Comparison of optic disk features in preterm and term infants.

Abstract

PURPOSE:To compare the optic disk features of preterm and term infants. METHODS:Digital fundus images of preterm infants were compared with those of infants born at term, imaged within 1 week of birth. The optic disk horizontal diameter to vertical diameter ratio, the disk-macula to disk-diameter ratio, and the presence or absence of double ring sign was noted. RESULTS:Images of 649 infants (324 preterm and 325 term) were analyzed. Of the preterm infants, 129 (40%) had a double ring sign, compared to 4% in term infants. The double ring was seen more frequently in infants of European descent and was more common with younger gestational age. The mean horizontal to vertical disk diameter in preterm infants on first examination was 0.75 ± 0.063, increasing to 0.80 ± 0.069 at final examination. Term infants had a horizontal to vertical disk diameter ratio of 0.79 ± 0.064. At final examination, the ratio of disk-to-macula distance to the horizontal disk diameter was 3.9 in preterm infants and 3.7 for term infants. CONCLUSIONS:In our study population preterm infants often had a double ring sign around the optic disk in the absence of optic nerve hypoplasia. Preterm disks tend to be more vertically oval, which becomes less oval closer to term. The mean disk-to-macula to disk-diameter ratio among normal preterm infants was higher than previously reported.