Comparing accommodative function between the dominant and non-dominant eye

Background: To compare the accommodative amplitude (AA), facility (AF), and lag between dominant and non-dominant eyes. Methods: Seventy students [mean (SD) age: 21.2 (1.7) years, range 18-25] from Zahedan University of Medical Sciences were selected. Retinoscopy and subjective refraction was used to determine the refractive error. The hole-in-the card method was used to determine eye dominance. The accommodative amplitude (AA) was measured in the dominant and non-dominant eye using the push-up method, and accommodative facility (AF) using ±2.00 dioptre flipper lenses at 40 cm. Accommodative lag was determined using monocular estimate method (MEM) retinoscopy at 40 cm. Results: The right eye was dominant in 53 subjects (75.7%). There was no significant difference in refractive error (sphere, cylinder, and spherical equivalent) between dominant and non-dominant eyes. The mean (SD) for the AA, AF, and lag in dominant eyes was 12.48 (2.56) dioptres, 12.45 (4.83) cycles per minute, and 0.80 (0.27) dioptres respectively. The mean (SD) for the AA, AF, and lag in non-dominant eyes was 12.16 (2.37) dioptres, 12.20 (4.88) cycles per minute, and 0.83 (0.28) dioptres respectively. The mean (SD) difference in AA, AF, and lag between dominant and non dominant eyes was 0.32 (0.75) dioptres (P=0.001), 0.25 (1.05) cycles per minute (P=0.04), and -0.02 (0.11) dioptres (P=0.10) respectively. The AA and AF was statistically better (P<0.05) in the dominant eye group than in the non-dominant eye group. These data provided little evidence of any difference in the accommodative lag between dominant and non-dominant eyes (P>0.05). Conclusion: The right eye was dominant in 76% of subjects. Superior AA and AF was found in the dominant eye as determined by hole-in-the card method in young healthy adults, although these differences are perhaps not of clinical significance (<0.50 dioptres and <2 cycles per minute).