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Volume 48, 1998, p. 122130

Comparative Study of the MTI Photoscreener™, Visual Acuity and Lang Stereopsis Test for Amblyogenic Factors in Mentally Delayed Children (Abstract)
Sandra I. Holgado MD, Silvia Arfeli MD, Eduardo Gomez-Demmel MD, José Espinosa MD

Amblyopia and strabismus afflict at least 5% of children. Amblyopia, if undetected during the years of visual plasticity, is not susceptible to treatment. Mass screening at preschool age, and perhaps ultimately of infants, is the only viable solution to this problem. The purpose of this study was to evaluate the incidence of amblyogenic factors and the accuracy of the MTI Photoscreener™, visual acuity (E's Test) and Lang stereopsis test in one of the hardest populations to examine, mentally delayed children.

Forty-five mentally delayed children between ages 4 and 25 years were screened with a standard visual acuity test (Snellen chart), Lang stereopsis test and with the MTI Photoscreener™. The results were compared with a complete ophthalmologic examination including cycloplegic refraction.


Results: The incidence of amblyogenic factors was 56.52%. Of those, 37.77% were strabismus, 4.44% media opacity or aphakia, 2.22% nystagmus, 8.88% anisometropia and 4.44% astigmatism. The sensitivity of the MTI Photoscreener™ was determined to be 76.92%, with a specificity of 70%. The sensitivity and specificity of the visual acuity test was 68.96% and 93.75% respectively. The sensitivity of the Lang stereopsis test was determined to be 92%, and the specificity was 76.19%. The percentage of examinations not completed due to lack of cooperation was 50% for the visual acuity test, 39.13% for the Lang stereopsis test and 0.02% for the MTI Photoscreener™.


Conclusion: The incidence of amblyogenic factors in mentally delayed children is high. The subjective tests (visual acuity and Lang stereopsis test) have a high rate of noncooperation.