following parameters were noted: baseline patient characteristics, time frame of IOL opacification, original misdiagnosis, subsequent surgical procedures, and postexplantation outcomes and complications. Two explanted lenses from this series were available for laboratory analyses. They underwent gross and light microscopic evaluation and scanning electron microscopy with energy-dispersive x-ray spectroscopy (EDS).

MAIN OUTCOME MEASURES

Patient parameters noted above. The IOLs were examined for distribution, structure, and composition of the deposits causing opacification of their optic components.

RESULTS

All 8 patients' IOLs were implanted between August 1999 and March 2000. Complaints of decreased visual function occurred 13 to 58 months after implantation. Half of the patients were initially diagnosed as having posterior capsular opacification and underwent neodymium:yttrium-aluminum-garnet laser capsulotomy. The other half were initially diagnosed with some form of vitreous involvement and underwent vitrectomies. Six of the 8 patients underwent subsequent lens exchanges, with 3 of them having postexchange complications including endophthalmitis, cystoid macular edema, and retinal detachment. Scanning electron microscopy with EDS confirmed the presence of calcified deposits on the surface of the 2 explants available for analysis. The deposits also stained positive for calcium.

CONCLUSIONS

Despite previous reports, misdiagnosis of MemoryLens IOL calcification leading to optic opacification still occurs. Not recognizing this process can lead to potentially avoidable surgical procedures and increased risk of complications after repeated interventions.

Long-term Effect of 1-Piece and 3-Piece Hydrophobic Acrylic Intraocular Lens on Posterior Capsule Opacification

PURPOSE

To compare the intensity of posterior capsule opacification (PCO) between the 1-piece and 3-piece haptic designs of the foldable hydrophobic acrylic AcrySof intraocular lens (IOL) over a 5-year period.

DESIGN

Randomized, prospective, patient- and examiner-masked clinical trial with intraindividual comparison.

PARTICIPANTS

Fifty-two patients with bilateral age-related cataract (104 eyes).

METHODS

Each study patient had cataract surgery in both eyes and received a 1-piece AcrySof IOL in 1 eye and a 3-piece AcrySof IOL in the other eye. Follow-up examinations were performed at 1 week, 1 month, 6 months, and 1, 2, and 5 years. Digital retroillumination images were obtained of each eye. The amount of posterior capsule opacification (score range, 0-10) was assessed subjectively at the slit lamp and objectively using automated image analysis software 1, 2, and 5 years after surgery.

MAIN OUTCOME MEASURE

Posterior capsule opacification score (scale, 0-10).

RESULTS

There was no significant difference between the 1-piece and 3-piece AcrySof IOL in best-corrected visual acuity, overlap of rhexis and IOL, capsular folds, anterior capsule opacification, and posterior capsule opacification (1-piece AcrySof PCO score, 1.7+/-1.7; 3-piece AcrySof PCO score, 1.3+/-1.4; P = 0.30).

CONCLUSIONS

Modification of the IOL haptic design of the sharp optic edged AcrySof IOL from a 3-piece to a 1-piece haptic design caused no significant change in PCO intensity and neodymium:yttrium-aluminium-garnet laser treatment rate 5 years after surgery.

The surgical management of cataract: barriers, best practices and outcomes

Cataract is the leading cause of blindness in the world. Cataract surgery has been shown by multiple studies to be one of the most cost-effective health interventions, and leads to a dramatic increase in quality of life and productivity for many patients. Though there has been marked improvement in the last several decades, surgical delivery services in developing nations are still suboptimal, and a large backlog in cataract cases continues to grow. To decrease this backlog, barriers to surgery, such as direct and indirect patient costs, geographic access to surgical facilities and surgeons, cultural factors, and patient education, must be addressed. In particular, access to services by women and rural patients needs to be improved. It is clear that extracapsular techniques are cost-effective and lead to better post-operative outcomes than intracapsular cataract extraction with aphakic correction. In addition, monitoring surgical outcomes is essential for improving the quality of surgical services. However, other issues regarding the delivery of cataract surgical services, including the role of average power intraocular lenses and the role of non-physician surgeons, are yet unresolved. Information about the true cost of surgery, including costs of surgeon training, equipment, and patient outreach programs, is needed so that the goal of self-sustaining programs may be obtained.

Interventions for preventing posterior capsule opacification

BACKGROUND

Posterior capsule opacification (PCO) remains the most common long-term complication after cataract surgery. It can be treated by Nd:YAG laser capsulotomy, however, this may lead to other complications and laser treatment is not available in large parts of the developing world. Therefore, many studies try to find factors influencing the development of PCO.

