PURPOSE: The purpose of this study was to describe and evaluate the frequent parameter changes required in aphakic infants fit with rigid gas permeable (RGP) contact lenses. METHODS: Twenty-five eyes from 18 patients with congenital cataracts were fit postoperatively with RGP lenses and followed for an average of 19 months. The original lens specifications were determined by keratometer readings, corneal diameter, and axial length or retinoscopy obtained under sedation just prior to or after cataract extraction surgery. The frequency of changes in contact lens power, base curve, and diameter was recorded and analyzed. RESULTS: Due to rapid growth and/or difficulty in achieving accurate measurements, repeated contact lens adjustments were needed to ensure proper power and fit. CONCLUSIONS: The data contained in this study indicates a relatively stable period--from 6 to 12 months postoperatively--where the likelihood that contact lenses will need to be modified falls below 50%.