|Epithelial Basement Membrane Dystrophy
Approximately 10 percent of affected individuals develop transient
blurred vision with painful recurrent epithelial erosions. Most patients experience
fluctuating visual acuity without discomfort. Signs of EBMD include corneal epithelial
microcysts, whorling defects known as "fingerprints" or "mare's
tails," and positive and negative sodium fluorescein staining.
Anterior EBMDs are variants of one cardinal pathophysiology. They are
diagnosed and named principally by their appearance. In EBMD disorders, the basal
epithelial cells manufacture abnormal finger-like projections that protrude from the
abnormally thickened basement membrane. These projections reduce adherence of the
overlying epithelium, and produce the characteristic changes. Fibrogranular ridges
associated with, and adjacent to, these extensions form the fingerprint patterns. These
protuberances bend in the epithelium, trapping cells and intercellular debris to mold
microcysts. When a series of microcysts become grouped together and migrate forward,
corneal surface abnormalities and RCE occur.
As opposed to the end of day symptoms of dry eye, the symptoms of EBMD are most severe in the morning. Sodium fluorescein staining reveals surface irregularities and illuminates areas of positive staining (bright green: missing epithelium) and negative staining (free of fluorescein: heaped epithelium). As an option, use rose bengal or lissamine green to reveal areas of devitalized corneal cells.
Treat asymptomatic patients with prophylactic supportive therapies. Artificial tear drops QID PRN, ointments HS-TID, punctal plugs, blindfolds during sleep and goggles or spectacles that prevent dust exposure and add ocular moisture retention support are helpful. Moderate presentations may require hypertonic drops and ointments (NaCl 5%), Q3H to QID, for a minimum of six months. You can prescribe soft contact lenses to smooth surface disturbances when intolerable levels of acuity exist in severe presentations.
Patients with acute recurrent corneal erosion may require debridement of the loose epithelium, topical cycloplegia (cyclopentolate 1% TID or homatropine 5% BID), topical prophylactic antibiotic drops QID (tobramycin, ofloxacin), or ointments and topical hypertonic drops and/or ointment. Manage pain with cold compresses, oral analgesics or topical nonsteroidal anti-inflammatory preparations (Voltaren, BID to QID, or Acular, BID to QID).
The long-term management of RCE follows the same course as EBMD. Cases
of RCE that resist medical management may require surgical procedures. Anterior stromal
puncture (ASP) under topical anesthesia involves the use of a 25g needle to place 0.1mm
deep perforations, breaching Bowmans's membrane, at 0.25mm intervals in a chronic RCE zone
in an attempt to initiate scar formation and healing. ASP can also be achieved using the
Nd:Yag laser. Dispense appropriate topical cycloplegic, antibiotic, steroidal and
hypertonic medications following the procedure. Pressure patching is also an option.
Excimer photorefractive therapeutic keratectomy (PTK) to smooth the corneal surface is an
effective alternative modality.
Other reports in this section
Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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