In vitro and in vivo evaluation of a hydrophilized silicone intraocular lens

Mitomycin against posterior capsular opacification: an experimental study in rabbits

AIMS/BACKGROUND

Posterior capsular opacification is the most common postoperative complication of extracapsular cataract surgery. The purpose of this study was to attempt to inhibit this secondary cataract formation by using mitomycin (an antimitotic drug).

METHODS

A solution containing mitomycin was used to perform hydrodissection (with a 5 minute pause) during extracapsular lens extraction in rabbits. This way of administration was chosen to reduce as much as possible drug diffusion into the anterior chamber. Heparin was added to the irrigating solution to avoid fibrin formation. Its ability to prevent posterior cataract opacification was also evaluated at the end of the study. The animals were sacrificed 4 or 6 months after surgery. Grading concerning two aspects of secondary cataract (proliferation and fibrosis) was obtained on gross examination. Histological analysis was subsequently performed.

RESULTS

This study demonstrated that mitomycin has a significant inhibitory effect on secondary cataract formation (proliferation as well as fibrosis) in rabbits whereas heparin does not seem to have the same effectiveness.

CONCLUSION

This work is a preliminary study concerning the use of mitomycin for prevention of posterior capsular opacification. It has proved its effectiveness in rabbits but more in depth studies are still necessary before its application in humans.

Lens refilling and endocapsular polymerization of an injectable intraocular lens: in vitro and in vivo study of potential risks and benefits

Endocapsular cataract removal and injection of a liquid artificial lens has several advantages, including restitution of accommodation, small corneoscleral incision, a more physiological position of the intraocular lens, and a reduced rate of secondary opacification. Our technique consists of bimanual phacofragmentation followed by injection of a fluid monomeric material that can be polymerized inside the capsular bag by short light exposure. Our study assessed the potential risks of the technique (e.g., heat damage to ocular tissue, light damage to the retina) and investigated the technique in vivo. We performed in vitro experiments on porcine cadaver eyes and an in vivo study on 15 rabbits. After a clinical follow-up of at least 12 weeks, the eyes were investigated histopathologically. During the polymerization process, the highest temperature measured at the posterior lens capsule was 45.1 degrees Celsius for a few seconds. The measured irradiance (0.065 watts per cm2) and the risk of photochemical damage to the retina during 20 seconds of polymerization were comparable to that caused by 1.5 minutes of standard coaxial illumination with the operating microscope. In vivo there were no serious inflammatory reactions except in four cases in which there had been intraoperative problems. The rate of secondary opacification appeared less than in conventional intraocular lens implantation in rabbits, especially when the capsule refilled completely. Retinal damage could not be detected histopathologically. In conclusion, refilling techniques may be successful once appropriate refilling materials become available.