Final Amount of Myopic Refractive Error and Family History of Myopia

Abstract

Abstract: : Purpose:The final amount of myopic refractive error developed in adults is in some way related to the rate of progression of myopia during youth. Previous research has found an association between family history and presence of myopia. It is possible that family history could also be related to the final amount of refractive error developed. If that were true, then family history of myopia could have predictive value for the amount of refractive error a subject would develop after first lens prescription. This work was developed to find a possible association between family history of myopia and final refractive error. Methods: Consecutive myopic adult outpatients attending to a Clinic were enrolled during the year 2003. They received a subjective refractive examination and a questionnaire concerning age of onset of lens use, academic achievement, and parental history of myopia. The refraction in adulthood was considered the final amount of myopic refractive error. Results: Among the 37 subjects with high myopia (> 6 diopters) 70% had at least one myopic parent. There were 271 subjects with simple myopia (lower than 6 diopters) and among them 58 % had at least one myopic parent. In this last simple myopic group, the presence or absence of family history of myopia was not associated with either the final average refractive error (–3.2 ± 1.5 diopters and –2.9 ± 1.3 diopters respectively, p = 0.08) or the age of onset of lens use (17.0 ± 6.2 years vs. 18.1 ± 6.7 years respectively, p = 0.15). Besides, in this simple myopic group, 32 % of subjects turned to develop low amounts (<2 diopters) of final myopic refractive error. When the subjects with high myopia were included for the analysis, a small significant difference in final refractive error could be found (–4.2 ± 3.1 diopters for positive family history vs. –3.3 ± 1.9 diopters for no family history, p = 0.0054). Conclusions: In this retrospective study of a clinical sample of mild and moderate myopic subjects, family history of myopia did not show predictive value for either the age of first prescription, or the final refractive error developed in adulthood. Besides, nearly 1/3 of these myopic subjects turned to develop myopia of low amount (under 2 diopters); these subjects surely had a very slow progressing myopia when they were developing their refractive error. A drug used to arrest myopia progression should be used preferably in those subjects who have progressive myopia and not in those with stable myopias. When a safe treatment is available, these subjects could avoid such treatment if they could be identified prospectively.

Keywords: myopia • refractive error development • clinical (human) or epidemiologic studies: risk factor assessment