marginal reflex distance test 1 and 2(redirected from MRD1, MRD2)
marginal reflex distance test 1 and 2,
A measurement (1) of the distance between the corneal light reflex in the pupillary center, and (2) of the margin of the upper eyelid when the eye is held in primary position. The normal distance is 2.5 mm or greater and is reduced in people with ptotic eyelids. The MRD2 is the distance from the center of the light reflex to the margin of the lower eyelid. This distance is greater than 5 mm in the normal eye.