Amblyopia in children: Management and outcome

INTRODUCTION — Amblyopia is a functional reduction in visual acuity caused by abnormal visual development early in life. It is the most common cause of pediatric visual impairment, occurring in an estimated 1 to 4 percent of children. Early detection and treatment of amblyopia facilitates earlier treatment, which improves visual outcomes. This is the basis for screening preschool-age children for vision problems and amblyopia (table 1A-B). (See "Vision screening and assessment in infants and children", section on 'Vision screening'.)

The management and outcome of amblyopia in children is reviewed here. The definition, classification, and diagnosis of amblyopia are reviewed separately. (See "Amblyopia in children: Classification, screening, and evaluation".)

The management of strabismus and refractive errors in children are also discussed separately. (See "Evaluation and management of strabismus in children" and "Refractive errors in children".)

TERMINOLOGY — Amblyopia is classified by the underlying cause of the visual disturbance [1]:

●Strabismic amblyopia — Caused by abnormal alignment of the eyes (see "Amblyopia in children: Classification, screening, and evaluation", section on 'Strabismic amblyopia' and "Evaluation and management of strabismus in children")

●Refractive amblyopia — Caused by unequal focus between eyes (see "Amblyopia in children: Classification, screening, and evaluation", section on 'Refractive amblyopia' and "Refractive errors in children")

●Deprivation amblyopia — Caused by structural abnormalities of the eye that obscure incoming images (eg, cataract) (see "Amblyopia in children: Classification, screening, and evaluation", section on 'Deprivation amblyopia' and "Cataract in children")

MANAGEMENT — Stepwise treatment of amblyopia includes:

●Eliminating any visual obstructions (eg, cataracts, ptosis), if necessary (see "Cataract in children", section on 'Management')

●Correcting refractive errors (see "Refractive errors in children", section on 'Optical correction')

●Encouraging use of the amblyopic eye (eg, patching, pharmacologic penalization) (see 'Patching' below and 'Pharmacologic penalization (atropine)' below)

●Monitoring for recurrence and treating it if it occurs (see 'Recurrence' below)

Children with amblyopia should be managed by an eye specialist who is appropriately trained and experienced in treating children [2]. The goal of treatment is to achieve maximal potential visual acuity.

Timing — Treatment should be initiated as early as possible since clinical trials have demonstrated improved long-term outcomes when treatment is started at young age (ie, <5 years) [3]. Amblyopia is most responsive to treatment when initiated before age 7 years, and the upper age limit for optimal therapy is considered to be in the range of 9 to 10 years [4-9]. Although it is optimal to begin therapy in early childhood, we agree with the American Academy of Ophthalmology's recommendation to attempt treatment in all children with previously untreated amblyopia, regardless of age [2]. Approximately half of older children (7 to 17 years) with previously untreated amblyopia respond to treatment [10]. (See 'Children seven years and older' below.)

Vision correction — The cause of visual deprivation (eg, cataracts, ptosis) must be eliminated in children with deprivation amblyopia before the use of the amblyopic eye can be encouraged. Similarly, significant refractive error must be corrected with glasses and/or contact lenses in children with amblyopia due to a refractive error. Patching the better-seeing eye in the treatment of amblyopia is of little benefit if the amblyopic eye remains unable to focus clearly because of uncorrected refractive error. (See "Refractive errors in children".)

In children with mild to moderate refractive amblyopia (ie, visual acuity 20/40 to 20/80), refractive correction alone may be sufficient treatment in up to a third of patients [11-14]. Such patients may be treated initially with glasses alone and are followed up in three to four months. The patient can continue to be observed if the vision continues to improve with glasses alone. If amblyopia persists, patching or pharmacologic penalization is started. (See 'Patching' below and 'Pharmacologic penalization (atropine)' below.)

