Megalocornea (MGCN, MGCN1) is an extremely rare nonprogressive condition in which the
cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
has an enlarged
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...
, reaching and exceeding 13 mm. It is thought to have two subforms, one with autosomal inheritance and the other X-linked (Xq21.3-q22).
The X-linked form is more common and males generally constitute 90% of cases.
It may be associated with
Alport syndrome
Alport syndrome is a genetic disorder affecting around 1 in 5,000-10,000 children, characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. Alport syndrome can also affect the eyes, though the changes do not usually affect v ...
,
craniosynostosis
Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. Because the skull cannot expand perpe ...
,
dwarfism
Dwarfism is a condition wherein an organism is exceptionally small, and mostly occurs in the animal kingdom. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dw ...
,
Down syndrome
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...
,
Parry–Romberg syndrome
Parry–Romberg syndrome (PRS) is a rare disease characterized by progressive shrinkage and degeneration of the tissues beneath the skin, usually on only one side of the face (hemifacial atrophy) but occasionally extending to other parts of th ...
,
Marfan syndrome
Marfan syndrome (MFS) is a multi-systemic genetic disorder that affects the connective tissue. Those with the condition tend to be tall and thin, with long arms, legs, fingers, and toes. They also typically have exceptionally flexible joints a ...
,
mucolipidosis
Mucolipidosis is a group of inherited metabolic disorders that affect the body's ability to carry out the normal turnover of various materials within cells.
When originally named, the mucolipidoses derived their name from the similarity in pre ...
,
Frank–ter Haar syndrome,
crouzon syndrome
Crouzon syndrome is an autosomal dominant genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial (or pharyngeal) arch, which is the precursor of the maxilla and mandible. Since the branchial ...
, megalocornea-mental retardation syndrome etc.
Clinical features
Eyes are usually highly
myopic
Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include ...
.
There may be 'with the rule'
astigmatism
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at nig ...
.
Lens
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
may be luxated due to
zonular streaching.
In rare cases, it might be
associated with intellectual disabilities.
References
External links
Megalocornea-
eMedicine
eMedicine is an online clinical medical knowledge base founded in 1996 by doctors Scott Plantz and Jonathan Adler, and computer engineer Jeffrey Berezin. The eMedicine website consists of approximately 6,800 medical topic review articles, each of ...
ophthalmology; May 15, 2009; Thomas A Oetting, MD, Mark A Hendrix, MD
An Infant With Enlarged Corneas- medscape
{{Congenital malformations and deformations of eye
Congenital disorders of eyes