Steven J. Wiffen

Introduction

In a discussion at the Cornea World Congress in 1964, José Barraquer described the use of an autograft of limbus from the unaffected eye in cases of superficial burns as a preparatory procedure before keratoplasty.¹ He noted that this improved the state of the corneal epithelium but the mechanism was not discussed. In 1966, Strampelli et al. reported two cases of improvement in vascularized opaque corneas with transplantation of a complete ring of limbus from the other eye.² They described the technique in more detail at the Second International Corneo-Plastic Conference in London in 1967.³ It was not until some time later that the role of the limbus as the niche for the stem cells responsible for the corneal epithelium was elucidated, and Kenyon and Tseng reported on the use of autografts of conjunctiva and limbus for management of diffuse unilateral limbal deficiency in 1989.⁴ Conjunctival limbal autografts (CLAU) were described within a classification system for epithelial transplantation proposed by Holland and Schwartz in 1996.⁵ Since then, there have been many reports describing the use of limbal autografts, and the role of CLAU in management of unilateral ocular surface disease has been comprehensively reviewed.^6–9

Indications

Conjunctival limbal autograft (CLAU) is indicated for management of symptomatic partial or total unilateral limbal deficiency.

Clinical signs of limbal deficiency include varying combinations of conjunctivalization of the cornea, with associated vascularization and fibrovascular pannus, persistent or recurrent epithelial defects and scarring or stromal haze.⁹ Symptoms include poor vision, chronic or recurrent discomfort and photophobia.

Limbal deficiency may be primary, as in aniridia, or secondary to chemical or thermal trauma, multiple surgeries, chronic inflammation, contact lens-induced keratopathy, or ocular surface squamous neoplasia.

Probably the most common use of limbal autografts has been in surgery for pterygium in the form of an ipsilateral limbal translocation, though there is little evidence that the limbal part of the autograft adds any benefit over a standard conjunctival autograft.¹⁰ In most other forms of unilateral limbal deficiency the autograft is harvested from the other eye. In this situation, a unilateral chemical injury is probably the most common clinical scenario. Figure 40.1 demonstrates improvement in the ocular surface with CLAU after chemical injury.

Preoperative Assessment and Considerations

It has been recognized that the state of the rest of the ocular surface is critical to the outcome of limbal transplantation. Preoperative assessment must include thorough examination of the ocular adnexa and ocular surface. The nature of chemical injuries and many of the other causes of limbal deficiency is such that other ocular surface or adnexal problems are commonly associated. Two important considerations in determining management are whether the condition is unilateral or bilateral and whether there is conjunctival involvement.⁵

Lid malposition, symblepharon, and trichiasis all need to be dealt with prior to limbal transplantation. The most common pre-existing problem is that of dry eye and this is a major prognostic factor.¹¹ If aqueous tear function is inadequate, then punctal occlusion should be performed. Blepharitis or ocular surface inflammation should be controlled optimally before surgery if possible.

In chemical injury cases, timing of CLAU is an important factor. CLAU may be performed either in the acute phase to aid healing or later once the cornea has conjunctivalized and inflammation has settled. In the acute phase, a limbal graft will not survive if the limbus is ischemic, and Tenon’s advancement may be required. In addition, the inflammation that occurs in the acute and subacute stages of a chemical injury will often cause the CLAU to fail. Therefore it is advisable to wait until the inflammation has resolved before performing a CLAU. The delay in CLAU surgery is especially critical as the fellow eye can only be used once as a donor.

Intraocular pressure should be estimated, taking into account that tonometry may not be accurate with an abnormal ocular surface and cornea. Secondary glaucoma is common in the context of chemical injuries and steroid-related intraocular pressure rises may occur postoperatively. It is easy to overlook glaucoma when there are severe ocular surface problems, and loss of vision may occur even when epithelial transplantation is successful.

An assessment of the visual potential of the affected eye is required. If the eye has no visual potential, then it is not sensible to risk the donor eye, when another procedure, such as a conjunctival flap, may stabilize the ocular surface and provide comfort. Thorough discussion with the patient of the risks and benefits of surgery are required. In particular, the risk to the donor eye needs to be discussed. If the fellow eye has a history of trauma, then a careful examination of the conjunctiva, limbus and cornea is critical before recommending a CLAU. In addition, a history of long-term contact lens wear can result in subclinical damage to the limbal stem cells and may be a contraindication for CLAU.

Surgical Technique

Surgery may be performed under local or general anesthetic but the patient will need to be able to manage having both eyes operated on both during and after the procedure under local anesthetic.

Both eyes are prepped and draped. A well-fitting speculum is required. At the start of surgery vasoconstriction may be achieved with topical epinephrine 1/10 000 or, with apraclonidine 0.5% (Iopidine) or brimonidine 0.1% (Alphagan P) to avoid pupil dilation.