This K23 project serves two purposes: 1) It provides research career development and training for Loretta Szczotka, O.D., M.S., who has made a commitment to focus on patient-oriented research, to launch an independent career in clinical research. 2) It provides her with the knowledge and research skills necessary to translate the findings of previous studies performed by investigators at Case Western Reserve University (CWRU) into the proposed clinical research project, the Longitudinal Analysis of Silicone Hydrogel (LASH) Contact Lens Study. The five-year program, will to lead to 1) the Ph.D. in Epidemiology from the Department of Epidemiology and Biostatistics at CWRU, 2) additional training in the relevant basic and clinical science discipline of ocular immunology, and 3) a better scientific understanding of the factors and mechanisms of inflammatory and mechanical complications of silicone hydrogel continuous wear (CW) contact lens use. The LASH Contact Lens Study, and her training in epidemiology, will allow the candidate to enhance her independent research skills in an area of her clinical expertise, by serving as principal investigator in all phases of the study design, implementation, data management, and data analysis under the guidance of outstanding scientist-mentors in the fields of biometrics, immunology, and ophthalmology. The LASH Contact Lens Study will test the hypothesis that complement activation and regulation coupled with bacterial contamination of lenses and the ocular surfaces are risk factors for contact lens associated inflammatory complications. Additionally, this project will test the hypothesis that novel quantitative central and peripheral corneal shape descriptors, measured by corneal topography, are associated with mechanical complications during long term wear of silicone hydrogel lenses. 224 patients will be enrolled and followed for three years in this longitudinal cohort study.