Morphologically classified lenses from 100 cataract patients from the Mansoura Eye Hospital (Egypt) were microdissected and the crystallin composition and distribution were analyzed by thin-layer isoelectric focusing (IEF). The IEF profiles of cataractous lenses were compared with each other, with those of sclerotic lenses and with a normal lens profile. The alterations in the composition of high-molecular-weight (HMW)-, α-, β<sub>H</sub>-, β<sub>L</sub>-, β<sub>S</sub>-, and γ-crystallins along with normal aging, are superimposed by pronounced cataract-related changes which are different for the various types of cataracts. The general feature includes a continuous loss of γ-, β<sub>S</sub>- and β<sub>L</sub>-crystallins of higher IEPs and an increase of HMW material. This is highly pronounced in the nucleus of nuclear cataractous lenses. In cortical cataractous lenses, changes start in the cortical layers. No differences could be observed between alterations in Caucasian lenses and this extended Egyptian lens population.