The Age-Related Eye Disease Study (AREDA) has developed a simplified clinical cataract grading system to assess the severity of nuclear, cortical and posterior subcapsular cataracts, the 3 main types of age-related cataract. The system is designed to require minimal examiner training for persons already proficient in the use of the slit lamp. A total 150 participants with cataracts of varying severity, who are already participating in other NEI protocols, will be recruited to evaluate the reliability of the system. After being dilated, each participant will have a lens grading performed independently by 2 examiners. To provide information on the validity of the clinical gradings, lens photographs will be taken and graded using the detailed AREDS system for grading photographs. The data will allow us to evaluate (1) the agreement between the AREDS clinical lens grading system and the AREDS photographic system of grading lens opacities, and (2) the agreement on assessment of cataract severity among opthalmologists (with varying subspecialty) using the AREDS clinical lens grading method.