Inhibition of posterior capsule opacification: the effect of colchicine in a sustained drug delivery system

Relationship between intraocular lens biomaterials and posterior capsule opacification

PURPOSE

To determine whether posterior capsule opacification (PCO) is influenced by intraocular lens (IOL) material.

SETTING

A British teaching hospital eye department.

METHODS

Ninety eyes were prospectively randomized to receive a poly(methyl methacrylate) (PMMA), silicone, or AcrySof IOL. All lenses had 6.0 mm optics and PMMA haptics. A standardized surgical protocol was performed by a single surgeon using an extracapsular technique with capsulorhexis. Patients having surgical complications were excluded and all patients had standardized medication and follow-up. Posterior capsule opacification was assessed by a digital retroillumination camera using a dedicated software program based on the analysis of texture in the image and calculated as the percentage area of opacified capsule. Data were analyzed 2 years postoperatively.

RESULTS

There was a significant difference in percentage of PCO at 2 years among the three lens types (P < .0001). The AcrySof lenses were associated with less PCO (median 11.75%) than PMMA (43.65%) and silicone (33.50%) lenses (P < .001 and P = .025, respectively). The difference between PMMA and silicone lenses was not statistically significant.

CONCLUSION

Intraocular lenses made from AcrySof were associated with a significantly reduced degree of PCO.

Immunolocalization of prolyl 4-hydroxylase subunits, alpha-smooth muscle actin, and extracellular matrix components in human lens capsules with lens implants

Lens capsules become fibrotic after the extraction of a cataract. To understand this phenomenon, we evaluated the immunolocalization of prolyl 4-hydroxylase (an enzyme involved in procollagen hydroxylation), and extracellular matrix components and cytoskeletal components in a normal human lens capsule and in others with intraocular lenses. Lens capsules containing intraocular lenses were removed from a patient with proliferative vitreoretinopathy and three with proliferative diabetic retinopathy during vitreous surgery. Two circular sections of the anterior capsules with lens epithelial cells were obtained by anterior capsulotomy during cataract surgery. In addition, a lens capsular bag was obtained immediately after phacoemulsification. The lens capsules were processed for light microscopic immunohistochemical detection of the alpha and beta subunits of prolyl 4-hydroxylase, extracellular matrix components (including collagen types, laminin and cellular fibronectin) or cytoskeletal components (such as cytokeratin, vimentin and alpha-smooth muscle actin). Monolayer lens epithelial cells were seen on the inner surface of the normal anterior capsules. Each intraocular lens was found to be fixed in the capsular bag. Light microscopic immunohistochemistry showed that these proliferating cells expressed vimentin and alpha-smooth muscle actin; in contrast, quiescent lens epithelial cells did not stain for alpha-smooth muscle actin. Marked immunostaining for subunits of prolyl 4-hydroxylase was detected in lens epithelial cells proliferating on the capsules, while no or only faint prolyl 4-hydroxylase immunoreactivity was detected in quiescent lens epithelial cells immediately after phacoemulsification. Collagen types I, III and VI and cellular fibronectin were observed diffusely in accumulated connective tissue on a capsule with an intraocular lens. Type IV collagen immunoreactivity was seen both in the capsules and in the connective tissue accumulation on the capsules. Collagen V and laminin were detected in association with cellular proliferation. Collagen VII and VIII and laminin 5 were not seen. We concluded that during wound healing of the lens capsule after cataract extraction, the lens epithelial cells that proliferate on the inner surface of the capsule transform it into a myofibroblastic phenotype, expressing prolyl 4-hydroxylase and alpha-smooth muscle actin. These proliferating cells are involved in the production of collagen on the lens capsule. This results in a postoperative fibrotic process and contraction of the lens capsule.

Caffeic acid phenethyl ester to inhibit posterior capsule opacification in rabbits

PURPOSE

To assess whether caffeic acid phenethyl ester (CAPE) prevents posterior capsule opacification (PCO) by suppressing the transformation of the lens epithelial cells.

SETTING

Departments of Ophthalmology, Chemistry, and Pathology, Turgut Ozal Medical Center, University of Inonu, Malatya, Turkey.

