Cochrane Review: Conventional occlusion versus pharmacologic penalization for amblyopia
Authors: Li Tianjing , Shotton Kate 
Published: December 2010

Background

Amblyopia is defined as defective visual acuity in one or both eyes without demonstrable abnormality of the visual pathway, and is not immediately resolved by wearing glasses.

Objectives

To assess the effectiveness and safety of conventional occlusion versus atropine penalization for amblyopia.

Search strategy

We searched CENTRAL, MEDLINE, EMBASE, LILACS, the WHO International Clinical Trials Registry Platform, preference lists, science citation index and ongoing trials up to June 2009.

Selection criteria

We included randomized/quasi‐randomized controlled trials comparing conventional occlusion to atropine penalization for amblyopia.

Data collection and analysis

Two authors independently screened abstracts and full text articles, abstracted data, and assessed the risk of bias.

Main results

Three trials with a total of 525 amblyopic eyes were included. One trial was assessed as having a low risk of bias among these three trials, and one was assessed as having a high risk of bias.

Evidence from three trials suggests atropine penalization is as effective as conventional occlusion. One trial found similar improvement in vision at six and 24 months. At six months, visual acuity in the amblyopic eye improved from baseline 3.16 lines in the occlusion and 2.84 lines in the atropine group (mean difference 0.034 logMAR; 95% confidence interval (CI) 0.005 to 0.064 logMAR). At 24 months, additional improvement was seen in both groups; but there continued to be no meaningful difference (mean difference 0.01 logMAR; 95% CI −0.02 to 0.04 logMAR). The second trial reported atropine to be more effective than occlusion. At six months, visual acuity improved 1.8 lines in the patching group and 3.4 lines in the atropine penalization group, and was in favor of atropine (mean difference ‐0.16 logMAR; 95% CI ‐0.23 to ‐0.09 logMAR). Different occlusion modalities were used in these two trials. The third trial had inherent methodological flaws and limited inference could be drawn.

No difference in ocular alignment, stereo acuity and sound eye visual acuity between occlusion and atropine penalization was found. Although both treatments were well tolerated, compliance was better in atropine. Atropine penalization costs less than conventional occlusion. The results indicate that atropine penalization is as effective as conventional occlusion.

Authors' conclusions

Both conventional occlusion and atropine penalization produce visual acuity improvement in the amblyopic eye. Atropine penalization appears to be as effective as conventional occlusion, although the magnitude of improvement differed among the three trials. Atropine penalization can be used as first line treatment for amblyopia.

Plain Language Summary

Treatment of amblyopia (lazy eye) with patching or drops/drug treatment

Amblyopia (referred to as lazy eye) is a common childhood condition, and is defined as defective visual acuity in one or both eyes, which is present with no demonstrable abnormality of the visual pathway and is not immediately resolved by wearing glasses. Treatment for amblyopia usually starts with prescribing necessary glasses to correct visually important refractive errors followed by promoting the use of the amblyopic eye. This systematic review aimed to synthesize the best available evidence regarding the effectiveness and safety of two different treatment options used to promote the use of the amblyopic eye: conventional occlusion (patching) and atropine penalization (drops). Conventional occlusion involves patching the non‐amblyopic eye with an opaque patch for a set number of hours per day. Atropine penalization involves the instillation of atropine sulphate to blur the eyesight of the better‐seeing eye.

We included three randomized or quasi‐randomized controlled trials with a total of 525 amblyopic eyes. Evidence from three trials (one of good methodological quality) suggests both conventional occlusion and atropine penalization produce visual acuity improvement in the short‐term (six months) and long‐term (24 months) in the amblyopic eye after initiation of therapy. The results of this review show atropine penalization to be as effective as conventional occlusion, although the amount of improvement achieved differed among the three trials. Although both treatments were well tolerated, compliance was better with atropine penalization. Atropine penalization can be used as first line treatment for amblyopia.