OBJECTIVES

To summarise the effects of different interventions to inhibit PCO. These include modifications of surgical technique and intraocular lens (IOL) design, implantation of additional devices and pharmacological interventions.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, LILACS in January 2007 and reference lists of identified trial reports.

SELECTION CRITERIA

We included only prospective, randomised and controlled trials with a follow-up time of at least 12 months. Interventions included modifications in surgical technique explicitly to inhibit PCO, modifications in IOL design (material and geometry), implantation of additional devices, and pharmacological therapy, compared to each other, placebo or standard treatment.

DATA COLLECTION AND ANALYSIS

Data were extracted and entered into Review Manager. Visual acuity data, PCO score and YAG capsulotomy rates were compared and a meta-analysis was performed when possible.

MAIN RESULTS

Fifty three studies were included in the review. The review was divided into three parts. (1) Influence of IOL optic material on the development of PCO. Compared to other materials, the meta-analysis of the included studies showed a significantly higher PCO score (overall effect: 12.39 (95% confidence interval: 9.82 to 14.95), scale 0 to 100) and YAG rate (odds ratio: 8.37 (3.74 to 20.36)) only in hydrogel IOLs. (2) Influence of IOL optic design on the development of PCO. There was a significantly lower PCO score (-8.65 (-10.72 to -6.59), scale 0 to 100) and YAG rate (0.19 (0.11 to 0.35)) in sharp edged than in round edged IOLs, however, not between 1-piece and 3-piece IOLs. (3) Influence of surgical technique and drugs on the development of PCO. There was no significant difference between different types of intra-/postoperative anti-inflammatory treatment except for treatment with an immunotoxin (MDX-A) leading to a significantly lower PCO rate.

AUTHORS' CONCLUSIONS

Due to the highly significant difference between round and sharp edge IOL optics, IOLs with sharp (posterior) optic edges should be preferred. There is no clear difference between optic materials, except for hydrogel IOLs, that showed more PCO than the other materials. The choice of postoperative anti-inflammatory treatment does not seem to influence PCO development.

Effect of intraocular lens edge profile on posterior capsule opacification after extracapsular cataract surgery in a developing country

PURPOSE

To determine whether square-edged polymethyl methacrylate (PMMA) intraocular lenses (IOLs) reduce posterior capsule opacification (PCO) in the context of extracapsular cataract surgery in a developing country.

SETTING

A rural hospital in India.

METHODS

This was a prospective randomized double-masked fellow-eye controlled study. Over a 4-month period, 118 patients with normal eyes apart from age-related cataract were randomized to receive a square-edged or round-edged PMMA IOL in the first eye. The IOLs were identical apart from the edge profile. The fellow-eye had implantation of the alternative IOL within 1 month. Retroillumination images of the posterior capsule were taken using a dedicated camera system and analyzed to quantify the PCO area using POCO software 1 and 2 years postoperatively and the PCO area and severity using POCOman semiqualitative software at 2 years. Visual acuity was measured using a Gujarati logMAR chart.

RESULTS

One hundred fifteen patients were available for examination at 1 year and 107 at 2 years. With POCO software, the PCO area was reduced in the square-edged IOL group at 1 year (median 30% versus 20%, P=.001) and at 2 years (median 45% versus 35%, P=.006). With POCOman, the PCO area and severity were reduced in the square-edged group at 2 years (median 41.5% versus 33.2%, P=.019 and 0.59 versus 0.46, P=.037, respectively). There was no significant difference in visual acuity between the 2 groups at 1 or 2 years.

CONCLUSIONS

Sophisticated image analysis techniques can be used in developing countries to quantify PCO. Using extracapsular surgery, square-edged PMMA IOLs reduced the PCO area and severity compared with an identical round-edged IOL; however, the differences were not as marked as those reported with phacoemulsification. This may be due to the difficulty of performing a capsulorhexis that lies on the IOL surface in this situation. Nevertheless, square-edged IOLs offer a potential benefit for extracapsular surgery in the developing world.

The influence of posterior capsular opacification removal on anterior segment birefringence parameters as measured by scanning laser polarimetry

PURPOSE

To determine the effect of posterior capsular opacification (PCO) removal on anterior segment birefringence (ASB) and its influence on peripapillary retinal nerve fibre layer (RNFL) retardation measurements obtained by means of scanning laser polarimetry.

METHODS

In this prospective interventional study, scanning laser polarimetry was performed using GDx variable corneal compensation on 26 eyes of 26 patients who developed clinically significant PCO (after uncomplicated cataract surgery and with no other ocular pathology) both before and between 1 and 4 weeks after Nd:YAG capsulotomy. Best-corrected visual acuity (BCVA), intraocular pressure, corneal polarization axis (CPA), corneal polarization magnitude (CPM) were compared using the Student t-test and Wilcoxon signed ranks test. Spearman correlations between changes (differences between values after and before capsulotomy) in the CPA, CPM, BCVA and RNFL data were also performed.

