CONSTRICTION OF THE VISUAL-FIELD OF CHILDREN AFTER EARLY VISUAL DEPRIVATION

Purpose: We measured the extent of the monocular visual fields of chil dren deprived of normal visual experience and examined the influence o f the timing and duration of deprivation, of whether deprivation was m onocular or binocular, of having patched the fellow eye, and of optica l factors. Methods: The Goldmann perimeter and a 6.4' stimulus of eith er 31.8 cd/m(2) (target I2e) or of 318 cd/m(2)(target I4e) were used t o test 44 children treated fbr a dense and central cataract in one (n= 25) or both (n=31) eyes that developed before 6 years of age. Then, th e influence of optical factors was assessed in two adults treated for a late-onset, unilateral cataract and in two children treated for unil ateral congenital cataract. Results: Compared with age norms or the no rmal fellow eye, all children treated for cataract showed a restricted field, especially temporally, even when deprivation began as late as 6 years of age and lasted less than 6 months, The restrictions were la rger than those shown by the adults who developed cataracts. The restr ictions were larger after longer deprivation and monocular deprivation than after binocular deprivation. However, children who regularly pat ched the fellow nondeprived eye and, therefore, experienced less inter ocular competition, exhibited smaller restrictions temporally, Neither visual acuity nor optical factors could account for all of the restri ctions in the deprived children, Conclusions: The development of the v isual field is vulnerable to the effects of deprivation, especially to unilateral deprivation and to long deprivation. The losses likely ref lect alterations in the visual pathways subserving peripheral vision.