Abstract
Purpose :
Suppression plays a key role in the binocular deficit and yet there is no clinical gold standard to quantify it. A new clinically convenient tool, the Dichoptic Contrast Ordering Test (DiCOT), was developed for measuring the degree of imbalance based on perceived contrast on a handheld device. The goal was to compare the test-retest reliability of two recent clinical tests for suppression, one that measures surround suppression (DiCOT) and the other overlay suppression (Dichoptic Letters Test: DLT), on participants with normal vision, using a variety of different methods to introduce interocular imbalances that result in suppression.
Methods :
Interocular suppression was measured twice, using the DLT and the newly developed DiCOT in 12 adult participants (19-71 yrs) with normal or corrected-to-normal vision. Their vision was deprived by placing either a Bangerter filter, a 1ND filter or a Lens +3 in front of one eye. Deprivation of both eyes and a control (no filter) condition were measured, making a total of 7 conditions by subject. Test-retest reliability was evaluated using Pearson’s Product Moment Correlation coefficient and Bland and Altman difference plot for both tests.
Results :
Pearson’s correlations coefficient of r = 0.915 (p < 0.001) for the DiCOT and r = 0.971 (p < 0.001) for the DLT demonstrated excellent agreements between the first and second measurements across the various conditions of interocular imbalance for both assessment methods. The Bland and Altman mean difference values of − 0.304 (p<0.001) for the DiCOT and 0.147 (p<0.001) for the DLT, indicated the absence of significant bias in both tests. The magnitude of the DLT was larger than that of the DiCOT. Pearson’s correlation coefficient of r = 0.554 (p < 0.001) demonstrated strong agreement between the two interocular suppression assessment methods.
Conclusions :
The test-retest reliability was excellent for both the DiCOT and DLT under different viewing conditions designed to affect interocular balance. Comparisons between the two tests reveal that the two are measuring distinct aspects of binocular imbalance. The DLT (overlay suppression) resulted in higher values than the DiCOT test (surround suppression). Despite difference in magnitude, most likely reflecting suppression of different origins, there was a strong agreement between these two complementary interocular suppression assessment methods.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.