What is hyphema?
Hyphema is an ocular condition characterized by the presence of blood in the anterior chamber of the eye, which is located between the cornea and the iris. Trauma to the eye is a common cause of this...
What is hypertropia?
Hypertropia is a type of strabismus in which one eye is misaligned upwards in comparison to the other. This misalignment can cause significant visual disturbances, such as double vision, eye strain, and difficulty detecting depth. Hypertropia can...
What is hypertensive retinopathy?
Chronic high blood pressure affects the retina, the light-sensitive tissue at the back of the eye, resulting in hypertensive retinopathy. Prolonged hypertension damages the blood vessels of the retina, resulting in a variety of visual symptoms...
What is hyperphoria?
Hyperphoria is a type of latent strabismus (eye misalignment) in which one eye deviates upwards relative to the other when not actively focused on an object. Unlike manifest strabismus, hyperphoria is typically controlled by the brain's fusion...
What is hyperopia?
Hyperopia, also known as farsightedness, is a refractive error in which distant objects appear more clearly than close ones. This condition develops when the eye is shorter than normal or the cornea has too little curvature, causing...
What is hyperlysinemia?
Hyperlysinemia is a rare metabolic disorder characterized by high levels of the amino acid lysine in the blood due to a lack of the enzyme saccharopine dehydrogenase. This enzyme is essential in the lysine degradation pathway, and...
What is Horner Syndrome?
Horner's syndrome, also known as oculosympathetic paresis, is a neurological disorder caused by a disruption of the sympathetic nerves that supply the eye and surrounding facial muscles. This condition presents with the classic triad of symptoms:...
What is Hordeolum?
Hordeolum, also known as a stye, is an acute infection or inflammation of the oil glands in the eyelid that causes a painful, red lump near the edge of the eye. This condition is caused by a...
What is Homonymous Hemianopia?
Homonymous hemianopia is a visual field defect that affects the same side of both eyes. This condition is caused by damage to the brain's visual pathways, specifically the optic tract, optic radiation, and occipital cortex. Individuals...
What is homocystinuria?
Homocystinuria is a rare inherited metabolic disorder marked by an excess of homocysteine in the blood and urine. This condition is caused by a deficiency in one of several enzymes involved in the methionine metabolism. Ectopia lentis,...
What is herpes simplex keratitis?
Herpes simplex keratitis (HSK) is an ocular infection caused by the herpes simplex virus (HSV), specifically HSV-1. It is the leading cause of infectious blindness in developed countries, and if not treated properly, it can...
What is hereditary retinal dystrophies?
Hereditary retinal dystrophies are a group of genetic disorders that cause progressive retinal degeneration, resulting in vision loss. These conditions are caused by mutations in the genes that control retinal cell development and function. Symptoms...
What is Hereditary Optic Neuropathy?
Hereditary optic neuropathies are a class of genetic disorders marked by progressive degeneration of the optic nerves, resulting in visual impairment. These conditions are inherited and can occur at any stage of life, from infancy...
What is Hemangiopericytoma of the Orbit?
Hemangiopericytoma of the orbit is a rare vascular tumor that develops from the pericytes, which are contractile cells that surround the capillaries and veins. These tumors can develop anywhere in the body, but they...
What is Gyrate Atrophy?
Gyrate atrophy of the choroid and retina is a rare inherited retinal dystrophy with progressive vision loss. It is caused by mutations in the OAT gene, which codes for the enzyme ornithine aminotransferase. This enzyme deficiency...
What is Graves Orbitopathy?
Graves' Orbitopathy, also known as Thyroid Eye Disease (TED), is an autoimmune disorder that affects the orbit of the eye. It is frequently associated with Graves' disease, a condition characterized by hyperthyroidism, or excessive thyroid activity....
What is gonococcal conjunctivitis?
Gonococcal conjunctivitis is a severe and acute bacterial eye infection caused by Neisseria gonorrhoeae, which is also responsible for the sexually transmitted infection gonorrhea. This condition most commonly affects newborns (neonatal conjunctivitis) and sexually active adults....
What is Goldenhar syndrome?
Goldenhar Syndrome, also known as the oculo-auriculo-vertebral (OAV) spectrum, is a rare congenital condition marked by craniofacial anomalies that primarily affect the development of the eyes, ears, and vertebrae. The ocular manifestations of Goldenhar Syndrome are...
What is Globe Rupture?
Globe rupture is a severe ocular condition in which the integrity of the eye's outer membranes, including the sclera and cornea, is compromised due to trauma. This injury causes the extrusion of intraocular contents, which can...
Overview of Glaucomatocyclitic Crisis
Glaucomatocyclitic crisis, also known as Posner-Schlossman Syndrome (PSS), is a rare eye condition marked by recurrent episodes of significantly elevated intraocular pressure (IOP) and mild anterior uveitis. PSS typically affects young to middle-aged adults and manifests...
What is Glaucoma?
Glaucoma caused by retinal disorders is a secondary type of glaucoma that develops as a result of underlying retinal diseases. These retinal conditions can raise intraocular pressure (IOP) or damage the optic nerve, resulting in glaucomatous changes....
What is glaucoma?
Glaucoma is a group of eye conditions that damage the optic nerve, which is essential for clear vision. This damage is frequently caused by elevated intraocular pressure (IOP) within the eye. Glaucoma is a leading cause of...
Basics of Tumor-Related Glaucoma
Glaucoma associated with ocular tumors is a secondary form of glaucoma caused by an intraocular tumor. These tumors can directly or indirectly raise intraocular pressure (IOP), resulting in glaucomatous optic neuropathy. This condition is especially difficult...
Introduction to Elevated EVP Glaucoma
Glaucoma with elevated episcleral venous pressure (EVP) is a type of secondary open-angle glaucoma in which an increase in intraocular pressure (IOP) is directly related to increased pressure in the episcleral veins. This condition occurs...
Basics of Glaucoma from Corneal Disorders
Glaucoma associated with corneal disorders is a complex condition in which corneal abnormalities contribute to the development or progression of glaucoma. Glaucoma is a group of eye diseases that cause damage to the optic...
What are Giant Cell Arteritis' Ocular Manifestations?
Giant Cell Arteritis (GCA), also known as temporal arteritis, is an inflammatory condition affecting large and medium-sized arteries, primarily in the head and neck. This vasculitis can cause severe ocular manifestations, which are...
What is fungal keratitis?
Fungal Keratitis is a severe and potentially sight-threatening cornea infection caused by fungal organisms. The cornea is a clear, dome-shaped surface that covers the front of the eye and is essential for focusing vision. Fungal infections...
Definition of Functional Lacrimal Duct Obstruction
Functional Lacrimal Duct Obstruction (FLDO) occurs when the lacrimal (tear) duct, which drains tears from the eye into the nose, fails to function properly, resulting in excessive tearing (epiphora) or recurring eye infections. Unlike...
What is Fuchs Heterochromic Iridocyclitis?
Fuchs' Heterochromic Iridocyclitis (FHI) is a chronic, usually unilateral inflammatory condition of the eye. It is distinguished by an unusual combination of iris color changes (heterochromia), low-grade anterior uveitis (iridocyclitis), and the presence of small,...
What is Fuchs Dystrophy?
Fuchs' Dystrophy is a progressive eye disease that affects the cornea, or clear front surface of the eye. This condition is distinguished by the progressive deterioration of the endothelial cells that line the inner layer of...
