The magnitude of pterygium varies widely from 1.1% to
53% globally. Pterygium formation's underlying mechanism is not well
understood. Numerous studies have shown how exposure to ultraviolet (UV)
radiation affects pterygium. Nonetheless, there have been contradictory reports
on the effects of smoking, age, and gender on pterygium. Pterygium's precise
pathophysiology is still unknown. Numerous studies have revealed that race is a
risk factor for pterygium. Research involving two or more ethnic groups may
shed additional light on how lifestyle variations or genetic predispositions
affect pterygium. In this study, about 22 (36.7%) respondents lies between 31
years to 40 years and 18 (30.0%) respondents lies between 20 years to 30 years.
Mean ± SD of the respondents was 39.5 ± 1.3 years. More than half of the
patient 34 (56.70%) were male and 26 (43.30%) patients were female. About 39
(46.9%) were married, 8 (13.3%) were widowed, 5 (8.3%) were divorced and 8
(13.3%) were single. Nearly half of the participants 29 (48.3%) had 4–6 members
in their family. Only 10 (16.7%) of the participants had completed their
college/university, 23 (38.3%) had completed primary school, 21 (35.0%) had
completed secondary school and 6 (10.0%) were illiterate. About 21 (35.0%) were
businessman, 17 (28.3%) were employed, 12 (20.0%) were Farmer/labor and 7
(11.7%) were student. More than half 33 (55.0%) of the participants had a
history of sun exposure for five and more hours per day. Indoor was the working
area more than half 37 (61.7%) of the participants. About 19 (31.7%) of the
participants had a history of dust exposure. Only 16 (26.7%) use sunglasses/hat
for protection. Only 7 (11.7%) had a family history of pterygium. In another
study, there were 400 study participants in the assessment of pterygium with a
response rate of99.50%. The mean age of the study participants was 39.9 ±
9.8years. More than half 219(54.75%) of the study participants were males and
slightly higher than two-third 273(68.25%) of the participants were living in
rural areas. Among the study participants, almost half 206(51.50%) were married
and 179(44.80%) hada family size of 4–6 children in a house. Only 114 (28.50%)
of the participants could read and write as well as 164(41.00%) were merchants.
More than half 212(53.00%) of the participants had a history of sun exposure
for five and more hours per day. Whereas only 97(24.30%) use sunglasses/hat for
protection. Besides, almost three-fourth of the study participants 294(73.40%)
never use any alcohol product and only 63 (15.80%) had a family history of
pterygium. The overall prevalence of pterygium among adults aged 18 years and
above in Gambella town was 127(31.80%), (95% CI: 27.30, 36.30) in either eye.
Most of the pterygium 101(79.53%) was located to the nasal side of the cornea
and the rest 26(20.47%) was located to the temporal part of the cornea. More
than half 69(54.33%) of the pterygium was unilateral and the remaining
58(45.67%) was bilateral [23]. In another study conducted in Hebei, China
showed that a total of 3790 individuals (2351 Hans and1439 Manchus) met the
study criteria, of which 248nwere diagnosed with pterygium (6.5%). There was no
significant difference between the prevalence rates in Hans (6.2%) and Manchus
(7.2%) (p=0.232). Multi variate analysis revealed that the risk factors for
grade 2 or higher pterygium were increasing age (p<0.001) and rural
residence (OR 1.83; 95% CI 1.11 to 3.02; p=0.018), while the protective factors
include gender (female) (OR 0.58;95% CI 0.37 to 0.88; p=0.011), cigarette
smoking (OR0.53; 95% CI 0.34 to 0.83; p=0.005) and myopia (OR 0.50;95% CI 0.33
to 0.77; p=0.002). Premature menopause (OR2.66; 95% CI 1.05 to 6.72; p=0.038)
increased the risk of grade 2 or higher pterygium in females, while higher
high-density lipoprotein (HDL) (OR 1.94; 95% CI 1.08 to 3.47; p=0.027) was a
risk factor of grade 2 or higher pterygium in males [24]. A possible reason
behind our high finding could be it is carried out in a hot, dry, and dusty
environment with low latitude that might contribute to the occurrence of
pterygium [25,26]. Furthermore, different geographical areas nearer to the
equator (tropical area) have greater exposure to ultraviolet-B that intern
contributes to the occurrence of pterygium [10,20]. The proportion of pterygium
in this study is similar to other studies done in Southwest, Japan (30.8%)
[10], China (33.98%) [25]. although these countries are located in different
geographical areas, the possible reason might be all studies were carried out
with similar study design. On the other side, the proportion of pterygium in
this study is lower than other studies done in Northwest Ethiopia (38.7%)
[8].This might due to geographical, latitudinal, economic, and environmental
variations that contribute to the occurrence of the disease [20, 27]. The other
possible reason could due to the age groups included in the studies. Adults
aged 18years and above were included in this study but, the study done in
Gondar, Ethiopia includes adult’s age greater than 20 years that might
contribute to the occurrence of the pterygium [4,19,21]. Those adults who were
exposed to sunlight five hours and above were 6.86 times more likely to develop
pterygium than those who were not exposed (AOR = 6.86 (95% CI: 4.00,11.79).
This is in line with studies done in South Korea [28], Australia [5], India
[30], Koladiba Ethiopia [27]. Although it is difficult to quantify the true
amount of one’s exposure to sunlight with ultraviolet radiation, many studies
had shown that outdoor workers have a higher risk of the development of
pterygium [2, 28]. Even though some amount of ultraviolent is important for our
body, exposure for five hours and more for acute or long time could cause
disorders in skin, conjunctiva, cornea, and lens [2, 20]. Lots of controversies
are raised regarding the association of gender and pterygium in different kinds
of literature. This study showed that being male was 2.10 times more likely to
develop pterygium as compared to females. This result is supported by studies
done in Ethiopia [8], Australia [5], China [1, 26], Japan [12], Malaya
Indonesia [29], and Central India [20]. Males spent most of their time in
outdoor activities in most African countries including Ethiopia. This might
intern expose them to develop pterygium [8]. Whereas a study in South Korea
[24] showed that being female was associated with pterygium. In contrast,
studies in Japan, China [4,30], and Iran [34] indicated that there were no
significant differences in the association of gender and pterygium. Cultural
differences, differences in ethnicity, and varied environmental factors could
affect the exposure status of males and females for pterygium [21]. On the
other side, adults who wore sunglass/hat were 62% less likely to develop
pterygium as compared to those who did not wear sunglass/hat. This is
consistent with studies done in Gondar, Ethiopia [8], and Benin City, Nigeria.
A possible reason could be wearing hat/protective sunglasses might reduce the
exposure status from UV light and dust particles that might also reduce the
development of pterygium [5].