RESULTS

PCO removal is associated with a shift in CPA (from 10.86 to 15.03 degrees, P = 0.004) and CPM (from 28.54 to 37.92 nm, P = 0.004). Significant correlations were found between changes in the parameters of ASB and BCVA. Furthermore, RNFL measurements (nerve fibre indicator, temporal-superior-nasal-inferior-temporal average and superior average) were also well related to the CPA and CPM shifts.

CONCLUSIONS

PCO induces an inaccurate compensation of ASB which affects RNFL assessment. Thus, it is necessary to recompensate ASB after posterior capsulotomy.

In situ ablation of lens epithelial cells in porcine eyes with the laser photolysis system

PURPOSE

To evaluate the efficacy of the laser photolysis system (LPS) (A.R.C. Laser GmbH) in removing lens epithelial cells (LECs) to prevent posterior capsule opacification (PCO) in an in situ model.

SETTING

Department of Ophthalmology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.

METHODS

Twelve enucleated porcine eyes fixed in a specially developed eye holder were randomly assigned to the control or treatment group. The cornea and iris were removed from all eyes, and a small paracentral capsulorhexis was performed. The lens nucleus and cortex were extracted by hydroexpression. The tip of the LPS was inserted into the capsular bag of eyes in the treatment group, and 50 pulses (10 mJ) were applied to the anterior capsule. All capsules were evaluated for remaining LECs by confocal laser scanning microscopy (HRT II with the Rostock Cornea Module, Heidelberg Engineering) and standard histology (hematoxylin-eosin and periodic acid-Schiff stains).

RESULTS

In the control group, a homogenous layer of LECs attached to the anterior capsule was seen with both evaluation methods. In the treatment group, no LECs adherent to the anterior capsule were detected, suggesting complete ablation of LECs from the capsule. Small islands of equatorial LECs were found in places in which the remaining cortical fibers protected cells from the laser shockwave. The results of the confocal laser scanning microscopy were confirmed by standard histology.

CONCLUSIONS

The LPS completely ablated LECs in an in situ model of cataract extraction. This system might prevent formation of PCO in vivo.

Lens stem cells may reside outside the lens capsule: an hypothesis

In this paper, we consider the ocular lens in the context of contemporary developments in biological ideas. We attempt to reconcile lens biology with stem cell concepts and a dearth of lens tumors.

Historically, the lens has been viewed as a closed system, in which cells at the periphery of the lens epithelium differentiate into fiber cells. Theoretical considerations led us to question whether the intracapsular lens is indeed self-contained. Since stem cells generate tumors and the lens does not naturally develop tumors, we reasoned that lens stem cells may not be present within the capsule. We hypothesize that lens stem cells reside outside the lens capsule, in the nearby ciliary body. Our ideas challenge the existing lens biology paradigm.

We begin our discussion with lens background information, in order to describe our lens stem cell hypothesis in the context of published data. Then we present the ciliary body as a possible source for lens stem cells, and conclude by comparing the ocular lens with the corneal epithelium.

Effects of bicistronic lentiviral vector-mediated herpes simplex virus thymidine kinase/ganciclovir system on human lens epithelial cells

Posterior capsule opacification (PCO) is the most common complication after phacoemulsification cataract surgery. Hyperplasia of the lens epithelial cell after phacoemulsification is thought to be an important feature contributing to PCO. In this study,we investigated the feasibility of killing the human lens epithelial cells (HLECs) by lentivirus-mediated herpes simplex virus thymidine kinase (HSV-tk) gene/ganciclovir (GCV) in HLECs and studied the bystander effect. HLECs were infected with lentiviral vectors coexpressing HSV-tk and enhanced green fluorescent protein (EGFP) or expressing EGFP alone and treated with ganciclovir. Infection efficiency was assessed by fluorescence microscopy, fluorescence-activated cell sorting, and reverse transcription PCR. The cytotoxicity of the HSV-tk/GCV suicide gene therapy system was assessed by DNA ladder and electron microscopy. The time effect and bystander effect of HLEC growth inhibition were evaluated with cell proliferation assay. Lentiviral vector-mediated stable integration and efficient expression of HSV-tk in HLECs, with infection efficiency exceeding 95% GCV at concentrations of 15 approximately 25 mug/ml, significantly induced apoptosis or necrosis of infected HLECs. GCV also killed normal cells mixed with HSV-tk infected cells. The bystander effect markedly increased the cytotoxicity of the HSV-tk/GCV system. Our results suggest that bicistronic lentiviral vectors can efficiently integrate several genes into HLECs and may be a gene therapy platform. Lentivirus-mediated suicide gene therapy might be a feasible treatment strategy to prevent capsule opacification.

