[A study of refractive state in premature infants without retinopathy of prematurity during their early life].

OBJECTIVE

To understand the development of the refractive status in premature infants during their early life.

METHODS

It was a cross-sectional study. Two hundred fifty-three premature infants without retinopathy of prematurity (ROP) were screened for ROP at 4-6 weeks after born. Refraction with cycloplegic retinoscopy was determined. The refractions of 38 infants were compared with those of mature infants at 40-44 weeks' correct gestational age (CGA).

RESULTS

The spherical equivalent (SE) increased progressively (become more hypermetropic) along with increasing gestational age (GA), birth weight (BW) and CGA at test. BW was the main factor for SE. The incidence of myopia and astigmatism was 14.43% (73 eyes) and 10.28% (52 eyes). The former decreased and the latter did not change along with increasing CGA. The median of astigmatism was 1.00DC, while Percentile 25 (P25) and Percentile 75 (P75) were 0.50DC and 1.13DC, respectively. The degree of astigmatism increased along with increasing CGA and did not change along with GA or BW. The median of axis of astigmatism (AX) was 90 degrees, while P25 and P75 were 90 degrees and 100 degrees, respectively. The AX was not correlated with CGA, GA or BW. Five observations, including SE, incidence of myopia and astigmatism, the degree and axis of astigmatism between premature and mature infants at 40 to 44 weeks' CGA, were compared. It shows that there was no statistical difference between the two groups in all items mentioned above but SE, which indicating that there was more myopic in premature infants.

CONCLUSIONS

The refraction of premature infants shifts towards hypermetropia along with development, but is still more myopic than mature infants at 40 to 44 weeks' CGA. Further studies on the underlying mechanisms of myopia and the subsequent refractive development are needed.