Color vision defects
Clinical background Key symptoms and signs “Normal” color vision refers to the form of trichromatic color vision shared by most humans. It is mediated by three types of retinal cone…
Diabetic macular edema
Overview Diabetic macular edema (DME) can cause structural retinal changes severe enough to make it the most common cause of visual loss in patients with diabetes. DME is defined by…
Dry age-related macular degeneration and age-related macular degeneration pathogenesis
Clinical background Clinical manifestations of dry age-related macular degeneration (AMD) include drusen, retinal pigment epithelium (RPE) hyperplasia, RPE depigmentation, and geographic atrophy (GA) ( Box 68.1 ). The prevalence of…
Neovascularization in diabetic retinopathy
Clinical background Introduction Diabetes mellitus is a metabolic disorder caused by defects in insulin secretion (type 1), insulin action (type 2), or both. It is characterized by chronic hyperglycemia which…
Vascular damage in diabetic retinopathy
Overview Diabetic retinopathy remains a major cause of morbidity in diabetic patients. To date, the retinopathy has been defined based on lesions that are clinically demonstrable, and all of those…
Duane syndrome
Clinical background Duane retraction syndrome is a congenital cranial dysinnervation disorder characterized by uni- or bilateral abduction deficit, narrowing of the palpebral fissure on adduction, and globe retraction with occasional…
Strabismus
Evolution has bestowed humans and other frontal-eyed foveate animals with considerable overlap of the visual fields from the right and left eye. This allows for binocular vision and stereopsis. The…
Sebaceous cell carcinoma
Overview Sebaceous cell carcinomas account for 1–5% of all eyelid malignancies and primarily affect older adults with a slight female gender bias. Despite representing a small fraction of all eyelid…
