Abstract
M.Sc. (Optometry)
The difference between objective automatic and subjective
clinical refraction is studied using new statistical techniques.
The question, by how much the two refraction techniques differ,
is investigated by subtracting the subjective refraction finding
from the auto refractory finding and then examining the
distribution of the difference or excess as it will be called
here. Computerized procedures were developed to automate
mathematical and statistical methods of analysis. The methods
were applied to two different samples: one of patients visiting
an ordinary optometric practice (the clinical sample) and the
other of children refracted in a screening program (the sample
of school children) .
The clinical sample, consisting of mainly older patients, is
examined first. The difference between the autorefractor and
subjective findings is studied and described. This difference
could be used to compare different types of auto refractors
assuming that the subjective refraction is correct. For the
purpose of this study, however, the results of eight
autorefractors are grouped together, combining left and right
eyes, to serve as basis for studying the older population.
The study shows that on the average there is no clinically
significant excess. This means that there is on average no
clinically significant difference between the automatic and
clinical refraction for this population.