METHODS

Twenty pigmented island rabbits having phacoemulsification in their right eyes were randomized into two groups. In group 1, 10 micrograms/ml of CAPE was added to the anterior chamber irrigating solution and a 1% solution of CAPE was injected subconjunctivally for 3 weeks postoperatively. The irrigating solution in Group 2 (control) did not include CAPE. The development of PCO was assessed weekly and its density was graded by slitlamp biomicroscopy. Histologic analysis was performed 3 months after surgery.

RESULTS

Group 1 had clear capsules or minor PCO. Group 2 developed more severe PCO or complete opacification. The difference between the two groups was statistically significant (P = .04).

CONCLUSION

These preliminary results indicate that CAPE is effective in suppressing PCO in pigmented rabbits and may be beneficial in clinical use in humans because it has no documented harmful effects on normal cells.

Photographic image analysis system of posterior capsule opacification

PURPOSE

To describe a morphological scoring system of posterior capsule opacification (PCO) that is not based on visual acuity testing.

SETTING

Department of Ophthalmology, University of Heidelberg, Germany.

METHODS

Following dilation of the pupil, standardized photographs of the pseudophakic anterior segments were obtained using a photo slitlamp. Posterior capsule opacification was scored by evaluating retroillumination photographs. The individual PCO score was calculated by multiplying the density of the opacification (graded from 0 to 4) by the fraction of capsule area involved behind the intraocular lens (IOL) optic. To evaluate the reliability of the morphological scoring system, six observers examined photographs of five eyes each (Experiment A, interindividual reliability). The same observer scored the PCO in three eyes on five different days (Experiment B, intraindividual reliability).

RESULTS

Morphological PCO scores were very reliable. With PCO scoring from 0 to 4, the interindividual reliability showed standard deviations between 0.08 and 0.25. The intraindividual reliability showed standard deviations between 0.06 and 0.19 of the mean individual PCO scores. Standard deviation was 0.12 when different photographs of the same eye were scored.

CONCLUSION

The morphological scoring system evaluates the entire area behind the IOL optic and thus includes a larger area of the posterior capsule than does visual acuity testing. The method revealed high reliability and insignificant investigator-dependent variations. When using a standardized photographic setup, systematic errors by the photographic technique were not relevant. This method may be an important tool to accurately test for differences in PCO formation with various IOL styles and surgical methods.

Inhibition of migrating lens epithelial cells by blocking the adhesion molecule integrin: a preliminary report

PURPOSE

To evaluate the preventive effect of blocking integrins by sustained release of RGD peptide (arginine-glycin-aspartic acid sequence) or a combination of RGD peptide and ethylenediaminotetraacetic acid (EDTA) on lens epithelial cell (LEC) migration.

SETTING

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

METHOD

A polylactic-glycolic acid disk containing 4% RGD or a combination of 23% EDTA and 10% RGD was implanted in the capsular bag in five rabbit eyes following standard cataract surgery. The release rate in vitro was 4.4 microg/h for RGD peptide alone and 7.8 and 7.6 microg/h for combined EDTA and RGD peptide, respectively. The contralateral eye received a disk without agents as a control.

RESULTS

After 1 month, a slight inhibition of LEC migration onto the posterior capsule was observed histopathologically in eyes receiving RGD peptide. A significant inhibition was observed in eyes with combined EDTA and RGD.

CONCLUSIONS

Application of RGD peptide and EDTA and RGD peptide may inhibit LEC migration by inhibiting the integrins expressed on the LECs. Blocking adhesion molecules expressed on LECs may reduce posterior capsule opacification.

Heparin eyedrops to prevent posterior capsule opacification

PURPOSE

To evaluate whether heparin eyedrops prevent or reduce posterior capsule opacification (PCO) after extracapsular cataract extraction (ECCE) with intraocular lens (IOL) implantation.

SETTING

Institute of Ophthalmology, University G. d'Annunzio, Chieti, Italy.

METHODS

This 4 year, prospective, case-controlled study evaluated 200 patients who had ECCE and implantation of the same type of posterior chamber IOL. Patients were randomly assigned to receive topical heparin eyedrops postoperatively (heparin group, n = 100) or not to receive the eyedrops (control group, n = 100). Postoperative cell response, cellular precipitates on the IOL, and presence of PCO were evaluated.

