A systematic overview of the incidence of posterior capsule opacification

Detection of integrins in cataract lens epithelial cells

PURPOSE

To detect the expression of integrin subunits in lens epithelial cells (LECs) of human cataracts.

SETTING

Research Laboratory, International Intraocular Implant Training Centre, Tianjin Medical University, China.

METHODS

The circular sections of the anterior capsules with attached LECs were obtained during cataract surgery from 100 patients. The LECs were stained with an avidin-biotin-complex immunohistochemical technique using 5 monoclonal antibodies specific for alpha subunits 2, 3, 5 and beta subunits 1, 2.

RESULTS

All integrin subunits studied were found to varying degrees in specimens. The positive percentages were 70%, 65%, 75%, 70%, and 80%, respectively.

CONCLUSION

Integrin subunits were present in LECs of human cataracts. These molecules may serve in the adhesion of LECs to the lens capsule and play a role in cell-posterior capsule interaction after cataract surgery.

Surgical prevention of posterior capsule opacification. Part 1: Progress in eliminating this complication of cataract surgery

PURPOSE

To evaluate over almost 2 decades the success of a component of cataract surgery that represents a critical step in reducing the incidence of posterior capsule opacification (PCO); namely, the efficacy of 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

Accessioned from the early 1980s to 1997, 3320 eyes obtained postmortem with posterior chamber intraocular lenses were analyzed with respect to formation of a postoperative Soemmering's ring. This anatomic lesion, the precursor of clinical PCO, represents an important and measurable indication of the quality of cortical cleanup. Its formation was documented using Miyake-Apple posterior photographic analysis.

RESULTS

The quality and thoroughness of cortical cleanup and overall effectiveness in eliminating retained and/or regenerating cortical cells, as measured by scoring of Soemmering's rings, showed virtually no net change since the early 1980s. The intensity of Soemmering's ring was higher in the most recent specimens than in those in the early 1980s.

CONCLUSION

The results indicate that renewed attention to cortical cleanup in cataract surgery is warranted for significant reduction in incidence or the elimination of PCO. More attention to the hydrodissection (cortical cleaving hydrodissection) step of the procedure is likely a practical, immediately implementable, and inexpensive remedy.

Posterior capsule opacification. Part 2: Clinical findings

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

Posterior capsular opacification after cataract surgery

This is a review of the current status of clinical research on the prevention of posterior capsular opacification (PCO), which is now the commonest complication of cataract surgery occurring in up to 50% of patients by 2 to 3 years after the operation. PCO is caused by lens epithelial cells retained in the capsular bag following surgery which then proliferate, migrate and transform to myofibroblasts. Interest in the prevention of PCO has centred around surgical technique, pharmacological methods to remove or destroy lens epithelial cells and changes in intraocular lens material and design. Changes in surgical technique have little effect in prevention of PCO although a capsulorhexis size which lies on the optic diameter appears to be beneficial. Many different cytotoxic drugs and pharmacological agents have been used experimentally to prevent PCO but the problem has limited damage only to lens epithelial cells. So far, no method has been shown to be safe for clinical use. Current interest is centred once again on the intraocular lens itself, particularly the material that it is made from and changes in its edge profile.

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

PURPOSE

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

DESIGN

Prospective analysis of pseudophakic eyes obtained postmortem.

PARTICIPANTS

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

METHODS

Miyake-Apple posterior photographic technique.

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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