Conjunctival Flap for Corneal Disease
A conjunctival flap can be used to cover an unstable or painful corneal surface with a hinged flap of more durable conjunctiva when there is little chance of resolution by normal corneal wound healing. Conjunctival flaps provide a vascularized epithelial cover for the cornea but are not optically clear. Conjunctival flap surgery is performed less frequently now than in the past because of the availability of bandage and scleral contact lenses, commercially available amniotic membrane, use of tarsorrhaphy, and broadened indications for penetrating keratoplasty (PK) and lamellar keratoplasty (see Chapter 15). Nevertheless, the conjunctival flap remains an effective method for managing inflammatory and structural corneal disorders when restoration of vision is not the primary concern. The use of a conjunctival flap is controversial in patients with active microbial keratitis or corneal perforation because residual infectious organisms may proliferate in the avascular corneal stroma beneath the flap. A corneal perforation may continue to leak under the flap.
The principal indications for a conjunctival flap are as follows:
chronic, sterile, nonhealing epithelial defects (stromal herpes simplex or herpes zoster virus keratitis, chemical and thermal burns, keratoconjunctivitis sicca, post-infectious 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
The disadvantages of conjunctival flap surgery are a reduced view of the anterior chamber and the creation of a potential barrier to drug penetration through the cornea into the anterior chamber. However, a successful conjunctival graft, free of buttonholes, will thin out and if blood vessels regress, may eventually enable usable vision.
A complete (Gundersen) flap (Figs 13-3, 13-4) is a highly successful technique if the surgeon pays close attention to several fundamental principles for covering the corneal surface with vascularized tissue and keeping this tissue in place:
complete removal of the corneal epithelium and debridement of necrotic tissue from the cornea
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, which may lead to flap retraction
Figure 13-3 Gundersen flap.
(Courtesy of Woodford S. Van Meter, MD.)
Figure 13-4 Surgical steps for the Gundersen conjunctival flap. A, Removal of the corneal epithelium using cellulose sponges. B, A 360° peritomy with relaxing incisions, placement of a superior limbal traction suture, a superior forniceal incision, and dissection of a thin flap. C, Positioning of the flap. D, Suturing of the flap into position with multiple interrupted sutures.
(Reproduced with permission from Mannis MJ. Conjunctival flaps. Int Ophthalmol Clin. 1988;28(2):165–168.)
Retrobulbar, peribulbar, or general anesthesia should be used for this procedure. The corneal epithelium and all necrotic tissue are first removed, and the eye is retracted inferiorly with an intracorneal traction suture (6-0 silk) at the superior limbus. Elevation of the flap with subconjunctival injection of lidocaine 1%–2% with epinephrine to separate the conjunctiva from underlying Tenon capsule 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 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 removal 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 polyglactin or 10-0 nylon sutures, depending on the surgeon’s preference.
Alternatives to the Gundersen flap are smaller or temporary conjunctival flaps (Fig 13-5):
single pedicle flap
A, Bipedicle flap. B, Advancement flap. C, Single pedicle flap.
(Illustration by Mark Miller.)
These flaps may be used for temporary coverage of small peripheral corneal wounds or areas of ulceration. The advantage is that only small or partial areas of the cornea are covered, so details of the anterior chamber can be visualized, and the patient may regain functional vision. As retraction is a common feature of all of these temporary flaps, the surgeon should take care to minimize tension on any conjunctival flap when it is placed.
Johnson DA. Gundersen flap. In: Basic Techniques of Ophthalmic Surgery. 2nd ed. San Francisco: American Academy of Ophthalmology; 2015:125–130.
Retraction is the most common complication of conjunctival flaps, 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 in elderly patients, may also occur postoperatively and may or may not be related to the flap itself. Unsatisfactory cosmetic appearance can be improved with a painted cosmetic contact lens. Progressive corneal disease under any type of conjunctival flap is a concern in patients with infectious or autoimmune conditions.
Considerations in removal of a flap
If PK or lamellar keratoplasty is to be performed in an eye with a conjunctival flap, the flap may be removed either as a separate procedure or at the time of keratoplasty. Removal of the flap (without keratoplasty) usually does not succeed in restoring vision, as the underlying cornea is almost always opaque from subepithelial scarring and/or thinned. Because the conjunctival flap procedure tends to destroy or displace most limbal stem cells, a limbal autograft or allograft after removal of the flap may be necessary in order to provide a permanent source of normal epithelial cells before an optical corneal transplant is attempted.
Khodadoust A, Quinter AP. Microsurgical approach to the conjunctival flap. Arch Ophthalmol. 2003;121(8):1189–1193.
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.