Section 12 of the Academy’s Basic and Clinical Science Course (TM) (BCSC (R)) is arranged into three parts. Part one begins with an overview of the retina and its relationship to the pigment epithelium, choroid and vitreous plus discusses the major retinal disorders and their appropriate diagnostic methods and treatment principles. Part two cover specific diseases and trauma to the posterior segment and provides appropriate diagnostic techniques, plus reviews vitreoretinal diseases and management and therapy of retinal diseases. Part three provides key knowledge about cryotherapy for posterior segment diseases and includes select therapeutic topics, plus laser therapy and vitreoretinal surgery. A chapter on gene therapy covers the common types of DNA therapy: gene augmentation, optogenetics, and genome editing. This section features 19 videos, including videos on posterior segment treatment approaches and common vitreoretinal procedures. More than 175 figures, illustrations and photos plus ten interactive animations, are included to aid your understanding. Upon completion of Section 12, readers should be able to: Select appropriate methods of examination and ancillary studies for the diagnosis of vitreoretinal disorders Describe the principles of medical and surgical treatment of vitreoretinal disorders Incorporate data from major prospective clinical trials in the management of selected vitreoretinal disorders Describe and explain the urgency, appropriateness and timing of vitreoretinal conditions and interventions.