Related Experiment Video
Updated: Aug 18, 2026
Quantification of Oculomotor Responses and Accommodation Through Instrumentation and Analysis Toolboxes
Published on: March 3, 2023
Accommodation, accommodative convergence, and response AC/A ratios before and at the onset of myopia in children
Jane Gwiazda1, Frank Thorn, Richard Held
1Myopia Research Center, The New England College of Optometry, Boston, Massachusetts 02115, USA. gwiazdaj@neco.edu
Purpose:
The purpose of this study was to investigate accommodation, accommodative convergence, and AC/A ratios before and at the onset of myopia in children.
Methods:
Refractive error, accommodation, and phorias were measured annually over a period of 3 years in 80 6- to 18-year-old children (mean age at first visit = 11.1 years), including 26 who acquired myopia of at least -0.50 D and 54 who remained emmetropic (-0.25 to + 0.75 D). Refraction was measured by noncycloplegic distance retinoscopy. Concomitant measures of accommodation and phorias were taken for letter targets at 4.0 m and 0.33 m using the Canon R-1 open field-of-view autorefractor with an attached motorized Risley prism and Maddox rod. The accommodation and phoria measurements were used to calculate response AC/A ratios.
Results:
Compared with children who remained emmetropic, those who became myopic had elevated response AC/A ratios at 1 and 2 years before the onset of myopia, in addition to at onset and 1 year later (t's = -2.97 to -4.04, p < 0.01 at all times). The significantly higher AC/A ratios in the children who became myopic are a result of significantly reduced accommodation. Accommodative convergence was significantly greater in myopes only at onset.
Conclusions:
These findings suggest that the abnormal oculomotor factors found before the onset of myopia may contribute to myopigenesis by producing hyperopic retinal defocus when a child is engaged in near-viewing tasks.
