Amblyopia Treatment & Management
- Author: Kimberly G Yen, MD; Chief Editor: Hampton Roy, Sr, MD more...
The clinician must first rule out an organic cause and treat any obstacle to vision (eg, cataract, occlusion of the eye from other etiologies).
Remove cataracts in the first 2 months of life, and aphakic correction must occur quickly.
Treatment of anisometropia and refractive errors must occur next.[10, 11, 12, 13] The amblyopic eye must have the most accurate optical correction possible. This should occur prior to any occlusion therapy because vision may improve with spectacles alone. This improvement is frequently seen in patients with unilateral refractive amblyopia.
Full cycloplegic refraction should be given to patients with accommodative esotropia and amblyopia. In other patients, a prescription less than the full plus measurement that was refracted may be prescribed given that the decrease in plus is symmetric between the two eyes. Because accommodative amplitude is believed to be decreased in amblyopic eyes, one needs to be cautious about cutting back too much on the amount of plus. Refractive correction alone has been shown to improve amblyopia in up to one-fourth of patients in a nationwide trial.
Patients with bilateral refractive amblyopia do well with spectacle correction alone, with most children aged 3-10 years achieving 20/25 or better within a year.[16, 17]
The next step is forcing the use of the amblyopic eye by occlusion therapy. Occlusion therapy has been the mainstay of treatment since the 18th century. The following are general guidelines for occlusion therapy:
Patching may be full-time or part-time. Standard teaching has been that children need to be observed at intervals of 1 week per year of age, if undergoing full-time occlusion to avoid occlusion amblyopia in the sound eye. The Amblyopia Treatment Studies (ATS) have helped to provide new information on the effect of various amounts of patching. [18, 19, 20]
Always consider lack of compliance in a child where visual acuity is not improving. Compliance is difficult to measure but is an important factor in determining the success of this therapy.
In addition to adhesive patches, opaque contact lenses, occluders mounted on spectacles, and adhesive tape on glasses have been used.
Establishing the fact that the vision of the better eye has been degraded sufficiently with the chosen therapy is important.
The Amblyopia Treatment Studies have helped to define the role of full-time patching versus part-time patching in patients with amblyopia. The studies have demonstrated that, in patients aged 3-7 years with severe amblyopia (visual acuity between 20/100 and 20/400), full-time patching produced a similar effect to that of 6 hours of patching per day. In a separate study, 2 hours of daily patching produced an improvement in visual acuity similar to that of 6 hours of daily patching when treating moderate amblyopia (visual acuity better than 20/100) in children aged 3-7 years. In this study, patching was prescribed in combination with 1 hour of near visual activities.
Data from the Amblyopia Treatment Studies are also available for older patients, although patients younger than 7 years are the most responsive to treatment. For patients aged 7-12 years, the Amblyopia Treatment Studies have suggested that prescribing 2-6 hours a day of patching can improve visual acuity even if the amblyopia has been previously treated. Among patients aged 13-17 years, prescribing 2-6 hours a day of patching improved vision in 47% of patients whose amblyopia had not been previously treated and improved vision in 25% of patients whose amblyopia had been previously treated with patching. 
The Amblyopia Treatment Studies have also found that about one fourth of children with amblyopia who were successfully treated experience a recurrence within the first year after discontinuation of treatment. Data from these studies suggest that patients treated with 6 or more hours a day of patching have a greater risk of recurrence when patching is stopped abruptly rather than when it is reduced to 2 hours a day prior to cessation of patching.
There is some evidence that having children wear an eye patch for 6 hours daily rather than 2 hours can yield greater improvement in visual acuity at 10 weeks. The significantly greater improvement in visual acuity noted with the more intense patching protocol suggests that this strategy is worth considering in children with residual amblyopia. The results have the following implications:
If there is stable residual amblyopia after 12 weeks of 2-hour patching, an increase to 6-hour patching can bring about further improvement
If the goal is to achieve the best result in the shortest amount of time, it may be worthwhile to bypass 2-hour patching and start with 6-hour patching instead
In the past, penalization therapy was reserved for children who would not wear a patch or in whom compliance was an issue. The Amblyopia Treatment Studies, however, have demonstrated that atropine penalization in patients with moderate amblyopia (defined by the study as visual acuity better than 20/100) is as effective as patching. The Amblyopia Treatment Studies were performed in children aged 3-7 years.[23, 24, 25, 26]
The Amblyopia Treatment Studies have also demonstrated that weekend use of atropine provided an improvement in visual acuity similar to that of daily use of atropine when treating moderate amblyopia in children aged 3-7 years.
Atropine drops or ointment is instilled in the nonamblyopic eye. This therapy is sometimes used in conjunction with patching or occlusion of the glasses (eg, adhesive tape, nail polish) by individual practitioners. In the Amblyopia Treatment Studies that evaluated patching versus atropine penalization, atropine penalization and patching were used in conjunction with 1 hour of near visual activities.
This technique may also be used for maintenance therapy, which is useful, especially in patients with mild amblyopia.
Other options include optical blurring through contact lenses or elevated bifocal segments.
In a prospective cohort study of 105 children who had previously participated in a randomized trial comparing atropine and patching for moderate amblyopia, researchers observed, after controlling for baseline refractive error, a decrease in amblyopic eye spherical equivalent refractive error to less hyperopia. This shift toward emmetropia was associated with ocular alignment, supporting the idea that better motor and sensory fusion promote emmetropization.
The desired endpoint of therapy is spontaneous alternation of fixation or equal visual acuity in both eyes. When visual acuity is stable, patching may be decreased slowly, depending on the child's tendency for the amblyopia to recur. There is no established standard for tapering the patching treatment. Because amblyopia recurs in a large number of patients (see Prognosis), maintenance therapy or tapering of therapy should be strongly considered. This tapering is controversial, so individual physicians vary in their approaches.
Even though there have been many advances in amblyopia treatment, tailoring the treatment with individual treatment plans is still difficult because the dose/effect response from the amount of occlusion is not fully understood.
Treatment of strabismus generally occurs last. The endpoint of strabismic amblyopia is freely alternating fixation or equal vision. Surgery generally is performed when the endpoint has been reached.
Surgical therapy for strabismus generally should occur after amblyopia is reversed. Disadvantages to surgical therapy prior to correction of amblyopia include difficulty in telling if amblyopia is present because there is no longer a strabismus to assess fixation preference in nonverbal patients and higher potential to being lost to follow-up, as the child cosmetically looks better. The improved cosmesis gives the parents a false sense of security about the vision improving.
Close supervision during occlusion therapy is necessary to make sure children do not peek. Various methods of preventing children from removing patches have been considered, from a reward system for older children to arm splints and mittens for infants.
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