Use of amblyopic eye — In children with strabismic amblyopia and those with severe (ie, visual acuity of 20/100 or worse) refractive amblyopia, correction of refractive errors alone is generally not sufficient treatment. The child must be encouraged to use the amblyopic eye. This is accomplished by discouraging use of the better-seeing eye with a patch (occlusion) or cycloplegic eye drops (penalization) [15-18]. A 2014 systematic review that included three randomized trials concluded that the combination of refractive correction plus occlusion/penalization was more effective than refractive correction alone for the treatment of strabismic amblyopia [19].

Patching — Occlusion therapy involves patching the eye with better vision. Close-range visual activities (eg, arts and crafts activities, board games, reading, writing) during patching are commonly used to encourage use of the amblyopic eye; however, the benefit of near activities is unproven [19,20].

The prescribed duration of patching varies from two hours to all waking hours per day, depending upon the age of the child (younger children generally require less occlusion than do older children), the cause and severity of the amblyopia (severe amblyopia usually requires more intensive patching than does mild to moderate amblyopia), and the preferences of the treating specialist and parents. For most patients with mild to moderate amblyopia, treatment can be initiated with two hours of daily patching [2]. If no improvement is achieved at the first or second follow-up visit, the patching dose is increased to four to six hours per day or more [21,22]. (See 'Residual amblyopia' below.)

In a randomized controlled trial comparing two hours of daily patching with glasses alone (if needed) in 180 children with strabismic and anisometropic amblyopia, visual acuity (measured with the Snellen chart) improved to a greater degree after five weeks of patching (average improvement of 1.1 lines) compared with glasses alone (average improvement of 0.5 lines) [23].

In a retrospective study of 246 children with strabismic (68 percent) and anisometropic (32 percent) amblyopia treated with occlusion therapy, successful outcomes (linear acuity 6/12 or better) were achieved in 85 percent of the children with strabismic amblyopia and 100 percent of those with anisometropia [24]. Factors correlated with unsuccessful outcome included poor visual acuity at the start of treatment, more than one diopter of anisometropia, hypermetropia of more than three diopters, and poor or only fair compliance with the treatment plan [24]. Neither age at presentation nor age at start of treatment correlated with outcome in this study. However, other studies have shown better results with early referral [7,25].

Clinical trials evaluating different durations of patching (eg, 6 versus 24 hours, 2 versus 6 hours) in children with severe and moderate amblyopia have found similar improvements regardless of the prescribed duration of patching [14,23,26-28]. One reason for this may be that patches are worn for fewer hours than they are prescribed. In a study in which adherence with prescribed patching was objectively monitored, the patch was actually worn 4.2 and 6.2 hours per day in children for whom it was prescribed for 6 and 12 hours, respectively [29].

The major disadvantage to occlusion therapy is compliance. Many children resist wearing the patch. They may remove it or peel it back enough to allow peeking. Both of these measures may render treatment less effective or completely ineffective. Adherence to the treatment plan is more likely in younger children and is a critical factor in outcome [24,30,31]. In addition, clear communication, including written instructions for parents and pictures for children, improves compliance with patching [32-34]. (See "Amblyopia in children: Classification, screening, and evaluation", section on 'Information for patients'.)

Strategies to encourage compliance include allowing the child to play a favorite video game or watch television only when the patch is worn. Digital applications for smartphones, tablets, and other devices have been developed that can provide binocular training as a compliment or alternative to patching. Data are limited on the efficacy of these devices [35-38]. In addition, the games available on these platforms may not hold the child's attention for a sufficient amount of time. Other strategies to improve compliance have been explored (eg, supervised inpatient occlusion treatment and suturing or gluing the occluder in place), but these are generally impractical [39-41].

Children undergoing patching therapy are at risk for developing occlusion amblyopia in the fellow eye, and it is therefore important to monitor visual acuity in both eyes at each visit [42]. Based upon the results of the Amblyopia Treatment Studies demonstrating that fewer hours of prescribed patching were as effective as the prescription of full-time patching [26-28], many ophthalmologists prescribe fewer hours per day of patching, and as a result, occlusion amblyopia is much less frequent than it was previously. Fear of occlusion amblyopia may cause some parents to limit patching or avoid it altogether; however, it is important to recognize that it occurs rarely and is almost always reversible. Occlusion amblyopia is not necessarily a reason to curtail or discontinue treatment unless the drop in visual acuity worsens on subsequent visits.

