Tritan thresholds of flashed optotypes are markedly elevated in patients with mild retinal changes associated with Age–related Maculopathy, but no loss of visual acuity.

Abstract

Abstract: : Purpose: To provide a simple test that detects the onset of ARM, and can be used to monitor its severity. Methods: Colour –contrast sensitivity was measured using computer – graphics techniques. Colour thresholds were measured along tritan and protan colour–confusion axes in the presence of dynamic luminance noise, with a test algorithm that ensures a predetermined precision has been achieved. Thresholds were determined separately for two sizes of optotypes (6.5º and1.5º). Natural pupils were used. Results: Normal values for the test have been established. In all patients with unilateral AMD, the smaller optotype was invisible in that eye, and in almost all, the larger optotype could not be seen. In the fellow eyes, which were symptomless, the larger optotype thresholds were raised. The degree of loss was larger for tritan hues. For the smaller optotype, protan thresholds were elevated in the majority of patients. Tritan losses were greater and disproportionate to the loss seen with the larger optotype. Every person, including those with minimal fundal changes, had tritan test results for 1.5 degree optotypes > 2 SD above the normal mean. Conclusions: The test is sensitive, simple and quick to administer and easy for patients to take. Therefore, it should be useful in detecting and monitoring elderly persons with age–related changes in their fundi, before irreversible loss of vision has occurred.

Keywords: age–related macular degeneration • retina • color vision