Approach

Screening and early detection are key to preventing and successfully treating amblyopia. See Screening.

Offer treatment to all children with amblyopia, regardless of age (especially if not treated previously) and despite declining success rates with increasing age. Preferred treatment will depend on the child's age, amblyopia subtype, and severity.[1]​​[49]

The goals of treatment are to:[1]​​[49]

  • Correct any cause of visual deprivation

  • Correct refractive errors likely to cause blur

  • Promote use of the amblyopic eye to improve visual acuity

​Start by ensuring treatment and ongoing management of the underlying cause. Treating the refractive error alone can improve visual acuity in anisometropic, strabismic, or combined amblyopia, whether unilateral or bilateral. Patching and atropine penalization of the better-seeing eye is usually sufficient to promote use of the amblyopic eye.[1]​ Additional options include overplussed lenses (induced hyperopia), surgical correction of visual axis occlusion causing deprivation amblyopia (e.g., cataract, ptosis), or refractive surgery.[1]​ Once maximal visual acuity is obtained, taper and stop ongoing treatment.

Mild to moderate strabismic and/or mild to moderate anisometropic amblyopia (visual acuity better than 20/100)

All types of amblyopia require optical correction of refractive errors, if present.[1] If amblyopia does not resolve with spectacles alone, patching or atropine penalization are usually added after a period of refractive adaptation, during which improvements in visual acuity are allowed to plateau.[51][52][53][54][55]

The recommended period to achieve maximum refractive adaptation in the amblyopic eye is 18-22 weeks, but most improvement is seen by 4-12 weeks.[51][54]​​​​ Children with combined-mechanism amblyopia may require a more extended period of optical correction. Additional treatments then include plano lens placement in the atropinized eye and other types of optical penalization (e.g., induced hyperopia).

Optical correction of refractive errors

For mild to moderate strabismic and/or anisometropic amblyopia, first-line treatment is with optical correction alone.[51][52]​​​​ Guidelines for prescribing spectacles to treat amblyopia in young children depend on patient age and other risk factors.

  • Factors associated with successful optical correction: include better baseline visual acuity of the amblyopic eye, interocular difference in visual acuity, stereoacuity, and amblyopic eye spherical-equivalence refractive error.[56]

  • Extended optical correction before patching: may be associated with lower treatment success. The EuPatch multicenter, randomized controlled trial found that early patching (wearing spectacles for only 3 weeks before patching) was more effective than extended optical treatment (18 weeks of optical correction before patching) for children with anisometropic, strabismic, or combined-mechanism amblyopia.[57]​ Early patching was more beneficial for severe amblyopia, older children, and larger differences in refractive errors between eyes; extended optical treatment was more beneficial in younger children and mild amblyopia.[57]

  • Compliance: children and parents or caregivers should be made aware of the importance of good adherence to spectacles wearing, which is often suboptimal and highly variable.[58]

Patching

Patches are used to occlude the eye with better vision. Patching should be applied directly to the periorbital skin for full occlusive therapy, as opposed to being applied to the spectacle lens, as the latter allows children to look around the patch.[1]​ Over-spectacle patching may be a useful alternative for children experiencing skin irritation with adhesive patching.[59]​ A dose-response relationship probably exists between patching duration and amblyopia treatment response.[60][61][62][63]

  • Daily treatment duration: improvement of visual acuity of the amblyopic eye (from baseline to 4 months) did not differ between children (with moderate amblyopia) randomized to 2 hours or to 6 hours of daily patching.[64]​ In another randomized study, 2 hours of daily patching was significantly superior to optical treatment alone in children with mild to severe strabismic and/or anisometropic amblyopia.[65]

  • Dose intensity and overall treatment duration: one multicenter, randomized controlled trial reported that early intense patching (10 hours/day for 6 days/week) was more effective than extended optical treatment for shortening the treatment period, reducing the number of patching hours over time, and improving compliance.[57]​ A faster treatment response may be seen in strabismic and/or severe amblyopia, in younger children, and during the first month of occlusive therapy.[63]

  • Compliance: patients are often noncompliant with patching due to adverse effects such as irritation, forced use of an eye with degraded vision, poor cosmesis, and lengthy treatment periods. Interventional materials may improve compliance in poorly adherent children and in children of non-native parents who speak the host country language poorly.[66][67]​ Poor visual acuity at baseline has been associated with poor compliance.[60]

[Figure caption and citation for the preceding image starts]: Treatment of amblyopia with spectacles and patchingFrom the collection of Tina Rutar, MD [Citation ends].com.bmj.content.model.Caption@2a2e9669

​Atropine

Atropine eye drops to blur the vision in the better eye (atropine or optical penalization therapy) are sometimes used as an alternative to patching. Patching and atropine penalization are equally effective in this group, and visual benefits of treatment are maintained in the long term.[68][69]​​​​ Atropine has been associated with better adherence and quality of life compared with patching, but with increased risk for adverse events.[70]

