Peripheral overall blur is largely influenced by a combination of defocus and oblique astigmatism, states an investigation in Investigative Ophthalmology and Visual Science.

Dr B. Jaeken et al., Laboratorio de Óptica, Universidad de Murcia, Campus de Espinardo, Murcia, Spain, measured the optical image quality of 202 eyes of 101 subjects with different central refractions.

The relationship between peripheral optics and central refraction was evaluated using various metrics. Average foveal refraction was -0.8, with 64 non-myopes and 37 myopes.

The findings demonstrated that the relative peripheral refraction was significantly different when comparing the emmetropic and myopic eyes from 15° temporal retina and from 20° nasal retina.

The mean relative peripheral refraction metric was linked to the central refraction of the subject. Image quality was similar for a number of refractive groups at angles of 30-40°.

The study could indicate an argument against the previous hypothesis that a relative peripheral hyperopa could cause myopia.