Efficacy of different intraocular lens materials and optic edge designs in preventing posterior capsular opacification: a meta-analysis

PURPOSE

To evaluate the efficacy of different intraocular lens (IOL) materials and optic edge designs in preventing posterior capsular opacification (PCO).

DESIGN

Systematic review and meta-analysis.

METHODS

Pertinent studies were selected through an electronic search of the Cochrane Library, MEDLINE, and Embase. The randomized controlled trials meeting the predefined criteria were reviewed systematically by meta-analysis. The treatment effects were measured as risk difference, and the pooled estimates were computed according to a random effect model.

RESULTS

In total, 23 randomized controlled trials were included in the present meta-analysis. The pooled risk differences of Nd:YAG laser capsulotomy rates were -24% (95% confidence interval [CI], -29% to -20%) comparing acrylic with polymethylmethacrylate (PMMA) lenses; -9% (95% CI, -17% to -1%) comparing silicone with PMMA lenses; 14% (95% CI, -8% to 36%) comparing hydrogel with PMMA lenses; 4% (95% CI, -2% to 10%) comparing silicone with acrylic lenses; 19% (95% CI, 8% to 30%) comparing hydrogel with acrylic lenses; and 28% (95% CI, 10% to 46%) comparing hydrogel with silicone lenses. The pooled risk differences of PCO rates were -39% (95% CI, -47% to -31%) comparing acrylic with PMMA lenses; -14% (95% CI, -29% to 0%) comparing silicone with acrylic lenses; 56% (95% CI, 36% to 75%) comparing hydrogel with acrylic lenses; and 48% (95% CI, 31% to 64%) comparing hydrogel with silicone lenses. When comparing sharp with rounded-edge designs, pooled risk differences of capsulotomy rates were -47% (95% CI, -77% to -17%) in PMMA lenses, -22% (95% CI, -47% to 2%) in acrylic lenses, and -9% (95% CI, -17% to 0%) in silicone lenses; pooled risk differences of PCO rates were -28% (95% CI, -50% to -7%) in acrylic lenses and -37% (95% CI, -46% to -27%) in silicone lenses.

CONCLUSIONS

The rates of PCO and Nd:YAG laser capsulotomy may be influenced by different IOL biomaterials and optic edge designs. The lenses made by acrylic and silicone and those with sharp optic edges are superior in lowering the rates of PCO and laser capsulotomy.

[After-cataract following intraocular lens implantation. Part I. Genesis and prevention by optimizing conventional lens implants and surgical techniques]

After-cataract is the most common complication in cataract surgery. Implementing a sharp posterior optic edge has, together with improved cortical aspiration, drastically reduced its rate. The impact of optic design and material has been systematically studied in detail in Vienna in a series of prospectively randomized intra-individual comparison studies using objective evaluation methods. Circular rhexis-optic overlap is essential for the durability of the posterior sharp optic edge barrier effect. Using haptics with a capsular bag design and a slim junction to the optic enhanced it further. The use of fibrosis-inducing optic materials has been shown to prolong the barrier effect, which was decreased after anterior capsule polishing. Although the incidence of clinically significant after-cataract has been significantly reduced by these conventional measures, it still cannot be completely avoided.

Posterior capsule opacification after extra capsular cataract extraction in Indian rural population: foldable acrylic vs poly (methyl-methacrylate) intraocular lenses a randomized clinical trial

PURPOSE

To compare the performance of single-piece acrylic vspoly (methylmethacrylate) intraocular lenses (IOL) on the development of posterior capsule opacification (PCO) after conventional extra capsular cataract extraction (ECCE).

MATERIALS AND METHODS

One hundred and eighty-two eyes of 91 patients with bilateral senile cataract undergoing ECCE were prospectively randomized to receive a single-piece Alcon AcrySof SA60AT IOL or a single-piece EPOCH polymethylmethacrylate IOL in the first eye to have surgery. At 1, 6 and 12 months post-operative follow-up, digital retro illumination images of the posterior capsule were taken for PCO assessment semi-objectively using PCO (POCO automated analysis software) system. Relationship of anterior capsule contact (total off and partial cover) on optic for PCO was analyzed.

RESULTS

The AcrySof IOL was associated with less PCO than EPOCH lens at 6 months (10.01+/-8.75% vs 32.26+/-27.44%; P<0.001) and 1-year (11.65+/-10.55% vs 38.38+/-29.62%; P<0.001) follow-up. The EPOCH IOL showed a remarkably significant difference on development of PCO with anterior capsule overlap on IOL optic (total off and part on) 1 year (P<0.039), whereas no such difference was observed with the AcrySof IOL (P=0.197).

