Observer variation in ophthalmology.

Data collected by clinicians and nurses from patients with clinically diagnosed lens opacities revealed that there was poor repeatability of the description of the position of lens opacities, statistically significant observer variation in determining visual acuity, and good repeatability as to what visual tasks the patient can perform. It is suggested that clinicans should give more weight to the visual handicap revealed by performance of visual tasks in making a decision for cataract surgery than at present.