Section 4 presents materials in two parts:: Part I, Ophthalmic Pathology; and Part II, Intraocular Tumors. Part I uses a hierarchy that moves from general to specific to help derive a differential diagnosis for a specific tissue. Part II is a compilation of selected clinical aspects of importance to the general ophthalmologist. Additionally, this section has a variety of images and videos. Both print and digital version users have access to the videos. Upon completion of Section 4, readers should be able to:: - Describe a structured approach to understanding major ocular conditions based on a hierarchical framework of topography, disease process, general diagnosis and differential diagnosis. - Summarize the steps in handling ocular specimens for pathologic study, including obtaining, dissecting, processing, and staining tissues. -Identify those ophthalmic lesions that indicate systemic disease and are potentially life-threatening.