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Refractive changes among Norwegian university students--a three-year longitudinal study.

PURPOSE
The aim of this study was to investigate the changes in refractive error during a three-year period among university students exposed to high educational demands.


METHODS
A three-year longitudinal cohort study was performed among 224 Norwegian engineering students (mean age 20.6 years, 117 females and 107 males) measuring their refraction at the beginning and the end of the period. The examinations included automated and clinical refraction in cycloplegia. A total of 192 students (100 females and 92 males) completed the study.


RESULTS
In the student population under study the prevalence of myopia increased significantly from 48% to 65% (p<0.001, right eye) and the mean refractive error increased significantly from -0.64+/-2.18 D (n=224) to -1.21+/-2.30 D (n=192) (p<0.001, right eye) during the period. Of eyes emmetropic at the start of the study (n=49, right eye), 59% became myopic. Among the eyes initially myopic (n=92, right eye), 73% progressed further into myopia, with at least -0.37 D during the three-year period. Of eyes initially hyperopic (n=51, right eye), 8% became myopic, while 14% became emmetropic.


CONCLUSIONS
A shift in refraction towards myopia is frequent among university students during their study period.