Occlusion therapy (patching) is commonly used to treat unilateral amblyopia. The sound eye is covered, obligating the child to use the amblyopic eye. Adhesive patches are usually employed, but spectacle-mounted occluders or opaque contact lenses are alternatives if skin irritation or inadequate adhesion is a problem. With spectacle-mounted occluders, close supervision is necessary to ensure that the patient does not peek around the occluder.
Full-time occlusion, defined as occlusion during all waking hours, can cause reverse amblyopia and strabismus (see the section Complications and Challenges of Therapy). For severe amblyopia, part-time occlusion of 6 hours per day achieves results similar to those obtained with prescribed full-time occlusion. The relative duration of patch-on and patch-off intervals should reflect the degree of amblyopia. For severe deficits (visual acuity of 20/125–20/400), 6 hours per day is preferred. For moderate deficits (visual acuity of 20/100 or better), 2 hours of daily patching may be effective. It is not necessary for the patient to engage in specific activities (eg, near work) while patched.
Follow-up timing depends on patient age and treatment intensity. Part-time treatment permits less frequent follow-up; reexamination 2–3 months after initiating treatment is typical. Subsequent visits can be at longer intervals, based on early response.
The desired endpoint of therapy for unilateral amblyopia is free alternation of fixation and/or linear recognition acuity that differs by no more than 1 line between the 2 eyes. The time required to complete treatment depends on amblyopia severity, treatment intensity, and patient adherence and age. More severe amblyopia and older children require more intensive or longer treatment. Occlusion during infancy may reverse substantial strabismic amblyopia in less than 1 month. In contrast, an older child who wears a patch only after school and on weekends may require several months to overcome a moderate deficit.
Adherence to occlusion therapy for amblyopia declines with increasing age. However, studies in older children and teenagers with strabismic or anisometropic amblyopia show that treatment can still be beneficial beyond the first decade of life. This is especially true in children who have not previously undergone treatment.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.