Abstract
Purpose To study the development of refractive status from 36 weeks to one year of postmenstrual age and to identify factors that contribute to development of myopia, including gender, birth weight, gestational age, and retinopathy of prematurity (ROP). Methods Premature infants underwent full cycloplegic retinoscopy at 36 weeks, 38 weeks, 40 weeks, 42 weeks, 44 weeks, 46 weeks, 48 weeks, 3 months, 6 months, 9 months, and 12 months of postmenstrual age. The infants were grouped by gender, birth weight, gestational age, and the severity of ROP to evaluate the correlation with refractive status at each postmenstrual age. Results A total of 942 infants were recruited in this study. A total of 2716 readings were obtained. Refractive state had a hyperopic shift until 46 weeks of postmenstrual age (r = 0.42, P < 0.0001). After that, the mean spherical equivalent (SE) gradually declined (r = −0.30, P < 0.0001). Boys had lower hyperopia than girls at nine months (t = 3.10, P=0.003) and one year (t = 3.34, P=0.001) of postmenstrual age. Premature infants with ROP had a lower average SE at most of the postmenstrual ages; however, this value did not vary significantly (P > 0.05). Premature infants with severe ROP were less hyperopic than those without it at every postmenstrual age, and the average SE differed significantly at one year of postmenstrual age (t = 2.60, P=0.011). There was no significant difference between each birth weight and gestational age (P > 0.05). Conclusions The dioptric value of premature infants within one year was generally hyperopic. Different gender, birth weight, gestational age, and ROP did not affect the overall development of refractive status. Females may have higher hyperopia at nine months of postmenstrual age. Birth weight and gestational age had little effect on change of refractive status. Severe ROP was an important contributing factor in myopia progression, which may be related to the treatment required. Further study may be carried out to understand the mechanism behind myopia progression in premature infants, including changes in refractive system parameters and emmetropization process.
Highlights
With the improvement of neonatal care technology, the number of premature infants is increasing
Infants were grouped according to gestational age (GA ≤ 30 weeks; GA > 30 weeks) and birth weight (BW ≤ 1500 g; BW > 1500 g) to evaluate the correlation between refractive status and the two variables, respectively
The mean refractive index was +1.12 D at 36 weeks of postmenstrual age followed by a hyperopic shift until the refractive index reached +3.62 D at 46 weeks of postmenstrual age. en, the mean spherical equivalent (SE) gradually declined and reached +0.64 D at one year of postmenstrual age
Summary
With the improvement of neonatal care technology, the number of premature infants is increasing. A number of studies have reported presence of refractive errors to be more common in prematurely born children [1,2,3,4]. It has been suggested that gender, birth weight, gestational age, and retinopathy of prematurity (ROP) may be associated with myopia [5,6,7]. These studies mainly focused on the first year of life. Ere is a lack of large-sample studies on the early postnatal period. It remains controversial whether either ROP disease or ROP treatment or both of them are myopia-related factors These studies mainly focused on the first year of life. ere is a lack of large-sample studies on the early postnatal period.
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