Abstract
Background: The prevalence of myopia is increasing worldwide. Several studies were reported about myopia progression in the adult population with a high level of education.
Objective: To investigate the changes in refractive errors, biometric measurements, and environmental variables among medical university students during two years in Brazil.
Methods: A two-year longitudinal prospective study was proposed. Cycloplegic refractive examinations were conducted, and corneal topography and ocular optical biometry. The lens power was calculated by Bennett and Rozema’s formula. A questionnaire on lifestyle visual activities was applied. Only participants with normal ophthalmological exams were included in the study. Statistical significance was assessed at the level of 0.05.
Results: One hundred twenty-eight students were eligible for the first exams and 89 (69.53%) completed the two-year follow-up. The mean age at baseline was 21.00 ± 1.92 years. Thirty-seven (41.57%) participants were males. Regarding refractive errors, 11 (12.36%) were hyperopic, 28 (31.46%) were emmetropic, 45 (50.56%) were myopic, and 5 (5.61%) were high myopic. There was a positive correlation between refraction and axial length in all groups, and a negative correlation with lens power. No significant two-year change in Km was found in all groups. The average of hours per day spent in outdoor and near-work activities were 1.36 ± 0.8 and 8.66 ± 1.77 h, respectively.
Conclusion: The results showed that the main correlation to change in refraction was axial length. There were some cases of myopia progression in myopic students. The contribution of crystalline lens power for keeping slow myopia progression was significant.