CHANGES IN OCULAR REFRACTION AND ITS COMPONENTS AMONG MEDICAL-STUDENTS - A 5-YEAR LONGITUDINAL-STUDY

Purpose. Myopic progression has been noted, especially during the peri od of puberty. It is interesting to investigate whether myopia will pr ogress after the age of puberty and at what rate the changes in ocular components occur during its progression. Methods. A 5-year longitudin al study was made of refraction and its components among 345 National Taiwan University medical students (690 eyes). The examinations includ ed corneal curvature and cycloplegic refraction measured by auto-refra ctor and retinoscopy, and axial length measurement with A scan ultraso nography. The same procedures and instruments were used again after 5 years. Results. The myopic prevalence increased from 92.8 to 95.8%; 21 new cases of myopia developed in the 5 years. The mean refractive err or significantly increased from -4.26 +/- 2.66 D of freshmen to -4.94 +/- 2.70 D of clerks. The change in refractive error at the 5-year fol low-up was 0.70 +/- 0.65 D more myopic for males and 0.54 +/- 0.64 D f or females. The main change in the ocular components was in axial leng th, which increased from 25.54 to 26.05 mm in males and from 24.60 to 24.95 mm in females. Other optical components-including corneal curvat ure, anterior chamber depth, lens thickness-all remained relatively un changed from the initial values. Conclusions. Myopia can progress afte r the age of puberty, but at a slower rate than during childhood. Axia l elongation of the eyeball is the main component that changes in myop ic progression.