An investigation of stimulus and response AC/A ratios in myopia based on MEM dynamic retinoscopy

Abstract

Objective To study the correlation between the stimulus and response AC/A ratios by measuring a patient's accommodative lag and eye position using different stimuli to induce accommodation.Methods A cross-sectional study was used.Twenty-nine myopic college students (average age 23.3±3.8) were randomly selected for the study.Phoria was measured at distances of 40 cm and 5 m by prism separation when wearing full correction.Phoria was measured again at a distance of 40 cm after adding spherical lenses of +1.00 D,+1.50 D,-1.00 D and-2.00 D.Accommodative lag was then measured with each lens power by the monocular estimation method using dynamic retionscopy.Finally,the data were analyzed by a rank-sum test.Results There were statistically significant differences between accommodative lag and gradient response and stimulus AC/A ratios when different accommodative stimuli were used (x2=116.85,8.992,17.319,P＜0.05).The correlation coefficients between response and stimulus AC/A ratios based on the gradient method were 0.542 (P＜0.01),0.789 (P＜0.01),and 0.812 (P＜0.01) with added lenses of +1.00 D,-1.00 D,-2.00 D.And the correlation coefficient between response and stimulus AC/A ratios based on the calculation method was 0.859 (P＜0.01).Conclusion A subject has less accommodative response and more accommodative lag with minus spherical addition than with a plus spherical addition lens.The correlation between stimulus and response AC/A ratios is highest when using a calculation method. Key words: Myopia; Lag of accommodation ; Accommodative convergence/accommodation