A pterygium is a wing-shaped pannus of conjunctiva and fibrovascular tissue on the superficial cornea (see Chapter 6). Indications for pterygium excision include ocular discomfort, decreased vision secondary to scarring or visually significant astigmatism, cosmesis, growth of the pterygium over the cornea toward the visual axis (Fig 13-1), and restricted ocular motility. The goal in pterygium excision is to achieve a clear and topographically smooth ocular surface. After excision, the most commonly used technique for coverage of exposed sclera is an autologous free graft from the same or fellow eye. The procedure is performed on an outpatient basis using topical anesthesia, although in some cases, such as a recurrent pterygium complicated by excessive proliferation of the Tenon layer, peribulbar or retrobulbar anesthesia may be required.
A traction suture (eg, 6-0 silk or polyglactin on a spatulated needle, placed at the 12-o’clock position, that can be clamped down in various positions to the surgical drape) facilitates maximal exposure of both the pterygium for excision and the superior conjunctival graft site if a conjunctival transplant is planned. A common surgical technique is to remove the pterygium from the cornea by using a flat or angled crescent blade and dissecting a smooth tissue plane toward the limbus, between the pterygium and the underlying corneal tissue (ideally leaving the Bowman layer intact). Although it is preferable to dissect down to bare sclera at the limbus, the surgeon should be careful when dissecting Tenon tissue posteriorly, as doing so can sometimes lead to bleeding and later scarring from inadvertent trauma to subjacent medial rectus muscle tissue and muscle check ligaments.
Figure 13-1 Pterygium on the cornea, encroaching on the visual axis. Opacification of the leading edge indicates that the pterygium has been present for some time.
(Courtesy of Woodford S. Van Meter, MD.)
After excision, gentle pressure or light cautery may be applied to the sclera to control hemostasis. It is important to remove as much as possible of the fibrovascular scar tissue in the Tenon layer, down to bare sclera, because residual Tenon tissue is a template for recurrence of the pterygium. If the medial rectus muscle is involved, it should be isolated and carefully freed of all scar tissue. A smooth scleral surface at the site of dissection is a desirable endpoint. Leaving the sclera bare is associated with a higher recurrence rate (32%–88%; Table 13-2). It also increases the occurrence of postoperative pain, perforation, and pyogenic granuloma, as well as corneal complications such as dellen and vascularization. There are many techniques for coverage of bare sclera: a conjunctival flap from contiguous tissue, a free conjunctival graft from the same or fellow eye, application of amniotic membrane using fibrin glue or sutures, and simple limbal epithelial transplantation.
Conjunctival autografting and other techniques for coverage of bare sclera
If there is only a small area of bare sclera after ptyergium excision, many surgeons use a sliding flap technique. This is performed by undermining contiguous conjunctival tissue and rotating it in place without tension. If there is a larger defect, conjunctival autograft transplantation using tissue from the superior bulbar conjunctiva is optimal. With a surgical pen, the area to be harvested is marked 0.5–1.0 mm larger than the size of the defect to account for some later retraction of the graft. It is essential to procure a flap of thin conjunctival tissue with only minimal or no Tenon tissue, which is facilitated by injecting a small amount of anesthetic (lidocaine 1% or 2% without epinephrine) between the conjunctiva and Tenon capsule. The donor material should be oriented in the host bed so that the limbal side of the graft is adjacent to the cornea in the excision site. The superior bulbar donor site under the eyelid can be left bare. Figure 13-2 shows various types of surgical wound closures after pterygium excision. Covering the entire defect decreases postoperative inflammation and speeds reepithelialization of the ocular surface.
Table 13-2 Recurrence Rates of Pterygium With Different Surgical Treatment Options
Figure 13-2 Surgical wound closures following pterygium excision. A, Bare sclera. B, Simple closure with fine, absorbable sutures. C, Sliding flap that is closed with interrupted and/or continuous suture. D, Rotational flap from the superior bulbar conjunctiva. E, Conjunctival autograft that is secured with interrupted and/or continuous sutures.
(Reproduced from Gans LA. Surgical treatment of pterygium. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 1996, module 12. Illustration by Christine Gralapp.)
In the case of either a sliding flap or free graft, the conjunctival tissue is then secured to adjacent conjunctiva (with or without incorporating episclera) with either 8-0 polyglactin (absorbable) sutures or 10-0 nylon (nonabsorbable) sutures, or alternatively with commercially available fibrin glue. Elimination of sutures reduces surgical time and decreases postoperative pain and inflammation.
