True Exfoliation in Chinese Population in a Tropical Area -The Sanya Eye Study -

Abstract

Purpose:: To investigate the prevalence and clinical features of true exfoliation of lens capsule (TEX) in subjects of the Sanya Eye Study aged 50 yrs and over.

Methods:: All 841 citizens aged 50 yrs and above living in Miaolin village located 15km west of Sanya city located at latitude 19 N and longitude 108 E were approached by the local government. Some 140 were out of town leaving 701 of which 558, mostly farmers, (79.6% of eligible) volunteered to be subjects and were examined in March 2006. TEX was documented by slitlamp biomicroscopy and anterior eye segment analysis system (EAS 1000, NIDEK) with undilated and dilated pupils.

Results:: Among the 558 subjects, five cases showed TEX as a thin, transparent membrane rising from the lens surface. One case was bilateral and the other four were unilateral- right eyes. From the retroillumination images, all five cases demonstrated separation of the anterior capsule which was sharp with a round line that had a grayish surface inside suggesting this was the initial event for TEX. There were another two cases that showed this feature without any thin, transparent membrane rising from the lens surface suggesting this feature describes the onset of TEX. The mean age of these seven cases (three males and four females) was 72.3±9.2 yrs. None of them had any history that is known to contribute to true exfoliation including exposure to excessive heat, ocular trauma, or intraocular inflammation. All the eyes with TEX showed severe nuclear cataract and retrodots.

Conclusions:: Although true exfoliation of the lens capsule is believed to be a very rare disorder in which the superficial portion of the lens capsule splits from the deeper layer, this condition might be more prevalent in this population. Although the reason why TEX was present in this population is unknown, the length of time spent outdoors and high temperature of the environment might play some role. As far as the authors know, this is the first report to show the initial signs of TEX in retroillumination images without the presence of any superficial splitting of the anterior capsule.

Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: outcomes/complications • clinical (human) or epidemiologic studies: systems/equipment/techniques