July 29, 2010

Study shows standard treatment best for congenital cataracts

Study shows standard treatment best for congenital cataracts

David Morrison, M.D.

David Morrison, M.D.

Vanderbilt Eye Institute

For more than 30 years, removable contact lenses have been the treatment used in managing pediatric cataracts. With the introduction of a recent technology to surgically implant a lens in the eye of an infant, ophthalmologists were armed with another tool in the treatment of congenital cataracts.

In both cases, there was no question that the first step to treating a cataract, the clouding of the lens of the eye, is to surgically remove it in a procedure called lensectomy and anterior vitrectomy.

But practitioners were puzzled over which approach was best in the management of monocular infant cataracts. It led to the formation of the Infant Aphakia Treatment Study (IATS) group to compare the outcomes and adverse effects of removable contact lenses versus surgical lens replacement (intraocular lens correction or IOL).

“Congenital cataracts are visually devastating,” said David Morrison, M.D., assistant professor of Ophthalmology and Visual Sciences and principal investigator for Vanderbilt’s arm of the study. “The neural pathways rapidly degenerate because of the failure to receive visual information through the eye. If we don’t remove the cataract by the age of 3 months, the child is permanently blind. It is imperative to clear the visual axis.

“What we want to know is how best to help the child after the removal of the cataract,” said Morrison. “We needed to know which group had better outcomes both visually and from aspects of complications and safety.”

The findings of the study, published in the July issue of the Archives of Ophthalmology, showed that the vision in both groups of patients was the same. But at one year, ophthalmologists found that patients who received the intraocular lens were at a greater risk of having adverse events, requiring additional surgery.

The randomized, multi-center clinical trial enrolled 114 patients. Vanderbilt treated 10 patients, with equal numbers randomized to both treatment modalities.

“What this study tells us is that there is no shorter visual benefit to implanting lenses and that we should use caution in recommending IOL placement in infants,” said Morrison. “We don’t know long term how these children will do, but in the short term there was no visual benefit, but there was a higher complication rate.”

The rate of complications during lensectomy surgery was 16 of 57 in the intraocular lens group, while six in 57 in the contact lens group experienced a surgical complication. Although visual acuity results did not differ between the groups at one year of age, more adverse events occurred among the IOL population – 44 patients versus 14 in the contact lens group. Many of these adverse events required additional surgery.

“Intraocular lens patients were five times more likely to undergo additional intraocular operations,” said Morrison. “At this point our data indicates that the preferable treatment for infants a unilateral congenital cataract would be to correct their vision using contact lenses after surgery.”

It is this far-reaching recommendation that places Vanderbilt among the top eye centers in the country, said Sean Donahue, M.D., Ph.D., professor and chief, Pediatric Ophthalmology.

“Having Vanderbilt involved is a testament to our abilities and those of Dr. Morrison,” he said. “We are nationally recognized as leaders in the field of pediatric cataracts and we were one of the leading recruiting sites.”

Congenital cataracts, although deemed rare, are seen in one in 10,000 births. Morrison said not all cases require surgical intervention.