CONCLUSION

The AcrySof IOL led to significantly less PCO than the EPOCH IOL post-operatively after extracapsular cataract extraction.

Causes of blindness and visual impairment in Pakistan. The Pakistan national blindness and visual impairment survey

OBJECTIVE

To determine the causes of blindness and visual impairment in adults (> or =30 years old) in Pakistan, and to explore socio-demographic variations in cause.

METHODS

A multi-stage, stratified, cluster random sampling survey was used to select a nationally representative sample of adults. Each subject was interviewed, had their visual acuity measured and underwent autorefraction and fundus/optic disc examination. Those with a visual acuity of <6/12 in either eye underwent a more detailed ophthalmic examination. Causes of visual impairment were classified according to the accepted World Health Organization (WHO) methodology. An exploration of demographic variables was conducted using regression modeling.

RESULTS

A sample of 16 507 adults (95.5% of those enumerated) was examined. Cataract was the most common cause of blindness (51.5%; defined as <3/60 in the better eye on presentation) followed by corneal opacity (11.8%), uncorrected aphakia (8.6%) and glaucoma (7.1%). Posterior capsular opacification accounted for 3.6% of blindness. Among the moderately visually impaired (<6/18 to > or =6/60), refractive error was the most common cause (43%), followed by cataract (42%). Refractive error as a cause of severe visual impairment/blindness was significantly higher in rural dwellers than in urban dwellers (odds ratio (OR) 3.5, 95% CI 1.1 to 11.7). Significant provincial differences were also identified. Overall we estimate that 85.5% of causes were avoidable and that 904 000 adults in Pakistan have cataract (<6/60) requiring surgical intervention.

CONCLUSIONS

This comprehensive survey provides reliable estimates of the causes of blindness and visual impairment in Pakistan. Despite expanded surgical services, cataract still accounts for over half of the cases of blindness in Pakistan. One in eight blind adults has visual loss from sequelae of cataract surgery. Services for refractive errors need to be further expanded and integrated into eye care services, particularly those serving rural populations.

Changes in Scanning Laser Polarimetry Before and After Laser Capsulotomy for Posterior Capsular Opacification

PURPOSE

To investigate changes in scanning laser polarimetry with variable corneal compensation (GDx-VCC) parameters caused by posterior capsular opacification (PCO).

METHODS

In this comparative case-control series, 20 eyes due to undergo YAG laser capsulotomy for PCO were recruited. GDx-VCC was performed before and after laser capsulotomy, and digital photographs were taken of the PCO to assess their severity and type. The other eye of each subject was used as the control group.

RESULTS

Typical scan score was significantly improved after laser from 33 to 55.1 (P=0.001; n=19) and TSNIT score was significantly lower, dropping from 62.3 to 58.9 (P=0.03; n=19). There was no change in the nerve fiber index. All parameters in the control group remained unchanged except the Q-score which rose from 8.1 to 8.8 (P=0.05; n=16). There was no correlation between severity of PCO or the pearly/fibrous nature and the change in parameter values.

CONCLUSIONS

We conclude that in subjects being considered with GDx-VCC, the presence of visually significant PCO may introduce artifact as judged by the typical scan score.

Outcomes of acute postoperative inflammation after cataract surgery

PURPOSE

To determine characteristics and final visual and surgical outcomes of patients who experienced early onset postoperative inflammation after cataract surgery and their early and late complications.

METHODS

This is a prospective case series of 126 patients out of 1500 cases who underwent cataract surgery and experienced early onset postoperative inflammation during the first 2 weeks after cataract surgery. All the patients received complete ocular examinations at onset of signs and symptoms of inflammation. A total of 110 patients with follow-up examinations between 3 and 30 months after recovery of early onset postoperative inflammation (mean follow-up 11.6 months) were enrolled in the next part of the study to evaluate the final visual and surgical outcomes. Background systemic and ocular diseases, type of surgery, type of intraocular lenses and viscoelastic agent, early and late complications, and final best-corrected visual acuity were studied.

RESULTS

Among 1500 patients, 126 cases (8.4%) had early onset postoperative inflammation, 64 cases (50.7%) were male, and 62 cases (49.3%) were female. Early complications were posterior synechia in 9 cases (7.1%), pupillary block in 2 cases (1.5%), and acute rise of intraocular pressure in 6 cases (4.7%). Late complications consisted of posterior capsular opacity in 38 cases (34.5%) and cystoid macular edema in 4 cases (3.2%). Peak of signs and symptoms of inflammation was during 2 weeks after surgery and all patients responded well to topical steroids. Final best-corrected visual acuity (BCVA) was 20/30 and better in 76 cases (69%), between 20/40 and 20/80 in 24 cases (22%), and less than 20/80 in 10 cases (9%). All cases with BCVA less than 20/80 had ocular diseases like choroidal neovascularization scar or age-related macular degeneration, advanced glaucoma, or corneal opacity.

