Primary pterygium excision involves ‘peeling-off’ technique

Procedure incorporates preserved human amniotic membrane transplantation and fibrin glue.

Thomas John

The name pterygium is derived from the Greek word meaning wing, which describes its typical shape, extending from the scleral side on to the cornea. It is commonly found on the nasal side within the interpalpebral fissure. There is a higher incidence of pterygium in individuals who are often exposed to sunlight, dust, wind, fumes and other noxious stimuli. It is more common in the tropical and subtropical regions.

Surgical indications for removal of a pterygium include increasing size with compromised vision, recurrent inflammation and discomfort, progressive growth toward the central cornea/ visual axis, restricted ocular motility and cosmetic reasons. However, when recurrences occur after surgical excision, it can be worse than the initial primary pterygium. Hence, the choice of the surgical procedure is important. A bare sclera technique is not acceptable because of its high recurrence rate after surgery. Other techniques with varying degrees of surgical success include simple closure, sliding flap, rotational flap, conjunctival autograft and human amniotic membrane transplantation.

In this issue, I describe the removal of a primary pterygium using a “peeling-off” technique in a reverse direction from the scleral side on to the cornea, combined with preserved human amniotic membrane transplantation with the use of fibrin glue (Tisseel, Baxter AG). In this case, the primary pterygium is large, and it involves the central cornea and the visual axis (Figure 1).

Anesthesia

General anesthesia, peribulbar or retrobulbar block, or topical anesthesia with monitored anesthesia care may be used depending on the individual case and surgeon preference. General anesthesia may be considered for the younger patients. For topical anesthesia with monitored anesthesia care, Xylocaine 2% jelly (lidocaine HCl, AstraZeneca) is applied to the ocular surface with a sterile cotton swab or with a 5 mL syringe.

Pterygium excision

In this nasal pterygium, rotating the globe temporally will increase the exposure and surgical access. A 6-0 silk suture is passed through the peripheral cornea, close to the limbus, and the globe is rotated temporally (Figure 1). Alternatively, a second 6-0 silk suture may be passed through the peripheral cornea in the opposite side, 180° from the first suture (my usual preference).

Large pterygium involving the central cornea, including the visual axis (main); Corneal bridle suture, 6-0 silk is passed through the peripheral cornea (upper insert); Globe is rotated temporally for increased exposure of the pterygium (lower insert). Images: John T	Low-temperature, disposable eye cautery is used to apply spot-cautery marks on the conjunctival surface at a distance of 5 mm from the limbus, as indicated by the surgical Castroviejo calipers (upper row); The spot-cautery marks are highlighted with methylene blue (lower row).
The pterygium is excised from the scleral toward the corneal direction using both blunt and sharp dissection. Cautery is used to obtain hemostasis.	Pterygium is peeled-off from the corneal surface using a hemostat. A straight crescent blade (Alcon) is used to make the limbal and corneal surface smooth (bottom right).
Pterygium has been excised and scleral hemostasis is achieved (upper left); Conjunctival margins are attached to the episcleral tissue using interrupted 10-0 Vicryl sutures (upper right); Preserved human amniotic membrane is introduced with the epithelial side up and the stromal side facing the ocular surface. Amniotic membrane covers the scleral region and the peripheral cornea past the surgical limbus (bottom row).	Amniotic membrane is reflected, such that the stromal side is exposed (upper left); Component 1 of the fibrin glue is applied to the exposed stromal side of the amniotic membrane (upper right); Component 2 of the fibrin glue is applied to the bare sclera and the exposed peripheral cornea (lower left); Amniotic membrane is reflected back into position (lower right).
	A muscle hook is used to ‘iron’ the surface of the amniotic membrane, such that the surface is smooth and well adherent to the ocular surface (upper row); A 10-0 nylon suture is passed through the amniotic membrane, anchoring it to the peripheral cornea (lower left); Completed view of the procedure (lower right).

The sutures may be anchored to the surgical drape using a small hemostat or with Steri-Strips. The area to be excised is demarcated using spot-cautery marks that are highlighted with methylene blue (Figure 2). I have been using a mini-excision technique for more than 10 years with good success.

The surgical Castroviejo calipers are set at 5 mm and form the boundary of the excision (Figure 2). The pterygium is excised from the scleral side toward the corneal direction using blunt and sharp dissection, utilizing Westcott scissors and 0.12 forceps (Figure 3).

Cautery is used to obtain hemostasis (Figure 3). No residual pterygium tissue is left at the limbus. The “bunched-up” pterygium tissue on the surface of the peripheral cornea (Figures 3 and 4) is held at its base with a small hemostat, and the pterygium is peeled-off from the corneal surface, including the central cornea and the region of the visual axis. The peeling-off is carried out in one smooth, steady motion.

