Ocular growth in infant aphakia

Abstract

In a prospective study the changes in the ocular axial lengths and in the overall refractions were examined in cases of unilateral and bilateral congenital cataract requiring surgery during the first year of life. Measurements were taken on 18 children with unilateral and on 20 children with bilateral congenital cataract at the time of surgery and up to eight years postoperatively. Surgery was performed via a pars plana/plicata approach, and all infants were fitted with contact lenses. In cases of unilateral cataract, the ocular axial length tended to be superior to the age-matched values already prior to surgery. After four to eight years, one third of the eyes were clearly above normal. In cases of bilateral cataract, the axial lengths were reduced at the age of surgery in the majority of cases, and particularly in eyes that required surgery during the first six months of life. The curvatures of the contact lenses tended to remain unchanged in bilateral cataract, and decreased by about 0.7 mm in unilateral cases. This also reflects the high degree of microphthalmia in bilateral cases. After four to eight years, the degree of microphthalmia had usually increased. The overall refraction decreased significantly in unilateral and bilateral cataract during the first four years of life. The mean values were higher in bilateral than in unilateral cataract at all ages. The mean decrease was 15 diopters in unilateral cataract (SD 5.5 dpt), and 10 diopters in bilateral cataract (SD 6 dpt). When correlating the age-matched differences in the ocular axial lengths at the time of surgery with the overall refractions after four to eight years, a good correlation was found in the unilateral cases (eight eyes), and a poor correlation in the bilateral cases (24 eyes). The data indicate that intraocular implants should not be used in bilateral cataract requiring surgery during the first year of life as long as there is no possibility to change their refraction while in place. In unilateral cases, a relatively accurate prediction appears possible in a small number of eight eyes. However, an additional important correction with glasses would be needed before reaching the final refraction resulting in a high degree of aniseiconia, and eliminating the chances for binocular vision that are small anyway. Furthermore, data from other authors would indicate that the change in refraction may be much more important than expected when using intraocular implants in unilateral congenital cataract requiring surgery during the first year of life. By the use of contact lenses, good to excellent visual functions can be achieved.

Key Words:

• congenital cataract
• unilateral
• bilateral
• infant aphakia
• ocular growth
• microphthalmia
• refractive development