The Genetic and Environmental Factors for Keratoconus

Table 2

Population-based epidemiological studies of KC.

Author	Location	Age in years (mean)	Sample size	Prevalence/100,000 (cases)	Method	Sampling method
Hofstetter (1959) [65]	Indianapolis, USA	1–79	13345	120 (16)	Placido disc	Rural volunteers
Santiago et al. (1995) [66]	France	18–22	670	1190	Topography	Army recruits
Jonas et al. (2009) [33]	Maharashtra, India	>30; (49.4 ± 13.4)	4667	2300 (128)	Keratometry	Rural volunteers (8 villages)
Millodot et al. (2011) [27]	Jerusalem, Israel	18–54; (24.4 ± 5.7)	981	2340 (23)	Topography	Urban volunteers (1 college)
Waked et al. (2012) [67]	Beirut, Lebanon	22–26	92	3300 (3)	Topography	Urban volunteers (1 college)
Xu et al. (2012) [68]	Beijing, China	50–93; (64.2 ± 9.8)	3166	900 (27)	Optical low coherence reflectometry	Rural + urban volunteers
Hashemi et al. (2013) [69]	Shahrud, Iran	50.83 ± 0.12	4592	760 (35)	Topography	Urban volunteers from random cluster
Hashemi et al. (2013) [70]	Tehran, Iran	14–81; (40.8 ± 17.1)	426	3300 (14)	Topography	Urban volunteers (stratified cluster)
Shneor et al. (2014) [41]	Haifa, Israel	18–60; (25.05 ± 8.83)	314	3180 (10)	Topography	Urban volunteers (1 college)
Hashemi et al. (2014) [71]	Mashhad, Iran	20–34; (26.1 ± 2.3)	1073	2500 (26)	Topography	Urban volunteers (stratified cluster in 1 university)

The methods for detecting KC used in these studies are now considered inadequate and the results should be interpreted with caution.