Basement Membrane Failure
BY ALLISON CHINN, OD, & LEO SEMES, OD, FAAO
A 51-year old Caucasian female presented with complaints of blurred vision in both eyes at distance and near, worsening over the past year. Her ocular history included a long-standing diagnosis of epithelial basement membrane dystrophy (EBMD), and her medical history included genital herpes controlled with oral medication. Despite being correctable to 20/20 in each eye, she controlled her blurry vision with reading glasses for near work and tear supplements as needed. There was no evidence of ocular surface disruption with fluorescein dye and no history of recurrent corneal erosion (RCE), the most frequent complication.
EBMD is the most common corneal dystrophy seen in clinical practices (Kanski and Bowling, 2011; Ehlers et al, 2008; Webvision, 2015; Veire, 2010; and others. Full list available at www.clspectrum.com/references.). While variable, it commonly presents with dot-like epithelial opacities, whorl-like fingerprint lines, and circumscribed grey map-like patterns (Veire, 2010); EBMD is also referred to as a map-dot-fingerprint dystrophy. A consistent feature is the formation of microcysts in the corneal epithelium with alterations in the basement membrane.
Treatment focuses on treating situational RCE. Typical onset is in the second decade of life. About 10% of patients develop RCEs in the third decade, and the remainder will not develop symptoms (Kanski and Bowling, 2011). RCE treatment can include a cycloplegic drop for pain management, a prophylactic antibiotic solution/ointment four to six times daily, and sodium chloride hypertonicity ophthalmic ointment q.d.s.
Figure 1. Corneal cross-section showing subepithelial figures representing EBMD in the present case.
After the epithelial defect has healed, artificial tears and bland ointments are recommended along with the sodium chloride ointment for at least three to six months to prevent recurrence. In the absence of an ointment, an adjunctive bandage contact lens with the topical cycloplegic/prophylactic antibiotic solution may prove effective.
Recently, autologous serum eye drops have also been used to treat ocular surface disease, and these drops have better results compared to antibiotics, corticosteroids, or tear supplements (Azari and Rapuano, 2015). If the erosions persist, consider epithelial debridement (ED), anterior stromal puncture, or phototherapeutic keratectomy (PTK) (Ehlers et al, 2008). Two common procedures for patients who have significant EBMD-associated corneal epithelial irregularity are ED and PTK (Aldave et al, 2009).
ED with diamond burr polishing of Bowman’s layer is especially common for larger defects and those along the visual axis (Ehlers et al, 2008). Anterior stromal puncture is usually used in symptomatic, refractory cases, often after a trauma outside of the visual axis, but can leave small, permanent corneal scars that have no visual significance.
PTK is similarly effective as ED. This procedure uses an excimer laser to ablate the superficial stroma (Ehlers et al, 2008). An alternative treatment is alcohol delamination. The cornea is swabbed with alcohol, thoroughly washed, and the affected epithelium is peeled loose. Afterward, an unpreserved antibiotic drop is prescribed, and a bandage contact lens is applied until the epithelial defect has resolved (Chan et al, 2014). CLS
For references, please visit www.clspectrum.com/references and click on document #233.
Dr. Chinn is currently the family practice resident at the UAB School of Optometry. Dr. Semes is a professor of optometry at the UAB School of Optometry. He is a consultant or advisor to Alcon, Allergan, and Regeneron, and he is a stock shareholder in HPO.