An extension of an accommodation and convergence model of emmetropization to include the effects of illumination intensity

The Flitcroft (1998) emmetropization model incorporates a classical model o f accommodation and convergence with blur-driven feedback control of eye gr owth. We have modified this model by incorporating the effects of illuminat ion (with or without extensive near work) on accommodation, vergence, pupil diameter and emmetropization. In addition to replicating Flitcroft's resul ts, we show that (1) decreased illumination and (2) a low convergence accom modation/convergence (CAC) ratio exacerbate the progression of near-work-in duced myopia. Our model further indicates that prescription of negative len ses, under these conditions, augments the advancement of myopia. (C) 1999 T he College of Optometrists. Published by Elsevier Science Ltd. All rights r eserved.