The minimum occlusion trial for the treatment of amblyopia

doi:10.1016/S0161-6420(02)01282-4

Ophthalmology

Volume 109, Issue 12, December 2002, Pages 2261-2264

https://doi.org/10.1016/S0161-6420(02)01282-4 Get rights and content

Abstract

Objective

To determine whether the traditional regimen of three intervals of full-time occlusion (FTO) for amblyopia without any measurable improvement in visual acuity constitutes an adequate trial.

Design

Retrospective, noncomparative, interventional case series.

Participants

Sixty-four children younger than 10 years of age with unilateral amblyopia.

Methods

The medical records of patients treated for amblyopia in a university outpatient clinic were reviewed. Patients who underwent one FTO interval without an improvement in visual acuity followed by at least one additional FTO interval were included in the study.

Main outcome measures

Improvement in visual acuity.

Results

Sixty-four patients underwent 81 occlusion trials consisting of one FTO interval without improvement followed by one or more FTO intervals. Visual acuity improved after the second FTO interval in 25 (31%) of the trials. Of the 44 occlusion trials consisting of two FTO intervals without improvement, visual acuity improved after the third FTO interval in 12 (27%) of the trials. Of the 11 occlusion trials consisting of three FTO intervals without improvement followed by one or more additional FTO intervals, acuity did not improve with any of the trials.

Conclusions

A minimum of three intervals of FTO is necessary to determine whether an amblyopia patient will be unresponsive to occlusion therapy. After three FTO intervals without improvement, additional FTO is unlikely to result in an improvement in visual acuity.

Section snippets

Materials and methods

The medical records of all patients treated for amblyopia between 1990 and 1996 at the University of Iowa Hospitals and Clinics were reviewed. Only patients that met the following criteria were included in the study:

•
Documentation in the medical record of one or more occlusion trials,
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Younger than 10 years of age during the occlusion trial,
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Visual acuity assessed by optotype acuity tests,
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Absence of any organic ocular condition that could result in visual impairment,
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At least 75% or more compliance

Results

Sixty-four patients were included in the study group. There were 31 females and 33 males. The mean age at the onset of the occlusion trial was 2 years 10 months (range, 2.0–9.5 years). The amblyopia was classified as anisometropic amblyopia in 32 patients (50%) and strabismic amblyopia in 32 patients (50%).

There were 81 occlusion trials that included one FTO interval without improvement followed by a second FTO interval (Fig 1). Visual acuity improved after the second FTO interval in 25 (31%)

Discussion

We determined the probability of visual acuity improvement in amblyopia patients with additional intervals of occlusion therapy who initially do not respond to treatment. Our study demonstrates that a clinically significant percentage of patients who initially did not respond to FTO did have an improvement in their acuity with a second or third interval of FTO. As may be predicted, the greater number of consecutive occlusion intervals without improvement corresponded to a decreased probability

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Occlusion therapy for strabismic amblyopia
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There are more references available in the full text version of this article.

Cited by (16)

