Abstract
Purpose:
To investigate the effects of near additions and prismatic lenses on accommodative micro-fluctuations and horizontal heterophoria in Chinese myopic children.
Methods:
14 myopic children (SE: -0.75D to -3.75D) aged from 9 to 13 participated in the study. Accommodative micro-fluctuations and horizontal heterophoria were measured through multiple lenses by means of an open-field infrared autorefractor (WAM-5500, Grand Seiko Co., Ltd., Hiroshima, Japan) and modified Thorington technique. Tested lenses were additions (-1.00, 0, +1.00, +2.00 and +3.00D on each eye) and horizontal prisms (3ΔBI, 2ΔBI, 1ΔBI, 0, 1ΔBO and 2ΔBO on each eye). Lens order was randomized. During accommodation measurements, children were looking at RSVP (rapid serial verbal presentations) of Chinese characters at 25cm.
Results:
RMS (root mean square) of accommodative response increased significantly in the condition of -1.0D near addition (0.28±0.11D) compared to plano lens (0.18±0.06D, p<0.001). No significant difference in RMS was found between plano and positive addition lenses (p > 0.05), even though smaller RMS were found for +1.0D and +2.0D lenses (respectively 0.14±0.05D, 0.13±0.15D). No significant difference in RMS was found between prismatic lenses (p=0.22). Heterophoria decreased (more exophoric) with plus-power addition lenses (p<0.001) and increased with base-in prismatic lenses (p=0.038). RMS was found to be correlated with the phoria state (r = 0.345, p < 0.001).
Conclusions:
Over-correction resulted in higher accommodative micro-fluctuations while plus-power addition lenses and prismatic lenses had no influence on accommodative micro-fluctuations. Phoria decreased with plus-power addition lenses and increased with base-in prismatic lenses.
Keywords: 404 accommodation •
605 myopia •
751 vergence