[Morphoscopic perception at variable contrast and luminance levels in 97 subjects]

Morphoscopic perception at variable contrast and luminance levels has been assessed in various diseases and in occupational medicine. To our 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.

A total of 97 subjects (194 eyes) with a mean age of 22.4 (standard deviation 1.16) years were assessed with the Gradual monitor. After visual acuity was measured, morphoscopic perception was assessed at a mean light level of 85 cd/m2, at low, medium and high spatial frequencies, with myopic correction. All subjects whose visual acuity was not correctable to 10/10 in both eyes or whose score was statistically too different from the mean underwent a complete ophthalmologic examination.

Overall, 87 subjects had a visual acuity correctable to 10/10 or better in both eyes. For 34 of the 87, at least one of the six scores was more than 1 standard deviation below the mean; however, for 16 subjects the result was within normal limits after minor adjustment of the correction, often of a small degree of astigmatism. Of the 18 remaining subjects 7 had microstrabismus, 8 had anatomic lesions and 3 had lesions of unknown origin. Of the 13 subjects with a visual acuity of less than 10/10, 5 had relative amblyopia, 2 had major ametropia, 2 had unilateral and 2 bilateral ophthalmologic lesions, and 2 had reduced acuity of unknown cause.

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 with binocular vision, with or without amblyopia (11%). In these subjects contrast sensitivity was reduced in the nondominant eye and, in five cases, in the dominant eye also.