Atropine treatment of moderate amblyopia assessed

Baltimore-Prescribed weekend atropine sulfate 1% appears to be as effective as prescribed daily use for treating moderate amblyopia in young children, according to results from a study conducted by the Pediatric Eye Disease Investigator Group.

Speaking on behalf of his fellow investigators, Michael X. Repka, MD, reported the outcomes from the multicenter, single-masked, randomized trial comparing the two atropine regimens in 186 patients ages 3 to <7 years old. The study was recently published in Ophthalmology (2004; 111:2076-2085).

About 95% of all children were seen at the end of 4 months, and the visual acuity (VA) analyses showed the two groups were identical with respect to mean improvement from baseline VA in the amblyopic eye (2.3 lines), mean VA (20/32^-1), and the proportion achieving VA of 20/32 or a 3-line improvement (~2/3). The evaluation of outcomes after 5 weeks of treatment showed the rate of VA improvement was also similar in the two groups.

Treatment group comparisons also found no differences in mean VA in the sound eye after 4 months, and only a few patients (3%) had a 2-line reduction from baseline in VA of the sound eye. Treatment compliance was also similar in both study groups and both regimens were well-tolerated, although four patients using atropine daily had treatment stopped or reduced because of possible side effects. No patient following a weekend regimen experienced adverse effects that warranted a change in atropine use.

"These results indicate that a reduced-frequency regimen of atropine is another alternative treatment for moderate amblyopia management in children ages 3 to <7 years old. The efficacy outcomes in our two study groups could not have been more similar, and surprisingly as well, the VA improvement achieved in this trial was also comparable to what we previously reported for the same level of moderate amblyopia treated with 2 hours or 6 hours of prescribed patching," said Dr. Repka.

Other analyses from the study reinforced the importance of individualizing treatment duration. According to the protocol, patients with a partial response were defined as patients whose amblyopic eye had improved 2 lines from baseline but was still worse than 20/25 in the sound eye, so they were allowed to continue atropine. Among the patients with a partial response in the daily and weekend groups, 34% and 39%, respectively, continued with treatment for a mean of 10 weeks (range, 8 to 26 weeks). In each group, there was an average VA improvement of 0.8 lines. Overall, while 80% of children achieved maximal improvement by 4 months, another 20% took substantially longer.

"Keep in mind that treatment is not over for many patients at 4 months," Dr. Repka said.

Various subgroup analyses were performed to see if there were any factors that might predict which patients do better with a given treatment. The variables investigated included age, cause of amblyopia, baseline VA in the amblyopic eye, iris color, and the amount of blur at near sight. No differences in treatment effect were identified.

Light sensitivity was the most common adverse effect, reported by 16% of patients in the daily group and 29% of the weekend users, but in no case was treatment modified because of that reaction.

The study was conducted at 30 sites, which were about equally divided between community and university treatment settings. VA had to be between 20/40 and 20/80 in the amblyopic eye and 20/40 or better in the sound eye with an inter-eye acuity difference of 3 logMAR lines, thus confirming the diagnosis of amblyopia. In addition, children had to have worn correction for at least 4 weeks prior to enrolling.

The 168 patients were predominantly male (61%) and Caucasian (79%) with a mean age of 5.3 years. One-third had strabismic amblyopia, 41% had anisometropic amblyopia, and the rest had a combined cause.

Patients were not allowed to have received amblyopia treatment within the past month and could have had no more than 1 month of treatment during the prior 6 months, but only 18% had received any intervention for their amblyopia.

The FDA has not approved atropine for the treatment of amblyopia.