Pharmacologic penalization (atropine) — Visual blurring, through the use of a cycloplegic agent in the sound eye, temporarily handicaps the sound eye, thus encouraging use of the amblyopic eye. Pharmacologic penalization is not effective for patients with myopia.

Atropine is the cycloplegic agent used most commonly, but other agents (eg, homatropine, scopolamine) are used by some ophthalmologists. In our practice, when pharmacologic penalization is prescribed, we typically use atropine (1% ophthalmic solution, one drop to the sound eye once a day on weekends or daily) for children ≥2 years and cyclopentolate (1% ophthalmic solution, one drop to the sound eye once a day on weekends or daily) for children <2 years. However, we generally prefer patching over pharmacologic penalization in children <2 years because the risk of systemic side effects with cycloplegic agents (as described below) is likely higher in this age group. (See 'Choice of treatment' below.)

Atropine causes pupillary dilation, temporary paralysis of the ciliary body, and loss of the ability to accommodate. The loss of ability to accommodate reduces the ability of the sound eye to focus, thereby providing the amblyopic eye with a competitive advantage and encouraging its use.

Side effects of atropine include light sensitivity, conjunctival irritation, eye pain, fever, flushing, headache, dry mouth, rapid heart rate, and allergic reaction. Other cycloplegic agents, all of which are anticholinergic agents, have similar side effects. In a large clinical trial, side effects were reported in 26 percent of patients treated with atropine drops [43]. The most common adverse effects were light sensitivity (18 percent) and conjunctival irritation (4 percent). Clinical trials of atropine drops have generally not included children <3 years, and systemic side effects may be more likely in this age group.

Atropine penalization appears to be as effective as patching [3,43-46]. In a large multicenter randomized trial comparing atropine with patching (for a minimum of six hours per day) in 419 young children with moderate amblyopia, visual acuity in the amblyopic eye (measured with the Snellen chart) improved after six months of treatment by three lines in similar proportions of both groups (79 percent of the patching group and 74 percent of the atropine group) [43]. In follow-up studies, no differences were observed in visual acuity of amblyopic and fellow eyes at 10 and 15 years of age [3,47]. Visual acuity in the amblyopic eye was maintained at 20/25 or better in 60 percent of patients at age 15 years [3].

Different schedules of atropine are used. In children with mild to moderate amblyopia (visual acuity 20/80 or better), weekend atropine is equally effective compared with daily use [48].

Blurring of the sound eye can also be accomplished with optical penalization, although this is usually less effective than atropine due to the ability of the child to simply remove the spectacles or contact lens. It is almost always used in conjunction with pharmacologic penalization. (See 'Ineffective and unproven therapies' below.)

Choice of treatment — In choosing the initial treatment for a child with amblyopia, the clinician should consider the following factors:

●Likelihood of compliance with prescribed therapy – Adherence to prescribed treatment is better with atropine compared with patching. In the clinical trial described previously, patient adherence to the prescribed treatment was rated as "excellent" in 78 percent in the atropine group compared with 49 percent in the patching group [43]. Adherence with patching is more likely in younger children.

●Potential side effects – Side effects (including light sensitivity, conjunctival irritation, eye pain, fever, flushing, headache, dry mouth, rapid heart rate, and allergic reactions) occur in one-quarter of children treated with atropine drops [43]. The most common side effect is light sensitivity. Reverse amblyopia (ie, reduced visual acuity in the previously nonamblyopic eye) can occur with either patching or atropine, but it occurs more frequently with atropine. Skin irritation is common with patching, but it is generally mild.

●Age of the patient – In children <2 years old, we prefer patching over atropine because the risk of systemic side effects with atropine is likely higher in this age group. When pharmacologic penalization is used in children <2 years, we typically use cyclopentolate (1% ophthalmic solution, one drop to the sound eye daily) rather than atropine.

