Epithelial Basement Membrane Dystrophy
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Disease Entity
Epithelial Basement Membrane Dystrophy (also known as map-dot-fingerprint, Cogan's microcystic dystrophy, or anterior basement membrane dystrophy)
Disease
Epithelial basement membrane dystrophy (EBMD) is a disease that affects the anterior cornea, causing characteristic slit lamp findings which may result in decreased vision and/or recurrent corneal erosions. There is actually some debate as to whether EBMD is a true dystrophy (a disease which occurs more commonly within affected families than in the general population) or a corneal degeneration (a disease which more commonly occurs randomly than in affected families).
Etiology
Although most patients do not seem to be aware of a family history, there are autosomal dominant pedigrees of EBMD that have been described. Certain point mutations in the TGFBI gene on chromosome 5 may be responsible for some EBMD cases.
Risk Factors
Known family history and age are probably the most important risk factors for EBMD. There are no known controllable risk factors. Risk factors for progression or exacerbation of the disease include trauma such as corneal abrasion, LASIK, or other intraocular surgery.
General Pathology
In EBMD, extra sheets of basement membrane extend, abnormally, into the corneal epithelium (presenting as "maps"). Maturing epithelial cells migrating towards the anterior surface of the epithelium become entrapped in these extra sheets and form cysts (or "dots"). Parallel or concentric lines of thickened basement membrane present as "fingerprints." These abnormalities within the epithelium may cause blurred vision. Abnormalities of the basement membrane may interfere with adherence of the epithelial cells to the basement membrane and lead to painful recurrent corneal erosions.
Primary prevention
There is no real prevention for EBMD. If recurrent corneal erosions are present with the EBMD, they may be prevented with nighttime lubricating or hypertonic saline ointments or with various surgical procedures described below and in the eyewiki article "Anterior Stromal Puncture."
Diagnosis
Diagnosis is clinical and is based on characteristic slit lamp findings described below.
History
Patients could be asked about mild fluctuations in vision or mild foreign body sensation. They could also be asked about a history of recurrent corneal erosion. Recurrent corneal erosions usually present as pain (sometimes severe) in one eye in the middle of the night or immediately upon opening the eyes in the morning. There is great variability in the severity of the pain and the frequency of recurrence.
Physical examination
The characteristic slit lamp findings for EBMD are best described by the name "map-dot-fingerprint." The "map" changes are the most common ones seen in many EBMD patients. They appear as amorphous or geographic, sharply demarcated clear zones within light grayish areas. The "dots" appear as small, irregular putty-like grayish white opacities. And the "fingerprints" consist of small clusters of curved, parallel lines. Other findings include areas or irregular circles of negative staining when the cornea is viewed through blue light after the instillation of topical fluorescein.
Symptoms
Many patients are asymptomatic although symptoms may include blurry vision, variable vision, foreign body sensation, and pain associated with recurrent corneal erosions.
Clinical diagnosis
The clinical diagnosis is based on history and physical exam.
Diagnostic procedures
No procedures are required for diagnosis. The diagnosis is clinical.
Laboratory test
At this time, there are no laboratory tests available.
Differential diagnosis
The differential diagnosis may include other anterior corneal dystrophies such as Meesman's Juvenile Epithelial Dystrophy or Reis-Bucklers' Dystrophy. The differential cause of recurrent corneal erosions includes corneal abrasion. HSV or HZV keratitis might cause sub-epithelial/anterior stromal scarring or epithelial defects that could be confused for EBMD associated scarring or erosions.
Management
The goal of management for EBMD is to improve vision and to reduce the rate of recurrence of recurrent corneal erosions. Sometimes, surgical management may be recommended in order to obtain more reliable keratometry readings before cataract surgery and improve refractive outcomes after cataract surgery[1]. First line treatment options usually involve the use of nighttime lubricating ointments or hypertonic saline ointments. Symptomatic erosions may be treated with bandage contact lenses, antibiotic ointments, or patching. There is some evidence that topical steroids or oral doxycycline may provide some benefit for patients with frequently occurring erosions. Various procedures such as anterior stromal puncture (outside the visual axis), YAG laser micropuncture, cautery, epithelial debridement and/or diamond burr polishing, phototherapeutic keratectomy (PTK), and extended bandage contact lens wear can be of benefit in reducing the rate of recurrent erosions. More recently, some ophthalmologists have touted the use of autologous serum tears or amniotic membranes to help treat recurrent corneal erosions and to help prevent new ones from occurring. A 2022 study by Yeu et al revealed that the placement of amniotic membranes after corneal debridement for EBMD resulted in slightly quicker re-epithelialization; however, there this was not statistically significant and there were no other benefits.[2]
Complications
Scarring from recurrent corneal erosions can result in loss of best corrected visual acuity.
Prognosis
The prognosis is very variable. The disease tends to progress with age although many patients can experience a waxing and waning of symptoms throughout their lives or even an improvement over time.
References
Krachmer, Mannis, and Holland, CORNEA, 2nd ed, vol 1, Elsevier Mosby, 2005, pp 898-902.
