Interface Tattooing With Fibrin Glue–Assisted Superficial Anterior Lamellar Keratoplasty Using Small Incision Lenticule Extraction Lenticule for Limbal Dermoids

Soosan Jacob, MS, FRCS, DNB, MNAMS and Smita Narasimhan, MBBS

Limbal dermoid is a sporadically occurring congenital tumor that straddles the limbus and is generally found in the inferotemporal quadrant.¹ It is a choristoma, having a keratinized surface with hair follicles seen on the surface. They are classified as Grade 1, which is superficial and measures less than 5 mm; Grade 2, which is larger and also deeper and extends to the Descemet’s membrane; and Grade 3, where the entire anterior segment is involved. These can be cosmetically disfiguring, may cause foreign body sensation, astigmatism, lipid infiltration on the cornea, dellen formation, inability to close the lids completely, or, rarely, completely obstruct the visual axis. They may also be associated with other syndromes, such as the Goldenhar syndrome, Duane retraction syndrome, and SCALP (sebaceous nevus syndrome, central nervous system malformations, aplasia cutis congenita, limbal dermoid, pigmented nevus with neurocutaneous melanosis) syndrome.

Limbal dermoids may be observed without necessarily having to be removed, however, because it can be cosmetically disfiguring, many patients/parents of affected children do opt for surgery. If surgery is decided on, various options have been described in the past.^2–5 These include superficial sclerokeratectomy, deep excision with lamellar keratoplasty, amniotic membrane grafting, and full-thickness excision with penetrating sclerokeratoplasty.^1,6–14

The author (SJ) has described a technique for Type 1 limbal dermoids where a donor lenticule extracted from a small incision lenticule extraction (SMILE) surgery for correction of myopia is used for corneal resurfacing after lamellar excision of the dermoid.15 Interface tattoo is also used to enhance the cosmetic outcome.

TECHNIQUE

A 26-gauge needle is used to inject balanced salt solution (BSS) under the conjunctiva adjacent to the dermoid. The ballooned free conjunctiva is then dissected off the surface of the dermoid up to the extent possible. An inked trephine is used to mark a shallow groove around the corneal part of the limbal dermoid and this is then deepened with a crescent blade. The dermoid tissue is then dissected in a lamellar plane minimally below the level of the adjacent normal cornea. Dissection is carried onto the scleral surface and the limbal dermoid is thus removed. Any bleeding vessels on the scleral surface are cauterized and the limbal outline contiguous with the adjacent cornea is marked with a fine-tipped marker pen. The circular outline marked is again verified under natural room light illumination with the microscope light turned off, and once confirmed to be contiguous with the darker appearance of the iris seen through adjacent cornea, tattoo pigment (Appasamy Associates) is applied carefully on a dry bed within the circular marked outline of the excised corneal portion of the limbal dermoid. Care is taken to not allow the pigment to spread anywhere outside the marked outline. Circularity and cosmesis is again assessed under room light illumination. A donor SMILE lenticule harvested from a suitably screened refractive candidate (negative for anti-HIV-1 and anti-HIV-2, Hepatitis B surface antigen, anti–Hepatitis C virus, and venereal disease research laboratory test) is then applied to the bed using minimal fibrin glue. Any excess lenticule lying outside the limbus can be trimmed and the conjunctiva is finally stuck into position using fibrin glue. Amniotic membrane may be used to cover any large area of deficient conjunctiva (Figure 12-1).

ADVANTAGES

Current techniques for excision have many disadvantages. They may leave a bluish-white scar seen in 50% of cases, which is more markedly visible in darkcolored eyes. Sutured apposition of full-thickness or lamellar grafts can lead to suture-induced astigmatism. Suture bites close to the visual axis cause scars in the line of vision and irregular astigmatism. Scleral outlines of thicker grafts are often visible through overlying conjunctiva, even under room illumination, giving a poor cosmetic outcome.

Our technique has the advantage of using the SMILE lenticule as a thin lamellar graft for superficial corneal resurfacing. SMILE lenticules have already been used in the past for treatment of presbyopia (PrEsbyopic Allogeneic Refractive Lenticule [PEARL], a technique described by one of the authors [SJ]),¹⁶ hyperopia, keratoconus, and other applications with proven safety and efficacy (Figure 12-2).^17–21

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