Brief daily periods of unrestricted vision can prevent form-deprivation amblyopia

Janice M. Wensveen, Ronald S. Harwerth, Li Fang Hung, Ramkumar Ramamirtham, Chea Su Kee, Earl L. Smith

Research output: Journal article publicationJournal articleAcademic researchpeer-review

25 Citations (Scopus)


PURPOSE. To characterize how the mechanisms that produce unilateral form-deprivation amblyopia integrate the effects of normal and abnormal vision over time, the effects of brief daily periods of unrestricted vision on the spatial vision losses produced by monocular form deprivation were investigated in infant monkeys. METHODS. Beginning at 3 weeks of age, unilateral form deprivation was initiated in 18 infant monkeys by securing a diffuser spectacle lens in front of one eye and a clear plano lens in front of the fellow eye. During the treatment period (18 weeks), three infants wore the diffusers continuously. For the other experimental infants, the diffusers were removed daily and replaced with clear, zero-powered lenses for 1 (n = 5), 2 (n = 6), or 4 (n = 4) hours. Four infants reared with binocular zero-powered lenses and four normally reared monkeys provided control data. RESULTS. The degree of amblyopia varied significantly with the daily duration of unrestricted vision. Continuous form deprivation caused severe amblyopia. However, 1 hour of unrestricted vision reduced the degree of amblyopia by 65%, 2 hours reduced the deficits by 90%, and 4 hours preserved near-normal spatial contrast sensitivity. CONCLUSIONS. The severely amblyogenic effects of form deprivation in infant primates are substantially reduced by relatively short daily periods of unrestricted vision. The manner in which the mechanisms responsible for amblyopia integrate the effects of normal and abnormal vision over time promotes normal visual development and has important implications for the management of human infants with conditions that potentially cause amblyopia.
Original languageEnglish
Pages (from-to)2468-2477
Number of pages10
JournalInvestigative Ophthalmology and Visual Science
Issue number6
Publication statusPublished - 1 Jun 2006
Externally publishedYes

ASJC Scopus subject areas

  • Ophthalmology


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