Refractive errors of medical students in Turkey: One year follow-up of refraction and biometry

Abstract

Purpose. This study was conducted to determine the prevalence of refractive errors in Turkish medical students as well as to determine the change in refractive status of medical students within 1 year. Besides general refractive characteristics of the students, the possible relationship between the occurrence of myopia and several factors was also determined. Methods. Two hundred and seven medical students (114 female/93 male) were checked for their refractive status as determined by cycloplegic autorefraction. In addition to keratometric and biometric measurements students also answered a detailed questionnaire. One year later, medical students who participated to the study were re-examined. Results. Myopia occurred in 32.9% of medical students with low myopia (spherical equivalent between -0.75 diopters [D] and -2.99 D) being the most common type (81%). The frequency of myopia was not significantly different between female and male medical students (37.7 and 26.8%, respectively; p = 0.13). Adult onset myopia (onset at age 18 years or older) comprised 14.7% of all myopia cases. Myopic students were significantly more likely to report parental myopia. The percentage of myopes and nonmyopes reporting having one or two myopic parents was 51.5 and 28.8%, respectively (p = 0.002). Parental myopia was also an independent risk factor associated with the occurrence of myopia on multivariate analysis (odds ratio [OR] = 3.69, 95% confidence interval [CI] = 1.98-6.87). Nonmyopes also reported a significantly higher prevalence of outdoor activity before and at age seven (68.4%) than did myopes (48.6%), (p = 0.009). Outdoor activity during early childhood was found to be protective for myopia on multivariate analysis (OR = 0.44, %95 CI = 0.23-0.82). There was no significant difference between myopes and nonmyopes with respect to amount of close-up activity. No significant shift of refraction occurred within 1 year. Conclusions. About one-third of Turkish medical students had myopia. Parental myopia was more common among myopic students and was a risk factor for the occurrence of myopia suggesting a familial predisposition. Outdoor activity in early childhood has had a protective role against the development of myopia in this study sample.