Optimal Dioptric Value of Near Addition Lenses for Slowing Myopic Progression

Signature Grand, Davie, Florida, USA

Purpose. The purpose of this study was to determine the optimal power value of near addition lenses, which would create the least error in accommodative and vergence responses. Methods. We evaluated accommodative response, phoria, and fixation disparity when the subject viewed through various addition lenses at three working distances for 30 young adults (11 emmetropic, 17 myopic, and 2 hyperopic). Accommodative response was determined with a Canon R-1 infrared optometer under binocular viewing conditions, phoria was determined by the alternating cover test with prism neutralization, and fixation disparity was measured with a Sheedy disparometer. Results. For each working distance, the data of accommodative response, phoria, and fixation disparity averaged across the 30 subjects were plotted as the function of the power of the addition lenses, respectively. We fitted the data with regression curves to determine the optimal powers of near addition lenses. In addition, we found high correlations between the initial accommodative error and the optimal power of the near addition lenses and between the initial near phoria and the optimal power of the near addition lenses. Conclusions. The results suggest that when the effects of near addition lenses on the accommodative and vergence systems are both considered, the optimal dioptric power of the near addition lens is in a range between +0.20 D and +1.28 D for the three viewing distances. Using progressive lenses to delay the progression of myopia may have promising results if each subject’s prescription is customized based on establishing a balance between the accommodative and vergence systems. Formulas derived from this study provide a basis for such considerations. Grants. This study was supported by NSU HPD grant #335203 and NSU PFRDG grant #335441.