Amblyopia 

  • Author: Kimberly G Yen, MD; Chief Editor: Hampton Roy Sr, MD   more...
 
Updated: Mar 9, 2011
 

Background

Amblyopia refers to a decrease of vision, either unilaterally or bilaterally, for which no cause can be found by physical examination of the eye. The term functional amblyopia often is used to describe amblyopia, which is potentially reversible by occlusion therapy. Organic amblyopia refers to irreversible amblyopia.[1, 2, 3]

Most vision loss from amblyopia is preventable or reversible with the right kind of intervention. The recovery of vision depends on how mature the visual connections are, the length of deprivation, and at what age the therapy is begun. It is important to rule out any organic cause of decreased vision because many diseases may not be detectable on routine examination.

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Pathophysiology

Although many types of amblyopia exist, it is believed that their basic mechanisms are the same even though each factor may contribute different amounts to each specific type of amblyopia. In general, amblyopia is believed to result from disuse from inadequate foveal or peripheral retinal stimulation and/or abnormal binocular interaction that causes different visual input from the foveae.[4]

Three critical periods of human visual acuity development have been determined.[5, 6] During these time periods, vision can be affected by the various mechanisms to cause or reverse amblyopia. These periods are as follows:

  • The development of visual acuity from the 20/200 range to 20/20, which occurs from birth to age 3-5 years.
  • The period of the highest risk of deprivation amblyopia, from a few months to 7 or 8 years.
  • The period during which recovery from amblyopia can be obtained, from the time of deprivation up to the teenage years or even sometimes the adult years.

Whether different visual functions (eg, contrast sensitivity, stereopsis) have different critical periods is not known. In the future, determination of these time frames may help modify treatment of amblyopia.

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Epidemiology

Frequency

United States

Prevalence of amblyopia is difficult to assess and varies in the literature, ranging from 1-3.5% in healthy children to 4-5.3% in children with ophthalmic problems. Most data show that about 2% of the general population has amblyopia.

Amblyopia was shown in the Visual Acuity Impairment Survey sponsored by the National Eye Institute (NEI) to be the leading cause of monocular vision loss in adults aged 20-70 years or older. Prevalence of amblyopia has not changed much over the years.

Mortality/Morbidity

Amblyopia is an important socioeconomic problem. Studies have shown that it is the number one cause of monocular vision loss in adults. Furthermore, persons with amblyopia have a higher risk of becoming blind because of potential loss to the sound eye from other causes.

Race

No racial preference is known.

Sex

No gender preference is known.

Age

Amblyopia occurs during the critical periods of visual development. An increased risk exists in those children who are developmentally delayed, were premature, and/or have a positive family history.

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Contributor Information and Disclosures
Author

Kimberly G Yen, MD  Assistant Professor of Ophthalmology, Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine

Kimberly G Yen, MD is a member of the following medical societies: Association for Research in Vision and Ophthalmology

Disclosure: Nothing to disclose.

Specialty Editor Board

Gerhard W Cibis, MD  Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas, Kansas City

Gerhard W Cibis, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Ophthalmological Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

J James Rowsey, MD  Former Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida

J James Rowsey, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, American Medical Association, Association for Research in Vision and Ophthalmology, Florida Medical Association, Pan-American Association of Ophthalmology, Sigma Xi, and Southern Medical Association

Disclosure: Nothing to disclose.

Lance L Brown, OD, MD  Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD  Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

References

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  2. Kushner, BJ. Amblyopia. In: Nelson LB, ed. Harley's Pediatric Ophthalmology. 1998:125-39.

  3. von Noorden GK. Binocular Vision and Ocular Motility: Theory and Management. 1996;216-54.

  4. Lempert P. Retinal area and optic disc rim area in amblyopic, fellow, and normal hyperopic eyes: a hypothesis for decreased acuity in amblyopia. Ophthalmology. Dec 2008;115(12):2259-61. [Medline].

