The relation between pterygium size and refractive astigmatism among a group of patients in Erbil city

* Erbil Directorate of Health, Erbil, Iraq. ** Department of Surgery , College of Medicine, Hawler Medical University, Erbil, Iraq. Introduction A pterygium is a triangular fibrovascular subepithelial in growth of degenerative bulbar conjunctival tissue over the limbus onto the cornea. It typically develops in patients who have been living in hot climates; it may represent a response to ultraviolet exposure and possibly to other factors such as chronic surface dryness. The histopathology of it shows elastotic degeneration of the stromal collagen with subepithelial fibrovascular tissue. Due to sunlight exposure, pterygium is regarded as a public health problem in rural areas. Independent factors in the incidence of pterygium such as older age, male and the history of outdoor activities indicate the multi-factorial causes of pterygium. The prevalence of pterygia increases steadily with proximity to the equator. Regular and irregular astigmatism occurs in proportion to its size. A pigmented iron line (Stockerline) may be seen at the central anterior edge of the pterygium on the cornea when longstanding and stable. Excision is indicated if the pterygium approaches the visual axis, causing loss of vision from irregular astigmatism or in cases of considerable irritation. The type of Background and objective: A pterygium is a triangular fibrovascular subepithelial ingrowth of degenerative bulbar conjunctival tissue over the limbus onto the cornea. Excision is indicated if the pterygium approaches the visual axis, causing loss of vision from irregular astigmatism or in cases of considerable irritation. This study aimed to determine the percentage of astigmatism in patients presented with pterygium and measure the effect of size (width and height) of pterygium on a degree of astigmatism and indication of early surgery. Methods: A hospital based cross-sectional study using non-probability convenience sampling was conducted in the ophthalmology department of Rizgary and Erbil teaching hospital in Erbil city from June 2015 to February 2016. Ninety-six eyes of eighty patients with pterygium were included in this study. Results: The mean age ± SD of the 80 patients included in the study was 37.5 ± 9.62 years ranging from 22-58 years. There were 45 male and 35 female patients. Two-thirds of eyes (72.6%) had with-the-rule astigmatism while 12.6 % of eyes had against-the-rule astigmatism. A highly significant strong correlation was seen between a fraction of corneal area encroached by pterygium with induced astigmatism (r = 0.727, P <0.001). A highly significant strong correlation was found between the area of pterygium and corneal astigmatism in a case of severe pterygium (pterygium encroaching > 4 mm area on the cornea) (r = 0.802, P <0.001). Conclusion: Pterygium size has a significant correlation to the amount of induced astigmatism. The correlation is stronger in the pterygia of severe degree (>4 mm) as in this group they are encroaching on the visual axis.