Medscape Medical News
Patching, Drops Improve Vision Over Long Term in Amblyopia
Veronica Hackethal, MD
May 01, 2014
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Patching or atropine eye drops both improved visual acuity in a long-term follow-up of a randomized controlled trial (RCT) in children with amblyopia, according to new results from the Pediatric Eye Disease Investigator Group (PEDIG).
The long-term results from the PEDIG trial, which both had a high proportion of children followed-up to the end of the study and used standardized measurement throughout, add to the study's previous findings.
The new PEDIG results, published online May 1 in JAMA Ophthalmology, show that visual improvement is durable. The new findings contrast with previous reports from retrospective case series that have suggested regression is common after stopping treatment, first author Michael X. Repka, MD, MBA, professor of ophthalmology and pediatrics at the Johns Hopkins School of Medicine, Baltimore, Maryland, told Medscape Medical News.
The multicenter PEDIG trial included 419 children with amblyopia who were younger than 7 years when enrollment began in 1999. The researchers randomly assigned participants to 6 hours per day of patching or 1 drop per day of 1% atropine sulfate. They conducted masked outcome exams at 6 months and 2 years, after which treatment was at the discretion of investigators. Results at 6 months found a 3 logMAR improvement in visual acuity in both groups. From 6 months to 2 years, visual acuity improved in both treatment groups. About 50% of amblyopic eyes were 20/25 or better at 2 years.
At the 2-year exam, 188 of the children were enrolled in long-term follow-up. The researchers conducted visual testing (acuity, manifest and cycloplegic fractions, ocular alignment, and stereoacuity) again at 10 and 15 years in this group. At age 10 years, about 46% of amblyopic eyes were still 20/25 or better.
At age 15 years, mean visual acuity in 59.9% of amblyopic eyes was 20/25 or better, whereas in 33.3%, mean visual acuity was 20/20 vision or better. Mean interocular acuity difference was about the same at 10 and 15 years of age (2.0 and 2.1 logMAR lines, respectively; P = .39).
Visual acuity at age 15 years was better among those younger than 5 years at the time of enrollment compared with those between the ages of 5 and 6 years at trial entry (about 20/25 and 20/32, respectively; P < .001). At age 15 years, there were no differences in visual acuity between subgroups based on initial treatment with atropine or patching (P = .44 and P = .43, respectively). Stereoacuity testing looking at whether treatment for amblyopia affects binocular vision was similar at 15 years for the treatment groups (P = .44 for all and P = .85 for those with no ocular deviation at 15 years).
The authors write that their study could have been limited by selection bias, as participants had better visual acuity in the amblyopic eye when they were enrolled in the long-term follow-up group compared with nonparticipants. This could have biased the 15-year results toward better visual acuity in the amblyopic eye.
The better outcomes detected in children who initiated therapy at a younger age might be explained, according to the authors, if plasticity decreases over time or if shorter exposure to untreated amblyopia decreases damage to the visual system.
"Amblyopia therapy improves the vision of the eye in most cases, and that improvement appears to be durable," Dr. Repka emphasized, "Many children do have some residual amblyopia, [although] the initial choice of therapy does not appear to impact the final outcome."
This study was by the National Eye Institute. The authors have disclosed no relevant financial relationships.
JAMA Ophthalmol. Published online May 1, 2014.