Nearsightedness - (Minus Diopters) That condition of the ocular refraction
in which the posterior principal focus of the eye lies in front of the retinal
plane, so that neutral light waves, entering the eye in a state of rest, instead
of focusing on the retina, come to a focus before they reach it, are reversed,
and fall on the retina in diffusion circles of plus waves. |
Far sightedness - (Positive Diopters) That condition of
ocular refraction in which the posterior principal focus of the eye lies back of
the retinal plane, so that neutral light waves instead of focusing on the
retina, fall on the retina in diffusion circles of unfocused waves. |
