The association of astigmatism and spherical refractive error in a high myopia cohort.

Publications // Young Lab // Apr 01 2005

PubMed ID: 15829852

Author(s): Heidary G, Ying GS, Maguire MG, Young TL. The association of astigmatism and spherical refractive error in a high myopia cohort. Optom Vis Sci. 2005 Apr;82(4):244-7. PMID 15829852

Journal: Optometry And Vision Science : Official Publication Of The American Academy Of Optometry, Volume 82, Issue 4, Apr 2005

PURPOSE The purposes of this study were to determine whether the degree of myopia influences the presence and degree of total astigmatism, and to assess risk factors of astigmatism in patients with familial nonsyndromic severe myopia.

METHODS We performed a retrospective study of 217 subjects from families with two or more subjects from successive generations with a myopic spherical refractive error of at least -5 D or greater in one eye. Mean myopic spherical equivalent was -10 D and the mean age of myopia onset was 7 years. Refractive error measurements were obtained and the association between the degree of myopia and cylinder power was examined by correlation analysis.

RESULTS The prevalence of astigmatism (1.0 D of cylinder) was 36.1%. With-the-rule astigmatism was most common (55.8%), and the majority of astigmats had between 1.0 and 2.5 D of cylinder (77.6%). Statistically significant associations were found between the presence of astigmatism and risk factors of age and the age of myopia onset. In those patients with astigmatism, however, there was a moderate correlation between the degree of spherical equivalent and cylinder power (r = -0.34, p < 0.0001). Younger age (<16 years) (p = 0.03) was associated with higher cylinder power.

CONCLUSIONS In severely myopic patients, there is a high prevalence of astigmatism that is predominantly with-the-rule. The degree of myopic spherical refractive error is correlated with astigmatism severity but is not a risk factor for the presence of astigmatism.