Subjective and objective visual acuity testing techniques
S. G. Khan, K. F. Chen and M. Frenkel
The Catford apparatus for determining the objective visual acuity was
elevated with 20 normal (20 eyes) and 40 abnormal (75 diseased eyes)
patients. The vision of the normal individuals was fogged with
neutral-density filters and convex lenses. Eyes with normal or near normal
vision showed good correlation between optokinetic response and visual
acuity, but no correlation was observed in eyes with poor vision. These
findings, which vary from those of Catford, indicate that objective methods
of visual acuity testing using a nystagmoid response do not appear useful
for general clinical purposes.
