On slit lamp examination, there is significant meibomian gland dysfunction (MGD) and a fleshy fibrovascular tissue advancing 4 mm onto his right cornea ( Fig. 20.1 ). The remainder of the exam was unremarkable.
A primary pterygium near the visual axis
What Treatment Options Would You Recommend?
Because of his decreased vision and high amounts of astigmatism, an elective surgery is recommended—after at least 3 months of treating his MGD. In patients with any level of MGD, even minimal surgical manipulation of the ocular surface can result in refractory annoying symptoms. Based on this fact, we treat all MGD patients before any type of ocular surface surgery. Dry eyes, either due to evaporative or aqueous deficient dry eye, is present in nearly all patients with pterygium.
What Is Your Preferred Technique for Pterygium Excision?
It is usually possible to perform surgery in primary pterygium with topical + subconjunctival anesthesia, although peribulbar anesthesia may be preferred in more pain-sensitive patients. For better exposure of the surgical site, we use a limbal or episcleal traction suture at the 6 and 12 o’clock position. The upper and lower borders of pterygium must be marked as well as the nasal border. After infiltrating the pterygium with lidocaine with epinephrine, scissors are used to cut into the pterygium along the nasal border which is extended to the upper and lower borders.
We propose a simple technique for cutting the firm attachment between pterygium and cornea. As we know the cornea is a multilamellar tissue and fibrovascular tissue of pterygium attaches to the cornea in different depths (deeper in periphery and more superficial in central area). If we attempt to avulse the pterygium as a whole from the cornea, deep centrally located intact corneal lamella must be sacrificed simultaneously with peripheral deep fibrovascular tissue, and this can result in thinning of the central cornea and a flattening effect in 180° meridian and high amounts of with-the-rule astigmatism. In our technique named “multiple rhexis” method , we grasp the fibrovascular tissue superficially as much as possible and try to separate one plane of fibrovascular tissue by capsulorhexis-like movements. This fibrovascular rhexis must be repeated plane by plane until all of fibrous tissue is separated from cornea. Afterwards any stromal irregularity must be smoothened with a rotary burr.
How Much Fibrovascular Tissue Should Be Excised from Free Borders of Conjunctiva?
Many authors believe that activated fibroblasts at the free borders of excised conjunctiva play a major role in the pathogenesis of recurrence. Therefore, all fibrovascular tissue should be excised with extension of at least 1–2 mm under the conjunctival free edge. The end point of this step is obtaining 1–2 mm of transparent conjunctiva at all free margins.
How and When Are Antifibrotic Agents Used?
Antimetabolite such as mitomycin C suppresses the activated fibroblasts that lead to the recurrence. Antifibrotic agents can be used in different ways. Many surgeons prefer to use them intraoperatively. In this method many pieces of soaked sponges with 0.02% mitomycin C will be placed for 1–2 min in the subconjunctival area near the free conjunctival rim. It is important not to use mitomycin C directly on the bare episclera as it can prevent remodeling of episcleral tissue after surgery and increase the risk of thinning and perforation, especially if cautery has been applied. In primary pterygium, we typically use mitomycin C only in cases that we use amniotic membrane and otherwise in cases where a conjunctival autograft is used mitomycin C is usually not necessary (except in younger patients with very inflamed Tenon’s where we believe there is a higher risk of recurrence).
What Is the Preferred Technique for Closing/Covering the Defect?
Almost always after excising the pterygium, the defect area should be covered. Simple closure, conjunctival grafts, conjunctival flaps, and amniotic membrane all can be used for this purpose . Simple closure can be used only in small pterygia with minimal defects and judicious dissection and separation of conjunctiva from underlying Tenon’s capsule (the tractional forces can sever the sutures and cause the defect to open postoperatively). Conjunctival graft is the gold standard for defect management in pterygium surgery with the lowest recurrence rate and good cosmetic appearance. Attention should be paid not to include Tenon’s in the graft. Conjunctival flap also can be used with recurrence rates comparable to conjunctival grafting. The cosmetic results with a flap may be inferior to an autograft. Amniotic membrane grafting is another option for covering defects where conjunctival autograft is not used . If the conjunctival defect is very large, it is advisable to perform a temporary medial tarsorrhaphy at the end of surgery. Likewise, inferior punctal cautery may be performed at the end of the case.
We prefer to use fibrin glue to secure the graft (autograft or amniotic membrane). It decreases the operative time, improves patient comfort postoperatively, and reduces postoperative inflammation compared to suturing. Theoretically, recurrence rate with fibrin glue may be lower than suturing because of reduction of inflammation.
What Is the Postoperative Management of a Patient After Pterygium Surgery?
The two important points after pterygium excision are to decrease inflammation and to promote reepithelialization. Subconjunctival steroid at the end of surgery and frequent topical steroid in the early period after surgery are vital for reducing inflammation. Steroids are typically used for 3–4 months on a tapering dose. We prefer potent steroid drop such as betamethasone or prednisolone acetate 1% for 1 month after surgery and after that exchange it with a low-potent one such as fluorometholone. We often use a bandage contact lens to help promote epithelialization. Antibiotics are used while contact lens is in place. To promote reepithelialization, aggressive non-preserved lubrication and nighttime ointment (after removal of contact lens) are used.
Lid hygiene and warm compress were recommended to the patient. Systemic azithromycin was also prescribed. Three months later he underwent pterygium excision with application of mitomycin C 0.02% for 1 1/2 min. Amniotic membrane was attached to conjunctival defect with fibrin glue and subconjunctival long-acting steroid was injected. Postoperatively, he was maintained on a tapering dose of steroids up to 3 months. At 12-month follow-up, the patient’s best spectacle-corrected visual acuity had improved to 20/20 with minimal residual astigmatism.
Case 2: Recurrent Pterygium
The slit lamp photograph belongs to a 34-year-old man with history of pterygium surgery 4 years ago. The operation was done with mitomycin C application and amniotic membrane (AM) transplantation. Refraction is +2.0-6.0 @ 175 with BCVA 20/20. He complains of decreased vision and eye redness ( Fig. 20.2 ).
Photograph of a large pterygium recurrence with induced corneal horizontal flattening, compatible with decreased vision and with-the-rule astigmatism
What Are the Important Issues That Must Be Considered When Planning Surgery for Recurrent Pterygium?
Since the specifics of the prior surgical procedure(s) may not be available, one should be ready for the worst-case scenario. One may encounter significant complicating factors such as corneal thinning, medial rectus fibrosis, contracture, severe conjunctival deficiency, and symblepharon. A preoperative OCT is helpful to determine the residual corneal thickness below the pterygium.
How Do You Explain the Prognosis to the Patient?
The patient should understand that the operation will be more challenging than the primary surgery. The chances of recurrence are higher and the visual outcomes; especially postoperative astigmatism are unpredictable . The astigmatism (regular and irregular) will usually decrease after surgery, but more often than not, there will be visually significant residual astigmatism. If the pterygium involves the more central aspect of the cornea, the stromal haze will likely persist after surgery and affect the final visual outcome. Postoperatively, the patient will require closer follow-up and likely need topical medications, especially steroids, for several months, thus increasing the risk of increased intraocular pressure.
What Is the Preferred Method for Anesthesia?
Anesthesia will be very important in these cases. Topical or subconjunctival lidocaine is usually insufficient for recurrent pterygium surgery. Subenon’s or peribulbar injection with good sedation is advisable. General anesthesia may be even necessary.