Epithelial basement membrane dystrophy (EBMD) is a disorder of the eye that can cause pain and dryness. EBMD, also known as map-dot-fingerprint dystrophy and Cogan microcystic epithelial dystrophy, is a corneal epithelial disease that may result in
recurrent corneal erosions, irregular corneal
astigmatism
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. The lens and cornea of an eye without astigmatism are nearly spherical, with only a single radius of curvature, and any refractive errors ...
, and decreased vision.
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
Dry eye syndrome, also known as keratoconjunctivitis sicca, is the condition of having dry eyes. Symptoms include dryness in the eye, irritation, redness, discharge, blurred vision, and easily fatigued eyes. Symptoms range from mild and occa ...
, 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
According to research published in 2006, in some families
autosomal dominant inheritance
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the Phenotype, effect of a different variant of the same gene on Homologous chromosome, the other copy of the chromosome. The firs ...
and point mutations in the
transforming growth factor, beta-induced (TGFBI) 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, also known as base 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 epithelial tis ...
of
corneal epithelium
The corneal epithelium (epithelium corneae anterior layer) is made up of epithelial tissue and covers the front of the cornea. It acts as a barrier to protect the cornea, resisting the free flow of fluids from the tears, and prevents bacteria fr ...
. 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, or peeling skin, is the shedding of dead cells from the outermost layer of skin.
The term is .
Physiologic desquamation
Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratin ...
.
For patients with granular corneal dystrophy type 2 (GCD2) who have the ''TGFBI'' p.(R124H) mutation, complications have been observed following
LASIK
LASIK or Lasik (; "laser-assisted in situ keratomileusis"), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and astigmatism. LASIK surgery is p ...
surgery.
Treatment
Phototherapeutic keratectomy (PTK) done by an
ophthalmologist
Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders.
An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a ...
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 ...
References
{{Human corneal dystrophy
Disorders of sclera and cornea