For many years the exact mechanisms of environmentally induced myopia have been sought. Many have investigated the roles played by the accommodative and vergence systems in this type of myopia. The present study sought to expand the knowledge base regarding the role of the vergence system by comparing the vergence adaptability of late-onset and early-onset myopes. Fixation disparities were measured on forty first year optometry students, before and after a nearpoint task comprised of reading while wearing base out prism. Information comparing the levels of psychological stress and anxiety between the two groups was also gathered, using the State-Trait Anxiety Inventory and the Stress-Arousal Check List. No significant differences were found in the fixation disparity data. In the psycholgical stress/anxiety data one significant difference was found between groups regarding trait anxiety. Conclusions and suggestions for future work are discussed.
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