Investigation of relationship between colour discrimination ability and stereoscopic acuity using Farnsworth Munsell 100 hue test and stereo tests.

OBJECTIVE: To evaluate the effect of colour discrimination ability on the stereoscopic acuity by comparing individuals having congenital colour vision deficiency (CCVD) with healthy individuals. DESIGN: A comparative study. PARTICIPANTS: The study included 53 binocular males, of whom 26 (mean age, 36.04 ± 9.30 years) were in the healthy group and 27 (mean age, 33.04 ± 9.81 years) were in the CCVD group. METHODS: The following tests were used: the Ishihara pseudo-isochromatic plate test for detecting CCVD, the Farnsworth Munsell 100 (FM100) hue test for colour discrimination ability, the TNO and Titmus stereo tests for stereoscopic acuity. RESULTS: In the CCVD group, 20 males were deutan and 7 males were protan. According to the FM100 hue test, total error score (TES), blue/yellow (b/y) local error score (LES), and red/green LES were significantly lower in the healthy group (30.23 ± 18.78, 15.15 ± 10.38, and 13.88 ± 11.93, respectively) than in the CCVD group (133.59 ± 67.45, 41.15 ± 22.03, and 89.15 ± 52.16, respectively) (p < 0.01 for each). The stereo test scores revealed significantly higher stereoscopic acuity in the healthy group (43.85 ± 33.92 arcsec for the TNO test and 40.00 ± 0.00 arcsec for the Titmus test) than in the CCVD group (93.33 ± 90.51 arcsec for TNO stereo test and 52.96 ± 24.62 arcsec for the Titmus test) (p < 0.05 for each). The TNO test score was significantly and positively correlated with the TES (r = 0.390, p = 0.049) and b/y LES (r = 0.490, p = 0.011) in the healthy group. CONCLUSIONS: Colour discrimination ability affected stereoscopic acuity. Moreover, stereoscopic acuity increased with increasing colour discrimination ability, which could be originated from the b/y colour region.