Strabismus, stereoacuity, accommodation and convergence in young adults born premature and screened for retinopathy of prematurity
Dýrleif Pétursdóttir, Gerd Holmström, Eva Larsson
Abstract
PURPOSE: The aim of the study was to evaluate strabismus, stereoacuity, accommodation and convergence in prematurely born young adults; screened for retinopathy of prematurity in the neonatal period and compare with term-born individuals of the same age. MATERIALS AND METHODS: The study participants included 59 prematurely born individuals with a birthweight of ≤1,500 grams and 44 term-born controls, all born during 1988-1990 in Stockholm County, Sweden. Ocular alignment was assessed with a cover test, stereoacuity with the TNO stereo test and the amplitude of accommodation and the near point of convergence with the Royal Air Force Rule. RESULTS: Seven of 59 (12%) preterms had manifest strabismus, 4/59 (7%) had esotropia and 3/59 (5%) exotropia. One of 44 (2%) controls had esotropia; no other controls had manifest strabismus. Stereoacuity was within normal limits in 38/59 (64%) preterms and 43/44 (98%) controls, p < 0.01; the difference remained after excluding those with strabismus. A neurological complication at 2.5 years of age was the strongest risk factor for subnormal stereoacuity within the preterm group after excluding those with strabismus. The mean amplitude of accommodation was poorer in the preterms than the controls in better (p < 0.05) and worse eyes (p < 0.05). The preterms were more likely to have an amplitude of accommodation below the minimum, according to Hofstetter's equation. There were no differences between the groups regarding the near point of convergence. CONCLUSION: Prematurely born young adults had a higher prevalence of strabismus, reduced stereoacuity and worse amplitude of accommodation than term-born controls.