Levodopa for amblyopia explored as novel modality

Take home:

A study of children with residual amblyopia did not find an advantage with the use of levodopa compared with a placebo group.

By Vanessa Caceres; Reviewed by Michael X. Repka, MD, MBA

Baltimore-In children ages 7 to 12 with residual amblyopia use of the medication, levodopa, did not lead to a meaningful improvement in visual acuity compared with placebo, said Michael X. Repka, MD, MBA.

There are a few medical therapies currently tried for amblyopia-including atropine, oral levodopa, and oral and intramuscular citicholine-although results with levodopa and citicholine have been mixed, said Dr. Repka, the David L. Guyton, M.D., and Feduniak Family Professor of Ophthalmology, and professor of pediatric medicine, Johns Hopkins University School of Medicine, Wilmer Eye Institute, Baltimore.

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All three agents are not currently approved by the FDA for the treatment of amblyopia, he added.

There are six trials that have analyzed the use of levodopa for amblyopia against placebo, but they have had varied results, Dr. Repka said.

One 2012 meta-analysis found that the drug compared with placebo was favorable by about 1 line.¹ However, the results are hard to follow from the various trials because of various treatment durations and treatment times that differed with respect to amblyopia.

About the PEDIG Study

The Pediatric Eye Disease Investigator Group (PEDIG) that Dr. Repka participated in had the primary objective of comparing oral levodopa plus patching with oral placebo plus patching for residual amblyopia for older children. The 139 children who participated over more than 3 years came from 27 different centers; all were between the ages of 7 and 12. Patients had strabismus and/or amblyopia; they had patching for at least 2 hours daily for at least 3 months prior to enrollment.

“That period of patching could be longer, and in many cases, it was much longer,” Dr. Repka said.

To participate in the study, patients could not have had any improvement over 6 weeks. The eligible range of visual acuity ranged from 20/50 to 20/400 for the eye that was examined, but the fellow eye had to be 20/25 or better.

Patients were randomly assigned at a 2:1 ratio (90 in the levodopa group and 49 in the placebo group) to receive levodopa 0.76 mg/kg with carbidopa 0.17 mg/kg three times a day. The carbidopa was given to reduce nausea associated with levodopa. Patients were treated for 16 weeks or longer, with a rapid initiation and taper of the drug.

Both study groups had similar characteristics, although there was more strabismus in the group receiving levodopa. Nearly all patients remained in the study for the entire duration, Dr. Repka said.

The mean change in visual acuity from baseline was 5.2 letters in the levodopa group and 3.8 letters in the placebo group, Dr. Repka said.

“That difference of 1.4 letters, after adjusting for disparities in visual acuity at entry, was not significant,” he said.

Fifteen percent in the levodopa group improved 10 letters or more, compared with 4% in the patching group. Although more children improved in the levodopa group, that was not statistically significant, he added.

Looking at the 18-week outcome, a similar lack of treatment effect was found as in the primary analysis.

Investigators analyzed adverse effects of treatment by examining systemic symptoms, visual acuity in the fellow eye, ocular alignment, and stereoacuity; they found no changes in the latter two items. Systemic effects, such as headaches, were reported at least once during treatment in 20% of the levodopa patients and 8% of the placebo group.

“Interestingly, nausea was reported in 7% of the levodopa group and 12% of the placebo group, so without the placebo, we would have wrongly concluded nausea was associated with the drug,” he said. “It was more associated with placebo.”

Although levodopa was not associated with a meaningful improvement over placebo, patients still seemed to experience a subtle but slow improvement over time, Dr. Repka said.

“We did not evaluate levodopa as an initial therapy,” he said. “It could be effective in that setting.”

Reference

1. Yang X, Luo D, Liao M, Chen B, Liu L. Efficacy and tolerance of levodopa to treat amblyopia: a systematic review and meta-analysis. Eur J Ophthalmol. 2012;May 29:0.

Michael X. Repka, MD, MBA

E: mrepka@jhmi.edu

This article was adapted from Dr. Repka’s presentation at the 2014 meeting of the American Academy of Ophthalmology. Dr. Repka did not indicate any proprietary interest in the subject matter.