RESULTS

There were no significant differences between groups in postoperative inflammation. The incidence of cellular precipitates was significantly lower in the heparin group than in the control group (P < .001). A neodymium:YAG (Nd:YAG) posterior capsulotomy was done in 7 patients in the heparin group and 14 in the control group (P = .15). During the first 24 months after surgery, the heparin group had a significantly lower incidence of Nd:YAG capsulotomy (P < .05) and fibrotic PCO (P = .02).

CONCLUSION

Topical heparin eyedrops were effective in reducing fibrotic PCO in the long term, indicating their usefulness in the postoperative management of ECCE.

Complicated posterior capsulorhexis: aetiology, management, and outcome

BACKGROUND

A 1 year retrospective analysis of 650 patients, who underwent a posterior capsulorhexis on their intact capsules, was performed to examine the incidence of complications, their aetiologies, and the outcome.

METHODS

Data were analysed on 32 patients with complicated capsulorhexis for type of surgery, preoperative and postoperative factors, and relative risk factors for vitreous issue.

RESULTS

There were six patients with vitreous loss. The posterior capsulorhexis was uncontrolled in 14 cases and difficult to perform in 12 cases. Implantation into the capsular bag was possible in all cases. Systemic vascular hazard and old age (over 80 years) were found to be statistically significant risk factors for vitreous loss (p = 0.002 and p = 0.03 respectively). The mean follow up was 13.5 months (range 4-25 months). One patient developed a retinal detachment and two had a transient clinical cystoid macular oedema. Visual acuity of > or = 20/40 was obtained in 93% of the patients.

CONCLUSION

Loss of control of the posterior capsulorhexis has a low incidence but can lead to serious problems during surgery. A good knowledge of the technique is necessary to complete the procedure with a posterior capsulorhexis of the optimum size without vitreous loss.

Inhibition of posterior capsule opacification by an intraocular-lens-bound sustained drug delivery system: an experimental animal study and literature review

PURPOSE

To find a way to prevent or significantly reduce posterior capsule opacification (PCO) with modern phacoemulsification and in-the-bag intraocular lens (IOL) implantation.

SETTING

Department of Ophthalmology and Institute for Pharmaceutical Technology and Biopharmacy, Ruprecht-Karls-University of Heidelberg, Germany.

METHODS

We evaluated the effects of an IOL-bound sustained drug delivery system (SDDS) consisting of the carrier substance poly-DL-lactid and the drug daunorubicin or indomethacin. The system was applied to the IOL surface and implanted in rabbit eyes. At 8 weeks postoperatively, PCO wet mass was determined. Toxic and inflammatory effects were documented by histopathology.

RESULTS

The average PCO wet mass was 54.6 mg in the control group, 28.6 mg with daunorubicin, and 64.1 mg with indomethacin. Statistical analysis showed a significant reduction of PCO with daunorubicin (Mann-Whitney U-test, P = .025) and no PCO-reducing effect with indomethacin. Light microscopy of the specimens revealed mild inflammation, especially at the limbus, and some endothelial cell loss in the daunorubicin group and iris and ciliary body inflammation in the indomethacin group.

CONCLUSION

In the rabbit eye, slow release of daunorubicin reduced PCO formation by approximately 50%. It must be determined whether the endothelial side effects are specific to the rabbit species or whether the human cornea is as sensitive. The principle of the IOL-bound SDDS and the evaluation procedure can be standardized and used for systematic tests in the future.

Effect of intraocular sustained release of indomethacin on postoperative inflammation and posterior capsule opacification

PURPOSE

To assess whether the sustained release of indomethacin significantly reduces postoperative inflammation and posterior capsule opacification (PCO).

SETTING

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

METHODS

A 7 mm diameter, 1 mm thick polylactic-polyglycolic acid disk containing 7 mg of indomethacin was implanted in five rabbit eyes after continuous curvilinear capsulorhexis and phacoemulsification. The disk and an IOL placed above it were implanted in the capsular bag. The contralateral eyes, which served as controls, received a disk without indomethacin and the same type IOL in the same manner.

