Reliability of power measurement of toric soft contact lenses.
We studied the reliability of lensometer measurements of hydrated toric soft contact lenses in air and compared them to similar measurements of toric hard contact lenses and a spherocylindrical spectacle lens. Twenty measurements were made of each of five soft lenses, three hard lenses, and one spectacle lens. One-half of the measurements used an eyepiece lensometer and one-half a projection lensometer. The reliability of the technique was found to be lower for soft lenses than for hard lenses and highest for the spectacle lens. Reliability was sufficiently high for hydrated toric soft lenses with either type of lensometer to support recommendation of a standard tolerance of +/-0.25 D when applied to the mean of five measurements.
D003261:Contact Lenses / Q000592:standards; D003263:Contact Lenses, Hydrophilic / Q000592:standards*; D005139:Eyeglasses / Q000592:standards