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Year : 2021  |  Volume : 24  |  Issue : 8  |  Page : 1206-1210

Pterygium in Onitsha, Nigeria

Department of Ophthalmology, Nnamdi Azikiwe University, Awka; Guinness Eye Centre, Onitsha, Nigeria

Date of Submission22-Feb-2021
Date of Acceptance15-May-2021
Date of Web Publication14-Aug-2021

Correspondence Address:
Dr. C U Uba-Obiano
Department of Ophthalmology, Nnamdi Azikiwe University, Awka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njcp.njcp_89_21

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Objective: To determine the pattern and risk factors of pterygium in adults at the Guinness Eye Centre Onitsha, Nigeria. Materials and Methods: Consecutive adults aged ≥30 years with pterygium were studied. Each patient had comprehensive ocular examination including visual acuity, anterior segment, and adnexal assessment and fundoscopy. The pterygium was graded in terms of severity and type. Results: A total of 156 patients with pterygium participated; 92 (59%) females versus 64 (41%) males (F:M =3:2). The age range was 30–65 years; mean: 43.9 ± 8.4 years. The majority of the study population (36.5%) was of the age group 40–49 years. The subjects were predominately traders 78 (50%) and 93 (59.6%) of the pterygium patients were outdoor workers. Bivariate analysis indicated that those involved in outdoor work were six times at greater risk of developing pterygium than indoor workers (P = 0.001; OR = 6.2). Out of the 156 pterygium patients seen, 107 (68.6%) of them complained of associated symptoms. Redness of the eye was the commonest symptom reported by 79 (50.9%) cases while 8 (5.1%) cases complained of burning sensation. There was a preponderance of nasal pterygia with temporal pterygia being the least. Blinding pterygium was seen in three eyes (1.3%). Conclusion: Pterygium is a common disorder presenting at eye clinics. Outdoor workers are at a greater risk of developing pterygium. Thus, health education is of great importance.

Keywords: Location, pattern, presentation, pterygium, risk factors, symptoms

How to cite this article:
Uba-Obiano C U, N Nwosu S N, Okpala N E. Pterygium in Onitsha, Nigeria. Niger J Clin Pract 2021;24:1206-10

How to cite this URL:
Uba-Obiano C U, N Nwosu S N, Okpala N E. Pterygium in Onitsha, Nigeria. Niger J Clin Pract [serial online] 2021 [cited 2022 Jan 25];24:1206-10. Available from:

   Introduction Top

Pterygium is a triangular subconjunctival growth characterized by the invasion of the cornea by fibro-vascular tissue from the bulbar conjunctiva across the limbus and onto the cornea.[1] It is a degeneration of the fibrous tissue, which took its name from the Greek word for wing and was first described by Hippocrates.[1] It is characterized by its location in the inter-palpebral region, along the horizontal axis of the cornea, usually nasal but occasionally temporal or both nasal and temporal. It may be unilateral or bilateral. It consists of three parts: the head with a cap, the neck, and the body.[2] It may appear thick, fleshy, and vascular (progressive pterygium) or may appear thin, atrophic, and attenuated (regressive pterygium).[3] It could be symptomless. However, it may be inflamed or can cause burning, irritation, and foreign body sensation.[3] Visual disturbance can also occur as a result of induced irregular corneal astigmatism, tear film abnormalities, corneal scarring, or obscuration of the visual axis by the growth.[1],[3] Pterygium is associated with variable degrees of ocular morbidity which may lead to low vision or, in severe cases, blindness.[4] The Nigerian National Blindness and Low Vision Survey reported pterygium to account for 0.5% of blindness.[5] The exact etiology of pterygium is unknown.[6] Exposure to sunlight, and in particular, broad-band ultraviolet (UV) radiation (240–400 nm) is thought to be the major environmental risk factor.[6] Age, hereditary factors, chronic inflammation, micro-trauma from dust and smoke, hot climate, viral infection (human papillomavirus), limbal stem deficiency, and tear film abnormalities resulting in dry eyes are also identified risk factors for the development of pterygium.[7],[8],[9],[10] There is speculation that pterygium is located medially mainly in relation to the drying of the interpalpebral tear film.[11] This could be because this part is farthest from the lacrimal gland and nearest to the puncta, and also, when the eyes are partially closed against the glare or wind, the medial part of the conjunctiva is more exposed than the lateral thus making the patients with decreased tear production more prone to the damaging effects of UV rays in the sunlight.[11] It is found to be more common in tropical and subtropical areas as a result of its warm, dry climates where there is a steady increase with proximity to the equator.[6] The pterygium belt lies between the latitude of 37° North and 37° South of the Equator. Its prevalence is as high as 22% in the equatorial areas where sunlight ultraviolet intensity is stronger and less than 2% in latitudes above 40°.[2] Epidemiological studies[12] around the world have shown that the prevalence rates of pterygium range from 0.3 to 37.5% depending on geography, race, age, and gender. In Nigeria, the prevalence rates of pterygium in the general population varied from 4 to 9%.[13],[14],[15] Thus, the aim of this study is to determine the pattern and risk factors of pterygium in this environment which is within the pterygium belt. The information from this study would assist in the prevention and early intervention for those at risk.

