Approach

Small asymptomatic pterygia requires no treatment. Patients should be advised to protect their eyes from ultraviolet light with good-quality wraparound sunglasses and hats with peaked brims.

Symptomatic management

If the patient has symptoms of ocular irritation, burning, or itching, these may be alleviated with topical artificial tear preparations. If these symptoms are associated with inflammation of the pterygium, topical corticosteroids such as fluorometholone or loteprednol may be prescribed under ophthalmologic supervision with regular monitoring of intraocular pressure, initially at 2-3 weeks, because of the risk of topical corticosteroid-induced ocular hypertension/glaucoma.[15]​​

The indications for surgical intervention include:

  • Significant ocular irritation unresolved by medical therapy

  • Impaired ocular cosmesis

  • Reduced visual acuity from induced astigmatism or encroachment of the pterygium to or over the visual axis

  • Continued documented progression, so that it can be assumed that eventual visual impairment is likely

  • Double vision secondary to restriction or tethering of the medial rectus muscle.

Before surgery it must be ensured that the lesion is a true pterygium and not one of the mimicking conditions such as a pseudopterygium. The patient requires careful preoperative counseling that, while pterygium surgery is generally successful, symptoms of ocular irritation and burning may not be entirely relieved, and persistent redness and deep corneal scarring beneath the pterygium may mean that improvement in ocular cosmesis is only partial. Furthermore, the patient needs to be advised that recurrences after surgical removal are not infrequent and may be aggressive. For these reasons, surgery is not generally recommended for small pterygia or for cosmetic reasons alone.

There are a variety of surgical approaches, underscoring the point that no method is entirely successful.

Surgical techniques

Simple excision

  • Often this can be performed simply by mechanically shearing off the head and body of the pterygium from the underlying cornea using forceps and then excising it, leaving bare sclera underneath. If it is adherent, careful superficial dissection can be performed. While this is simple and quick to perform, high recurrence rates (>33%) have been reported after simple excision.[19]​​

Redirection of the head of the pterygium

  • These techniques, which entailed redirecting the pterygium head by burying it beneath the conjunctival edge following dissection of the pterygium from the cornea, have been abandoned due to high recurrence rates.

Conjunctival autografting and flaps

  • This is the most commonly used surgical technique and involves covering the bare scleral area created following pterygium removal and excision with either rotational conjunctival flaps above and/or below or with a free conjunctival graft taken from the superior bulbar conjunctiva. As well as covering the bare scleral area, it is thought that the graft acts as a barrier to recurrence. Published recurrence rates after conjunctival autografting techniques are encouraging (between 5% and 15%), with studies suggesting even lower rates with the inclusion of limbal tissue within the graft.[19]​​[20][21]​​[22]​ The use of fibrin sealant instead of sutures has been shown not only to reduce operative time but also to improve postoperative patient comfort.[23]​​[24]​ Results from meta-analyses suggest that it might reduce recurrence rates.[25]​​[26]​​ [ Cochrane Clinical Answers logo ] [ Cochrane Clinical Answers logo ]

Amniotic membrane transplantation

  • Instead of conjunctiva, amniotic membrane may be used to cover the bare scleral area, with some studies demonstrating recurrence rates comparable with those of conjunctival autografting, and others increased.[19][27]​​[28]​​[29]​ However, in cases where the pterygium is very extensive, necessitating a large area of coverage, and in glaucoma patients, where it is desirable to preserve the superior bulbar conjunctiva for future drainage surgery, amniotic membrane transplantation can be very useful.[27]​​[30]​​

Lamellar keratoplasty

  • Partial thickness corneal transplantation may be required if corneal thinning is significant. This is unusual and typically occurs in cases of recurrent pterygia following previous attempts at surgical removal. In very aggressive cases involving the visual axis, residual scarring and stromal irregularity may necessitate lamellar or even penetrating keratoplasty for visual rehabilitation.

Excimer laser phototherapeutic keratectomy (PTK)

  • This may be a useful adjunctive treatment in aggressive cases where the pterygium is encroaching on the visual axis. Following surgical removal, residual superficial scarring can be very precisely removed and surface irregularities smoothed using the excimer laser.

Typically such procedures are performed under local anesthesia. Subconjunctival injection of lidocaine is effective, as is topical application of ophthalmic lidocaine gel.[31]​​[Figure caption and citation for the preceding image starts]: Eye following pterygium excision and conjunctival autografting 1 day after surgeryFrom personal collection of David O'Brart; used with permission [Citation ends].com.bmj.content.model.Caption@257118f

Adjunctive medications and therapy

Various agents have been used in an effort to reduce recurrence after primary surgery and especially to treat recurrent disease. Such agents include postoperative regimens of thiotepa and mitomycin eye drops, perioperative mitomycin and daunorubicin application, fluorouracil, and beta-radiation therapy using strontium-90 plaques.[32]​​[33]​​[34]​​[35]​​[36]​​[37]​​[38][39]​ While such adjunctive agents may reduce rates of recurrence following simple excision, their use can be associated with significant sight-threatening complications such as corneal endothelial cell loss, scleral ulceration, melting, and even perforation.[39][40]​​[41]​​[42]​​​

In view of such potential complications and the limited follow-up studies available for cases where adjunctive medications have been used, conjunctival autografting is the most popular surgical technique.[30]​ In a 10-year follow-up study of a randomized controlled trial, limbal conjunctival autografting reduced pterygium recurrence compared with mitomycin, although no long-term complications or endothelial cell loss were seen in the mitomycin group.[43]​​

More recently the use of topical monoclonal antibodies against vascular endothelial growth factors (anti-VEGF) has been advocated as an adjunctive therapy postoperatively, either in drop form or as subconjunctival injections.[44] In a meta-analysis, topical/subconjunctival bevacizumab was relatively safe, associated only with an increased risk of subconjunctival hemorrhage, but it had no significant effect on preventing pterygium recurrence.[45]​ In another meta-analysis, conjunctival autograft combined with cyclosporine eye drops was the best adjunctive treatment to prevent recurrence following primary pterygium surgery.[46] The role of such agents as a primary therapy without adjunctive surgery is equivocal.[45]​​[47]​​[48]​​

Recurrent pterygia

Treatment of recurrent pterygia can be problematic. Dissection of recurrent lesions from the cornea can be difficult. Such lesions do not usually shear off the surface mechanically but adhere firmly to the underlying corneal stroma and require sharp dissection. Underlying thinning of the cornea may be present and, occasionally, lamellar corneal transplantation may be required to restore the normal surface contour.

Recurrent pterygia have a higher rate of recurrence after excision than primary lesions. Many surgeons advocate using adjunctive therapies such as topical mitomycin when treating such lesions, although their use can be associated with significant sight-threatening complications such as scleral melting.[40]​ It is the author's preference not to use such agents, but to perform a repeat conjunctival autografting technique with the inclusion of limbal tissue within the graft.[21]​​

Histology

It is highly recommended that all excised pterygia undergo formal histologic examination. Typical histologic features of pterygia include limbal epithelial cell proliferation, goblet cell hyperplasia, angiogenesis, inflammation, Bowman layer disruption, elastosis and stromal plaques. Pre-neoplastic lesions have been identified in pterygia, as well as reports of unsuspected and potentially malignant ocular surface disorders.[49]​​[50]​​​

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