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Michela Fresina, Chiara Basiricò, Giuseppe Giannaccare, Piera Versura, Emilio C. Campos; Myopia And Astigmatism: Is There A Correlation?. Invest. Ophthalmol. Vis. Sci. 2012;53(14):155.
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To find a possible correlation between myopia and astigmatism.
Refractive and keratometric data from 177 eyes of 177 patients (58 M and 119 F; aged 4 to 59 years; mean age 31±16 SD) with myopia of more than 1.25 diopters (D) and myopic astigmatism of more than 0.25 D, were retrospectively analyzed. All patients were divided into two different groups according to the degree of myopia: Group 1: 0-6 D and Group 2: >6 D. Exclusion criteria were: best corrected visual acuity less than 20/25, previous ocular surgery or disease, nystagmus, cataract or corneal abnormalities, contact lens wearing within 3 weeks, systemic diseases associated with ocular diseases, irregular corneal astigmatism. Objective cycloplegic refraction by streak retinoscopy was performed in all patients 20 minutes after the last of 3 instillations (every 5 minutes) of cyclopentolate eye drops. Statistical analysis using correlation coefficient Pearson’s R was performed in order to determine the correlation between myopia and total astigmatism first in the entire sample then in three different age groups (infantile group: 4-8 years; juvenile group: 9-23 years; adult group: 24-59 years). Student T test for independent variables was performed in order to demonstrate the different astigmatism trend between group 1 and group 2.
An inverse correlation between myopia and total astigmatism in the entire sample (r=-0.28; p=0.0001) was found , particularly evident in patients aged 9 - 23 years (r=-0,47; p=0,0002). A statistically significant higher astigmatism was also detected in Group 1 patients as compared with that one highlighted in Group 2 (1,65±1,04; 0,83±0,51; p<0,0001). No statistically significant differences according to gender were present.
A statistically significant decrease of total astigmatism when myopia increases, particularly evident in juvenile subjects was found, unlike results presented previously for a smaller patients sample (Kaye SB, Patterson A. Association between total astigmatism and myopia. J Cataract Refract Surg. 1997; 23:1496-1502). Astigmatism tends not to change significantly with age. Therefore, the presence of high astigmatism at an early age could be a possible negative predictor of severe myopia development during life.
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