recalcitrant recurrent erosions, particularly the dystrophic variant. By creating a large, shallow zone of ablation, this procedure can minimize the refractive effects; it can be used to correct an associated myopic refractive error as well. (See BCSC Section 13, Refractive Surgery, for further discussion.)

Ewald M, Hammersmith KM. Review of diagnosis and management of recurrent erosion syndrome. Curr Opin Ophthalmol. 2009;20(4):287–291.

Reidy JJ, Paulus MP, Gona S. Recurrent erosions of the cornea: epidemiology and treatment. Cornea. 2000;19(6):767–771. Wang L, Tsang H, Coroneo M. Treatment of recurrent corneal erosion syndrome using the combination of oral doxycycline and

topical corticosteroid. Clin Experiment Ophthalmol. 2008;36(1):8–12.

Wong VW, Chi SC, Lam DS. Diamond burr polishing for recurrent corneal erosions: results from a prospective randomized controlled trial. Cornea. 2009;28(2):152–156.

Neurotrophic Keratopathy and Persistent Corneal Epithelial Defects

PATHOGENESIS There are a number of causes of neurotrophic keratopathy, one being damage to the trigeminal nerve, which results in corneal hypoesthesia or anesthesia (Table 3-10). Probably the most common cause of neurotrophic keratopathy is herpetic keratitis, which can produce persistent corneal epithelial defects in the absence of replicating virus or active inflammation. Persistent corneal epithelial defects are characterized by central or paracentral areas of chronic nonhealing epithelium. The lesions frequently have elevated, round or oval, grayish edges associated with underlying stromal inflammation (Fig 3-24). The defects tend to be inferior or inferonasal as a result of the protective effect of Bell phenomenon on the superior cornea. Left untreated, persistent corneal epithelial defects can progress to vascularization and corneal opacification or scarring. Alternatively, progressive inflammation can lead to necrosis and thinning of the stroma, occasionally resulting in perforation.

Table 3-10

Figure 3-24 Neurotrophic ulcer. (Courtesy of Kenneth M. Goins, MD.)

Some medications used to treat ocular surface disease and glaucoma may impair epithelial wound healing and result in the formation of persistent corneal epithelial defects. The drugs most frequently implicated include topical anesthetics, topical nonsteroidal anti-inflammatory drugs (NSAIDs), trifluridine, β-blockers, carbonic anhydrase inhibitors, and, in sensitive individuals, all drops containing the preservative benzalkonium chloride (BAK). Some authors refer to the condition as toxic ulcerative keratopathy. This clinical problem may be unrecognized and usually presents as a diffuse punctate keratopathy. In some instances, pericentral pseudodendritiform lesions and pseudogeographic defects may occur. These clinical findings are often misinterpreted as a worsening of the underlying disease and thus may lead to even larger doses of the offending medication.

Persistent epithelial defects often occur in patients with diabetic retinopathy following epithelial debridement during vitreoretinal procedures. Diabetic neuropathy is thought to be a potential cause of neurotrophic keratopathy and nonhealing epithelial defects.

MANAGEMENT The management of neurotrophic keratopathy with or without persistent epithelial defects starts with a careful history. Initially, any potentially aggravating topical medications must be discontinued, as previously described. Frequent lubrication with nonpreserved ointments is suggested. Autologous serum drops (20%) containing growth factors and fibronectin can be very useful. In cases involving significant dry eye, temporary or permanent punctal occlusion is effective in improving the tear film and restoring the ocular surface.

Patching; low-water-content, highly oxygen-permeable therapeutic contact lenses; or scleralbearing contact lenses with a fluid-filled reservoir may facilitate reepithelialization or improve the

keratopathy. Lateral and/or medial tarsorrhaphy may be required to prevent surface desiccation. Tarsorrhaphy decreases tear-film evaporation and tear-film osmolarity, presumably by reducing the surface area of corneal exposure.

Medications with specific activity against MMPs, such as systemic tetracyclines, may help prevent or halt stromal melting in more severe cases. Corneal collagen crosslinking early in the course of a melt has been reported to be useful in a small number of patients. Amniotic membrane grafting has been reported to encourage healing of persistent epithelial ulcerations. Partial or total conjunctival flaps prevent corneal melting, but they should be used as a last resort in order to preserve the eye.