The limbal region and the peripheral corneal surface are made smooth using a straight crescent blade (Alcon) (Figure 4 on page 24). Hemostasis is achieved on the scleral side using a cautery. During the surgical excision of the pterygium, the cut edges of the conjunctiva usually retract and the area of bare sclera expands (Figure 5 on page 24). Pulling the cut margins of the conjunctiva and attaching the conjunctival tissue margins to the episcleral tissue using a few interrupted 10-0 Vicryl sutures restores the exposed bare scleral area where the pterygium was excised (Figure 5).

Amniotic membrane transplant

Preserved human amniotic membrane is introduced into the surgical field after gently irrigating the membrane with sterile balanced salt solution, and it is removed from its carrier sheet using smooth tying forceps (Figure 5).

The membrane is oriented on the carrier sheet with its stromal side in contact with the carrier sheet. When the membrane is about 60% released from the carrier sheet, the carrier sheet is turned upside down and the amniotic membrane is pulled from the carrier sheet. This ensures the membrane lands on the ocular surface with the stromal side down (Figure 5).

The membrane is spread evenly, so that it covers the bare scleral region and the peripheral cornea past the surgical limbus (Figure 5). The membrane may be anchored using two 10-0 Vicryl sutures on the conjunctival region.

Application of fibrin glue

The amniotic membrane is reflected on itself to expose the stromal side of the amniotic membrane (Figure 6). Component 1 of the fibrin glue is applied to the exposed stromal side of the amniotic membrane, while component 2 of the fibrin glue is applied to the bare sclera and the exposed peripheral cornea (Figure 6). The membrane is then reflected back into position to cover the entire bare sclera and the peripheral cornea past the limbus (Figure 6).

Completion of the procedure

A muscle hook is used to “iron” the surface of the amniotic membrane, such that the surface is smooth and well adherent to the ocular surface (Figure 7). A 10-0 nylon suture is passed through the amniotic membrane, anchoring it to the peripheral cornea (Figure 7). The excess amniotic membrane around the conjunctival margins is excised using Vannas scissors. Completed view of the procedure is shown in Figure 7, with the amniotic membrane graft in place.

Surgical pearls and tips

Measure with calipers 5 mm while applying spot-cautery marks using the disposable eye cautery. Highlight the spots with methylene blue, which will serve as a clear guide during the pterygium excision.
In this mini-excision technique, there is no excision of conjunctival tissue over the region of the medial rectus muscle (Figure 2).
The vertical height of tissue excision at the limbus should be greater than the vertical height of the pterygium as it crosses the limbus to help prevent recurrence (author’s personal observation).
Remove the pterygium in a reverse direction, namely from the scleral side to the corneal side. This ensures proper peeling-off of the pterygium and maintaining proper plane of excision on the cornea.
Apply the hemostat to the base of the partially excised pterygium close to the limbus and peel-off the pterygium from the corneal surface in one smooth, steady motion.
The limbal and the peripheral corneal regions are made smooth using a straight crescent blade.
Place the preserved human amniotic membrane with the stromal side facing the ocular surface and the epithelial side facing the surgeon. The other types of amniotic membrane include freeze-dried amniotic membrane. Alternatively, conjunctival autograft may be utilized in the place of amniotic membrane graft.
Apply fibrin glue separately, namely component 1 and 2.
Although fibrin glue holds the amniotic membrane in place, a few sutures as described above add more security.
This entire procedure may be performed without any sutures, using fibrin glue. However, in some cases, the margins of the amniotic graft may detach postoperatively, especially in cases in which the patient may rub his eye. The limited use of suture provides the additional anchorage of the amniotic membrane to the ocular surface.

Treatment

Postoperatively, a topical steroid, Pred Forte 1% (prednisolone acetate 1%, Allergan), and an antibiotic, Iquix (levofloxacin 1.5%, Vistakon), are used four times daily. Also, an NSAID is used, namely Xibrom 0.09% (bromfenac ophthalmic solution, Ista Pharmaceuticals), twice daily.

For globe protection, the patient is asked to wear glasses or an eye shield during the day and a shield at night for the operative eye. The patient is asked not to rub the eye.

For more information:

Thomas John, MD, is clinical associate professor at Loyola University at 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. Dr. John has no direct financial interest in the products discussed in this article. He is a paid consultant to Vistakon and is a speaker for Vistakon and Allergan.

References:

John T. Human amniotic membrane transplantation: past, present and future. Ophthalmol Clin North Am. 2003;16:43-65.

John T. Pterygium excision and conjunctival mini-autograft: preliminary report. Eye. 2001;15:292-296.

Katircioglu YA, Altiparmak UE, Duman S: Comparison of three methods for the treatment of pterygium: amniotic membrane graft, conjunctival autograft and conjunctival autograft plus mitomycin C. Orbit. 2007;26:5-13.

Yokoi N, Inatomi T, Kinoshita S: Surgery of the conjunctiva. Dev Ophthalmol. 2008;41:138-58.