G Wollensak1, J Wollensak. 1. Department of Ophthalmology, University of Freiburg, Germany.
Abstract
BACKGROUND: After curvilinear capsulorhexis in cataract surgery often a double-ring shape of the remaining capsular margins can be observed. In order to better understand this phenomenon we performed a histological study of excised capsules after continuous curvilinear capsulorhexis. METHODS: Ten anterior capsular specimens from cases with double-ring structure of the capsular margins after continuous curvilinear capsulorhexis (D-group) were examined light microscopically and compared with 10 normal cases (N-group) and 10 cases with pseudoexfoliation (P-group). Three cases from each group were also examined electron microscopically. RESULTS: A characteristic step formation in the capsular edges and in addition horizontal capsular splits in the border zone between the zonular lamella of the anterior capsule and the capsule proper could be demonstrated histologically in the D-group. CONCLUSIONS: There seems to be a weak point of the capsular tissue in the border zone between zonular lamella of the lens and the capsule proper. The superficial splits that we found histologically in this region might be a precursor or forme fruste of true exfoliation. The outward-directed traction force exerted by the zonular fibers seems to lead to further disruption in this weakened layer of the lens capsule during capsulorhexis, producing a double-ring contour of the capsular margins.
BACKGROUND: After curvilinear capsulorhexis in cataract surgery often a double-ring shape of the remaining capsular margins can be observed. In order to better understand this phenomenon we performed a histological study of excised capsules after continuous curvilinear capsulorhexis. METHODS: Ten anterior capsular specimens from cases with double-ring structure of the capsular margins after continuous curvilinear capsulorhexis (D-group) were examined light microscopically and compared with 10 normal cases (N-group) and 10 cases with pseudoexfoliation (P-group). Three cases from each group were also examined electron microscopically. RESULTS: A characteristic step formation in the capsular edges and in addition horizontal capsular splits in the border zone between the zonular lamella of the anterior capsule and the capsule proper could be demonstrated histologically in the D-group. CONCLUSIONS: There seems to be a weak point of the capsular tissue in the border zone between zonular lamella of the lens and the capsule proper. The superficial splits that we found histologically in this region might be a precursor or forme fruste of true exfoliation. The outward-directed traction force exerted by the zonular fibers seems to lead to further disruption in this weakened layer of the lens capsule during capsulorhexis, producing a double-ring contour of the capsular margins.