History

Fact Explanation
Visible growth Pterygium is a benign epithelial and fibrovascular outgrowth of the of the ocular surface that has proliferative, invasive, and highly vascularized microscopic appearance and invades the cornea and pupillary field. [1]
Foreign body sensation The fibrovascular elevation in pterygium causes a foreign body sensation in the eye prior, to it being visible to naked eye examination. [2]
Blurring of vision The as the lesion grows into the visual axis, the alteration of corneal contour, causes irregular astigmatism and breakup of the precorneal tear film, this results in a reduction in visual acuity. [3,4]
Previous history of pterygium Pterygium has a high recurrence rate even after surgical treatment. Recurrence following the bare sclera technique can be as high as 40%. [4]
Dryness, itchiness and redness Often seen in advanced pterygia, occurs as the pterygium grows larger. They cause ocular surface irritation, which is experienced as dryness and itchiness. Redness is due to inflammation of the pterygium. [5]
Risk factors: increased exposure to UV radiation Incidence is increased in the lower lattitudes, in the male gender, the elderly and occupations that involve sun exposure such as competitive surfing, farmers and welders. [6,7]
References
  1. CIMPEAN AM, SAVA MP, RAICA M. DNA damage in human pterygium: One-shot multiple targets Mol Vis [online] :348-356 [viewed 30 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3566892
  2. MOHAMMED I. Treatment of pterygium. Ann Afr Med [online] 2011 Jul-Sep, 10(3):197-203 [viewed 30 May 2014] Available from: doi:10.4103/1596-3519.84695
  3. WAZIRI-ERAMEH JM, OMOTI AE. Presenting visual acuities in a referral eye center in an oil-producing area of Nigeria. Middle East Afr J Ophthalmol [online] 2009 Apr, 16(2):80-4 [viewed 30 May 2014] Available from: doi:10.4103/0974-9233.53866
  4. OKOYE O, OGUEGO NC, CHUKA OKOSA CM, GHANTA M. Short term results of pterygium surgery with adjunctive amniotic membrane graft. Niger J Clin Pract [online] 2013 December [viewed 30 May 2014] Available from: doi:10.4103/1119-3077.113463
  5. CARLOCK BH, BIENSTOCK CA, ROGOSNITZKY M. Pterygium: Nonsurgical Treatment Using Topical Dipyridamole - A Case Report Case Rep Ophthalmol [online] , 5(1):98-103 [viewed 30 May 2014] Available from: doi:10.1159/000362113
  6. 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 [online] 2013 Nov 19, 3(11):e003787 [viewed 30 May 2014] Available from: doi:10.1136/bmjopen-2013-003787
  7. KARAI I, HORIGUCHI S. Pterygium in welders. Br J Ophthalmol [online] 1984 May, 68(5):347-9 [viewed 30 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/6712915

Examination

Fact Explanation
Growth towards the medial side of the eye This is a benign growth that causes a wedge-like fibrovascular growth of actinically damaged conjunctiva encroaching across the limbus and invading the cornea. [1]
References
  1. OKOYE O, OGUEGO NC, CHUKA OKOSA CM, GHANTA M. Short term results of pterygium surgery with adjunctive amniotic membrane graft. Niger J Clin Pract [online] 2013 December [viewed 30 May 2014] Available from: doi:10.4103/1119-3077.113463

Differential Diagnoses

Fact Explanation
Squamous cell carcinoma Ocular surface squamous neoplasia can have a similar presentation to pterygium. However it is a malignant growth, that needs to distinguished from benign diseases by means of histopathological examination. [1]
Pseudopterygium This occurs due to the traumatic destruction of the corneal epithelium. Causative factors may be caustic burn injuries or inflammation. [2]
References
  1. NGUENA MB, VAN DEN TWEEL JG, MAKUPA W, HU VH, WEISS HA, GICHUHI S, BURTON MJ. Diagnosing ocular surface squamous neoplasia in East Africa: case-control study of clinical and in vivo confocal microscopy assessment. Ophthalmology [online] 2014 Feb, 121(2):484-91 [viewed 30 May 2014] Available from: doi:10.1016/j.ophtha.2013.09.027
  2. HARTMAN DC. Use of free grafts in correction of recurrent pterygia, pseudopterygia and symblepharon. Calif Med [online] 1951 Oct, 75(4):279-80 [viewed 30 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/14879274

Investigations - for Diagnosis

Fact Explanation
Slit lamp examination Pterygium can be graded according to its slit lamp appearance. Grade I - between limbus and a point midway between limbus and pupillary margin Grade II - head of the pterygium present between a point midway between limbus and pupillary margin and pupillary margin (nasal papillary margin in case of nasal pterygium and temporal margin in case of temporal pterygium) Grade III - crossing pupillary margin [1]
Corneal topography A pterygium-induced refractive changes often leads to visual impairment. The distortion of the cornea can be documented by corneal topographic measurements. [1]
References
  1. MAHESHWARI S. Pterygium-induced corneal refractive changes Indian J Ophthalmol [online] 2007, 55(5):383-386 [viewed 30 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2636029

