Corneal shapes of Chinese emmetropes and myopic astigmats aged 10 to 45 years.
OBJECTIVE
Myopia and astigmatism are highly prevalent in the Hong Kong Chinese. This study aimed to determine the effects of age and myopic astigmatism (MA) on the corneal shape factors in the Hong Kong Chinese.


METHODS
One hundred subjects with compound MA or emmetropia (EM) were recruited from three age groups: 10 to 15 years (n = 32), 20 to 25 years (n = 37), and 40 to 45 years (n = 31). Refractive errors were measured by noncycloplegic subjective refraction. Corneal astigmatism and corneal shape factors were measured by the Scheimpflug-based Pentacam. The effects of age and refractive errors on the whole corneal shape (mean-P) and the semimeridian corneal shapes (semi-Ps) at the nasal, temporal, superior, and inferior corneal quadrants (from corneal apex to 3 mm peripheral cornea) were analyzed.


RESULTS
Age had significant effects on the mean-P and semi-Ps (both p < 0.001), with both EM and MA showing less prolate corneal shapes in older age groups. Partial correlation analyses adjusted for age showed that mean-P and semi-Ps were correlated with multiple refractive-error components (Pearson r = -0.30 to -0.78, all p < 0.05), with higher correlations found along the horizontal semi-Ps in MA (Pearson r = +0.37 to -0.78, all p < 0.01). Compared with EM, MA had more prolate temporal semi-Ps in all the three age groups (p < 0.05). Strikingly, age and refractive errors also had significant impacts on the asymmetry of the corneal shape along the horizontal meridian.


CONCLUSIONS
Corneal shapes were influenced by age and MA in the Hong Kong Chinese. These results highlight the importance of controlling these factors when designing a study on corneal shape.
*BSc(Hons)Optom †PDOptom, MPhil, PhD ‡BSc(Hons)Optom, MA, PhD School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Tsz-wing
TW
Leung
Andrew Kwok-cheung
AK
Lam
Chea-su
CS
Kee
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D044466:Asian People / Q000208:ethnology; D001251:Astigmatism / Q000208:ethnology / Q000503:physiopathology*; D002648:Child; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D058453:Emmetropia; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000208:ethnology / Q000503:physiopathology*; D055815:Young Adult