RESULTS

The indomethacin was fully released within 3 weeks in vitro, a release rate of about 14 micrograms/h. Postoperatively, aqueous flare intensity was significantly lower at days 2, 3, and 4 and at weeks 1, 2, and 3. Prostaglandin E2 was not detectable in the aqueous humor of the indomethacin-treated eyes on day 3 and at week 4. In the control eyes, mean concentration was 491 pg/ml +/- 54 (SD) and 990 +/- 243 pg/ml, respectively. Histopathological examination showed no significant decrease in PCO.

CONCLUSION

Although sustained release of indomethacin significantly decreased inflammation, it did not reduce PCO.

Capsular capture of silicone intraocular lenses

PURPOSE

To examine the incidence of capsular capture in silicone IOL implantation and determine its effect on visual acuity.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

This study comprised 144 eyes that had phacoemulsification with three-piece silicone intraocular lens (IOL) implantation that were evaluated about 3 months after surgery. The examination included the status of the haptic and optic placement, extent of posterior capsular opacification (PCO), and the best corrected visual acuity.

RESULTS

One hundred twenty-eight eyes had an in-in haptic placement, 15 had in-out placement, and 1 had out-out placement. Capsular capture occurred in 30 eyes (20.8%). The extent of PCO in eyes with capsular capture was greater than in those without capture. The best corrected visual acuity in eyes with capsular capture was worse than in those without capture. In addition, eyes with in-out and out-out haptic placement had significantly worse PCO and visual impairment than the eyes with in-in placement.

CONCLUSION

There was a high incidence of capsular capture after silicone IOL implantation. This complication, along with the undesirable placement of the haptics, led to PCO and thus visual impairment.

Inhibition of migrating lens epithelial cells by sustained release of ethylenediaminetetraacetic acid

PURPOSE

To evaluate the effect of the sustained-release of ethylenediaminetetraacetic acid (EDTA) chelating Ca++ on lens epithelial cell (LEC) migration.

SETTING

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

METHODS

Polylactic-glycolic acid disks containing 10% EDTA were placed in saline solution for about 2 weeks in vitro. About 60% (7 micrograms/hour) of the EDTA was released during that time. The disks with a posterior chamber intraocular lens placed above were implanted in the capsular bag in five rabbit eyes after continuous curvilinear capsulorhexis and phacoemulsification. A disk without EDTA and the same lens type were placed in the bag in the contralateral eyes, which served as controls.

RESULTS

After 2 to 3 months, opacification in the central posterior capsule was significantly reduced in all eyes that received the disk with EDTA.

CONCLUSION

The deprivation of Ca++ disrupted interaction between the posterior capsule and migrating LECs by inactivating the adhesion molecule integrin synthesized by LECs, significantly reducing LEC migration onto the posterior capsule.

Effect of indomethacin-coated posterior chamber intraocular lenses on postoperative inflammation and posterior capsule opacification

We implanted indomethacin-coated intraocular lenses (IOLs) in rabbit eyes to ascertain how the sustained release of the drug affects postoperative inflammation and posterior capsule opacification (PCO). A preoperative resolution test showed that 1% indomethacin-coated IOLs placed in balanced salt solution released a mean 14.0 +/- 0.6 micrograms of the drug within 24 hours. Postoperatively, aqueous flare intensity in eyes with 0.1% indomethacin-coated IOLs and in eyes with 1.0% indomethacin-coated IOLs was significantly less at day 2 and at days 2 and 3, respectively, than in control eyes with uncoated lenses. In another group of eyes, histopathological examination showed that those with 1.0% indomethacin-coated lenses had significantly less PCO than the contralateral control eyes with uncoated IOLs.

Effects of diclofenac sodium and indomethacin on proliferation and collagen synthesis of lens epithelial cells in vitro

We investigated the effects of diclofenac sodium and indomethacin on the proliferation of and collagen synthesis by lens epithelial cells (LECs) of human cataracts in culture. The anterior capsule with attached LECs, obtained by anterior capsulotomy during cataract surgery, was cultured directly without cell dispersion. When the culture became almost confluent, diclofenac sodium or indomethacin at various concentrations was added to the incubation medium. The incorporation of 3H-thymidine and 3H-proline into the LECs was measured after the cells were labeled with these radioactive materials. Both drugs greatly suppressed the incorporation of 3H-thymidine and of 3H-proline, indicating that they inhibit cell division and collagen synthesis by LECs. Both drugs may help prevent posterior capsule opacification.