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

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

) 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 Myopia, also known as near-sightedness and short-sightedness, is an eye condition where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry, while close objects appear normal. ...

that is no longer progressing, the crescent may be

asymptomatic Asymptomatic (or clinically silent) is an adjective categorising the medical conditions (i.e., injuries or diseases) that patients carry but without experiencing their symptoms, despite an explicit diagnosis (e.g., a positive medical test). P ...

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 t ...

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. Inflammation of these layers can lead to vision-threatening complications. If only the choroid is ...

, but myopic crescent is not an inflammatory process 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