Refractive outcome of premature infants with or without retinopathy of prematurity at 2 years of age: a prospective controlled cohort study

Abstract

This study evaluated the extent to which refractive morbidity is correlated to preterm birth or retinopathy of prematurity (ROP) itself, or both, and examined the risk factors associated with refractive errors in a cohort of preterm infants with and without ROP compared with full-term infants. This longitudinal, prospective, controlled cohort study enrolled 109 infants, including 74 preterm and 35 full-term infants. Infants were divided into the following groups: no ROP, regressed ROP, laser-treated threshold ROP, and full-term. Cycloplegic refraction was determined at 6 and 24 months' corrected age. Multiple regression models, analysis of variance (ANOVA) with post hoc comparisons, paired t test, and the χ(2) test were used for data analysis. ROP status was highly predictive of significant refractive errors in preterm infants. Eyes with laser-treated threshold ROP had significant myopia at both ages (mean spherical equivalent [MSE] in right eye at both refractions -0.72, -1.21 diopters [D]), astigmatism (MSE -1.62, -1.80 D), and anisometropia (MSE 0.82, 1.02 D; ANOVA p < 0.05), and increased refractive errors across ages (paired t test p < 0.05). Eyes with regressed ROP (MSE + 0.35 D) and eyes without ROP (MSE + 0.78 D) were less hyperopic than the controls (MSE + 1.60 D) before 1 year (post hoc comparisons p < 0.05). After 1 year, however, hyperopic status, astigmatism, and anisometropia were similar to eyes with regressed ROP (MSE + 0.38 D, astigmatism -0.94 D, anisometropia 0.32 D), eyes without ROP (MSE + 0.35 D, astigmatism -0.51 D, anisometropia 0.31 D) and the controls (MSE + 0.72 D, astigmatism -0.59 D, anisometropia 0.50 D) by post hoc comparisons (p > 0.05). Thus, the persistent hyperopic status across ages in patients with regressed ROP and in patients without ROP differed significantly (paired t test p > 0.05) from that in the full-term infants, with a reduction in hypermetropia noted for the first 2 years of life (paired t test p < 0.05). The incidence and magnitude of significant refractive errors increased with severe ROP and with age. Although the emmetropization process of preterm birth, including regressed ROP and no ROP, differed from full-term birth in early infancy, we found no differences in the refractive status after 1 year in patients with regressed ROP and in patients without ROP, who were at risk of developing ametropia similar to that of full-term patients. Therefore, apart from laser-treated ROP, children with regressed ROP and without ROP can likely be observed with a verbal vision screening at 3-4 years of age.