Five year changes in central and peripheral corneal thickness: The Shahroud Eye Cohort Study.
OBJECTIVE
To determine five year changes in corneal thickness from the apex to the 8mm periphery and related factors through a longitudinal population-based study of middle-aged Iranians.


METHODS
In the first phase, 4670 of the 5190 participants, and in the second phase, 4666 of the 4737 participants were examined with the Pentacam. In this report, analysis was done on right eye data of 2509 people who had no diabetes, pterygium, or history of eye surgery, and their image quality was displayed as "ok". Thickness changes in different parts of the cornea and their relation with age, gender, refractive error, and intraocular pressure (IOP) were assessed using repeated measures analysis of covariance.


RESULTS
Corneal thickness reduced by 1.5±11.7μm in the apex, 2.6±11.7μm in the thinnest point, and 5.3±12.2, 7.7±14.3, and 11.4±18.6μm in peripheral rings of 2, 3, and 4mm radius, respectively (all p<0.001 with and without adjusting for baseline thickness). Of the studied thickness variables, only changes in the 4mm ring significantly related with age (p<0.001) and gender (p<0.001); there was less change in older age and in men. Thickness changes were not related to refractive error or IOP (all p>0.05).


CONCLUSIONS
Corneal thickness decreased with age in this sample of 40-64year olds. There was significantly greater thinning in the periphery compared to the corneal center even after controlling for baseline thickness. Results of this longitudinal study can be helpful in understanding age-related changes in the cornea and the eye.
Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
Hassan
H
Hashemi
Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
Soheila
S
Asgari
Shahroud University of Medical Sciences, Shahroud, Iran.
Mohammad Hassan
MH
Emamian
Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
Shiva
S
Mehravaran
Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, P.O. Box 14155-6446, Tehran, Iran. Electronic address: afotouhi@tums.ac.ir.
Akbar
A
Fotouhi
D000328:Adult; D000375:Aging / Q000473:pathology*; D015331:Cohort Studies; D003315:Cornea / Q000473:pathology*; D005260:Female; D006801:Humans; D007492:Iran; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012030:Refractive Errors / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014065:Tonometry, Ocular / Q000706:statistics & numerical data*
Corneal thickness; Longitudinal study; Peripheral thickness; Population-based study