rarely occurs but can be most disturbing to the patient. Postoperative infections are rare, but cases reported in the literature reveal a poor visual outcome.

Hirst LW. Pterygium surgery. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2009, module 3.

Jacobs D, Kaufman SC. Ophthalmic Technology Assessment: Options and Adjuvants in Surgery for Pterygium. San Francisco: American Academy of Ophthalmology.

Mucous Membrane Grafting

Indications

In the absence of healthy conjunctiva (eg, in bilateral conjunctival cicatricial disorders), buccal mucosa or amniotic membrane may be employed to restore the conjunctival mucosal surface to a more functional state. The goal of restoring the conjunctival mucosal surface is to create a more normal forniceal architecture and reduce ocular surface inflammation as well as the amount of corneal damage resulting from abnormal eyelid–globe relationships (eg, entropion, trichiasis), chronic exposure (lagophthalmos), and direct corneal trauma (palpebral conjunctival keratinization) that usually occurs with bilateral cicatricial conjunctival disorders (see Table 14-1). Mucous membrane grafts increase ocular surface wetting by improving eyelid movement and distribution of the tear film over the cornea, thereby reducing exposure and evaporation; in addition, some grafts (eg, nasal mucosal) may increase mucus discharge. This procedure also provides favorable extracellular matrix substrate for better epithelial migration and adhesion. However, mucous membrane grafting is not effective in replacing normal stem cells.

Mucous membrane grafting has rarely been used as a treatment for unilateral chemical injury and is performed only in desperate cases of bilateral injury where advancement of the Tenon capsule is not possible and allograft limbal tissue is not available. Although good results have been reported in inactive cicatricial disorders such as late-stage, nonprogressive Stevens-Johnson syndrome, there is some reluctance to apply this technique to advanced (stage III or IV) mucous membrane pemphigoid (MMP) for fear of exacerbating this progressive inflammatory disorder. However, advances in immunosuppressive treatment have brought promise that mucous membrane grafting for the eyelid abnormalities associated with late-stage MMP can achieve some success. In a small series of patients with advanced MMP or Stevens-Johnson syndrome, combinations of allograft limbal transplantation, amniotic membrane transplantation, and tarsorrhaphy, followed by the use of serum-derived tears and systemic immunosuppression, were shown to reconstruct the ocular surface. These therapeutic modalities appear to provide an alternative to other difficult procedures, such as keratoprosthesis, for treating patients with desperate cicatricial keratoconjunctivitis (see Chapter 15).

There are many surgical techniques for mucosal grafting, and the reader should consult a surgical textbook or video for specifics. Potential complications, regardless of the particular technique, include buttonholing, graft retraction, trichiasis, surface keratinization of the graft, ptosis, blepharophimosis, depressed eyelid blink, incomplete eyelid closure, submucosal abscess formation, and persistent nonhealing epithelial defects of the cornea.

Chun YS, Park IK, Kim JC. Technique for autologous nasal mucosa transplantation in severe ocular surface disease. Eur J Ophthalmol. 2011;21(5):545–551.

Fu Y, Liu J, Tseng SC. Oral mucosal graft to correct lid margin pathologic features in cicatricial ocular surface diseases. Am J Ophthalmol. 2011;152(4):600–608.e1.

Liu J, Sheha H, Fu Y, Giegengack M, Tseng SC. Oral mucosal graft with amniotic membrane transplantation for total limbal stem cell deficiency. Am J Ophthalmol. 2011;152(5):739–747.

Sant’Anna AE, Hazarbassanov RM, de Freitas D, Gomes JA. Minor salivary glands and labial mucous membrane graft in the treatment of severe symblepharon and dry eye in patients with Stevens-Johnson syndrome. Br J Ophthalmol. 2012;96(2):234–

239.

Takeda K, Nakamura T, Inatomi T, Sotozono C, Watanabe A, Kinoshita S. Ocular surface reconstruction using the combination of autologous cultivated oral mucosal epithelial transplantation and eyelid surgery for severe ocular surface disease. Am J Ophthalmol. 2011;152(2):195–201.

