Stereoacuity of Normal Subjects Assessed by Frisby Davis Distance Stereotest

ABSTRACT

PURPOSE: The Frisby Davis Distance (FD2) Stereotest has been introduced to measure distance stereoacuity. The purpose of this study is to establish the range of normal distance stereoacuity responses on the FD2 Stereotest in a normal population. METHODS: This study comprised 65 subjects. All had best corrected vision of 20/25 or better in each eye at distance, 1.0 diopters or less of anisometropia, 8 prism diopters or less of phoria on alternate cover test at both distance and near, binocular fusion on the Worth four dot test and stereopsis on Titmus test. Distance stereoacuity was measured using the FD2 stereotest. RESULTS: The mean age of the subjects was 18.6 years (range, 3 to 59). The mean stereoacuity for distance was 15.61+/-10.41 sec (seconds of arc), and the mean stereoaucity of the subject over 10 years old was 12.98+/-6.86 sec. Results of the test-retest variability as well as of different test distances revealed no statistically significant differences. Of 60 subject with one eye closed, 11 (18.3%) of them detected the disparity of 200 sec but none could detect smaller disparity except one. CONCLUSIONS: The FD2 Stereotest is reliable test without test distance variance. The results of this study can be used as a normative data of distance stereoacuity by FD2.