This is a cataract. A cataract results from opacification of the crystalline lens. This opacification results from a series of events starting in the lens cortex with rarefaction, then liquefecation, of cortical cells. This leads to fragmentation of lens fibers and extracellular globule formation. In the lens nucleus there is a progressive increase in the amount of insoluble proteins which leads to hardening (sclerosis) and brownish discoloration (brunescence). [Image contributed by Nick Mamalis, MD, University of Utah]

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