Undercorrection Induces Peripheral Myopic Defocus in School Children in Kumasi, Ghana

The purpose of this study was to determine whether undercorrection single vision lenses altered the peripheral refractive error of myopic school children when targets are viewed at 2m. Seventy four children with mean age of 12.28 ± 1.33 years were assigned to full correction and undercorrection groups. Central and peripheral refraction was measured to 30° in the nasal and temporal retina using a free-space autorefractor. Full correction spectacle lenses caused a hyperopic shiftin spherical equivalence (M) in all peripheral locations (all p=0.001) whereas undercorrection caused a myopic defocus at 4 of the 6 retinal locations (all p=0.001). There were temporal-nasal asymmetries in J180 and J45 astigmatism. Undercorrection spectacle lenses induced more against- the- rule astigmatism at 30° nasal retina than with full correction. At temporal retina, full correction induced more against- the -rule astigmatism than with undercorrection. Undercorrection resulted in a myopic shiftin the horizontal retina of the myopic eye. Children who wear uncorrected spectacle lenses are more likely to have a reduction in myopia progression.