Camera-Like Device Helps Detect Signs of Lazy Eye
Sept. 15, 2000 — Doctors on the cutting edge of new technology are testing a system that allows them to detect early warning signs of a lazy eye, which if left untreated can lead to a lifetime of poor vision.
The best time to correct a lazy eye, scientifically termed amblyopia, is as early in childhood as possible — correctable symptoms may become apparent by six months of age. An estimated two or three of every 100 people have the condition, but accurately testing the vision of very small children is notoriously difficult because they can’t respond to questioning.
New devices known as photoscreeners may change all that by allowing doctors to get the information they need by taking pictures of the child’s eyes. The pictures can be taken relatively quickly and the film evaluated later. In fact, one team of researchers in Tennessee has been studying the feasibility of having trained non-medical volunteers take the pictures in places like day-care centers and send them on to doctors for evaluation. The photos detect early signs of lazy eyes so doctors can refer kids whose pictures hint at problems for a more detailed eye exam.
So far in this study, about 33,000 kids ages six months to four years old have had their eyes photographed by Lions Club volunteers working in partnership with doctors at Vanderbilt University Medical Center in Nashville.
“These are problems most children would not notice because they don’t have anything to compare it to, so they’re not going to complain of double vision. They’re not going to complain of any eye problem really because they don’t know what’s normal,” says study author Sean P. Donohue, MD, who reported in the September issue of Ophthalmology on the first 15,000 children evaluated with the handheld screeners.
But despite their promise, photoscreeners are not without problems. If not taken properly, the photos can be impossible to read correctly, meaning the child has to be retested. Also, Donohue’s study found that a significant percentage of children never see an eye doctor for problems picked up on the photographs.
But Donohue tells WebMD that by hiring a full-time staff person to communicate and coordinate with the volunteers, parents, and doctors, the rate of kids who are followed up and get help for their vision problem has improved dramatically.
Another study of photoscreeners, conducted by Patrick Y. Tong, MD, PhD, of Johns Hopkins University, in Baltimore, and published in the same journal, shows that the devices may not be as accurate as some researchers think they should be. The article also points out that photoscreening results can vary according to who is taking the photos and interpreting them.
The handheld screener used by the Donohue team is not the only one available, but Kurt Simons, PhD, points out that lack of standardization does not permit the various devices to be compared in any true scientific way.
Still, Simons, of the Krieger Children’s Eye Center at the Wilmer Institute at Johns Hopkins Hospital, says although some people have jumped on the photoscreening bandwagon a little too early, if the devices are validated by future studies they could be used in a variety of situations by pediatricians, such as at the time of immunizations or well-baby visits, to pick up correctable vision problems before they worsen and become a permanent disability.
Both Simons and Donohue say that, if all the kinks are worked out, photoscreening could become more widely available and may even be done with computerized equipment that doctors could use right in their offices to get immediate results.
Donohue says educating parents about the seriousness of amblyopia is important to ensure that kids get vision tests as early as possible.
“If it’s not picked up and not treated early, there’s a possibility you may never be able to treat it,” he says. “There’s no set age that you have to treat it by, but clearly the sooner you treat it, the better.” Ideally, he says, treatment for the weak eye should begin by age six.
Amblyopia sometimes runs in families. It may be caused by a misalignment of the eyes, poor focusing ability of one eye, or disease in the eye that causes vision to be cloudy or blurred. Treatment for amblyopia may include patching or covering the strong eye to force the child to use the weaker eye. Even after vision has been restored in the weak eye, occasional patching may be required to maintain the improvement. Glasses may be prescribed in some cases to correct errors in how the eye focuses.