Abstract
Abstract: :
Purpose: Although a variety of techniques exist for evaluating color vision in school-age children and adults, few exist for use with preschoolers and there is no clinical test available for infants. The emergence of a diagnostic tool for young pediatric patients would be significant for two reasons 1) to provide earlier identification of those with suspected or inherited color vision deficits 2) color vision anomalies help confirm diagnoses of particular ophthalmic, neural or systemic diseases that impact selectively the retinal photoreceptors and/or the parvocellular network within the geniculostriate pathway. Methods: Pease and Allen (1988) developed a pseudoisochromatic test for preschoolers composed of Ishihara/HRR-like plates, each of which contained a simple dot-matrix test square of one Munsell hue within a eqiluminant background of a second Munsell Hue. The hues for the test square and background were selected so that they fell on the respective confusion axes of those with moderate to severe R/G and B/Y color deficiencies. A control plate containing achromatic stimuli was also included. To make the Pease and Allen test more feasible for infants we modified it by increasing the size of the dots from 28 to 38 mm2 , the test square from 25 to 169 cm2 and the overall size of the plate from 10 x 30 cm to 18 by 45 cm (300 to 810 cm2). With these larger stimuli, we then used a Teller acuity card modified FPL technique to test 15 8-to-11-mo-olds and 10 preschoolers. For control purposes, color-normal and R/G-deficient adults were also tested. Results:Even with infants, the procedure appeared easy to perform with most subjects completing the test within 4 minutes. Results showed that preschoolers and color-normal adults detected all stimuli, but every R/G deficient adult and 65% of the infants could not detect the R/G test square. Interestingly, infant boys accounted for most of the R/G failures. Conclusions:Given its ease of use with very young patients and its success in identifying adults with known color deficiencies, the modified Pease and Allen pseudoisochromatic "card" test shows much promise as a time-efficient and sound procedure for identifying early color vision anomalies. The relatively high failure rate shown by infants with the R/G plate is likely accounted for by the fact that the low chromatic contrast of the test vs. background hues exceeds the thresholds of many infants. In future versions, this can be remedied by selecting hues on protanopic and deuteranopic axes with wider spectral separation.
Keywords: color vision • visual development: infancy and childhood • clinical research methodology