To clarify the effect of addition +0.75D lenses on different distance of accommodative lag and accommodative fluctuations during near reading.

Clinical case control study. There were 50 students from Tianjin Medical University investigated during September to November 2015, professional optometry and binocular vision were performed on the 50 students. The accommodative lag was measured when they viewed binocular vision in completely corrected lenses and addition +0.75D lenses states, the target was put on 50, 40, 33, 25, 20cm. Open field infared autorefractor measured accommodative response when the subjects read in 40cm.

With right eyes as subjects. All the subjects performed the increasing of the accommodative lag with the decreasing target distance (except 20cm). Accommodative lag decreased when viewed target at addition +0.75D lenses state in every distance (t=3.900, 3.737, 5.149, 6.022, 5.445, P <0.05). Under the completely corrected lenses state, the accommodative lag of the esophoria were significantly greater than the exophoria (except 25cm and 20cm) (t=-4.002, -2.569, 2.440, P <0.05). Accommodative fluctuations also decreased when reading at 40cm with addition +0.75D lenses (t=3.465, P <0.05). Under the completely corrected lenses state, the accommodative fluctuations in the emmetiopic group were significantly lower than in the low myopia and moderative myopia. Accommodative fluctuations were negatively correlated with amplitude of accommodation (r=-0.500, P <0.01).

In order to prevent degenerative myopia, the myopia with normal amplitude of accommodation can wear addition +0.75D lenses when they read in near distance, especially for the esophoria. Whether the abnormal amplitude of accommodation can wear addition +0.75D lenses need to be elucidated in the future study.

Accommodative lag; Accommodative fluctuation; Hetherophoria; Amplitude of accommodation