A non-invasive ophthalmic instrument that will measure objectively glare disability due to early cataract is greatly needed. The proposed instrument will measure the extent of blurring of an aerial image of an illuminated line projected on the retina, the line spread function (LSF). Clinical studies will be conducted on subjects with different types of cataract at various stages of development. All cataracts will be classified and graded in accord with the LOCS II classification system. The effect of common retinal pathologies on the LSF measurement also will be assessed. Sixty subjects, divided into six groups, will be measured with the instrument: l) young normals, 2) elderly normals, 3) elderly with early cataract and with no retinal problems, 4) elderly with maturing nuclear and/or posterior subcapsular cataracts and with no retinal problems, 5) elderly with maturing cortical cataracts and with no retinal problems, and 6) elderly with cataracts of any type and also presenting retinal drusen or epiretinal membrane formation. Subjects also will be tested subjectively for glare sensitivity (GS) and the LSF and GS test results compared. Both LSF and GS results will be compared to the LOCS II gradings.