Abstract
Purpose:
Both animal and human studies show that peripheral refraction has an impact on the development of central refractive error. Furthermore, there is evidence indicating the link between near work and myopia progression. The purpose of this study is to investigate the effect of accommodation during near work on peripheral refraction.
Methods:
Twenty six eyes (thirteen young subjects, 8 females and 5 males) with a narrow range of uncorrected refractive errors ranging from -0.50 to +1.00 diopters, and astigmatism less than -1.00 diopters were measured by a Grand Seiko WAM 5500 open field autorefractor. The refractive error was measured in 10° steps up to 30° across both the temporal and the nasal horizontal visual fields. The measurements were repeated with Maltese cross visual targets displayed at 20 ft distance, 40 cm and 25 cm. The near targets were arranged in an arc which allowed maintaining the same accommodative demand throughout the different directions of gaze. Central and peripheral refraction data were converted to power vectors M, J0, and J45.
Results:
Emmetropic eyes did have about 1.0 D myopic shift in 30° periphery. Increasing Against-The-Rule astigmatism was presented in the horizontal periphery. These results are in alignment with previous literature. With stimulated accommodation, there were no statistically significant differences of the peripheral spherical equivalents M and J0 astigmatism. Right eyes showed a positive linear slope of J45 profile across the horizontal visual field which was negative for left eyes. But with increasing accommodative demands, the slope of J45 profiles changed signs. J45 values varied within a range of 0.6 D.
Conclusions:
Near accommodation to 25 cm and 40 cm did not show significant effects on M and J0 components of peripheral refraction in emmetropic subjects. However, near accommodation had major effects on the J45 component. It remains unclear why J45 changed significantly. Further studies are needed to investigate the relationships between J45 and the states of accommodation.
Keywords: 404 accommodation •
676 refraction •
605 myopia