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Applying MMC to fibrovascular Tenon’s capsule protects sclera during pterygium surgery
Modified procedure lessens likelihood of recurrence and protects against corneal melt.
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 Thomas John |
Ophthalmologists often have to deal with pterygium surgery, especially in the sun-belt regions of the globe. Although the surgery may be relatively simple and straightforward, one may have to deal with recurrence of the pterygium, which usually is worse than the primary pterygium and requires more challenging surgical techniques for its effective removal with a good cosmetic and, in some cases, functional result.
Various techniques have been developed to decrease the incidence of pterygium recurrence, and one such proven technique is to use intraoperative mitomycin C or 5-fluorouracil. However, such chemotherapeutic applications have resulted in scleral and/or corneal melting after even a single application. This has resulted in most ophthalmic surgeons shying away from the intraoperative use of MMC and 5-FU in pterygium surgery.
In this column, Dr. Fass describes his surgical technique of selectively applying MMC to the fibrovascular tissues associated with the pterygium while protecting the underlying sclera and cornea from direct contact with MMC. Larger studies and longer follow-up are essential for evaluating the overall efficacy and safety of this procedure.
Thomas John, MD
OSN Surgical Maneuvers Editor
 Oren N. Fass |
A pterygium is a wing-shaped conjunctival growth on the cornea that is more common in hot climates. Pterygia require surgical removal when they cause irritation, irregular astigmatism or cosmetic disfigurement. Since the first description of pterygia removal in 1897 by Susruta, a variety of techniques has been developed. From the initial bare sclera method, an evolution of ideas has emerged, with a focus on re-covering the area left exposed by pterygia removal, in order to achieve lower recurrence rates and greater comfort during healing. With Dr. Jose I. Barraquer’s report of free conjunctival autograft in 1980, primary closure strategies gradually gave way to conjunctival autograft and amniotic membrane closure techniques, with or without sutures. Mitomycin C and 5-fluorouracil have also been instrumental in bringing about lower recurrence rates.
Perhaps the most feared complication of pterygia removal can result directly from the usage of these chemotherapeutic agents, and many ophthalmologists avoid the usage of both MMC and 5-FU in order to avoid the possibility of scleral melting. Scleral melting that is severe enough to cause complete scleral erosion and globe perforation after just one intraoperative dosage of MMC has been recorded. The ophthalmic literature is replete with scenarios of scleral and corneal melting after pterygia surgery with MMC that have required all varieties of corneal, pericardial or conjunctival patch grafts for repair.
 Figure 1. A sponge is soaked with MMC and secured onto a chalazia clamp for application during pterygium surgery. |
 Figure 2. The resected fibrovascular tissue is grasped with 0.12 forceps along with the conjunctiva and lifted. The clamp is then placed so that it treats the surgically cut edge and body of the fibrovascular tissue with MMC but protects the sclera. |
 Figure 3. The clamp with the MMC-soaked sponge may be placed in any area where the fibrovascular tissue has been excessive. |
 Figure 4. Selective MMC application to a different area where the fibrovascular tissue was excessive. Images: Fass ON |
In this column, we attempt to achieve the best of both worlds by using MMC along with conjunctival autografting or amniotic membrane, and doing so in a way that protects the bare sclera during the application of MMC. This technique relies on the fact that it is the fibrovascular Tenon’s capsule that we desire to administer our dosage of MMC to, not the bare sclera. It is the fibrovascular tissue that has the potential for pterygia regrowth, not the bare sclera. Hence, it is possible to separate the two layers: protecting one while thoroughly treating the other, and doing so with an instrument that every ophthalmologist already has in his operating room.
Pictured intraoperatively, a sponge is soaked with MMC and secured onto a chalazia clamp (Figure 1). If desired, second and third sponges soaked with balanced salt solution may be placed around it so there is an even more minimal chance of contact of MMC with the bare sclera. The resected fibrovascular tissue is grasped along with conjunctiva and lifted, and the clamp placed so that it treats the surgically cut edge and body of the fibrovascular tissue but protects the sclera (Figure 2). Irrigation with balanced salt solution may be performed after each application, and the clamp may be placed in any area where the fibrovascular tissue has been excessive (Figures 3 and 4).
This relatively simple surgical strategy for scleral and corneal protection from MMC affords the surgeon the confidence of performing a procedure that most likely will not require the patient to come back in the future for removal of a recurrent pterygium. This technique offers some tangible protection from one of our most feared complications of scleral and/or corneal melt after pterygium surgery with MMC.
References:
- Barraquer JI, Binder PS, Buxton JN, et al. Etiology and treatment of the pterygium. In: Symposium on Medical and Surgical Diseases of the Cornea. Transactions of the New Orleans Academy of Ophthalmology. St Louis: CV Mosby; 1980:167-168.
- Dougherty PJ, Hardten DR, Lindstrom RL. Corneoscleral melt after pterygium surgery using a single intraoperative application of mitomycin-C. Cornea. 1996;15(5):537-540.
- Jain AK, Bansal R, Sukhija J. Human amniotic membrane transplantation with fibrin glue in management of primary pterygia: a new tuck-in technique. Cornea. 2008;27(1):94-99.
- Kenyon KR, Wagoner MD, Hettinger ME. Conjunctival autograft transplantation for advanced and recurrent pterygium. Ophthalmology. 1985;92(11):1461-1470.
- Thomas John, MD, is a clinical associate professor at Loyola University Chicago and is in private practice in Tinley Park and Oak Lawn, Ill. He can be reached at 708-429-2223; fax: 708-429-2226; e-mail: tjcornea@gmail.com.
- Oren N. Fass, MD, can be reached at Vision Quest Surgery Center, 5421 La Sierra Drive, Dallas, TX 75231; e-mail: orenfass@gmail.com.
