الفهرس 
? Epidemiology of astigmatismOnly 14 pages are availabe for public view
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Abstract
Background : Corneal astigmatism is a common refractive error in all age groups , includes anterior and posterior corneal astigmatism (ACA & PCA). With more understanding about astigmatism ,better correction of it will improve quality of vision for all patients.
Aim of the work : To monitor both ACA & PCA and their correlations with age ,with each other and with other tomographic parameters in normal healthy eyes..
Patients and Method : One hundred eighty four eyes of one hundred and thirteen subjects with refractive astigmatism ≥ 0.5 D ,were included in prospective study and evaluated by Pentacam-HR .
These cases were collected from out-patient ophthalmic clinic of Ain Shams University Hospital during the period from July , 2018 till October ,2019.
Results : The mean age of our cases was 39.49 ± 18.02 years old with almost equal sex distribution of male (51.32%) and female (48.67% ). Most eyes had a with- rule astigmatism (WTR) of anterior corneal surface and an against –rule astigmatism (ATR) of posterior corneal surface.
Both ACA and PCA magnitudes were significantly correlated with age ,with all pentacam parameters .ACA had different degrees of correlations with PCA according to ACA axis orientation,
Conclusion: The age has a great effect on ACA rather than PCA . This might modify correction of astigmatism either in refractive surgery or planning and designing new toric intraocular lenses.