Ocular biometry in pre-term infants without retinopathy of prematurity.

Serial ocular A-scan ultrasound biometry was performed on 100 pre-term infants (less than 32 weeks gestation and/or less than 1500 g) who did not show features of retinopathy of prematurity (ROP) during a screening programme. Axial length increased from 15.38 +/- 0.25 mm at 33 weeks post-menstrual age to 16.88 +/- 0.59 mm at 41 weeks (rate of growth 0.18 mm/week, r = 0.99). The rate of growth appeared to slow down after 40 weeks (term) to 3 months post-term. Male infants had longer eyes and a greater rate of growth than female infants. Axial length (AL) was significantly correlated with birth weight, biparietal and occipito-frontal diameter in the weeks after birth. Between weeks 33 and 41, the anterior chamber depth (ACD) increased from 1.92 +/- 0.13 mm to 2.43 +/- 0.18 mm, and lens thickness (LT) increased from 3.82 +/- 0.33 mm to 3.90 +/- 0.13 mm. The largest percentage growth between weeks 33 and 41 occurred in ACD (22%), followed by vitreal length (10%), AL (9%) and LT (2%). These data will help in future studies on the role which ROP plays in the development of ocular growth.