Table 1.

Characteristics of subjects with and without pterygium

Pterygium	Subjects with any pterygium† (n = 101)	Subjects without any pterygium (n = 2211)	p-value	Subjects with bilateral pterygium‡ (n = 36)	Subjects without bilateral pterygium (n = 2276)	p-value
Age (years)	66.7 ± 7.4	64.2 ± 8.0	0.002	68.6 ± 6.6	64.2 ± 8.0	0.001
Gender (male/female)	37/64	906/1305	0.444	14/22	929/1347	0.950
Outdoor job history*	29.7%	22.3%	0.108	36.1%	22.5%	0.082
Smoking history	12.9%	14.3%	0.795	11.1%	14.3%	0.762

^*Outdoor jobs include full-time and part-time outdoor jobs during the lifetime of the subject.

^†Any pterygium is defined as pterygium in either eye or both eyes.

^‡Bilateral pterygium is defined as pterygium in both eyes.

p-value for subjects with pterygium versus without pterygium (unpaired t-test or chi-square test).