EBMD: Part 1

Epithelial basement membrane dystrophy (EBMD), also known as map-dot-fingerprint dystrophy, Cogan microcystic epithelial dystrophy, and anterior basement membrane dystrophy, can present with a spectrum of clinical findings, including map lines, dots, fingerprint lines, and blebs.¹ EBMD also varies greatly in severity, ranging from asymptomatic to causing debilitating pain when corneal erosions occur.^1,2 Its root cause is dysfunction in adhesion of basal epithelial cells and their hemidesmosomes to the basal laminar material.²

EBMD is relatively common, but is often overlooked in comprehensive eye examinations, surgical referrals, or consultations, including cataract and refractive preoperative examinations, and even dry eye evaluations.³ This is one of the most under-recognized and under-treated conditions, in my experience, with second opinion dry eye consults.

Basement membranes are extremely specialized extracellular matrices. They are dynamic and adaptable structures that moderate cellular responses to regulate tissue structure, function, and repair.^2,4 Ongoing research suggests that not only does this matrix provide structural support, but it also serves as a reservoir and modulator for growth factors that direct cellular functions.⁴

DIAGNOSING EBMD

The American Society of Cataract and Refractive Surgery’s algorithm for the preoperative diagnosis and treatment of ocular surface disorders has several great recommendations for preoperative examination. One suggestion is to employ the lift-and-pull technique using the upper eyelid, which should reveal the often-overlooked portion of the ocular surface.³

EBMD can be subtle and difficult to detect, even with use of vital dyes (Figure), because of the wide spectrum of disease presentation and the quick-healing nature of the corneal epithelium. In these instances, the corneal sweep test described by D. Brian Kim, MD, may bridge the gap in our diagnostic toolkit for corneal erosions.⁵ Dr. Kim developed the Kim Corneal Sweeper (Katena Products) to help aid in this diagnosis.

Steps for the corneal sweep test are as follows:⁵

1. Instill topical anesthetic eye drops with fluorescein dye.

2. Under slit-lamp examination with a cobalt blue light, place the corneal sweeper on the cornea in a tangential manner and gently sweep it across the epithelial surface with slight indentation pressure.

3. Brush the corneal sweeper across normal corneal epithelium smoothly and atraumatically.

4. If a subtle EBMD and/or area of erosion is present, the sweeper will cause the loose epithelium to move, resulting in a visible wrinkle and revealing the area of pathology.

THE IMPORTANCE OF PATIENT HISTORY

EBMD has a multitude of therapeutic options (stay tuned for part 2 in next month’s Snapshot).² Remember to listen closely for indicators of EBMD and corneal erosions when evaluating patients, including symptoms of pain upon waking and a history of ocular trauma.

Also be sure to look twice, especially at the superior cornea, as EBMD may be hidden behind the eyelids. If still not obvious, consider the corneal sweep test to “push” the cornea into revealing any hidden pathologies.