ACCOMMODATION AND PUPILLARY RESPONSE IN EARLY-ONSET MYOPIA AMONG SCHOOLCHILDREN

Purpose. To investigate changes in accommodation and pupillary reactio n in early-onset myopia among children. Methods. An objective infrared optometer and a pupillometer were used to evaluate simultaneously ton ic accommodation, accommodative response, accommodative adaptation, an d pupil diameter in 19 schoolchildren with early-onset myopia and 15 a ge-matched emmetropic controls. Results. Tonic accommodation in the ea rly-onset myopes (1.03 D) was significantly less than in the emmetrope s (1.37 D) (p < 0.05), whereas accommodative response and accommodativ e adaptation showed no significant difference between the early-onset myopes and emmetropes. The average pupil diameter after 20 min of dark adaptation in the early-onset myopes was 4.52 mm, which was significa ntly smaller than that in the emmetropes (5.21 mm) (p < 0.05). During nearwork stimulation, the average pupil diameter further decreased to 3.83 mm in the early-onset myopes and 4.78 mm in the emmetropes (p = 0 .003). Conclusion. These results suggest that low tonic accommodation and small pupil diameter may play important roles in the pathogenesis of early-onset myopia among schoolchildren.