November 2007




Kiddy cataracts: exploring outcomes

by Maxine Lipner Senior EyeWorld Contributing Editor



Congenital nuclear cataract

Above infant, before surgery (Insert is opposite, normal eye)

One year after surgey, infant with IOL

Source: JL Derner, Jules Stein Eye Institute

New data helps to bring to light who will do well with pediatric cataract extraction.

For adults of a certain age cataracts are to be expected, but unfortunately this is also a problem for some children as well. Pediatric cataracts are one of the leading causes of preventable blindness, according to Danielle M. Ledoux, M.D., assistant in ophthalmology, Children’s Hospital Boston, and instructor, ophthalmology, Harvard Medical School. New study results indicate that implantation of IOLs in such pediatric patients is safe and effective.

“The process of taking the cataract out is more challenging in kids then it is in adults,” Dr. Ledoux said. “In the selection of an IOL lens implant there are a lot more factors to think about in a growing child’s eye.” Dr. Ledoux finds that children are also a lot more likely to get secondary opacifications. “That means that you have to remove their posterior capsule and do a vitrectomy in most children,” she said. “But long term, the biggest challenge is amblyopia with these kids.”

“In deciding on which intraocular lens implant to insert, we strive to under correct the refractive status of the eye at the time of surgery in order to allow them to essentially grow into the lens,” Dr. Ledoux said. “Depending upon the age in which they have it taken out, a lot of kids will still need to be in glasses.” With time the glasses will grow progressively weaker, with a goal in most children toward having minimal refractive error when they are adults.

Reviewing pediatric cases

Since children’s eyes are so different from adults, investigators wanted to capitalize on the extensive data base kept by well-known pediatric surgeon M. Edward Wilson, M.D., professor and chairman of ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston. “We wanted to make use of the data base to take a look at visual outcomes since that hadn’t been published in his set of patients,” she said.

The retrospective study included a review of charts of 510 consecutive pediatric cataract patients. Among those excluded were traumatic cataract patients, those with retinopathy of prematurity, those who’d undergone secondary IOL implantation, those who were younger than four, and those with severe developmental delays. “We looked at the ages and set ourselves the lowest age limit that would allow for some form of objective postoperative visual acuity testing,” Dr. Ledoux said. “We preferred HOTV or Snellen line reading, but we would include Allen pictures also if that was all the child was able to do.”

Study results

Of the charts reviewed 139 eyes met inclusion criteria. The mean age that patients here underwent surgery was 5.12 years. Investigators found that in these patients visual outcomes were good. They determined that for all eyes the median visual acuity was 20/30. “Children with bilateral cataracts tended to do a little better than those with unilateral cataracts,” Dr. Ledoux said. “Also the older kids did better than the younger kids — likely because they had visual maturity before developing visually significant cataracts.” The median visual acuity of unilateral cataracts was 20/40 compared with mean outcomes 20/25 for bilateral cases.

“We also saw that the axial length difference between the two eyes at the time of surgery could be a relative predictor of visual acuity outcome,” she said. “Those with greater variations in intraocular axial length difference had poorer visual acuity outcomes in the long run.” Dr. Ledoux theorizes that when the eyes are longer, this could be a reflection of deprivational amblyopia, where the eye has elongated to try to make a clear image that had been impaired by the cataract. “It’s just one factor that can be considered at the time when you’re doing cataract surgery in hoping to give the parents a prognosis as to what to expect down the road for visual acuity outcome.”

There were 45 cases in which visual acuity of less than 20/40 was attained. Investigators attributed the cause of the poor vision to amblyopia alone in 76% of the cases.

Dodging amblyopia is one of the primary driving forces of pediatric cataract surgery. The goal with pediatric patients is to maintain a clear visual axis. “This means that when the time is right, you’ll remove the cataract and either put in an IOL implant or correct aphakia with a contact lens and then make sure that the visual axis stays clear,” Dr. Ledoux said. In the end, it comes back to amblyopia. “No matter whether it’s contact lenses or IOLs the biggest battle that the parents and the child have to go through is amblyopia management,” Dr. Ledoux said.

“In most cases the IOL correction of aphakia is safe and effective,” She said. “We would like to see there to be an expansion of the FDA [Food and Drug Administration] label to include children—we think that there has been sufficient studies to date to show their effectiveness and safety.”

Editor’s note: Dr. Ledoux has no financial interests related to her comments.

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