Changes in Ocular Growth after Pediatric Cataract Surgery.

The human eye undergoes extensive changes during early childhood, including axial elongation, corneal flattening and reduced lens power. Animal studies have shown that removing the crystalline lens during infancy retards axial elongation. Axial elongation has been studied in children after cataract extraction both directly and indirectly. Children with a unilateral congenital cataract generally have a shorter axial length in their cataractous eye than in their fellow eye. This difference usually persists after cataract surgery. While some studies have reported a modest reduction in axial elongation after cataract extraction, the magnitude of this effect is much less than what has been reported in animal models. Choosing an intraocular lens (IOL) power for implantation into a child's eye is complicated by continued ocular growth, the inaccuracy of IOL power calculation formulas for small eyes, and the difficulty of accurately measuring the biometrics of a child's eye. In addition, given the fixed position of an IOL in the eye, increasing elongation of the posterior segment of the eye relative to the anterior segment magnifies the myopic shift that occurs with ocular growth. The targeted refractive error in young children undergoing IOL implantation should be an undercorrection in anticipation of a future myopic shift.