  5. Daw NW. Critical periods and amblyopia. Arch Ophthalmol. Apr 1998;116(4):502-5. [Medline].

  6. Kirschen DG. Understanding Sensory Evaluation. In: Rosenbaum AL, Santiago AP, eds. Clinical Strabismus Management: Principles and Practice. 1999: 22-35.

  7. Lin LK, Uzcategui N, Chang EL. Effect of surgical correction of congenital ptosis on amblyopia. Ophthal Plast Reconstr Surg. Nov-Dec 2008;24(6):434-6. [Medline].

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  10. Flynn JT. 17th annual Frank Costenbader Lecture. Amblyopia revisited. J Pediatr Ophthalmol Strabismus. Jul-Aug 1991;28(4):183-201. [Medline].

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  12. Cotter SA, Edwards AR, Wallace DK, et al. Treatment of anisometropic amblyopia in children with refractive correction. Ophthalmology. Jun 2006;113(6):895-903. [Medline].

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  14. Holmes JM, Kraker RT, Beck RW, et al. A randomized trial of prescribed patching regimens for treatment of severe amblyopia in children. Ophthalmology. Nov 2003;110(11):2075-87. [Medline].

  15. Repka MX, Beck RW, Holmes JM, et al. A randomized trial of patching regimens for treatment of moderate amblyopia in children. Arch Ophthalmol. 2003;121:603-11. [Medline].

  16. Scheiman MM, Hertle RW, Beck RW, et al. Randomized trial of treatment of amblyopia in children aged 7 to 17 years. Arch Ophthalmol. Apr 2005;123(4):437-47. [Medline].

  17. Holmes JM, Beck RW, Kraker RT, et al. Risk of amblyopia recurrence after cessation of treatment. J AAPOS. 2004;8:420-8. [Medline].

  18. Pediatric Eye Disease Investigator Group. A randomized trial of atropine vs. patching for treatment of moderate amblyopia in children. Arch Ophthalmol. 2002;120:268-278. [Medline].

  19. Repka MX, Wallace DK, Beck RW, et al. Two-year follow-up of a 6-month randomized trial of atropine vs patching for treatment of moderate amblyopia in children. Arch Ophthalmol. 2005;123:149-157. [Medline]. [Full Text].

  20. Repka MX, Cotter SA, Beck RW, et al. A randomized trial of atropine regimens for treatment of moderate amblyopia in children. Ophthalmology. 2004;111:2076-85. [Medline].

  21. Scheiman MM, Hertle RW, Kraker RT, et al. Patching vs atropine to treat amblyopia in children aged 7 to 12 years: a randomized trial. Arch Ophthalmol. Dec 2008;126(12):1634-42. [Medline].

  22. Collins RS, McChesney ME, McCluer CA, et al. Occlusion properties of prosthetic contact lenses for the treatment of amblyopia. J AAPOS. Dec 2008;12(6):565-8. [Medline].

  23. Repka MX. How much amblyopia treatment is enough?. Arch Ophthalmol. Jul 2008;126(7):990-1. [Medline].

  24. Levartovsky S, Oliver M, Gottesman N, Shimshoni M. Factors affecting long term results of successfully treated amblyopia: initial visual acuity and type of amblyopia. Br J Ophthalmol. Mar 1995;79(3):225-8. [Medline].

  25. Longmuir SQ, Pfeifer W, Leon A, Olson RJ, Short L, Scott WE. Nine-year results of a volunteer lay network photoscreening program of 147 809 children using a photoscreener in Iowa. Ophthalmology. Oct 2010;117(10):1869-75. [Medline].

  26. Mirabella G, Hay S, Wong AM. Deficits in perception of images of real-world scenes in patients with a history of amblyopia. Arch Ophthalmol. Feb 2011;129(2):176-83. [Medline].

  27. Wallace DK, Edwards AR, Cotter SA, Beck RW, Arnold RW, Astle WF, et al. A randomized trial to evaluate 2 hours of daily patching for strabismic and anisometropic amblyopia in children. Ophthalmology. Jun 2006;113(6):904-12. [Medline].

 
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