Elastic properties and scanning electron microscopic appearance of manual continuous curvilinear capsulorhexis and vitrectorhexis in an animal model of pediatric cataract

Purpose: To compare the tear resistance of anterior capsulotomies using manual continuous curvilinear capsulorhexis (CCC) and vitrector-cut capsulotomy (vitrectorhexis) techniques in an animal model of the pediatric eye and in 2 pairs of human infant eyes. Setting: Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Methods: Continuous curvilinear capsulorhexis and automated vitrectorhexis capsulotomy techniques were performed in 20 pig eyes, 10 with each technique. The capsules were then stretched until they ruptured. The forces required for rupture after each technique were compared. The forces required for rupture of the pig eye lens capsule were also compared with those required for the human infant eye lens capsule. Scanning electron microscopy was performed in each group following intraocular lens (IOL) insertion. Results: All capsules stretched adequately for IOL insertion. The percentage of stretch prior to rupture was higher in the capsulorhexis group (mean 157%, range 147% to 169%) than in the vitrectorhexis group (mean 135%, range 124% to 147%) (P < .001). The percentage of stretch in the human infant eyes was not statistically different from that in the porcine eyes (P > .05). Conclusions: The manual CCC offered greater resistance to capsule tearing than the vitrectorhexis and also revealed a more smooth, regular edge. It therefore remains the gold standard. However, the vitrectorhexis displayed more than adequate resistance to unwanted anterior capsule tears when used for IOL insertion through capsulotomy sizes currently used in clinical practice.