Temporal and spatial growth patterns in the normal and cataractous human lens

This study presents a computational model of the growth of the normal human lens and the induction of spoke-like cortical cataract in the aging lens. The anterior lens is modelled as a 2-D disk with a circumferential germinat ive zone. Lens cortical fibre cells in the same generation cover the surfac e in three identical 120 deg growth wedge-shaped sectors, with centre cardi nal fibres at the 90, 210 and 330 deg meridians. In the foetal lens all pri mary fibre cells begin to elongate simultaneously. Anterior migration is sp atially asynchronous, where the centre fibre begins to move towards the ant erior pole first. The fibres at the end of the sector move last in the ante rior direction. Fibre elongation advanced at constant speed until the bound ary of the sector is reached. Spatio-temporal asynchrony and random fluctua tions were increased for the adult lens. The model foetal lens evolved Y-sh aped sutures anteriorly, and an inverted Y-shaped posteriorly. Fibre length varied periodically with meridional angle, The adult lens displayed irregu lar growth. If clusters of germinative cells are caused to opacify the resu ltant opacities are predominantly spoke-shaped. The model mimics crystallin e lens fibre growth to the extent of successfully evolving lens sutures. Fl uctuations in lens mass are consistent with an ordered pattern of growth, L ens senescence includes a progressive loss of spatio-temporal synchrony in fibre migration from the germinative zone, Peripheral light focusing by the anterior eye is a possible explanation for the nasal predilection and cune iform shape of age-related cortical cataract. (C) 2000 Academic Press.