Dr Mohaimen Al-Zubaidy1, Mr Mustafa Al-Zubaidy2
1F2 Doctor, Newcastle University Healthcare Trust
2Medical Student, Imperial College London
Introduction
Pterygium, also known as surfer’s eye, is a common ocular surface disorder originating in the limbal conjunctiva within the palpebral fissure with progressive involvement of the cornea. The fibrovascular lesion occurs more often at the nasal limbus than the temporal limbus, adopting a characteristic wing-like appearance (1,2). In this article we will discuss the presentation of pterygium, its underlying pathophysiology and the diagnostic steps taken by clinicians to recognise pterygium as well as the management of these patients.
Epidemiology
The current literature indicates that the prevalence of pterygium varies at around 10 percent globally (3). However, the rates differ in various parts of the world. They are highest in the “pterygium belt” which lies between 37° north and south of the equator. The prevalence of pterygium has been stated to vary widely from 0.3 to 29 percent in the world (1).
Risk Factors
A history of increased ultra-violet sunlight exposure is the most common environmental risk factor, with increased incidence noted in latitudes nearer the equator. Moreover, older age, male gender, outdoors occupation, and living in rural dry environments are also leading demographic risk factors for the development of pterygium (4).
Pathophysiology
Several theories exist to explain the pathogenesis of pterygium growth, however the increased prevalence in hot dry climates and regions nearer to the equator suggest environmental factors such as ultra-violet radiation play a key role.
Ultra-violet rays have been identified to cause insufficiency of the limbal stem cells of the cornea. This results in activation of the tissue growth factors, which result in further angiogenesis and cell proliferation (5). The damaged limbal stem cells result in invasion by aggressive fibroblasts that result in a fibrovascular overgrowth. Ultra-violet radiation may also cause mutations in the p53 tumour suppressor gene, resulting in the abnormal pterygial epithelium (6, 7). Actinic changes seen on histopathology similar to actinic keratoses on the skin also supports the role of UV radiation (2).
Clinical Presentation
Various ocular symptoms are the main presentations of pterygium. Patients often complain of irritation of the affected eye including excess lacrimation and foreign body sensation. Moreover, patients also complain of the cosmetic blemish, and various functional problems, which include diminution of vision and difficulty in the fitting of contact lens. Symptoms typically depend on the severity and size of the pterygium (2).
Investigations
Patients presenting with apparent pterygia should undergo a complete eye exam, focusing on assessment of visual and refractive impact as well as the exclusion of less common alternate diagnoses.
The diagnosis of pterygium is based on the appearance of the lesion often made by slit-lamp examination of the wing-shaped limbal growth at the characteristic location within the palpebral fissure. The diagnosis is most often clear clinically, but histopathologic confirmation is performed routinely, as there can be associated dysplasia of the overlying tissue (2).
Management
Several potential therapeutic options exist for the management of pterygia ranging from conservative management to surgical excision with conjunctival autografts (8).
Medical treatment involves the use of artificial tear drops for lubrication, or decongestants to provide short-term comfort and a slight improvement in cosmetics. Additionally topical NSAIDs and steroid eye drop bring added comfort. Vasoconstrictive agents and antihistamines also have a role to play, minimising erythema and reducing associated oedema and irritation (2).
In severe cases however, surgical treatment remains the preferred option. Patients with decreased vision due to visual axis infringement, abnormal astigmatism, chronic pain, persistent inflammation and restrictive ocular motility should be considered for surgical excision of the pterygium (1). However, it’s important to note that surgical excision must be carefully considered on a case-by-case basis due to recurrence and cosmesis post-surgery (5).
Conclusion
To conclude, pterygium is an ocular surface condition characterized by a wing-like fibrovascular overgrowth of the subconjunctival tissue encroaching on to the cornea in the medial and lateral palpebral fissure. It is important for us as clinicians to be able to recognise the clinical features associated with pterygium early in order to provide the best possible care for our patients.
References
1. Singh SK. Pterygium: epidemiology prevention and treatment. Community Eye Health. 2017;30(99):S5-S6. PMID: 29849437; PMCID: PMC5968422.
2. Sarkar P, Tripathy K. Pterygium. [Updated 2021 Aug 21].StatPearls. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK558907/
3. Liu L, Wu J, Geng J, Yuan Z, Huang D. Geographical prevalence and risk factors for pterygium: a systematic review and meta-analysis. BMJ Open. 2013 Nov 19;3(11):e003787. doi: 10.1136/bmjopen-2013-003787. Erratum in: BMJ Open. 2017 Dec 22;7(12 ):e003787corr1. PMID: 24253031; PMCID: PMC3840351.
4. Rezvan F, Khabazkhoob M, Hooshmand E, Yekta A, Saatchi M, Hashemi H. Prevalence and risk factors of pterygium: a systematic review and meta-analysis. Surv Ophthalmol. 2018 Sep-Oct;63(5):719-735. doi: 10.1016/j.survophthal.2018.03.001. Epub 2018 Mar 16. PMID: 29551597.
5. Shahraki T, Arabi A, Feizi S. Pterygium: an update on pathophysiology, clinical features, and management. Ther Adv Ophthalmol. 2021 May 31;13:25158414211020152. doi: 10.1177/25158414211020152. PMID: 34104871; PMCID: PMC8170279.
6. Di Girolamo N, Chui J, Coroneo MT, Wakefield D. Pathogenesis of pterygia: role of cytokines, growth factors, and matrix metalloproteinases. Prog Retin Eye Res. 2004 Mar;23(2):195-228. doi: 10.1016/j.preteyeres.2004.02.002. PMID: 15094131.
7. Hamed-Azzam S, Edison N, Briscoe D, Mukari A, Elmalah I. Identification of human papillomavirus in pterygium. Acta Ophthalmol. 2016 May;94(3):e195-7. doi: 10.1111/aos.12729. Epub 2015 Apr 12. PMID: 25864511.
8. Mohammed I. Treatment of pterygium. Ann Afr Med. 2011 Jul-Sep;10(3):197-203. doi: 10.4103/1596-3519.84695. PMID: 21912002.