Ocular axial length in children with unilateral congenital cataract.

Ocular axial length and thickness were measured in 12 children (age 4 to 418 days, median 103 days) with unilateral congenital cataract who were referred to St. Erik's Eye Hospital during 1991-1994. The measurements were performed in both eyes with A-scan ultrasonography before cataract extraction. In 4 children measurement of the axial length was repeated 1 to 4 months after the unilateral cataract extraction. All eyes with congenital cataract were shorter than the normal fellow eye. The individual axial length differences showed a mean value +/- SEM of 1.03 +/- 0.16 mm. This difference was statistically significant (P < 0.01). In the 4 children where measurement of the axial length was repeated, the difference between the eyes after unilateral cataract extraction had become greater than before. In addition, the thickness of the cataractous lens was 0.63 +/- 0.17 mm (mean +/- SEM) less than the non-operated clear lens. This difference was statistically significant (p < 0.01). In conclusion, in children with unilateral congenital cataract the affected eye has a shorter axial length and a thinner lens.