Evaluation of newly-developed aniseikonia testing method based on space eikonometry.

BACKGROUND: We have developed a new aniseikonia testing method based on the space eikonometry (ATSE) principle. The purpose of this study was to compare aniseikonia obtained by the ATSE to that of the conventional new aniseikonia tests (NAT), which is commonly used in Japan. METHODS: Thirty normal subjects (mean age: 22.8 years) without ocular disease except for refractive errors were studied. All of the subjects had normal binocular single vision with stereopsis. We excluded subjects with refractive errors greater than 1.00 D cylinder or anisometropia (spherical equivalent) greater than 1.00 D. We simulated overall aniseikonia of five and 10 per cent with afocal size lenses (HOYA, Tokyo, Japan) placed in the optical path of the fully corrected right eye. We measured aniseikonia three times with either the ATSE or NAT and the averages were used for the statistical analyses. RESULTS: The mean and standard deviation (SD) of aniseikonia determined by the ATSE was 5.1 ± 0.8 per cent with the five per cent afocal lens and 10.1 ± 0.8 per cent with the 10 per cent afocal lens. Aniseikonia was 2.8 ± 1.3 per cent with the five per cent afocal lens and 6.0 ± 2.5 per cent with the 10 per cent afocal lens by the NAT. The mean error was + two per cent of the theoretical value by the ATSE and -42 per cent by the NAT for both afocal lenses. CONCLUSION: We recommend the use of the new ATSE for quantitative determination of aniseikonia, as it is more accurate than the NAT.