Subjective measurement of peripheral refraction

The quality of the peripheral image affects several visual aspects. In particular, eye shape, determined by peripheral refraction, has been shown to be an important factor associated with refractive error in children. For this reason, analysis of off-axis refractive error is one of the subjective measurements that should be performed during refractive procedures. Peripheral refraction refers to the position of the focal point of light radiation reaching the eye when horizontal rays are focused on fovea, outside primary visual axis. Recent studies have found that peripheral refractive error plays an important role in the development of myopia: myopic individuals show hyperopic defocus unlike emmetropes or hyperopes, who have myopic defocus at the peripheral level; thus, in order to focus objects located in the peripheral visual field on the retina, the bulb is prone to elongation. The aim of the study was to develop a method for measuring peripheral refraction, accessible to all clinicians without special instruments, and that can be performed during the refractive examination to obtain an additional finding in addition to the central refractive data.