A myopic crescent is a moon-shaped feature that can develop at the temporal (

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...

) border of disc (it rarely occurs at the nasal border) of myopic eyes. It is primarily caused by

atrophic Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply t ...

changes that are genetically determined, with a minor contribution from stretching due to elongation of the eyeball. In

myopia 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 ...

that is no longer progressing, the crescent may be

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asy ...

except for its presence on ocular examination. However, in high-degree

, it may extend to the upper and lower borders, or form a complete ring around the

optic disc The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the ...

and form a

central scotoma A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision. Every normal mamma ...

. The myopic crescent is commonly seen in pathological axial

. The condition sometimes described erroneously as myopic

choroiditis Chorioretinitis is an inflammation of the choroid (thin pigmented vascular coat of the eye) and retina of the eye. It is a form of posterior uveitis. If only the choroid is inflamed, not the retina, the condition is termed choroiditis. The ophthalm ...

, but myopic crescent is not an

inflammatory process Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

and does not run parallel to the degree of myopia. It usually tends to occur after mid adult life. Myopic crescent is often associated with some degree of retinal degeneration and occasionally vitreous degeneration.

References

External links

*https://web.archive.org/web/20070427123308/http://www.opt.pacificu.edu/ce/catalog/COPE7536/KabatDisc.html Vision {{med-sign-stub