Section 8 of the Academy's Basic and Clinical Science Course™ (BCSC®) discusses the structure and function of the cornea and external eye and reviews relevant examination techniques.Section 8 includes recent statistics on indications for corneal transplants from the Eye Bank Association of America. In addition, this section discusses infectious and ocular surface diseases and disorders, surgery of the ocular surface, immune-mediated and neoplastic disorders, and congenital anomalies and degenerations. A chapter on the diagnosis and management of corneal dystrophies reflects the IC3D classification of the dystrophies according to a template consisting of clinical, pathologic, and genetic information. Toxic and traumatic injuries and corneal transplantation are also reviewed.This section also covers diagnostic imaging technologies, updates on endothelial replacement surgery, and best practices for early recognition and treatment of sebaceous cell carcinoma.Interactive elements throughout the text, such as an activity on corneal layers and corresponding confocal images, an animation demonstrating the development of the cornea, and a corneal ectasia case study, will help strengthen your clinical knowledge. This volume has forty-six videos, many demonstrating surgical techniques to aid your understanding. Both print and eBook users have access to the videos and activities.Upon completion of Section 8, readers should be able to:Explain the overall strategy, examination, and technology used for systematic evaluation of the cornea and the external eye.Describe the basic principles and the clinical approach to the diagnosis and treatment of viral, bacterial, fungal, and parasitic keratitis.List the risk factors, clinical signs, and breadth of management options of corneal ectasia.