CONCLUSIONS

Early onset postoperative inflammation causes pain, decreased vision, and patient anxiety in the acute phase but neither decreases final visual acuity nor has any significant or permanent ocular sequels.

Influence of three-piece and single-piece designs of two sharp-edge optic hydrophobic acrylic intraocular lenses on the prevention of posterior capsule opacification: a prospective, randomised, long-term clinical trial

BACKGROUND

Posterior capsule opacification (PCO) is still a major long-term complication of modern cataract surgery. We evaluated the impact of sharp-edged intraocular lenses (IOLs) with different haptic designs made from the same hydrophobic acrylic material on posterior and anterior lens capsule opacification.

SETTING

Eye clinic of Kaunas University of Medicine, Lithuania. Prospective randomised clinical study.

METHODS

Seventy-four eyes of 74 patients scheduled for cataract surgery were included in a prospective randomised clinical study. Thirty-seven eyes of 37 patients received a three-piece acrylic hydrophobic (AcrySof, MA3OBA, Alcon) IOL; and thirty-seven eyes of 37 patients received a one-piece acrylic hydrophobic (AcrySof, SA3OAL, Alcon) IOL. Visual acuity, anterior capsule opacification (ACO), capsular folds, capsulorrhexis/optic overlapping and posterior capsule opacification (PCO) were evaluated. ACO was assessed subjectively. PCO values in the entire IOL optic area and in the central 3 mm optic zone were assessed using a photographic image-analysis system (EPCO2000). Follow-ups were performed postoperatively at 1 day, 6 months, 1 year and 2 years.

RESULTS

There were no significant differences in best corrected visual acuity, grade of ACO and capsulorrhexis/optic overlapping between IOL types during the follow-up period. Patients in the one-piece acrylic hydrophobic IOL group more frequently presented with capsular folds behind the IOL optic area than those in the three-piece IOL group. In the three-piece acrylic hydrophobic IOL group, PCO values (mean (SD)) of the entire IOL optic area were significantly lower six months postoperative (three-piece: 0.002 (0.009); one-piece: 0.007 (0.017); p=0.04), one year postoperative (three-piece: 0.004 (0.016); one-piece: 0.026 (0.041); p=0.001) as well as one year postoperative in the central 3 mm optic zone (three-piece: 0.000 (0.0002); one-piece: 0.019 (0.049); p=0.001). However, two years postoperative, the PCO values of the groups did not show significant differences (entire IOL optic area: three-piece, 0.136 (0.223); one-piece, 0.154 (0.190); p=0.18; central zone: three-piece, 0.023 (0.065); one-piece: 0.020 (0.039); p=0.44).

CONCLUSION

The 2 year follow-up after cataract surgery showed no significant difference in ACO and PCO development between three-piece and one-piece acrylic hydrophobic intraocular lenses.

Posterior capsule opacification after implantation of a hydrophilic or a hydrophobic acrylic intraocular lens: one-year follow-up

PURPOSE

To evaluate the effect of hydrophilic and hydrophobic single-piece acrylic intraocular lenses (IOLs) on posterior capsule opacification (PCO) after cataract surgery.

SETTING

St. Erik's Eye Hospital, Stockholm, Sweden.

METHODS

In a prospective study, 120 patients having cataract surgery were randomized to implantation of a hydrophilic acrylic IOL (BL27, Bausch & Lomb) or a hydrophobic acrylic IOL (AcrySof SA60AT, Alcon). Surgery was performed according to a standardized protocol by 1 of 3 surgeons. Best corrected visual acuity, contrast sensitivity, glare, intraocular pressure, and flare were measured 1 week, 3 months, and 1 year after surgery. Posterior capsule opacification was assessed by digital retroillumination photography and analysis using POCOman software at 1 year. The rate of neodymium:YAG (Nd:YAG) capsulotomy for each IOL was also recorded.

RESULTS

At 1 year, the hydrophilic acrylic IOL group had a significantly greater percentage area and severity of PCO than the hydrophobic acrylic IOL group (P<.001). Two patients in the hydrophilic acrylic IOL group and 4 in the hydrophobic acrylic IOL group had an Nd:YAG capsulotomy within the first year (P>.05). Contrast sensitivity was significantly better in the hydrophilic acrylic group at 3 months (P<.05); however, at 12 months no difference between the IOLs was observed. There was no significant difference in the other measured parameters.

