Refractive errors of 567 eyes (286 patients), obtained by independent refractionists using retinoscopic and subjective techniques, were compared with those obtained by a trained technician operating the Ophthalmetron.
The Ophthalmetron was incapable of producing an interpretable tracing in 26% of eyes, primarily because of poor fixation by the patients. The spherical power agreed within ± 0.5 diopter by the two objective methods in 52.6% of eyes. The cylindrical power agreed within ± 0.5 D by the two objective methods in 71.5% of eyes. The cylindrical axis measured by the two objective methods was within five degrees in 40% of eyes.
The principal limitations of the infrared refracting instrument are related to (1) the lack of cooperation in very young and very old individuals; (2) disease states limiting the transparency of the ocular media, such as cataracts; and (3) aphakia.
Bizzell JW, Hendricks JC, Goldberg MF, Patel MK, Robbins GF. Clinical Evaluation of an Infrared Refracting Instrument. Arch Ophthalmol. 1974;92(2):103-108. doi:10.1001/archopht.1974.01010010109005