Differences in accommodative response and pupillary constriction during the near response among various refractive errors

抄録

The purpose of our study was to simultaneously measure and compare accommodation and pupillary constriction during the near response among hyperopia, emmetropia, and myopia (refractive errors). We examined 60 normal eyes of 30 subjects (10 males, 20 females) without signs of disease, aged 20–26 years (mean 21.2 years). The refractive error ranged from +5.50 diopters (D) to −8.50 D and was used to divide subjects into five groups of 12 eyes each: hyperopia, emmetropia, low myopia, moderate myopia, and high myopia groups. The gain of accommodation (%) and pupillary size (mm²) to step stimulus of +5 D were measured under adequate correction of refractive errors using a refraction/accommodation measurement device. The high-myopia group exhibited low gain of accommodation (76.7%) and maximum change in pupillary size (13.03 mm²). In contrast, the hyperopia group exhibited low gain of accommodation (72.5%) and minimum change in pupillary size (5.50 mm²). We observed differences in accommodation and pupillary responses in the context of different refractive errors. In high myopia, the large pupillary constriction in the near response compensated for weak accommodation, even at young ages. In hyperopia, small pupillary size daily compensates for accommodation by increasing the depth of focus; therefore, subjects could clearly view near objects despite the weak accommodation and small pupillary constriction.