Abstract
Purpose :
To measure monocular and dichoptic color vision thresholds in amblyopic patients, controls, and congenital color deficient subjects.
Methods :
Ten patients with amblyopia (mean age = 31.4 ± 9.2 years; 6 males) and without congenital color vision deficiency were included in the study. The control group (mean age = 27.8 ± 6.3 years) comprised 17 color normal (10 males) and 10 color deficient (8 males) subjects. Visual stimulation was based on pseudoisochromatic tests: the target was a mosaic made of small chromatic dots on a borderless background with random varying luminance (mean luminance = 11.9 ± 0.2 cd/m2) presented dynamically (10Hz). Color vision thresholds were measured from the reference stimulus (background mean chromaticity: u’=0.1894, v’=0.4415, CIE1976) towards u’=0.3187, v’=0.4583, approximating protan and towards u’=0.1821, v’=0.2354, approximating tritan confusion lines with a 3D calibrated (LG) display using interleaved polarization via 3D goggles. Measurements were performed monocularly and dichoptically (non-tested eye viewing background noise). Color deficient subjects also performed the Cambridge Colour Test (CCT) to characterize their color deficiency and to validate the new test.
Results :
There was high correlation between our monocular condition and CCT thresholds, especially for the protan vector (Spearman rho(N=9)=0.82, p=0.007, rho(N=9)=0.70, p=0.036 for protan and tritan, respectively). In the monocular condition, interocular differences were comparable for both protan and tritan thresholds (group main effect: F(2,34)=2.04, p =0.14, group*vector F(2,34)=0.70, p =0.50) among the groups, both eyes having similar thresholds (single mean t-test against zero mean: all t≤1.92, p≥0.09). On the other hand, protan and tritan interocular thresholds were significantly elevated in amblyopic subjects under dichoptic condition compared to both color normal and color deficient subjects (main effect of group: F(2,34)=7.70, p=0.0017, group*vector F(2,34)=0.40, p=0.67). Most likely, this increase is the result of unbalanced binocular interactions preventing the background noise presented to the amblyopic eye to influence color perception of the dominant eye in amblyopic subjects.
Conclusions :
The results emphasize potential use of dichoptic stimulation to measure color thresholds when evaluating amblyopic status as well as to test the effects of amblyopic treatment for visual improvement.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.