Is Prematurity a Risk Factor for Refractive Errors in Children? Results from School Vision Screening Program

Author(s): Kajal Seema Sukumaran1 , Jayalekshmi Thankamma2 , Prasenna Meleaveetil3 , Kavitha Syamala4

BACKGROUND The prevalence of refractive errors is reported to be higher in children born preterm. Factors like gestational age, birth weight and retinopathy of prematurity status have a significant impact on the refractive development in preterm infants. Population based long term follow up studies on the refractive status in preterm infants are limited. We designed this study to assess whether prematurity is a risk factor for refractive errors in children. METHODS This study was conducted among children aged 5 - 16 years who participated in the school vision screening program over a period of one year. All children underwent detailed ocular examination including measurement of best corrected visual acuity, cycloplegic refraction and fundoscopy. Visual acuity was assessed using an internally illuminated Snellen’s chart at 6 meters. Objective refraction by streak retinoscopy after instilling 1 % cyclopentolate eye drops was done in all children with visual acuity ≤ 6 / 9. Children were divided into two groups based on their gestational age at birth - preterm group and full-term group. Preterm birth was defined as childbirth before 37 completed weeks of gestation. Children were enrolled in the study only if the hospital birth document showing gestational age and birth weight was available. Children with co-existing organic disease affecting the eye contributing to the diminished visual acuity such as congenital cataract, glaucoma, and corneal opacities were excluded from the study. Those who had undergone any ocular surgery were also excluded. RESULTS One thousand two hundred and ninety-five children were enrolled in the study of which 700 (54.1 %) were boys and 595 (45.9 %) were girls. Median age of the enrolled children was 12 years. The number of pre-term births was 287 (22.2 %). Of the 1295 students screened, 273 (21 %) had refractive errors. Among the children with refractive errors, astigmatism was the most common refractive error (10.6 %), followed by myopia (8.5 %) and hypermetropia (1.9 %). Refractive errors were statistically more prevalent in preterm group (34.1 %), when compared with term born children (17.3 %), p = < 0.001. Compared to the term born children, preterm group had significantly higher prevalence of myopia; 16.4 % vs 6.3 % (p = < 0.001) and astigmatism; 15.3 % vs 9.3% (p = 0.003). There was no statistically significant difference in the prevalence of hypermetropia among the two groups; 2.4 vs. 1.8 (p = 0.477). CONCLUSIONS There is strong association between prematurity and refractive errors. These findings prompt long term monitoring of the refractive and visual outcome in preterm infants for diagnosing refractive errors at the earliest. This helps to prevent the consequent amblyopia and the ensuing permanent visual function deficits.