Conjunctival Flap

Indications

The conjunctival flap procedure covers an unstable or painful corneal surface with a hinged flap of more durable conjunctiva. Conjunctival flap surgery is performed less frequently now than in the past because of broadened indications for penetrating keratoplasty (PK) (see Chapters 10 and 15), more effective antimicrobial agents, availability of bandage contact lenses, and improved management of corneal inflammatory diseases. Nevertheless, this procedure remains an effective method for managing inflammatory and structural corneal disorders when restoration of vision is not an immediate concern. It should not be used for active microbial keratitis or corneal perforation, because residual infectious organisms may proliferate under a flap if an ulcer is not sterilized first. Any corneal perforation must first be sealed, or it will continue to leak under the flap. The procedure is not meant to provide tectonic support to a very thin cornea. The principal indications for this procedure are

chronic sterile epithelial and stromal ulcerations (stromal herpes simplex virus keratitis, chemical and thermal burns, keratoconjunctivitis sicca, postinfectious ulcers, neurotrophic keratopathy)

closed but unstable corneal wounds

painful bullous keratopathy in a patient who is not a good candidate for PK a phthisical eye being prepared for a prosthetic shell

A reduced view of the anterior chamber and the creation of a potential barrier against drug penetration are among the disadvantages of conjunctival flap surgery. However, a successful conjunctival graft, free of buttonholes, will thin out and enable functional vision.

Surgical technique

A complete (Gundersen) flap (Fig 14-3) is highly successful if attention is paid to several fundamental principles:

complete removal of the corneal epithelium and debridement of necrotic tissue reinforcement of thin areas with corneal or scleral tissue

creation of a mobile, thin conjunctival flap that contains minimal Tenon capsule absence of any conjunctival buttonholes

absence of any traction on the flap at its margins that may lead to flap retraction

with epinephrine enhances anesthesia, facilitates dissection, and reduces bleeding. The needle for this injection should not pierce the conjunctiva in the area to be used for the flap.

The dissection may start from either the limbus or the superior fornix. Dissection of conjunctiva from underlying Tenon fascia must be performed carefully under direct visualization to prevent conjunctival perforation, especially in eyes with previous conjunctival surgery. Once the flap has been dissected, a 360° peritomy is performed with relaxing incisions, followed by scraping of all remaining limbal and corneal epithelium. Additional undermining of the flap allows it to cover the entire cornea and to rest there without traction. Any residual tension may foster later retraction of the flap. After the flap is positioned over the prepared cornea, it is sutured to the sclera just posterior to the limbus superiorly and inferiorly with 8-0 polyglycolic acid suture or 10-0 nylon suture, depending on surgeon preference.

Partial conjunctival flap A partial, or bridge, flap may be used for temporary coverage of a peripheral wound or area of ulceration. Retraction is common despite adequate relaxation of the base. The flap should be well undermined to relieve tension and decrease the chance of retraction. The flaps are fixated to the cornea with nonabsorbable suture (9-0 or 10-0 nylon).

Bipedicle flap This partial, or bucket handle, flap can be used for small central or paracentral corneal lesions that do not require complete corneal coverage. It can be useful in a cornea with inferior exposure. The advantage is that the view of the anterior chamber and the remaining uninvolved cornea is not obstructed. The flap is fashioned similar to the Gundersen flap but with only enough dissection required to cover the lesion, plus a small margin (the width of the flap should be 1.3–1.5 times the width of the lesion). Subconjunctival anesthesia is administered, and the epithelium beneath the site of the flap is removed. After marking the bulbar conjunctiva with methylene blue, the surgeon can create the flap and move it into position for suturing with interrupted nylon suture.

Advancement flap Peripheral limbal or paralimbal corneal lesions can be covered with a simple advancement conjunctival flap. A limbal incision is created with relaxing components, and the conjunctiva is simply advanced onto the cornea to cover the defect. Scleral patch grafts and onlay grafts may also be used in conjunction with this technique. The disadvantage of this type of flap is a tendency to retract with time.

Single-pedicle flap Also known as a racquet flap, a single-pedicle flap can be used for peripheral corneal lesions that are not large enough to require a total flap. Although a single-pedicle flap is more difficult to dissect than an advancement flap, it is less likely to retract.

Complications

Retraction of the flap is the most common complication, occurring in approximately 10% of cases. Other complications include hemorrhage beneath the flap and epithelial cysts. In some cases, inclusion cysts enlarge to the point of requiring excision or marsupialization. Ptosis, usually due to levator dehiscence, may also occur postoperatively. Unsatisfactory cosmetic appearance can be improved with a painted contact lens. Progressive corneal disease under the flap is a concern with infectious and autoimmune conditions.

Considerations in removal of the flap

If PK is to be performed in an eye with a conjunctival flap, the flap may be removed as a separate procedure or at the time of PK. Simple removal of the flap (without keratoplasty) is usually unsatisfactory in restoring vision, as the underlying cornea is almost always scarred and/or thinned. Because the conjunctival flap procedure tends to destroy or displace most limbal stem cells, a limbal