Evaluation of Alcohol 20% for Separation of Pterygium Tissue During Pterygium Surgery and Comparison of Three Different Methods of Wound Closure in Pterygium Surgery: Bare Sclera, Sliding Flap, Amniotic Membrane With Biological Glue

Pterygium is a fibrovascular tissue growing on conjunctiva and cornea. The disturbance/morbidity caused by pterygium is diverse, ranging from mild esthetic disturbance and till recurrent inflammations and significant decrease of visual acuity. Rate of pterygium is between 20%-49% of general population, while increase in these numbers is observed in the population of equatorial regions. Pterygium usually appears at age of 22-49 years. While the rate of pterygium appearance increases with the age, the recurrence rate after surgical removal is higher in younger patients. Treatment of pterygium is surgical. The main challenges during surgery are peeling of pterygium and prevention of recurrence. During the last two decades several methods were developed and became widely accepted for pterygium surgery. The emphasis in modifying pterygium surgery is done on initial phase of surgery - techniques of pterygium separation and the final phase - the wound closure methods, additionally adjuncts (such as Mitomycine C) became widely used. These modifications are considered to improve the surgical outcomes and decrease the rate of complications and recurrence rate. Currently popular techniques of pterygium separation include Blunt dissection + keratectomy (blunt separation of the tissue + dissection of superficial layers of cornea); Avulsion technique (Avulsion of the pterygium head by creating tension on the cap edge+ further optional blunt dissection); Air assisted dissection (injection of air into the side of pterygium cap to create good separation plane).

Alcohol 20% is widely used in surface refractive surgery, where it helps to peel easily the epithelium of the cornea. Several reports show a positive role of alcohol in treatment of recurrent corneal erosions resistant to other treatments. At microscopic level - the ethanol splits basement membrane at the level between lamina lucida and lamina densa, additionally ethanol destroys the hemidesmosome junctions between epithelial cells. No consensus exists on ethanol influence on keratocyte viability and function: some studies show delayed wound healing and significant keratocyte damage, while other works show no significant alteration in keratocyte number while using alcohol.

At the phase of pterygium separation our purpose is to check the safety and efficiency of alcohol 20% for peeling of pterygium from ocular surface.

Various closure techniques exist, 3 of the widespread techniques are: Bare sclera (with adjunct such as mitomycine C) - the wound is left as it is, without closure. Sliding conjunctival flap- conjunctiva from adjacent region is dissected, moved to the wound area and sutured. Amniotic membrane transplantation, using biological glue to adhere the membrane. Amniotic membrane does not carry HLA antigens - so that no HLA compatibility tests are needed. Amniotic membrane underwent screening of infectious diseases and was cryopreserved. Amniotic membrane is applied with its mesenchimal part towards sclera and basement membrane side upwards. Adhesion of amniotic membrane is achieved by biological glue (containing thrombin and calcium as main ingredients)

We intend to compare each of these methods of wound closure in conjunction with using alcohol 20 % for pterygium separation.