Morphoscopic perception at variable contrast and luminance levels in 97 subjects

Background: Morphoscopic perception at variable contrast and luminance leve ls has been assessed in various diseases and in occupational medicine. To o ur knowledge, this function has not been studied in young adults of similar age. We performed-a prospective study to assess morphoscopic perception at variable contrast and luminance levels in a group of young servicemen. Methods: A total of 97 subjects (194 eyes) with a mean age of 22.4 (standar d deviation 1.16) years were assessed with the Gradual monitor. After visua l acuity was measured, morphoscopic perception was assessed at a mean light level of 85 cd/m(2), at low, medium and high spatial frequencies, with myo pic correction. All subjects whose visual acuity was not correctable to 10/ 10 in both eyes or whose score was statistically too different from the mea n underwent a complete ophthalmologic examination. Results: Overall, 87 subjects had a visual acuity correctable to 10/10 or b etter in both eyes. For 34 of the 87 at least one of the six scores was mor e than 1 standard deviation below the mean; however, for 16 subjects the re sult was within normal limits after minor adjustment of the correction, oft en of a small degree of astigmatism. Of the 18 remaining subjects 7 had mic rostrabismus, 8 had anatomic lesions and 3 had lesions of unknown origin. O f the 13 subjects with a visual acuity of less than 10/10, 5 had relative a mblyopia, 2 had major ametropia, 2 had unilateral and 2 bilateral ophthalmo logic lesions, and 2 had reduced acuity of unknown cause. Interpretation: In this young population the most frequent cause of reduced contrast sensitivity (40%) was associated with minor uncorrected or badly corrected refractive problems. The next most frequent cause was problems wi th binocular vision, with or without amblyopia (11%). In these subjects con trast sensitivity was reduced in the nondominant eye and, in five cases, in the dominant eye and, in five cases, in the dominant eye also.