   Materials and Methods Top

A descriptive study was conducted on consecutive adult patients with pterygium aged 30 years and above between August and October 2014. Onitsha is a commercial city on the eastern bank of the Niger River in Anambra State, Nigeria. It lies between latitude 6° 10′ North of the equator and longitude of 6° 47′ East.[16] Inclusion criteria were patients who gave consent, absence of any other ocular pathology, and not on topical medications. Exclusion criteria included the presence of other ocular pathology, systemic diseases such as diabetes mellitus and hypertension, previous ocular surgeries, patients on any topical or systemic medications, and patients who declined consent to the study. Ethical approval was obtained from the Ethics Committee and written informed consent was duly signed by the patients after the purpose and the procedure of the study were explained to them. A brief history was taken from those recruited. The distance visual acuity was measured for each eye separately at a distance of 6 m, using illuminated Snellen's chart or the illiterate E-chart as applicable. The anterior segment was examined with a pen torch and Carl Zeiss slit-lamp biomicroscope to rule out adnexal problems and other ocular surface disorders while the posterior segment was examined with a Welch Allyn's direct ophthalmoscope. A pre-tested, interviewer-administered, structured questionnaire was administered to elicit information on socio-demographic variables, ocular health, and presence of ocular symptoms (Approval was obtained on 31-01-2014).

Pterygium was graded based on the working classification by Nworah.[17]; pterygium translucency, and the visibility of underlying episcleral blood vessels (described as a marker of severity).[18]

Grade I: Incipient stage—early pterygium bordering on the limbus.

Grade II: Advanced stage—pterygium advancing about halfway between the limbus and the central corneal axis.

Grade III: Critical stage—at the pupillary margin with infiltration of the central region of the cornea.

Grade IV: Blinding stage—complete blockage of the pupillary aperture, covering the entire central cornea.

Results of the study were analyzed with Statistical Package for Social Sciences (SPSS) version 20 using both descriptive and inferential statistics. The alpha level was 0.05.

   Results Top

A total of 156 patients with pterygium were examined. [Table 1] shows the socio-demographic characteristics of the participants. The age range was 30–65 years with a mean age of 43.9 ± 8.4 years. Patients aged 40–49 years constituted the commonest age bracket (36.5%) while the age group ≥60 years had the least number of participants (2.6%); 92 (59%) were females while 64 (41%) were males. Two-thirds of the participants were urban dwellers. Traders constituted 78 (50%) of the patients while students were least accounting for 3 (1.9%); 94% (60.1%) had attained secondary or higher education while 14 (9.0%) had non-formal education. There was a positive family history of pterygium in 47 (30.1%); 93 (59.6%) were outdoor workers; 83 (53.2%) patients had bilateral pterygia. The right eye was involved in 38 (24.4%) and the left in 35 (22.4%) of the unilateral pterygial cases. There was a preponderance of nasal pterygia with temporal pterygia being the least. While 219 (91.6%) eyes had nasal pterygium, only 6 (2.5%) eyes had temporal pterygium, and 14 (5.9%) eyes had double pterygia. Eighty-five (54.5%) patients had atrophic pterygium while 71 (45.5%) had fleshy, vascular type. Fleshy, vascular pterygium was predominately seen in males (54.7%) and outdoor workers (58.1%). There was no significant difference between pterygium type and other socio-demographic variables (age and sex). However, a statistically significant difference was found between pterygium type and workplace (P < 0.001) [Table 2].
Table 1: Socio-demographic characteristics of respondents