●Presence/type of refractive error – Atropine is not effective for patients with myopia.

●Severity of amblyopia – Patching is generally preferred over atropine for patients with severe amblyopia.

●Preferences of the parent/patient – Patching is generally preferred by parents of young children (<2 years). For older children, studies have found that atropine drops had better acceptance by parents and children, particularly with regards to perceptions of social stigma and ability to comply with the treatment [49,50].

●Potential interference of pharmacologic blurring agents on driving and performance of other activities – This is particularly important in older children and adolescents. (See 'Children seven years and older' below.)

For most patients, patching and atropine are equally effective in treating amblyopia. Patching is often prescribed as the initial treatment, and it is generally preferred by parents of young children. Atropine, despite its occasional side effects, is also a reasonable first choice, particularly in patients expected to have poor compliance with patching.

After one or two follow-up intervals, it may be necessary to change treatment modality, particularly if any of the following occur:

●Adherence with the prescribed treatment is poor.

●Clinically significant side effects develop (eg, severe skin irritation with patching or severe photosensitivity with atropine).

●Visual acuity has not improved. Increasing treatment intensity (eg, patching for six rather than two hours; daily rather than weekend atropine) is another option for patients that have a poor response to initial therapy. (See 'Residual amblyopia' below.)

Children seven years and older — Visual outcomes for children with amblyopia are generally better when treatment is initiated in early childhood. However, there is emerging evidence that patching and atropine can be effective treatments in older children and adolescents, particularly if they have not previously been treated [2,10]. This evidence has challenged the previously held notion that the "sensitive period" (ie, the age at which successful treatment of amblyopia can be achieved) has an upper age limit of approximately seven years [4,5,8,9].

A multicenter randomized trial evaluated the effectiveness of treatment of amblyopia in 507 amblyopic children aged 7 to 17 years randomly assigned to receive optical correction alone or optical correction and additional treatment (consisting of two to six hours of daily patching for all children in the treatment group, plus atropine drops for children aged 7 to 12 years) [10]. Approximately one-quarter of the patients responded (ie, ≥2 lines improvement in visual acuity in the amblyopic eye) with visual correction alone. Among children aged 7 to 12 years, the response rate was greater in the treatment than the control group (53 versus 25 percent). The response rate was similar in both groups among children aged 13 to 17 years; however, among the treated children in this age group, the response rate was greater in those who had never been treated for amblyopia than in those who had (47 versus 20 percent). Most patients, including those who responded to treatment, had residual deficits in visual acuity. For this reason, many older children will reasonably decline treatment, unless the parents and child are unusually motivated and/or the amblyopia has not been previously treated. In addition, the rate of recurrence after treatment in late childhood is unknown.

Although these data provide encouraging evidence that it is possible to effectively treat amblyopia in late childhood, they should not de-emphasize the need to identify and treat children with amblyopia as early as possible. The difficulties inherent in treating older children (eg, lack of adherence to the treatment plan, potential interference of pharmacologic blurring agents on driving and performance of other activities) highlight the importance of early identification and treatment [51].

Duration of therapy — Treatment is continued until visual acuity is normal or near normal or until maximal improvement has been achieved, which is usually established when there is no further improvement observed between two or three follow-up intervals. In a study evaluating the time course of amblyopia improvement, the median duration of patching required to reach maximal improvement was 20.2 weeks [22]. A duration of six months or more of treatment is usually needed. More than two years of treatment is required in 30 to 40 percent of cases [6].

Once visual acuity has been maximally improved, maintenance therapy may be advised for another 4 to 12 months to prevent recurrence. In children treated with more intensive patching regimens, patching is typically tapered (eg, reduced to two hours a day) during this maintenance therapy period. Some experts recommend maintenance therapy be continued until the child is seven to eight years old, the age at which the visual system is essentially mature and recurrent amblyopia is unlikely to recur [52].

Residual amblyopia — Patients who have residual amblyopia after initial treatment with patching or atropine may benefit from increasing treatment intensity (eg, patching for six rather than two hours; daily atropine use rather than weekend only) or changing to a different treatment modality.

