pterygium excision and conjunctival limbal allograft
The name pterygium is derived from the Greek word meaning wing, which describes its typical shape, extending from the scleral side on to the cornea. It is commonly found on the nasal side within the interpalpebral fissure. There is a higher incidence of pterygium in individuals who are often exposed to sunlight, dust, wind, fumes and other noxious stimuli. It is more common in the tropical and subtropical regions.
Surgical indications for removal of a pterygium include increasing size with compromised vision, recurrent inflammation and discomfort, progressive growth toward the central cornea/ visual axis, restricted ocular motility and cosmetic reasons. However, when recurrences occur after surgical excision, it can be worse than the initial primary pterygium. Hence, the choice of the surgical procedure is important.

Limbal autograft transplantation (LTau), a procedure for unilateral ocular surface disorders in which the limbal tissue is obtained from the unaffected eye, was first reported by Kenyon and Tseng in 1989. Limbal allograft transplantation (LTal) has been introduced for bilateral ocular surface disorders in which a heterologous limbal tissue is transferred either from a living, related donor eye or from cadaveric eye. It has been reported that allograft transplantation results in a healthier ocular surface, particularly when the immunosuppression is performed even if the donor tissue is human leucocyte antigen (HLA) matched to the recipient. Compared to LTal, limbal autografts are believed to have a higher survival rate as there is no risk of graft rejection. Promising results of these two surgeries have led the ophthalmologists to use these treatment methods in many types of ocular surface disorders in the recent years. LTal is now proven to be successful for stabilizing ocular surface in patients with chemical and thermal burns. Comparisons of outcomes for ocular surface disorders due to various aetiologies and for the acute and chronic phases of corneal burns have been reported previously for limbal autografts and allografts separately.