CONCLUSION

Patients with the hydrophilic acrylic BL27 IOL had a significantly greater percentage area and severity of PCO than those with the hydrophobic acrylic SA60AT IOL 1 year after surgery.

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.

Incidence and risk factors of Nd:YAG capsulotomy after phacoemulsification in non-diabetic and diabetic patients

PURPOSE

To estimate the cumulative incidence and identify the risk factors of posterior capsule opacification (PCO) that required Nd:YAG capsulotomy in non-diabetic and diabetic patients.

METHODS

Retrospective case-note review of 806 consecutive patients that underwent phacoemulsification and intraocular lens (IOL) implantation, 327 (40.6%) of whom were diabetic.

RESULTS

The cumulative incidence of Nd:YAG capsulotomy were 10.6%, 14.8%, 21.2% and 28.6% in non-diabetic patients; and 9%, 9.4%, 15.3% and 5.3% in diabetic patients after 1, 2, 3 and 4 years, respectively. A multivariate Cox regression analysis showed that, over the follow-up period, diabetes mellitus was associated with a decreased risk of Nd:YAG capsulotomy (hazard ratio [HR]=0.69; 95% confidence interval [CI] 0.47-0.99; P=0.047), whereas age of 65 years or younger (HR=1.58; 95% CI 1.09-2.27; P=0.02), polymethylmethacrylate (PMMA) (HR=3.98; 95% CI 1.60-9.95; P=0.003) or plate-haptic silicone IOLs (HR=3.75; 95% CI 1.60-8.80; P=0.002) in comparison with three-piece silicone IOLs, postoperative inflammation (HR=2.62; 95% CI 1.56-4.42; P<0.001) and pars plana vitrectomy (HR=1.85; 95% CI 1.20-2.83; P=0.005) were associated with an increased risk. Subgroup analysis showed that in non-diabetic patients, male gender (HR=1.63; 95% CI 1.04-2.57; P=0.03) was an additional risk factor and in diabetic patients there was no significant association between diabetes type, duration or retinopathy grade and the risk of Nd:YAG capsulotomy.

CONCLUSION

Although diabetes mellitus appears to be associated with a lower long-term incidence and a decreased risk of Nd:YAG capsulotomy, younger age, pars plana vitrectomy, postoperative inflammation, plate-haptic silicone and PMMA IOLs in addition to male gender in non-diabetic patients appear to be associated with a greater risk. Estimation of the incidence and risk factors of PCO should help in patient counselling and to design methods to reduce or prevent its development.

Active oxygen processing for acrylic intraocular lenses to prevent posterior capsule opacification

PURPOSE

To evaluate active oxygen processing on the surface of acrylic intraocular lenses (IOLs) to prevent secondary posterior capsule opacification (PCO).

SETTING

Department of Ophthalmology, Dokkyo Medical University School of Medicine, Mibu City, Tochigi, Japan.

METHODS

Acrylic IOLs were prepared, and ultraviolet (UV)/ozone (UV/O3) or argon plasma was irradiated to the surface of the IOLs. Elemental analysis (electron spectroscopy for chemical analysis [ESCA]) of the IOL surfaces was performed to confirm surface modification. Changes produced by UV/O3 or argon plasma treatment were examined for fibronectin and lens epithelial cell (LEC) adhesion. To evaluate the PCO prevention by treated IOLs, 8-week-old albino rabbits were used. The rabbit eyes randomly had phacoemulcification and implantation of 3 different IOLs: the UV/O3-treated IOLs, argon plasma-treated IOLs, and the control IOLs. After 2 weeks, the rabbits were killed and their globes were dissected and fixed using formaldehyde 10%. The PCO was observed using light microscopy (DX51, ORIMPUS) after hematoxylin and eosin staining.

RESULTS

Comparison of IOL surface composition by ESCA showed an increase in nitrogen content and hydroxyl substitute and carboxyl substitute groups on surfaces of treated IOLs. The fibronectin adhesion and the LEC adhesion on the UV/O3-treated and argon plasma-treated samples were increased. In the untreated group, there was statistically significant inhibition of PCO formation in the UV/O3-treated and argon plasma-treated groups.

CONCLUSION

Active oxygen processing and argon plasma irradiation on the surface of IOLs was effective in preventing secondary PCO after cataract surgery.

Modification of the surface properties of a lens material to influence posterior capsular opacification

PURPOSE

To study the effect of surface properties of materials on cellular behaviour and the formation of posterior capsular opacification (PCO).

METHODS

Polymethylmethacrylate, silicone and a hydrophobic acrylic were plasma treated and used in tissue culture. The changes in surface properties were quantified by dynamic contact angle measurements. Bovine lens epithelial cells (BLECs) were seeded onto these materials and cultured for 1 month. Serial photographs were taken. The cells were then fixed and stained to facilitate counting.