Two randomized trials have evaluated treatment of residual amblyopia:

●After patching – For patients with residual amblyopia after treatment with patching, there is some evidence that increasing the prescribed patching time may provide further improvement in visual acuity.

In a multicenter trial, 169 children (3 to <8 years) with residual amblyopia after ≥12 weeks of patching for two hours per day were randomly assigned to two versus six hours of daily patching [21]. After 10 weeks, six hours of daily patching resulted in greater improvements in visual acuity (1.2 versus 0.5 lines), and more children assigned to six hours of patching had improvement in visual acuity ≥2 lines (40 versus 18 percent).

In cases of particularly refractory amblyopia, atropine is sometimes added to full-time patching to reduce the vision in the good eye when the child removes the patch. This makes the vision disparity between the amblyopic and normal eye less apparent to the child and sometimes permits better compliance with patching.

●After atropine – For patients with residual amblyopia after treatment with atropine, there may be a small benefit to augmenting atropine therapy with optical penalization (also called a plano lens).

In a randomized trial, 73 children (3 to <8 years) with residual amblyopia after ≥12 weeks of atropine treatment were randomly assigned to continuing weekend atropine alone or with optical penalization (ie, wearing a plano lens over the fellow eye in addition to continuing atropine) [53]. After 10 weeks, amblyopic eye visual acuity had improved an average of 1.1 lines with the plano lens and 0.6 lines with atropine only (difference between the two groups, adjusted for baseline visual acuity, was 0.5 lines; 95% CI -0.1 to +1.2). While the results from this study are promising, the relatively small number of children treated and the lack of a statistically significant difference between the two groups precludes drawing firm conclusions as to the benefit of this therapy. A larger study is needed to more precisely estimate the treatment effect.

Recurrence — Approximately one-quarter of patients treated for amblyopia experience recurrence within the first year after stopping therapy [6,28,54,55]. When amblyopia recurs after stopping therapy, restarting the previously prescribed treatment will usually restore visual acuity to its previous level [2,54].

In patients treated with moderately intense patching (six to eight hours per day), the risk of recurrence is reduced if patching is tapered to two hours a day prior to stopping therapy rather than stopping abruptly [55,56]. In addition, for patients prescribed glasses and/or contact lenses to correct refractive errors, it is imperative that they continue to wear glasses or contact lenses after stopping treatment with atropine or patching.

Refractive surgery — There is a small subset of children with amblyopia or amblyogenic levels of refractive error who can be treated with refractive surgery procedures (photorefractive keratectomy, laser in situ keratomileusis, refractive lens exchange, phakic intraocular lenses) with reasonable and sometimes excellent visual outcomes [57-60].

●Severe anisometropia with amblyopia – In children with extremely high refractive error in one eye only, correction with glasses causes a condition called aniseikonia (difference in image size) such that the eyes cannot function visually together. Secondarily, the children can experience asthenopia (eye fatigue, headache) from this correction and most refuse to wear the glasses. Contact lenses are another option, but they are difficult to insert in uncooperative children, loss is frequent, and they are costly. The consequence of this intolerance/noncompliance is severe amblyopia [57].

●Isoametropic amblyopia – The children with bilateral severe ametropia who refuse to wear glasses typically have neurobehavioral problems, such as autism, genetic disorders, or cerebral palsy, or craniofacial abnormalities such as microtia, that make wearing glasses impractical. These children live in a world of blur, and everything visual is only perceived when it is a few inches from their face. Thus, visual stimuli can be frightening, and the children typically are combative and difficult to manage. One author has coined the term "visual autism" for this condition [58].

Protection for the sound eye — Patients with residual unilateral vision impairment (ie, best corrected visual acuity of 20/50 or worse) after treatment for amblyopia should wear protective eyewear in order to prevent traumatic vision loss in the sound eye, even if they do not require optical correction [2]. Loss of vision in the nonamblyopic eye can result in permanent bilateral visual impairment or blindness [61,62]. In a population-based study of 370 individuals with unilateral amblyopia, the projected lifetime risk of bilateral vision loss was 1.2 to 3.3 percent [63]. In 16 percent of patients, vision loss in the nonamblyopic eye was a result of orbital or ocular trauma.