Goins KM. New insights into the diagnosis and treatment of neurotrophic keratopathy. Ocul Surf. 2005;3(2):96–110.

Jeng BH. Use of autologous serum in the treatment of ocular surface disorders. Arch Ophthalmol. 2011;129(12):1610–1612.

Trichiasis and Distichiasis

Trichiasis is an acquired condition in which eyelashes emerging from their normal anterior origin curve inward toward the cornea. Most cases are probably the result of subtle cicatricial entropion of the eyelid margin. Trichiasis can be idiopathic or secondary to chronic inflammatory conditions.

Distichiasis is a congenital (often autosomal dominant) or acquired condition in which an extra row of eyelashes emerges from the ducts of meibomian glands. These eyelashes can be fine and well tolerated or coarser and a threat to corneal integrity.

Aberrant eyelashes emerge from the tarsus as a result of chronic inflammatory conditions of the eyelids and conjunctiva, such as trachoma, mucous membrane pemphigoid, Stevens-Johnson syndrome, chronic blepharitis, and chemical burns.

Aberrant eyelashes and poor eyelid position and movement should be corrected. Aberrant eyelashes may be removed by epilation, electrolysis, or cryotherapy. Mechanical epilation is temporary because the eyelashes normally grow back within 2–3 weeks. Electrolysis works well only for removing a few eyelashes; however, it may be preferable in younger patients for cosmetic reasons. Cryotherapy is still a common treatment for aberrant eyelashes, but freezing can result in eyelid margin thinning, loss of adjacent normal eyelashes, and persistent lanugo (hairs), which may continue to abrade the cornea. Treatment at –20°C should be limited to less than 30 seconds to minimize complications. The preferred surgical technique for aberrant eyelashes is tarsotomy with eyelid margin rotation. For further discussion, see BCSC Section 7, Orbit, Eyelids, and Lacrimal System.

Woreta F, Munoz B, Alemayehu W, West SK. Three-year outcomes of the Surgery for Trichiasis, Antibiotics to Prevent Recurrence trial. Arch Ophthalmol. 2012;130(4):427–431.

Factitious Ocular Surface Disorders

Factitious disorders include a spectrum of self-induced injuries with symptoms or physical findings that the patient intentionally produces in order to assume the sick role. Factitious conjunctivitis usually shows evidence of mechanical injury to the inferior and nasal quadrants of the cornea and conjunctiva. The areas of involvement show sharply delineated borders. Patients often have medical training or work in a medical setting, and they generally have an attitude of serene indifference. The detached conjunctival tissues usually show no evidence of inflammation on pathologic examination.

Mucus-fishing syndrome

Mucus-fishing syndrome is characterized by a well-circumscribed pattern of rose bengal or lissamine

green staining on the nasal and inferior bulbar conjunctiva. All patients have a history of increased mucus production as a nonspecific response to ocular surface damage. The inciting event is typically KCS. Patients usually demonstrate vigorous eye rubbing and compulsive removal of mucus strands from the fornix (mucus fishing). The resultant epithelial injury heightens the ocular surface irritation, which in turn stimulates additional mucus production, resulting in a vicious circle.

Topical anesthetic abuse

Clinical application of topical anesthetics has become an integral part of the modern practice of ophthalmology. However, indiscriminate use of topical anesthetics can cause serious ocular surface toxicity and complications. Local anesthetics are known to inhibit epithelial migration and division. Loss of microvilli, reduction of desmosomes and other intercellular contacts, and swelling of mitochondria and lysosomes have been reported in ultrastructural studies. The clinical features of anesthetic abuse are characterized by the failure of the presenting condition, such as corneal abrasions or infectious keratitis, to respond to appropriate therapy.

Initially, a punctate keratopathy is seen. As the abuse continues, the eye becomes more injected and epithelial defects appear or take on a neurotrophic appearance. As the process continues, keratic precipitates and hypopyon develop, thus mimicking an infectious course. Diffuse stromal edema, dense stromal infiltrates, and large ring opacity are common presenting signs (Fig 3-25). Stromal vascularization may occur in chronic abuse, and secondary infection may ensue. Because of the presence of corneal infiltrates and anterior segment inflammation, infectious keratitis must be ruled out through corneal scraping, culture, or biopsy.