Refractive status and ocular axial length in preterm infants without retinopathy of prematurity with regard to birth weight and gestational age

Purpose: To obtain ultrasonographic measurements of ocular axial length (AL) in preterm infants without retinopathy of prematurity (ROP) but with different refractive power in regard to birth weight (BW) and gestational age (GA). Methods: Refraction was measured after cycloplegia (at 6 months of life) in 350 eyes of 180 preterm (non-astigmatic) infants without ROP. Subjects were grouped according to the refractive error: A [above -6.0 dioptres (D)]; B (-3.1 to -6.0 D); C (0 to -3.0 D); D (0.1 to +3.0 D); E (+3.1 to +6.0 D); F (above +6.0 D). The AL measurement was performed by ocular A-scan ultrasound biometry (10 MHz probe). Results: The longest AL was found in group B (20.62 mm) compared to group D and E (19.35, 19.28 mm; P <= 0.01) and group F and A (19.63, 19.39 mm; P <= 0.05). Only regressive correction for BW was statistically significant. Correlations between AL and BW (Rs = 0.23) or GA (Rs = 0.17) were found only in group E. Conclusions: AL of myopic eyes was significantly longer. In general, hyperopia was positively correlated with BW, whereas correlation between myopia and BW or GA was not found.