Abstract
M.Phil. (Optometry)
The accommodative-convergence accommodation (AC/A) ratio is
a commonly used relationship in the practice of optometry.
Many practitioners make use of the AC/A ratio as an aid to
diagnostic and prognostic decisions.
It is not perfectly clear what effects positive and
negative lenses have on the AC/A ratio. A number of
questions remain relating to linearity, symptomatology and
equality of lens effects on the AC/A ratio. This experiment
was designed and conducted in an attempt to answer some of
these unanswered questions and forms the foundation of this
thesis.
A literature review of available knowledge related to this
study is detailed. An instrument is described which was
constructed to measure the necessary accommodation and
vergence changes induced by various stimuli.
A sample of first year students at the Rand Afrikaans
University department of Optometry was selected according
to various acceptance criteria. A total of 109 students
were screened , of which a group of 26 students was
subjected to the experimental investigation. The data were
then subjected to a statistical analysis in an attempt to
reveal correlations, linearity and group formations.