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| Title: | Characteristics of astigmatism as a function of age in a Hong Kong clinical population | Authors: | Leung, TW Lam, AKC Deng, L Kee, CS |
Issue Date: | Jul-2012 | Source: | Optometry and vision science, July 2012, v. 89, no. 7, p. 984-992 | Abstract: | Purpose: To characterize astigmatism as a function of age in a Hong Kong clinical population. Methods: All records from new clinical patients at a university optometry clinic in the year 2007 were used for the study. Only data from subjects with corrected visual acuity ≥6/9 in both eyes and with completed subjective refraction were analyzed. The subjects were divided into seven age groups by decade (i.e., 3 to 10 years, 11 to 20 years, ⋯, >60 years). Refractive errors were decomposed into spherical-equivalent refractive error (M), J0, and J45 astigmatic components for analyses. Internal astigmatism was calculated by subtracting corneal astigmatism from refractive astigmatism (RA). Results: Of the 2759 cases that fulfilled our selection criteria, 58.9% had myopia (M ≥-0.75 D) and 28.4% had RA (Cyl ≥ 1.00 D). The prevalence of RA increased from 17.8% in the 3 to 10 years age group to 38.1% in the 21 to 30 years age group. It then dipped to 25.8% in 41 to 50 years age group but increased again to 41.8% in the >60 years age group. Among the astigmats, almost all 3- to 10-year-old children (92.6%) had with-the-rule (WTR) astigmatism, but a majority of the elderly (>60 years) had against-the-rule (ATR) astigmatism (79.7%). For a subset of subjects who had both subjective refraction and keratometric readings (n = 883), RA was more strongly correlated with corneal (r = 0.35 to 0.74) than with internal astigmatism (r = 0.01 to 0.35). More importantly, the magnitudes of both refractive and corneal J0 were consistent with synchronized decrements (-0.15 and -0.14 D per 10 years, respectively) after the age of 30 years, indicating that the shift toward more ATR astigmatism was related to corneal change. Conclusions: In this Hong Kong Chinese clinical population, the prevalence rates of both myopia and astigmatism increased during the first three decades and shared a similar trend before the age of 50 years. The manifest astigmatism was mainly corneal in nature, bilaterally mirror symmetric in axis, and shifted from predominantly WTR to ATR with age. | Keywords: | astigmatism Hong Kong Chinese myopia prevalence refractive errors |
Publisher: | Lippincott Williams & Wilkins | Journal: | Optometry and vision science | ISSN: | 1040-5488 | EISSN: | 1538-9235 | DOI: | 10.1097/OPX.0b013e31825da156 | Rights: | Copyright © 2012 American Academy of Optometry This is a non-final version of an article published in final form in Optometry and Vision Science: July 2012 - Volume 89 - Issue 7 - p 984-992. The Optometry and Vision Science’s website is available at https://journals.lww.com/optvissci/pages/default.aspx |
| Appears in Collections: | Journal/Magazine Article |
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| File | Description | Size | Format | |
|---|---|---|---|---|
| 1828_Leung 2012_Characteristics_of_astigmatism.pdf | Pre-Published version | 1.92 MB | Adobe PDF | View/Open |
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