Many factors influence amblyopia treatment efficacy

Chicago-While treatment for amblyopia is effective, there is no consensus as to what treatment works best. However a number of factors have an impact on treatment efficacy, according to Bruce A. Furr, CO, who spoke at the American Academy of Ophthalmology annual meeting.

"Treatment of amblyopia includes occlusion patches, optical penalization, occlusive contact lenses, and drug therapy, most commonly atropine eye drops," he said. "There is no consensus on the efficacy of which treatment method works best for amblyopia or what defines success. In published research, when treatment methods differ and success criteria differ, it is difficult to determine if therapy for amblyopia is efficacious."

When outcomes were considered based on patient compliance, one study divided patients into three age groups and the final visual acuity level for any age group was lower for those noncompliant with instructions, he said.

"Even those patients more than 8 years of age and compliant with treatment had 4.6 lines of visual improvement compared with 1.4 lines of improvement for those who were noncompliant," he reported. Visual acuity levels were found to be better for all three types of amblyopia in those patients who attended all clinic visits.

Age is not a factor

An analysis of age at presentation shows that this age does not seem to affect the final visual acuity outcome, according to Furr, who is from the Ida Lucy Iacobucci Orthoptic Clinic, University of Michigan Kellogg Eye Center, Ann Arbor. This finding seemed to be confirmed by another study of patients with amblyopia who ranged in age from 7 to 10 years, and regardless of the type of amblyopia being treated, older patients did as well as those who were younger.

"These findings suggested that the higher the refractive error, the more aggressive the treatment should be," Furr said. "In contrast, another study found that the best vision attained was not related to the amount of anisometropia."

Another consideration is the level of the initial vision and its effect on the final vision. Four studies showed a strong correlation between the initial visual acuity and outcome vision.

Other authors looked at combining visual activities with treatment to determine if a greater treatment effect occurred. Several studies, according to Furr, combined near activities in conjunction with atropine treatment and patching therapy.

"However, no recent study has documented the usefulness of this practice by comparing amblyopia therapy with and without near vision treatments," he said.

Finally, abrupt discontinuation of treatment produces greater regression than weaning patients from occlusion therapy.

"Patients experienced a disproportionately high degree of recidivism when occlusion therapy was discontinued suddenly, according to one study," he said. The loss of vision after cessation of therapy can occur in as many as 25% of patients by as much as 1 or more lines of visual acuity.