RESULTS

Plasma treatment significantly increased the hydrophilicity of surfaces. BLECs grew on all surfaces but significantly more cells adhered to the treated than the untreated surfaces. On the untreated surfaces the BLECs had a fibroblastic morphology whereas on the treated surfaces the cells maintained their epithelial morphology.

CONCLUSIONS

Posterior capsular opacification is a form of wound healing and the behaviour of lens epithelial cells is central to its progression. Emphasis has been on the elimination of residual lens epithelial cells to combat PCO. This study demonstrated that the phenotype of BLECs was influenced by the surface properties of the intraocular lens materials. Gas plasma treatment of the materials increased their hydrophilicity and allowed the adhered BLECs to maintain their normal epithelial morphology. We believe that controlled growth of lens epithelial cells may reduce the incidence of PCO.

Evaluation of the effects of hydrodissection with antimitotics using a rabbit model of Soemmering's ring formation

BACKGROUND

Regeneration/proliferation of lens material within the capsular bag still is the most frequent complication after cataract surgery. We aimed to evaluate the effects of hydrodissection with low doses of antimitotics on the overall regeneration/proliferation of lens material in rabbit eyes, using a model allowing the lens material to be confined to the equatorial region of the capsular bag, facilitating its quantification.

METHODS

Twelve albino rabbits underwent bilateral phacoemulsification. Their eyes were randomized to receive 0.4 cc of balanced salt solution, 5-fluorouracil (12.5 mg/mL) or mitomycin C (0.1 mg/mL) during hydrodissection. They were left aphakic, so the capsulorhexis would fuse with the posterior capsule postoperatively. After 4 weeks, killing/enucleation was performed. Regeneration/proliferation of lens material within the equatorial capsular bag (Soemmering's ring) was graded from the Miyake-Apple view (0-4). Its area was also calculated (microm(2)) from direct measurements performed on histological sections.

RESULTS

The capsulorhexis margin fused with the peripheral posterior capsule, so the central posterior capsule remained clear. There was no significant difference among the groups (Kruskal-Wallis test) regarding Soemmering's ring gross grading (P = 0.511), number of lens epithelial cell layers lining the inner surface of the capsular bag (P = 0.310) and Soemmering's ring microscopic cross-sectional area (P = 0.638).

CONCLUSIONS

The effect of different solutions on after-cataract should be assessed in terms of overall regeneration/proliferation of lens material within the capsular bag, in addition to posterior capsule opacification. When administered in low doses during hydrodissection, 5-fluorouracil and mitomycin C did not show a significant inhibitory effect on after-cataract formation in rabbit eyes.

Brimonidine 0.2% Versus Brimonidine Purite 0.15%: Prophylactic Effect on IOP Elevation After Nd:YAG Laser Posterior Capsulotomy

AIMS

The aim of this study was to compare the prophylactic effect of brimonidine 0.2% versus brimonidine Purite 0.15% on intraocular pressure (IOP) increase after Nd:YAG laser posterior capsulotomy.

METHODS

In this prospective, double-masked, randomized, controlled study, 106 patients (106 eyes) who underwent Nd:YAG laser posterior capsulotomy were allocated to a brimonidine 0.2% group (35 eyes), a brimonidine Purite 0.15% group (36 eyes), or a vehicle group (35 eyes). One (1) drop of brimonidine 0.2%, brimonidine Purite 0.15%, or vehicle was instilled 1 h preoperatively and 1 drop immediately after Nd:YAG laser posterior capsulotomy. IOPs were measured preoperatively and at 1, 2, 3, and 24 h postoperatively.

RESULTS

Decreases in IOP from baseline ranged from 2.3 to 2.7 mmHg in the brimonidine 0.2% group and 2.2-2.5 mmHg in the brimonidine Purite 0.15% group (P < 0.05), whereas the vehicle group exhibited a rise in IOP. IOP elevations of less than 5 mmHg occurred in 22.9% of patients in the brimonidine 0.2% group, 27.8% in the brimonidine Purite 0.15% group, and 48.6% in the vehicle group. Spikes of IOP greater than 10 mmHg occurred in 2.9% of patients in the brimonidine 0.2% group, 2.8% in the brimonidine Purite 0.15% group, and 8.6% in the vehicle group. The incidence of IOP elevation was not statistically significant between the brimonidine 0.2% and the brimonidine Purite 0.15% groups (P < 0.05).

CONCLUSIONS

Brimonidine 0.2% and brimonidine Purite 0.15% have similar efficacy in the prevention of IOP elevation after Nd:YAG laser posterior capsulotomy.