Fixation stability during the Rarebit Fovea Test

Abstract

Abstract Purpose: To evaluate the fixation stability in normal subjects during the Rarebit Fovea Test (RFT). The RFT is a computerized test designed to evaluate the integrity of the central retinal detector matrix. Methods: 11 healthy subjects with visual acuity ≥ 1.0, were examined, using the standard RFT setup, i.e. stimulus presentation on a 17 inch computer screen at a viewing distance of 2 m. The test principle is to briefly present one or two very small (< 0.5’) and bright dots in the central 4x3º visual field. The subject responds by clicking the computer mouse once or twice. The test time is approximately 90 sec and audio‐stimulation is given each time the fixation target is rotated in order to enhance central fixation. Fixation stability was measured during the RFT test using the PowerRefractor™ (Purkinje image eye‐tracking).One eye in each subject was tested. All measurement data were analyzed using SPSS and Matlab. Results: All subjects had normal RFT test results, i.e. close to 100% of the presented dots were perceived. 97% of the testing time fixation was maintained within 1.38° and 100% of the time within 2.76°. Conclusions: Normal subjects appear to maintain stable fixation during the RFT. Further studies of patients with minor macular changes are underway.