Ineffective and unproven therapies — A number of other therapies have been studied in children with amblyopia; however, based on the available evidence, they are not routinely recommended. These include:

●Optical penalization – Optical penalization involves altering the spectacles to produce blur in the better-seeing eye (also called a plano lens). A major disadvantage to isolated optical penalization is that children can easily avoid the undesired blur by removing or looking over their glasses. Optical penalization can be used alone or, more typically, in combination with pharmacologic penalization. A randomized clinical trial comparing isolated optical penalization with atropine therapy found atropine to be superior [64]. A subsequent clinical trial that evaluated the use of optical penalization in combination with atropine failed to demonstrate any advantage over atropine alone [65]. There may be a small benefit to augmenting atropine therapy with optical penalization in children with residual amblyopia after treatment with atropine; however, the evidence is insufficient to draw firm conclusions [53]. (See 'Residual amblyopia' above.)

●Systemic treatments – Systemic treatments have been attempted with limited success. Levodopa has been reported to improve visual acuity in both normal and amblyopic eyes; however, the improvement regresses after discontinuation of the drug [66,67]. A randomized placebo-controlled trial found that in older children (ages 7 to 12 years) with residual amblyopia after patching therapy, treatment with levodopa and continued patching did not result in improved visual acuity compared with placebo and patching [68]. Initial studies of citicoline (cytidine-5'-diphosphocholine) in amblyopic children were promising; however, definitive studies on this agent are lacking [69,70].

●Vision training – Novel binocular interactive video games have shown some promise in initial trials and are the subject of ongoing research [71-74]. Therapies such as eye movement exercises, vision training, passive occlusion, and methods designed to stimulate or suppress vision using flashing lights or rapidly rotating patterns have not been well investigated and have few data to support their use [2].

●Acupuncture – Acupuncture is commonly used for the treatment of amblyopia in China and East Asia. A randomized trial comparing acupuncture with patching in older children with anisometropic amblyopia found similar improvement in visual acuity with both therapies [75]. In another randomized crossover trial, young children with anisometropic amblyopia were found to have greater improvement in visual acuity when treated with acupuncture and glasses compared with glasses alone [76]. These trials were single-center studies with relatively small sample sizes, and the results have not been reproduced. In addition, the cost associated with acupuncture treatment is considerably greater than that of patching [77].

FOLLOW-UP — After stopping treatment, children with amblyopia require regular ongoing follow-up with a pediatric eye care specialist. The period of greatest risk for recurrence is within the first 13 weeks of stopping treatment; the risk is low beyond two years [54,78]. (See 'Recurrence' above.)

Most ophthalmologists follow-up patients with amblyopia three to four months after stopping active therapy to check for deterioration. If there is none, the follow-up interval usually is increased to six months and then increased further if the examination remains stable. Younger patients and those who have deterioration in their vision require longer follow-up.

OUTCOME

Visual function — Visual outcome for most children treated with patching or atropine before age seven years is good, although many children do not attain normal vision. Factors that are associated with a good prognosis include younger age (ie, <5 years) at the start of treatment, better baseline visual acuity in the amblyopic eye, and good compliance with prescribed treatment.

Long-term visual outcomes in children treated for amblyopia before age seven years were demonstrated in a follow-up study of 147 children who participated in a multicenter trial comparing patching and atropine [3,43]. At 15 years of age, the following findings were noted:

●The mean amblyopic eye acuity was approximately 20/25.

●60 percent of amblyopic eyes had a visual acuity of 20/25 or better, and 33 percent were 20/20 or better.

●Mean difference in visual acuity between eyes was 2.1 lines.

●Age <5 years at the time of enrollment was associated with better visual acuity outcome (mean visual acuity approximately 20/25 versus 20/32).