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Table 2: Pterygium type vs Socio-demographic variables

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Bivariate analysis indicated that those involved in outdoor work are six times at a greater risk of developing pterygium than indoor workers (χ2 = 53.26; DF=Degree of freedom = 1; P = 0.001; OR= Odd Ratio = 6.2). Protective devices against exposure to sunlight were used by 60 (38.5%) patients. Most of the patients had grade I pterygium in either eye, while grade IV (blinding stage) was the least [Table 3]. A greater number of pterygial eyes (88.7%) had visual acuity of 6/6–6/18 [Table 4]. There was no statistically significant difference between the visual acuity in pterygial eyes and non-pterygial eyes (P value = 0.273).[Table 5] shows the various ocular symptoms associated with pterygium. Symptoms reported by patients were redness in 79 (50.6%), sandy sensation in 77 (49.4%), itching in 71 (45.5%), and burning sensation in 8 (5.1%).
Table 3: Grade of pterygium

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Table 4: Visual acuity in pterygial eyes versus non-pterygial eyes

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Table 5: Symptoms associated with pterygium

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   Discussion Top

Pterygium is one of the most common degenerative conjunctival diseases among ophthalmic pathologies.[19],[20] The highest incidence was found among the age group 40–49 years in the present study. This age group comprises active and working individuals. This is similar to the results of previous studies by Onwasigwe et al.[21] Ashaye,[13] and Bekibele et al.[22]; this could be attributed to the fact that the studies were conducted in a similar environment in Nigeria with the present study. On the contrary, Rajiv[10] and Rohatgi[23] found pterygium the highest in the age group of 30–40 years. Some researchers[10],[20],[24],[25] noted pterygium in males more than females but the present study reported more females than males. This study concurs with the attribution of females being more particular about cosmetic appearance.[13] Also, in Onitsha, as in other parts of Southeastern Nigeria, women work outdoors like men. The finding of this study showed that outdoor workers are more likely to develop pterygium than indoor workers. This may be related to the fact that in Onitsha and its environment, a few traders stay indoors and conduct business within their shops, others, including women, stay completely outdoors in a dusty, open-air market under intense sunlight. In any case, traders and farmers are generally more exposed to dust and sun rays than civil servants who mostly work indoors. This result is similar to that of the other studies[13],[18],[23],[26] which have shown that spending longer time outdoors has led to an increased risk of pterygium. On the contrary, Roka et al.[27] found more indoor workers with pterygium while another study by Asokan et al.[28] showed that there is no association of pterygium with the nature of work.

Most of the participants in the present study reside in urban areas (67.9%). This is not surprising as our hospital is located in Onitsha, the foremost urban town in Anambra State, Nigeria. Most of those without post-secondary education are limited in employment, and are thus, more likely to be involved in outdoor works which expose them to UV radiation and pterygium. In the present study, a majority of the cases were without a post-secondary education. This agrees with studies[12],[29],[30] that have associated pterygium with fewer years of education. In this study, a few pterygium patients used protective devices against sunlight. Ukponmwan et al.[31] reported that a greater number of people with pterygium did not use protective devices. Their study suggested that the use of sunglass/hat reduces the risk of developing pterygium by absorbing and reducing the exposure to harmful ultraviolet light. Most kinds of literature[1],[2],[3] have documented pterygium to be unilateral or bilateral, and usually located on the nasal side of the limbus. In this study, pterygium was predominantly found on the nasal side. This finding is in concordance with the literature. Visual acuity of 6/6–6/18 was noted in most pterygial eyes. This could be due to the absence of encroachment onto the visual axis by pterygium, the absence of other ocular pathologies, and that the pterygium size was not large enough to cause corneal astigmatism. One or more ocular symptoms were reported by 107 (68.7%) patients and the commonest symptoms were redness (50.9%), itching (45.5%), and gritty sensation (32.7%). These ocular irritative symptoms may be due to the disruption of the precorneal tear film by the presence of pterygium leading to corneal and conjunctival dryness.

In conclusion, there is a need for health education/awareness creation on the predisposing factors and possible measures to prevent pterygium. The use of protective UV goggles should be encouraged among outdoor workers.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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