Purpose: In order to assess the sensitive period for strabismic amblyopia, the period of susceptibility to monocular occlusion was investigated in 407 children who ranged in age from 21 months to 12 years.
Methods: Patients were treated between 1975 and 1990 by occlusion of the best eye. The efficiency of the treatment was measured as the ratio of reduction of the amblyopia at the end of the occlusion.
Results: The efficiency of the occlusion is shown to depend on the age of the onset of the treatment: recovery of acuity of the amblyopic eye was maximum when the occlusion was initiated before 3 years of age, decreased as a function of age and was about null by the time the patient was 12 years of age.
Conclusion: This is assumed to be an indication of the sensitive period for strabismic amblyopia in humans. The results are discussed on the basis of the neurophysiological mechanisms of amblyopia established in animals.