Dr Ben Wild
Overview |
The cornea is the clear tissue in front of the colored iris of the eye. The cornea is comprised of 5 layers but can be simplified into 3 main layers; the epithelium (outer most layer), the stroma (middle layer) and endothelium (inner most layer).
Sagittal view of the front of the eye with the cornea being the leftmost blue tissue (left), frontal view of a healthy eye (right).
Epithelial basement membrane dystrophy (EBMD) is a common condition, often misdiagnosed, usually seen unilaterally if caused by trauma or bilaterally if related to genetics. Another term for this condition is “map-dot-fingerprint dystrophy”.
The corneal epithelium is continually shed and replenished. It is strongly attached to the underlying layers via a collagen network called the basement membrane. In EBMD, epithelial cells grow overtop of cellular debris on the basement membrane. This leads to raised areas of epithelium on the cornea. These areas can dry out more quickly and cause fluctuating vision throughout the day, making finding a reliable glasses prescription difficult, and at worst, can lead to recurrent corneal erosions (RCEs) in 10% of cases.
Sagittal view of the front of the eye with EBMD (left), frontal view of an eye with exaggerated EBMD (right).
When asleep, the eyes may dry out, the loose corneal epithelium associated with EBMD may attach to the inside of the eyelids, and upon awakening and opening the eyes, the epithelium may be torn. This situation, if recurrent, is RCE and can be extremely painful.
Signs and Symptoms |
Signs
Areas of microscopic white areas of debris on the cornea.
Symptoms
Fluctuating vision, dry eyes, difficulty finding a working glasses prescription, foreign body sensation, grittiness and extreme pain after opening eyes after sleep if associated with RCEs.
Causes and Risk Factors |
Causes
Genetics.
Risk Factors
Trauma.
Prevention and Treatment |
Prevention
Taking ocular ointments every night before sleep after a corneal abrasion, treating dry eyes correctly.
Treatments
EBMD
· Artificial tears or gel drops to manage the symptoms.
· Phototherapeutic keratectomy.
· See recurrent corneal erosions
Prognosis |
EBMD is an underdiagnosed cause of dry eyes and therefore a patient may suffer from dry eye symptoms longer than normal. Unfortunately, unlike other causes of dry eyes like blepharitis or meibomian gland dysfunction, there is no cure. It can, however, be managed well with artificial tears. If bad enough to cause RCEs, it can usually be managed with conventional therapy. If not, a simple surgery is 80-90% effective. EBMD does not cause permanent vision loss and is usually easily managed.
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