Fibrin glue (also called fibrin sealant, fibrin tissue adhesive) mimics natural fibrin formation, ultimately resulting in the formation of a fibrin clot. Several fibrin glues have been approved by the US Food and Drug Administration (FDA) and are commercially available. These products include TISSEEL Fibrin Sealant (Baxter Healthcare Corp, West-lake Village, CA), EVICEL Fibrin Sealant (Ethicon Inc, Somerville, NJ), and BioGlue Surgical Adhesive (CryoLife Inc, Kennesaw, GA). Another option is the CryoSeal FS System (ThermoGenesis Corp, Rancho Cordova, CA), which can be used in the automated preparation of fibrin sealant from the patient’s own plasma. Currently, use of these products in pterygium surgery is considered off-label. Also, because both pooled human plasma and bovine products are used to obtain some components of these sealants, the clinician should keep in mind the potential for disease transmission with their use.
If the defect created following dissection of the pterygium is considerably larger than what can be covered with an autologous conjunctival graft, then amniotic membrane grafting or simple limbal epithelial transplantation (SLET) are viable options. SLET is a newer technique that optimizes the use of limbal tissue from the healthy fellow eye by combining it with amniotic membrane; see the section Limbal Stem Cell Transplantation, later in the chapter, for a more detailed description.
Although there is evidence that the use of mitomycin C (MMC) with conjunctival grafting reduces the pterygium recurrence rate after surgical excision, further studies are necessary to determine the optimal route of administration and dose, as well as the duration of treatment with MMC and its long-term effects. Any use of topical MMC can be toxic and may cause visually significant complications, such as aseptic scleral necrosis and infectious sclerokeratitis. These complications may occur months or even years after use of the drug. If MMC use is being considered, it is safer to apply this agent intraoperatively than to give it to the patient for postoperative topical application.
Ganelis IB. Pterygium excision with transplantation surgery. In: Basic Techniques of Ophthalmic Surgery. 2nd ed. San Francisco: American Academy of Ophthalmology; 2015:101–108.
Hernandez-Bogantes E, Amescua G, Navas A, et al. Minor ipsilateral simple limbal epithelial transplantation (mini-SLET) for pterygium treatment. Br J Ophthalmol. 2015;99(7): 1598–1600.
Hirst LW. Pterygium surgery. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2009, module 3.
Kheirkhah A, Hashemi H, Adelpour M, Nikdel M, Rajabi MB, Behrouz MJ. Randomized trial of pterygium surgery with mitomycin C application using conjunctival autograft versus conjunctival-limbal autograft. Ophthalmology. 2012;119(2):227–232.
Lindquist TP, Lee WB. Amniotic membrane transplantation. In: Basic Techniques of Ophthalmic Surgery. 2nd ed. San Francisco: American Academy of Ophthalmology; 2015:109–114.
Long T, Li Z. Bare sclera resection followed by mitomycin C and/or autograft limbus conjunctiva in the surgery for pterygium: a meta-analysis. Int J Ophthalmol. 2015;8(5):1067–1073.
Pan HW, Zhong JX, Jing CX. Comparison of fibrin glue versus suture for conjunctival autografting in pterygium surgery: a meta-analysis. Ophthalmology. 2011;118(6):1049–1054.
Complications of pterygium excision include conjunctival graft edema, corneoscleral dellen, and epithelial cysts. Pyogenic granuloma due to incomplete removal of subconjunctival and Tenon fibrovascular tissue may also occur, as well as chronic nonhealing wounds if exposed sclera remains uncovered by autologous conjunctiva. Diplopia may result from severe scarring around the medial rectus muscle. Postoperative infections are rare, but cases reported in the literature reveal a poor visual outcome; thus, postoperative care should not be taken lightly.
Clearfield E, Muthappan V, Wang X, Kuo IC. Conjunctival autograft for pterygium. Cochrane Database Syst Rev. 2016;(2):CD011349.
Kaufman SC, Jacobs DS, Lee WB, Deng SX, Rosenblatt MI, Shtein RM. Options and adjuvants in surgery for pterygium: a report by the American Academy of Ophthalmology. Ophthalmology. 2013;120(1):201–208.
Masters JS, Harris DJ Jr. Low recurrence rate of pterygium after excision with conjunctival limbal autograft: a retrospective study with long-term follow-up. Cornea. 2015;34(12): 1569–1572.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.