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R.K. Zoltoski, R. Grostern, J.R. Kuszak; Structure/Function Characterization of Post–Trabeculectomy Induced Lens Changes in Aged Rabbits . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2901.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Trabeculectomy, generally considered the standard "filtration" type of surgery for open–angle glaucoma, very frequently leads to cataract. We have previously reported that 1.5 months post–trabeculectomy performed on young rabbits (3 months old ) an abnormal suture branch oriented directly toward the surgical site is formed that causes a quantifiable negative effect on lens optical quality. The purpose of this study was to determine if a comparable trabeculectomy induced structure/function compromise would occur in older rabbits, a population more representative of the human condition. Methods: Trabeculectomy was performed on retired breeder Dutch–belted rabbits (n=10) that were at least 5 years of age. Age–matched un–operated rabbits were used as controls (n=10). One and half to three months after surgery, lens function (spherical aberration [avg. back focal length, BFL] and sharpness of focus [variability in BFL, BFLV]) was quantified by low power helium neon laser scan analysis. These results were then correlated with lens structure as assessed by light, scanning electron microscopic and CAD reconstructions of lenses derived from micrographs. Results: Structural analysis demonstrated that the lens from "each" operated eye had an abnormal sub–branch that extended from the normal, age compromised crooked posterior line suture directly toward the surgical site. While the surgically induced formation of an abnormal suture branch 6 weeks after surgery did not effect a significant compromise in lens optical quality (control lenses: BFL = 16.89 ± 0.31mm and BFLV = 0.43 ± 0.03 vs. 6 week post surgery lenses BFL = 16.32 ± 0.15 and BFLV = 0.51 ± 0.06 ), 12 weeks after surgery a significant compromise had occurred (12 week post surger lenses BFL = 17.29 ± 0.38 and BFLV = 0.62 ± 0.06). Conclusions: Abnormal suture formation following disruption of the environment via trabeculectomy results in optical compromise in both young and aged rabbits but at a different time course. These sutural changes appear to be characteristic of early changes in lens structure that ultimately result in cataract formation. Prevention of these early sutural changes by inclusion of factors that promote normal fiber development and growth following surgery, even in older subjects may lead to a better surgical outcome.
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