Amblyopia may affect binocularity and fine depth perception. Fusion and stereopsis, the central formation of a three-dimensional image from the images perceived by each eye, are dependent upon receiving clear images from each eye simultaneously [79]. Whether impaired stereoacuity can be avoided or reversed by amblyopia treatment is not yet established [61]. Even if normal visual acuity is achieved with treatment, patients with a history of amblyopia may have deficits in perception of images in the real world, poor motor performance, and poor eye-hand coordination [80-83].

Patients with residual unilateral vision impairment after treatment for amblyopia are at risk for permanent bilateral visual impairment or blindness should vision loss occur in the nonamblyopic eye. (See 'Protection for the sound eye' above.)

Psychosocial consequences — It is unclear whether amblyopia has any long-term psychosocial consequences. In a survey of 25 patients with a history of amblyopia, approximately half responded that amblyopia interfered with their schooling, work, or lifestyle, and approximately 40 percent responded that it affected their ability to play sports or influenced their job choices [84]. However, in a population-based study of 3318 young children, of whom 71 (2.1 percent) had amblyopia, general health-related quality of life (as reported by parents) was similar in children with and without amblyopia [85]. In a study evaluating long-term psychosocial outcomes in patients with amblyopia using data from the 1958 British birth cohort, no differences were found between people with and without amblyopia in educational outcomes, employment, participation in social activities, injuries, general or mental health, or mortality [86].

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Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)

●Basics topic (see "Patient education: Crossed eyes and lazy eye (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Definition – Amblyopia is a functional reduction in visual acuity caused by abnormal visual development early in life and is classified based upon associated clinical findings. (See 'Introduction' above and 'Terminology' above and "Amblyopia in children: Classification, screening, and evaluation", section on 'Etiology and classification'.)

●Importance of early treatment – Early detection and treatment of amblyopia improves visual outcomes. This is the basis for screening preschool-age children for vision problems and amblyopia (table 1A-B). Amblyopia is most responsive to treatment when initiated before age seven years. However, all children with amblyopia should undergo treatment, regardless of their age. (See 'Timing' above and "Amblyopia in children: Classification, screening, and evaluation", section on 'Screening'.)

●Management – Children with amblyopia should be managed by an eye specialist who is appropriately trained and experienced in treating children. Treatment of amblyopia requires elimination of any visual obstruction and correction of refractive errors (if present), followed by encouragement of use of the amblyopic eye (through patching or atropine drops). (See 'Vision correction' above and 'Use of amblyopic eye' above.)

•Choice of treatment – Patching and atropine are equally effective in treating mild to moderate amblyopia. Patching is often prescribed as the initial treatment, and it is generally preferred by parents of young children. Atropine, despite its occasional side effects, is also a reasonable first choice, particularly in patients expected to have poor compliance with patching. (See 'Choice of treatment' above and 'Patching' above and 'Pharmacologic penalization (atropine)' above.)

•Limited role of refractive surgery – In rare cases of amblyopia associated with severe unilateral (anisometropic) or bilateral (isoametropic) refractive error, refractive surgery may be a helpful adjunct therapy. (See 'Refractive surgery' above.)

●Follow-up – After stopping treatment, children with amblyopia require regular ongoing follow-up with a pediatric eye care specialist. Approximately one-quarter of patients treated for amblyopia experience recurrence within the first year after stopping therapy. Recurrence is most likely to occur within 13 weeks after stopping treatment. (See 'Recurrence' above and 'Follow-up' above.)

●Outcome – Visual outcome for most children treated with patching or atropine before age seven years is good, although many children do not attain normal vision. Factors that are associated with a good prognosis include younger age (ie, <5 years) at start of treatment, better baseline visual acuity in the amblyopic eye, and good compliance with prescribed treatment. (See 'Outcome' above.)

●Protection of the sound eye – Patients with residual unilateral vision impairment after treatment for amblyopia are at risk for permanent bilateral visual impairment or blindness should vision loss occur in the nonamblyopic eye. Protective eyewear should be worn at all times in these patients, even if they do not require optical correction. (See 'Protection for the sound eye' above.)