Investigations - Screening/Staging

Fact Explanation
Testing of visual acuity Screening test, to evaluate visual acuity. Pterygium can cause irregular astigmatism that reduces visual acuity. [1]
Slit lamp examination of the anterior and ocular adnexa Done to rule out other ocular surface disorders. [1]
References
  1. OKOYE O, OGUEGO NC, CHUKA OKOSA CM, GHANTA M. Short term results of pterygium surgery with adjunctive amniotic membrane graft. Niger J Clin Pract [online] 2013 December [viewed 30 May 2014] Available from: doi:10.4103/1119-3077.113463

Management - General Measures

Fact Explanation
Protective eyewear Useful in primary prevention and to slow progression. An increased incidence of pterygium has been reported in the lower latitudes and in individuals with more UV exposure. [1,2]
Lubricating eye drops Provides lubrication to the ocular surface. Ocular surface irregularities are common in pterygium and this can be associated with an irregular tear film. [2]
Corticosteroid eye drops Prednisolone eye drops are prescribed in order to reduce inflammation in an inflamed pterygium. It is also prescribed in the post operative period. [1]
Follow up Close follow up is needed in the immediate post operative period for complications such as corneal scarring, infection etc. [2]
References
  1. TANO T, ONO K, HIRATSUKA Y, OTANI K, SEKIGUCHI M, KONNO S, KIKUCHI S, ONISHI Y, TAKEGAMI M, YAMADA M, FUKUHARA S, MURAKAMI A. Prevalence of pterygium in a population in Northern Japan: the Locomotive Syndrome and Health Outcome in Aizu Cohort Study. Acta Ophthalmol [online] 2013 May, 91(3):e232-6 [viewed 30 May 2014] Available from: doi:10.1111/aos.12044
  2. CARLOCK BH, BIENSTOCK CA, ROGOSNITZKY M. Pterygium: Nonsurgical Treatment Using Topical Dipyridamole - A Case Report Case Rep Ophthalmol [online] , 5(1):98-103 [viewed 30 May 2014] Available from: doi:10.1159/000362113

Management - Specific Treatments

Fact Explanation
Surgery: bare sclera technique Indications for surgery are: visual impairment; recurrent inflammation; motility restriction and cosmetic disfigurement.This technique involves the removal of the pterygium, and allows the the sclera to re-epithlialize. Is associated with a high percentage of recurrence (upto 40% in some studies). [1,2]
Surgery: conjunctival auto graft technique This has the lowest recurrence rates (less than 2% in some but can increase up to 30%). Involves harvesting a conjunctival autograft from a different part of the conjunctiva and subsequently grafting over the exposed scleral bed, where the pterygium was excised. [1]
Surgery: Amniotic membrane grafting The amniotic membrane is thought to naturally contain proteins which promote the adherence, migration and differentiation of epithelial cells and prevent their apoptosis. The amniotic membrane graft reduces recurrence of pterygium by promotion of conjunctival epithelial wound healing, suppression of fibroblasts and reduced extracellular matrix production. [2,4]
Mitomycin C eyedrops Used as an adjunct to surgical management to reduce recurrence rates. Mitomycin C (MMC) is used for its property of inhibiting fibroblast cells. Currently ophthalmologists use MMC intra operatively on the exposed scleral bed after pterygium excision; while some prescribe MMC eyedrops post operatively. [4]
Beta irradiation An adjunctive method employed intra operatively and post operatively in addition to primary surgery. Beta irradiation reduces mitosis of the rapidly dividing cells of the sclera to reduce recurrence. Possible side effects are: scleral necrosis, endophthalmitis and sectorial cataract formation. [5]
References
  1. ALPAY A, UğURBAş SH, ERDOğAN B. Comparing techniques for pterygium surgery. Clin Ophthalmol [online] 2009:69-74 [viewed 30 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/19668546
  2. OKOYE O, OGUEGO NC, CHUKA OKOSA CM, GHANTA M. Short term results of pterygium surgery with adjunctive amniotic membrane graft. Niger J Clin Pract [online] 2013 December [viewed 30 May 2014] Available from: doi:10.4103/1119-3077.113463
  3. KATBAAB A, ANVARI ARDEKANI HR, KHOSHNIYAT H, JAHADI HOSSEINI HR. Amniotic membrane transplantation for primary pterygium surgery. J Ophthalmic Vis Res [online] 2008 Jan, 3(1):23-7 [viewed 30 May 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/23479517
  4. RAISKUP F, SOLOMON A, LANDAU D, ILSAR M, FRUCHT-PERY J. Mitomycin C for pterygium: long term evaluation. Br J Ophthalmol [online] 2004 Nov, 88(11):1425-8 [viewed 30 May 2014] Available from: doi:10.1136/bjo.2003.039891
  5. LAI J, THAM C, LAM D. Comparative study of intraoperative mitomycin C and ? irradiation in pterygium surgery Br J Ophthalmol [online] 2001 Jan, 85(1):121 [viewed 30 May 2014] Available from: doi:10.1136/bjo.85.1.121