A randomized trial of levodopa as treatment for residual amblyopia in older children
2015, Ophthalmology
Citation Excerpt :
Placebo group participants and parents may have been more compliant with patching than they had been previously because they were being monitored in a research study. Nonetheless, the observation that some participants continued to improve with patching even after apparent VA stability was achieved should be considered by clinicians and parents when deciding to stop patching.20,21 Our finding of a lack of efficacy for levodopa must be viewed in the context of the study eligibility criteria: children 7 to 12 years of age with residual amblyopia from anisometropia, strabismus, or both, after a period of treatment with patching.
To assess the efficacy and short-term safety of levodopa as adjunctive treatment to patching for amblyopia.
Randomized, placebo-controlled trial.
One hundred thirty-nine children 7 to 12 years of age with residual amblyopia resulting from strabismus, anisometropia, or both combined (visual acuity [VA], 20/50–20/400) after patching.
Sixteen weeks of oral levodopa or placebo administered 3 times daily while patching the fellow eye 2 hours daily.
Mean change in best-corrected amblyopic-eye VA at 18 weeks.
At 18 weeks, amblyopic-eye VA improved from randomization by an average of 5.2 letters in the levodopa group and by 3.8 letters in the placebo group (difference adjusted for baseline VA, +1.4 letters; 1-sided P = 0.06; 2-sided 95% confidence interval, −0.4 to 3.3 letters). No serious adverse effects from levodopa were reported during treatment.
For children 7 to 12 years of age with residual amblyopia after patching therapy, oral levodopa while continuing to patch 2 hours daily does not produce a clinically or statistically meaningful improvement in VA compared with placebo and patching.
Recurrence of Amblyopia after Occlusion Therapy
2006, Ophthalmology
Citation Excerpt :
Long travel distances and rescheduled appointments occasionally necessitated less than FTO for a brief time; however, no patient was prescribed <8 hours of occlusion per day during treatment to improve VA. A patient was judged to have reached optimal vision in the amblyopic eye when the VA in that eye equaled or surpassed the vision in the normal sighted eye, or the VA improved as noted in the eligibility criteria followed by ≥3 FTO intervals without improvement in VA (Table 1).6 Once optimal VA was achieved, we recommended a progressive decrease in the daily duration of occlusion by approximately 50% every few months until occlusion was completely stopped or the patient had a recurrence of amblyopia.
To determine the stability of visual acuity (VA) after a standardized occlusion regimen in children with strabismic and/or anisometropic amblyopia.
Retrospective, population-based, consecutive observational case series.
Four hundred forty-nine patients younger than 10 years who underwent an occlusion trial for amblyopia and were observed until there was a recurrence of amblyopia or for a maximum of 1 year after decrease or cessation of occlusion therapy.
We performed a retrospective chart review of all patients treated by occlusion therapy for strabismic and/or anisometropic amblyopia at our institution over a 34-year period. Of the 1621 patients identified in our database, 449 met the eligibility criteria and were included in this study. Patients having at least a 2 logarithm of the minimum angle of resolution (logMAR)–level improvement in VA by optotypes or a change from unmaintained to maintained fixation preference during the course of occlusion therapy were included. A recurrence of amblyopia was defined as ≥2 logMAR levels of VA reduction or reversal of fixation preference within 1 year after a decrease or cessation of occlusion therapy.
Recurrence of amblyopia after a decrease or cessation of occlusion therapy and its relationship with patient age and VA of the amblyopic eye at the time of decrease or cessation of occlusion therapy.
Of 653 occlusion trials, 179 (27%) resulted in recurrence of amblyopia. The recurrence was found to be inversely correlated with patient age. There was no statistically significant association between the recurrence of amblyopia and VA of the amblyopic eye at the end of maximal occlusion therapy.
There is a clinically important risk of amblyopia recurrence when occlusion therapy is decreased before the age of 10 years. The risk of recurrence is inversely correlated with age (P<0.0001).
Window to other specialties: Visual clarity defects
2006, Anales de Pediatria Continuada
Amblyopia
2006, Lancet
Citation Excerpt :
Until recent trials,67,68 the amount of patching prescribed has been entirely a matter of individual preference. Some researchers have argued for full-time occlusion, recommending at least three cycles69 of a week of full-time occlusion per year of age. Others have preferred to patch less intensively (a few h per day), recognising that treatment could take longer than expected but could be just as effective with the advantage of being less disruptive.