Children ages 3 to <7 years old with moderate amblyopia who were randomized to weekend atropine demonstrated an equivalent treatment response (improvement in visual acuity of the amblyopic eye from baseline to 4 months of 2.3 lines) to that of children receiving daily atropine.[71]

Plano lens in the atropinized eye

A plano lens blurs the sound atropinized eye more than a typical refractive correction. There may be a small additional benefit of a plano lens in patients undergoing weekend atropine penalization.[72]

Other types of optical penalization

The eye can be penalized by using a lens higher than the patient's refractive error. The induced hyperopia blurs vision primarily at distance. Due to the limited evidence for this treatment, it is not generally recommended.[73]​ In practice, it is may be considered for a patient who refuses patching or is intolerant of atropine but accepts wearing spectacles or contact lenses that incorporate optical penalization.

Severe strabismic and/or severe anisometropic amblyopia (visual acuity of 20/100 or worse)

Children with severe strabismic and/or anisometropic amblyopia require optical correction of refractive errors and additional treatment with patching or optical penalization.[51][52]​ Patching is the standard addition, although evidence suggests atropine is also effective.[74]

Adding patching to spectacles once visual acuity has stabilized with spectacles alone is beneficial in this group.[65] Patching for 6 hours daily has been found to be equally effective to patching full time.[75] Compliance with patching needs to be taken into consideration. Patching for 2 hours daily improves visual acuity in severe amblyopia, although the magnitude of improvement may be less than with more robust patching regimens.[76] The EuPatch study found that early patching with an intensive starting dose of 10 hours per day (for 6 days a week) was beneficial in most children with severe amblyopia.[57]​ With improved visual acuity, the prescribed number of patching hours decreased significantly over the course of the trial.

Some clinicians may intensify treatment by adding topical atropine to the daily patching regiment, but the literature suggests minimal to no added benefit with this approach.[77][78]​​​​

Bilateral ametropic amblyopia

Often resolves with optical correction alone. One prospective study evaluated the response to spectacle treatment for bilateral ametropic amblyopia in children ages 3-9 years.[79]​ Mean binocular visual acuity improved from 20/63 at baseline to 20/25 at 1 year.

Form-deprivation amblyopia

Early surgery is recommended when the cause of amblyopia is obstruction of the visual axis, such as corneal opacity, cataract, nonclearing vitreous hemorrhage, or severe ptosis. Surgical intervention is less urgent when the form deprivation occurs bilaterally as opposed to unilaterally. Deprivation amblyopia may coexist with other forms of amblyopia, including anisometropic and strabismic. These should be addressed in conjunction with treatment to clear the visual axis.

To maximize visual outcomes, surgery for bilateral congenital cataracts should be performed before 14 weeks of age and earlier if possible, and surgery for unilateral congenital cataracts should be performed before 6 weeks of age.[80][81] For patients with unilateral or asymmetric amblyopia, such as children with unilateral congenital cataract, patching is a necessary adjunctive treatment.

Residual strabismic or anisometropic amblyopia

After treatment of moderate amblyopia resulting from strabismus or anisometropia with refractive correction and 2 hours of patching per day, some patients may have residual amblyopia. Increasing patching from 2-6 hours per day in children with stable residual amblyopia has been reported to be more effective than continuing patching at 2 hours daily (amblyopic eye visual acuity improvement of 1.2 lines in the 6-hour group and 0.5 line in the 2-hour group, respectively).[82]

Refractory amblyopia (noncompliant patient)

Refractory amblyopia in a noncompliant patient can be treated by closing the eyelid over the better-seeing eye temporarily, using surgical or medical techniques. These include the use of sutures, injection of botulinum toxin to the levator muscle, and application of cyanoacrylate glue to the eyelid margin.[83][84]​ Parents or caregivers might be hesitant to consent to these treatments given the need for anesthesia, as well as the cosmetic and psychological effects on the child.

Less invasive ways to improve compliance include the use of interventional materials, such as cartoons or information booklets. Randomized controlled trials have shown the benefit of using interventional materials to improve treatment compliance in poorly adherent children, and in children of non-native parents who speak their host country language poorly.[66][67]

Older patients (>7 years)

Treatment for amblyopia is regarded as being less effective in children age ≥7 years.[85][86]​​ There is, however, evidence to suggest that older children (ages 7-12 years) respond partially to amblyopia treatment with spectacles, atropine, and patching, and that the resultant visual benefits may be maintained for between at least 6 and 12 months.[87][88][89]

​Following randomization to treatment with full-time patching or with daily atropine therapy, similar improvements in visual acuity (2.3 to 2.4 lines) have been reported at 6 months in patients ages 8-20 years with anisometropic amblyopia (visual acuity of 20/40 to 20/200).[90]

The treatments do not differ for older children (at least to age 15 years), although the exact regimens may vary.​[1]​ 

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