Visual acuity promising after unilateral IOL implantation

The study also suggested that IOLs may support better acuity development when compliance with contact lens wear is moderate or poor or when a cataract is extracted after 1 year of age, according to Eileen E. Birch, PhD, senior research scientist, Retina Foundation of the Southwest, and adjunct professor of ophthalmology, University of Texas Southwestern Medical Center, Dallas. She presented the results at the annual meeting of the American Academy of Pediatric Ophthalmology and Strabismus. The study was sponsored by the National Eye Institute.

"Given our small samples, we can't say precisely that the treatments are equivalent, but the children had no significant difference in their mean acuity at 4 years of age," Dr. Birch said. The statistical power of this study would enable investigators to detect the equivalent of a two- to three-line difference on an eye chart, she added.

A growing trend

The study that she and her colleagues performed provides additional information on a growing trend in pediatric cataract treatment.

"A number of studies have been conducted over the years looking at the outcome of children with cataract who have been treated with aphakic contact lenses, but more recently there have been a number of pediatric ophthalmologists who are switching to using IOLs rather than contact lenses," Dr. Birch said. "The rationale for that is that even if a child goes through a noncompliant period, there will at least be a partial optical correction in place at all times to promote visual development.

"Because it's becoming more and more common, we wanted to look at whether the long-term visual acuity development was better in one treatment group than the other," she added.

Investigators prospectively assessed visual acuity using Teller Acuity Cards in 83 children referred by pediatric ophthalmologists in the Dallas area to the Pediatric Eye Research Laboratory at the Retina Foundation of the Southwest. Target ages for testing were 6 months and 1, 2, 3, and 4 years.

Outcomes for the children with dense congenital cataracts showed good results for both treatment groups. Infants who received a primary IOL after extraction of a dense unilateral congenital cataract by 6 months of age (n = 5) showed rapid improvement, Dr. Birch said. Mean visual acuity improved from 20/170 at 6 months to 20/50 at 4 years.

This 4-year acuity level was similar to that of children who had good or excellent compliance with aphakic contact lens wear (n = 33; 20/50) and better than that of children who had moderate or poor compliance (n = 8; 20/165).

Children who received IOLs following extraction of developmental unilateral cataracts in the first year of life (n = 3) had 4-year acuity outcomes similar to children treated with aphakic contact lenses (n = 5). Mean acuity at the age of 4 years was 20/40 for both groups.

A third group of children were those who had developmental unilateral cataracts extracted after 1 year of age.

"Vision improved slightly with the IOL when compared with the aphakic contact lens," Dr. Birch said. The 21 children who received IOLs had a mean acuity of 20/40 at age 4 years versus 20/110 in the eight children who received contact lenses.