Epithelial basement membrane dystrophy (EBMD) is a disorder of the eye that can cause pain and dryness.
It is sometimes included in the group of
corneal dystrophies.
It diverges from the formal definition of corneal dystrophy since it is non-familial in most cases. It also has a fluctuating course, while for a typical corneal dystrophy the course is progressive. When it is considered part of this group, it is the most common type of corneal dystrophy.
Signs and symptoms
Patients may complain of severe problems with
dry eyes, or with visual obscurations.
It can also be asymptomatic, and only discovered because of subtle lines and marks seen during an eye exam.
EBMD is a bilateral anterior corneal dystrophy characterized by grayish epithelial fingerprint lines, geographic map-like lines, and dots (or microcysts) on slit-lamp examination. Findings are variable and can change with time. While the disorder is usually asymptomatic, up to 10% of patients may have recurrent corneal erosions, usually beginning after age 30; conversely, 50% of patients presenting with idiopathic recurrent erosions have evidence of this dystrophy.
Pathophysiology
In some families autosomal dominant inheritance and point mutations in the
TGFBI
Transforming growth factor, beta-induced, 68kDa, also known as TGFBI (initially called BIGH3, BIG-H3), is a protein which in humans is encoded by the ''TGFBI'' gene, locus 5q31.
Function
This gene encodes an RGD-containing protein that binds ...
gene encoding keratoepithelin have been identified,
but according to the International Committee for Classification of Corneal Diseases (IC3D)
the available data still does not merit a confident inclusion of EBMD in the group of corneal dystrophies. In view of this, the more accurate designation of the disease is possibly not dystrophy but ''corneal degeneration''.
The main pathological feature of the disease is thickened, multilaminar and disfigured
basement membrane
The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between Epithelium, epithelial tissues including mesot ...
of
corneal epithelium. The change in the structure affects the epithelium, some cells of which may become entrapped in the rugged membrane and fail to migrate to the surface where they should undergo
desquamation
Desquamation occurs when the outermost layer of a tissue, such as the skin, is shed. The term is . Physiologic desquamation
Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratinocytes reside in ...
.
Treatment
Phototherapeutic keratectomy
Phototherapeutic keratectomy (PTK) is a type of eye surgery that uses a laser to treat various ocular disorders by removing tissue from the cornea. PTK allows the removal of superficial corneal opacities and surface irregularities. It is simila ...
(PTK) done by an
ophthalmologist
Ophthalmology ( ) is a surgery, surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders.
An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Followin ...
can restore and preserve useful visual function for a significant period of time in patients with anterior corneal dystrophies including EBMD.
See also
*
Corneal dystrophy
Corneal dystrophy is a group of rare hereditary disorders characterised by bilateral abnormal deposition of substances in the transparent front part of the eye called the cornea.
Signs and symptoms
Corneal dystrophy may not significantly affect v ...
References
{{Human corneal dystrophy
Disorders of sclera and cornea