Pharmacologic or Optical Treatment
Alternatives to occlusion therapy involve pharmacologic and/or optical degradation of the better eye’s vision such that it becomes temporarily inferior to the amblyopic eye’s vision, promoting use of the amblyopic eye. For patients with orthotropia or small-angle strabismus, an advantage of these treatments over occlusion therapy is that they allow a degree of binocularity, which is particularly beneficial in children with latent nystagmus.
Pharmacologic treatment of moderate amblyopia (visual acuity of 20/100 or better) is as effective as patching and may also be successful in more severe amblyopia (visual acuity of 20/125–20/400), particularly in younger children. A cycloplegic agent (usually atropine sulfate solution, 1%) is administered to the better-seeing eye so that it is unable to accommodate. Vision in the better eye is thus blurred at near and, if hyperopia is undercorrected, also for distance viewing. Atropine may be administered daily, but weekend administration is as effective for milder amblyopia. Regular follow-up is important to monitor for reverse amblyopia (see the section Complications and Challenges of Therapy).
Pharmacologic treatment is difficult for the child to thwart. It may not work well for myopic patients, however, because clear near vision persists in the dominant eye despite cycloplegia if the distance correction is not worn. In some children, attempts to accommodate with the dominant eye in the face of cycloplegia can increase accommodative convergence, worsening any underlying esotropia during treatment. Parents and caregivers should be counseled regarding the adverse effects of atropine, including light sensitivity, and potential systemic toxicity, the symptoms of which include fever, tachycardia, delirium, and dry mouth and skin (see Chapter 1).
Optical treatment involves the prescription of excessive plus lenses (fogging) or diffusing filters for the sound eye. This form of treatment avoids potential pharmacologic adverse effects and may be able to induce greater blur than cycloplegic agents. If the child wears glasses, a translucent filter, such as Scotch Magic Tape (3M, St Paul, MN) or a Bangerter foil (Ryser Optik AG, St Gallen, Switzerland), can be applied to the spectacle lens. Optical treatment may be more acceptable than occlusion therapy to many children and their parents, but patients must be closely monitored to ensure proper use (no peeking) of spectacle-borne devices.
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.