LARGE-FIELD S-CONE FLICKER TEST

Background: Disturbances of blue color vision and of temporal contrast sensitivity can indicate early damage in glaucoma. For the present st udy a quick and easy test was devised which examines both functions at one time by testing the temporal contrast sensitivity of a blue flick ering light on an intense yellow background. Methods: Large coextensiv e background and test fields (85 degrees) are used, making fixation un critical. Detailed experiments were made in two normal subjects to der ive spectral sensitivity curves from flicker-fusion frequency (FFF) ve rsus intensity functions and to obtain complete temporal contrast-sens itivity (De Lange) curves under different levels of adaptation and tes t lights. After selection of appropriate luminances and one stimulatio n frequency from these experiments, test-retest variability was studie d in four subjects in five repetitions. In addition, normal values wer e collected from 22 subjects. Results Spectral sensitivities for two l evels of FFF (15 Hz and 44 Hz) agree with Stiles' pi(1) at the low and with pi(4) at the high FFF. Temporal contrast-sensitivity curves show a low-frequency section with peak sensitivity at 1 Hz and a high-freq uency section with a peak at around 4 Hz. From the basic experiments t he following conditions for the clinical examination were selected: Ba ckground luminance 2600 cd/m(2), test luminance at 451 nm 0.8 cd/m(2), stimulation frequency 4 Hz. The test-retest variability showed an acc eptable intraclass correlation coefficient (0.6). Conclusions: The pre sent experiments carried out with a very large stimulus led to meaning ful results which are in rather good agreement with results reported i n the literature on small-field stimuli. The blue-on-yellow flicker te st carried out under the conditions mentioned above is a quick and eas y test which could be helpful in improving early glaucoma diagnosis.