Results from recent randomised clinical trials in amblyopia should change our approach to screening for and treatment of amblyopia. Based on the current evidence, if one screening session is used, screening at school entry could be the most reasonable time. Clinicians should preferably use age-appropriate LogMAR acuity tests, and treatment should only be considered for children who are clearly not in the typical range for their age. Any substantial refractive error should be corrected before further treatment is considered and the child should be followed in spectacles until no further improvement is recorded, which can take up to 6 months. Parents and carers should then be offered an informed choice between patching and atropine drops. Successful patching regimens can last as little as 1 h or 2 h a day, and successful atropine regimens as little as one drop twice a week. Intense and extended regimens might not be needed in initial therapy.
Amblyopia treatment outcomes
2005, Journal of AAPOS
Purpose: To determine the effectiveness and side effects of full-time occlusion for the treatment of amblyopia. Methods: Patients with unilateral amblyopia secondary to strabismus, anisometropia, or a combination of the two were retrospective reviewed. All patients had full-time occlusion encompassing 24 hours per day or all waking hours, followed to a defined endpoint. Success was defined as 20/30 or better or equal visual acuity by fixation pattern between the two eyes. The ultimate goal was equal visual acuity. Results: Six hundred patients fit the inclusion criteria. Mean follow-up after the cessation of full-time patching was 7.2 years. Eighty-nine percent were followed for more than 1 year. Mean age at last follow-up visit was 10.82 years. Ninety-six percent of patients attained a successful visual result. Sixty percent attained equal visual acuity. Younger patients required less occlusion time to endpoint and had a better visual outcome (P < 0.0001). Initial visual acuity was significantly related to best visual acuity attained (P < 0.0001). The incidence of occlusion amblyopia was 25.8%. Conclusions: Full-time occlusion produces excellent visual acuity results. It was shown to be effective with no long-term complications if patients proceed as directed.
Amblyopia characterization, treatment, and prophylaxis
2005, Survey of Ophthalmology
Citation Excerpt :
Invest Ophthalmol Vis Sci 44[Suppl]:S200, 2003) and parents of children with no previous history of patching preferred a part-day/full-week patching schedule over an all-day/part-week schedule.521 Although some studies report an effect of age at initial visit on outcome, based on univariate measures,185,507 many do not,42,95,98,206,258,290,366,572 including a study with a maintenance-free long-term follow-up of 1.1–9.8 years. 323 One ATS study reports a small age effect,214 but other ATS studies none.3,5
Amblyopia has a 1.6–3.6% prevalence, higher in the medically underserved. It is more complex than simply visual acuity loss and the better eye has sub-clinical deficits. Functional limitations appear more extensive and loss of vision in the better eye of amblyopes more prevalent than previously thought. Amblyopia screening and treatment are efficacious, but cost-effectiveness concerns remain. Refractive correction alone may successfully treat anisometropic amblyopia and it, minimal occlusion, and/or catecholamine treatment can provide initial vision improvement that may improve compliance with subsequent long-duration treatment. Atropine penalization appears as effective as occlusion for moderate amblyopia, with limited-day penalization as effective as full-time. Cytidin-5′-diphosphocholine may hold promise as a medical treatment. Interpretation of much of the amblyopia literature is made difficult by: inaccurate visual acuity measurement at initial visit, lack of adequate refractive correction prior to and during treatment, and lack of long-term follow-up results. Successful treatment can be achieved in at most 63–83% of patients. Treatment outcome is a function of initial visual acuity and type of amblyopia, and a reciprocal product of treatment efficacy, duration, and compliance. Age at treatment onset is not predictive of outcome in many studies but detection under versus over 2–3 years of age may be. Multiple screenings prior to that age, and prompt treatment, reduce prevalence. Would a single early cycloplegic photoscreening be as, or more, successful at detection or prediction than the multiple screenings, and more cost-effective? Penalization and occlusion have minimal incidence of reverse amblyopia and/or side-effects, no significant influence on emmetropization, and no consistent effect on sign or size of post-treatment changes in strabismic deviation. There may be a physiologic basis for better age-indifferent outcome than tapped by current treatment methodologies. Infant refractive correction substantially reduces accommodative esotropia and amblyopia incidence without interference with emmetropization. Compensatory prism, alone or post-operatively, and/or minus lens treatment, and/or wide-field fusional amplitude training, may reduce risk of early onset esotropia. Multivariate screening using continuous-scale measurements may be more effective than traditional single-test dichotomous pass/fail measures. Pigmentation may be one parameter because Caucasians are at higher risk for esotropia than non-whites.

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Article for CME creditThe minimum occlusion trial for the treatment of amblyopia

Abstract

Objective

Design

Participants

Methods

Main outcome measures

Results

Conclusions

Section snippets

Materials and methods

Results

Discussion

Ophthalmology

Am J Ophthalmol

Ophthalmology

Am Orthopt J

Practical management of amblyopia

J Pediatr Ophthalmol Strabismus

Occlusion therapy for strabismic amblyopia

Aust N Z J Ophthalmol

Article for CME credit
The minimum occlusion trial for the treatment of amblyopia