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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
 
Am J Ophthalmol. Author manuscript; available in PMC 2008 June 1.
Published in final edited form as:
PMCID: PMC2041929
NIHMSID: NIHMS25199

Treatment of Strabismic Amblyopia with Refractive Correction

Pediatric Eye Disease Investigator Group*

Abstract

Purpose:

To report data on the response of previously untreated strabismic amblyopia to spectacle correction.

Design:

Prospective, interventional case series

Methods:

12 patients with previously untreated strabismic amblyopia were prescribed spectacles and examined at 5-week intervals until visual acuity was not improved from the prior visit.

Results:

Amblyopic eye acuity improved by ≥ 2 lines from spectacle-corrected baseline acuity in 9 of the 12 patients (75%), resolving in 3 (IOD ≤ 1 line). Mean change from baseline to maximum improvement was 2.2 ± 1.8 lines. Improvement continued for up to 25 weeks.

Conclusion:

These results support the suggestion from a prior study that strabismic amblyopia can improve and even resolve with spectacle correction alone. Larger studies with concurrent controls are needed to confirm or refute these findings.

Keywords: amblyopia, strabismus, visual acuity, refractive correction

Brief Report

Stewart et. al. reported that refractive correction alone can be effective in treating young children with previously untreated strabismic amblyopia, even in the absence of anisometropia.1 In 16 patients with strabismic amblyopia treated with spectacles alone, they found amblyopic eye acuity improved a mean of 3.0 lines over an 18-week period. This was somewhat surprising because, in such cases, the amblyopia is presumably due to the ocular misalignment, which most often would not be fully corrected with spectacles alone. We reviewed data from our recent prospective study2 to determine if our results were consistent with those of Stewart and coworkers.

This study was registered at ClinicalTrials.gov (Identifier NCT00091923).3 The full study protocol is available online.4 The protocol and HIPAA-compliant informed consent forms were approved by the respective institutional review boards and the parent or guardian of each study patient gave written informed consent.

As a run-in phase to a randomized trial of patching treatment for amblyopia,5 spectacles were prescribed to correct refractive error, no other amblyopia treatment was prescribed, and patients were followed until visual acuity appeared stable. Results in patients with previously untreated anisometropic amblyopia have been reported2. Data were available for 12 patients (75% female, 83% white, mean age 5.0±0.9 years) with previously untreated strabismic amblyopia who had a constant strabismus at distance and near and anisometropia of ≤0.75 D in spherical equivalent or ≤1.25 D in astigmatism (Table 1). Spectacle-corrected monocular distance visual acuity was measured using the electronic Amblyopia Treatment Study HOTV protocol6, 7 at baseline and every 5 (±1) weeks provided amblyopic eye acuity had improved at least 1 line (0.1 logMAR) from the prior visit and remained at least 1 line worse than sound eye acuity. Patients whose acuity did not improve at least 1 line from the prior visit but still had ≥2 lines of interocular difference (IOD) entered a randomized trial.5 Those randomized to the control group continued spectacles if needed but did not start other therapy, and provide additional data on the course of the amblyopia treated with spectacles alone.

Table 1
Baseline Clinical Characteristics and Change in Amblyopic Eye Visual Acuity

Among the 12 strabismic patients, during the spectacles-only phase of follow up, amblyopic eye acuity improved by ≥ 2 lines from spectacle-corrected baseline acuity in 9 (75%) resolving in 3 (IOD ≤ 1 line), Table 2. Mean change from baseline to maximum improvement was 2.2 ± 1.8 lines. Improvement continued for up to 25 weeks. Additional amblyopia improvement ≥1 line occurred, though amblyopia did not resolve, in 3 of the 5 patients with residual amblyopia who entered the subsequent randomized trial as controls.

Table 2
Improvement in Amblyopic Eye Visual Acuity and Resolution of Amblyopia Stratified by Degree of Refractive Error in Amblyopic Eye

Our results support the suggestion of Stewart et al.1 that strabismic amblyopia can improve and even resolve with spectacle correction alone. Although the results are consistent, they are not conclusive, because neither study had a concurrent control group and both had small numbers of patients. It is not possible to rule out the possibility that change in strabismus angle, learning effect, age effect, regression to the mean, or chance could account for some of the observed improvement. Larger studies with concurrent controls are needed to confirm or refute these findings.

Acknowledgements

Writing Committee for the Pediatric Eye Disease Investigator Group*: Lead authors: Susan A. Cotter, O.D.; Allison R. Edwards, M.S.; Additional writing committee members (alphabetical): Robert W. Arnold, M.D.; William F. Astle, M.D.; Carmen N. Barnhardt, O.D.; Roy W. Beck, M.D., Ph.D.; Eileen E. Birch, Ph.D.; Sean P. Donahue, M.D., Ph.D.; Donald F. Everett, M.A.; Joost Felius, Ph.D.; Jonathan M. Holmes, B.M., B.Ch; Raymond T. Kraker, M.S.P.H.; B. Michele Melia, Sc.M.; Michael X. Repka, M.D.; David K. Wallace, M.D.; Katherine K. Weise, O.D., M.B.A.

1)FUNDING/SUPPORT - This study was supported by a cooperative agreement from the National Eye Institute, EY11751.

2)FINANCIAL DISCLOSURES - None

3) CONTRIBUTION OF AUTHORS Design of the study (SC, RA, WA, CB, RB, EB, SD, DE, JF, JH, RK, MR, DW, KW); all authors were involved in the collection, management, analysis, and interpretation of the data and the preparation, review, and final approval of the manuscript.

4)OTHER ACKNOWLEDGMENTS - None

Footnotes

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

*A list of Pediatric Eye Disease Investigator Group sites participating in this study appears in Ophthalmology 2006;113:895-903.

REFERENCES

1. Stewart CE, Moseley MJ, Fielder AR, Stephens DA, MOTAS Cooperative Refractive adaptation in amblyopia: quantification of effect and implications for practice. Br J Ophthalmol. 2004;88:1552–6. [PMC free article] [PubMed]
2. Pediatric Eye Disease Investigator Group Treatment of anisometropic amblyopia in children with refractive correction. Ophthalmology. 2006;113:895–903. [PMC free article] [PubMed]
3. ClinicalTrials.gov. Trial to Evaluate 2 Hours of Daily Patching for Amblyopia in Children (identifier NCT00091923): U.S. National Institutes of Health, 2006. Available at: http://clinicaltrials.gov/ct/show/NCT00091923?order=13. Accessed December 04, 2006.
4. Pediatric Eye Disease Investigator Group A Randomized Trial to Evaluate 2 Hours of Daily Patching for Amblyopia in Children. Full protocol available at http://public.pedig.jaeb.org/Completed_Studies.htm. Accessed December 4, 2006.
5. Pediatric Eye Disease Investigator Group A randomized trial to evaluate 2 hours of daily patching for strabismic and anisometropic amblyopia in children. Ophthalmology. 2006;113:904–12. [PMC free article] [PubMed]
6. Holmes JM, Beck RW, Repka MX, et al. The amblyopia treatment study visual acuity testing protocol. Arch Ophthalmol. 2001;119:1345–53. [PubMed]
7. Moke PS, Turpin AH, Beck RW, et al. Computerized method of visual acuity testing: adaptation of the amblyopia treatment study visual acuity testing protocol. Am J Ophthamol. 2001;132:903–9. [PubMed]