Non-arteritic anterior ischemic optic neuropathy (NAION) is a condition in which vision loss occurs suddenly due to insufficient blood flow to the optic nerve head. This condition primarily affects adults over the age of 50 and is one of...
Neuroretinitis is an ocular condition that causes inflammation of the optic nerve (optic neuritis) and the retina. It usually begins with sudden, painless vision loss in one eye, which is frequently accompanied by a central scotoma (a dark spot...
Neuromyelitis Optica (NMO), also known as Devic's disease, is a rare autoimmune disorder affecting primarily the optic nerves and spinal cord. It is defined by severe attacks of optic neuritis, which causes inflammation of the optic nerve, resulting in...
Neurofibromatosis (NF) is a genetic disorder characterized by the growth of tumors along nerves in the skin, brain, and other parts of the body. These tumors, known as neurofibromas, are typically benign but can cause serious health problems depending...
What is neurofibroma of the orbit?
Neurofibroma of the orbit is a benign tumor that develops from nerve sheath cells in the orbital cavity, which is the bony socket that houses the eye. This condition is commonly associated with Neurofibromatosis...
Neovascularization of the vitreous is a serious ocular condition characterized by the formation of new, abnormal blood vessels in the vitreous humor, a gel-like substance that fills the eye. These new blood vessels are often fragile and prone to...
Neovascular Glaucoma (NVG) is a severe type of secondary glaucoma characterized by the formation of new, abnormal blood vessels on the iris and drainage angle of the eyeball. These new blood vessels may obstruct the eye's drainage system, resulting...
What is necrotizing scleritis?
Necrotizing scleritis is a serious and potentially blinding ocular condition characterized by inflammation and necrosis of the sclera, the white outer layer of the eyeball. This condition is frequently associated with systemic autoimmune diseases, including rheumatoid...
Introduction
Nasolacrimal duct obstruction (NLDO) is a condition characterized by a blockage in the nasolacrimal duct, which drains tears from the eye into the nasal cavity. This blockage prevents the normal flow of tears, resulting in excessive tearing, recurring eye...
What is myopic maculopathy?
Myopic maculopathy, also known as myopic macular degeneration, is a serious ocular condition associated with high myopia in which excessive elongation of the eyeball causes degenerative changes in the retina, specifically the macula. The macula is...
Introduction to Myopia?
Myopia, also known as nearsightedness, is a common refractive error in which distant objects appear blurry while close objects are visible clearly. This condition develops when the eye is elongated or the cornea has excessive curvature, causing...
What is multifocal choroiditis and panuveitis?
Multifocal choroiditis and panuveitis (MCP) is a rare and complicated inflammatory eye disease affecting the choroid, retina, and vitreous. It is distinguished by multiple inflammatory lesions in the choroid and retina, which frequently progress...
Definition of Mucoepidermoid Carcinoma of the Lacrimal Gland
Mucoepidermoid carcinoma of the lacrimal gland is a rare but aggressive malignant tumor that develops from the epithelial cells of the lacrimal gland. The lacrimal gland, which produces tears, is located in...
What is a microstrabismus?
Microstrabismus, also known as microtropia, is a subtle form of strabismus (eye misalignment) in which the deviation is very small, usually less than 5 degrees. Unlike more visible forms of strabismus, microstrabismus is frequently difficult to...
Introduction
Microphthalmia is a rare congenital disorder characterized by underdevelopment of one or both eyes. The term "microphthalmia" comes from Greek, where "micro" means small and "ophthalmos" means eye. Microphthalmia is characterized by abnormally small eye(s) and other structural anomalies,...
What is Melanoma of the Eyelid?
Melanoma of the eyelid is a rare but serious type of skin cancer that develops from melanocytes, the skin's pigment-producing cells. This condition is a subset of periocular melanomas, which include melanomas in the...
Understanding Melanocytoma of the Optic Disc
Melanocytoma of the optic disc is a rare, benign tumor that develops from melanocytes, the cells that produce pigment in the body. These tumors are typically found on or near the optic disc, which...
What is the Meibomian Gland Dysfunction?
Meibomian gland dysfunction (MGD) is a common and often chronic condition that affects the meibomian glands in the eyelids, which secrete the lipid (oily) layer of the tear film. This lipid layer is essential...
Introduction
Malignant melanoma of the eyelid is a rare but aggressive type of skin cancer that develops from melanocytes, the pigment-producing cells in the skin. This condition falls under the category of periocular melanomas, which also includes melanomas of the...
What is malignant glaucoma?
Malignant glaucoma, also known as aqueous misdirection or ciliary block glaucoma, is a rare but serious type of glaucoma characterized by the misdirection of aqueous humor, the fluid inside the eye, into or around the vitreous...
Introduction to Macular Pucker
A macular pucker, also known as epiretinal membrane (ERM), is an ocular condition in which a thin layer of fibrous tissue forms on the macula's surface. The macula is the central part of the retina that...
What is a macular hole?
A macular hole is a small break or tear in the macula, the central part of the retina that allows for clear, detailed vision. The macula enables us to perform tasks requiring fine visual detail,...
Understanding Lenticonus and Lentiglobus
Lenticonus and lentiglobus are rare congenital lens deformities that severely impair vision. Lenticonus is characterized by a conical protrusion of the lens surface, which usually affects the anterior or posterior lens. This deformation causes irregular astigmatism...
What causes Leber's Hereditary Optic Neuropathy?
LHON is a rare inherited mitochondrial disorder that causes sudden and severe vision loss. It primarily affects young adults, usually between the ages of 15 and 35, but it can happen at any age....
What is Leber's Congenital Amaurosis?
Leber Congenital Amaurosis (LCA) is a rare inherited retinal dystrophy that causes severe vision loss or blindness at birth or during early childhood. It is named after Theodor Leber, a German ophthalmologist who first described...
What is lattice dystrophy?
Lattice dystrophy is a hereditary corneal condition characterized by the accumulation of abnormal protein deposits called amyloid in the corneal stroma. These deposits form a lattice-like pattern, hence their name. Lattice dystrophy typically appears in the...
Latent Nystagmus Introduction
Latent nystagmus is a type of involuntary eye movement that usually appears when one eye is covered or binocular vision is impaired. This condition is frequently congenital and is associated with infantile strabismus and other types of...
Lagophthalmos Overview
Lagophthalmos is an ocular condition defined by the inability to fully close the eyelids, resulting in incomplete or partial eye closure. This condition can progress to exposure keratopathy, in which the cornea becomes dry, irritated, and vulnerable to...
What is a Lacrimal Gland Tumor?
Lacrimal gland tumors are a wide range of neoplasms that develop from the lacrimal gland, which is located in the upper outer region of the orbit. These tumors can be benign or malignant, with...
What is lacrimal gland prolapse?
Lacrimal gland prolapse is an ocular condition in which the lacrimal gland moves downward from its normal location in the lacrimal fossa in the upper outer quadrant of the orbit. This gland produces tears, which...
