Objective: To discuss accommodative lag and near phoria varying with the near addition lenses and establish the mathematic equations of near adds and accommodative lag, near phoria respectively in order to getting the optimal adds, which would create the least error in accommodative and convergence responses.
Methods: To measure accommodative lag by Shin-Nippon and near phoria by Cover Test in 33 cm after providing 0D, +0.75D, +1.50D, +2.00D, +2.50D five near adds orderly to myopes after 110 simple myopes with esophoria have been corrected far vision wholly basing on MPMVA norm; to analyze the relation of near adds and accommodative lag, near phoria by linearity regression.
Results: While increasing dioptric value of the near adds, accommodative lag and esophoria decrease gradually. Both accommodative lag [F(262.76, 4), P < 0.01]and near phoria [F(223.45, 4), P < 0.01] show statistically significant difference among the five near adds. There is linearity correlation between the optimal adds and initial accommodative lag (r = 0.526, P < 0.01) and between the optimal adds and initial near phoria (r = 0.523, P < 0.01).
Conclusion: The range of optimal near adds can be gotten basing on initial accommodative lag and near phoria of myopic individual, so that it can be provided referenced strategy of determining the customized near addition lens for juvenile esophoric myopes.