A<unk>  is an opacity that develops in the crystalline lens of the eye or in its envelope. Early on in the development of age-related<unk>  the power of the crystalline lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colours.<unk> s typically progress slowly to cause vision loss and are potentially blinding if untreated. Moreover, with time the<unk>  cortex liquefies to form a milky white fluid in a Morgagnian<unk> , and can cause severe inflammation if the lens capsule ruptures and leaks. Untreated, the<unk>  can cause phacomorphic glaucoma. Very advanced<unk> s with weak zonules are liable to dislocation anteriorly or posteriorly.  Such spontaneous posterior dislocations (akin to the historical surgical procedure of couching) in ancient times were regarded as a blessing from the heavens, because it restored some perception of light in the bilaterally affected patients.<unk>  derives from the Latin<unk> a meaning "waterfall" and the Greek kataraktes and katarrhaktes, from katarassein meaning "to dash down" (kata-, "down"; arassein, "to strike, dash"). As rapidly running water turns white, the term may later have been used metaphorically to describe the similar appearance of mature ocular opacities. In Latin,<unk> a had the alternate meaning, "portcullis", so it is also possible that the name came about through the sense of "obstruction".
Cataract
Ocular hypertension
Glaucoma
Refractive error
Oculomotor nerve palsy
Cat eye syndrome
Color blindness
Otosclerosis