What is hypertropia?
Hypertropia is an ocular condition characterized by eye misalignment, with one eye higher than the other. This vertical deviation disrupts normal binocular vision and can cause a variety of visual issues, including double vision (diplopia), eyestrain, and...
What is hypertensive retinopathy?
Hypertensive retinopathy is an ocular condition caused by chronically high blood pressure, which can damage the retina, the light-sensitive tissue at the back of the eye. The retina plays an important role in vision by converting...
What is hyperphoria?
Hyperphoria is a type of latent strabismus in which one eye deviates upward relative to the other. This misalignment occurs only when the binocular vision system is disrupted, for example, when one eye is covered or stressed....
What is hyperopia?
Hyperopia, also known as farsightedness, is a common refractive error in which distant objects appear more clearly than near ones. This condition develops when the eyeball is too short or the cornea has insufficient curvature, causing light...
What is Hordeolum?
Hordeolum, also known as a stye, is an acute, localized infection or inflammation of the eyelid margin that usually affects the hair follicles of the eyelashes or the meibomian gland. It appears as a painful, red, and...
What is Homonymous Hemianopia?
Homonymous hemianopia is a visual field defect caused by damage to the brain's visual pathways, which is usually caused by a stroke, traumatic brain injury, tumors, or another neurological condition. This condition causes both eyes to...
What is herpes zoster ophthalmicus?
Herpes zoster ophthalmicus (HZO) occurs when the varicella-zoster virus (VZV), which causes chickenpox, reactivates within the ophthalmic branch of the trigeminal nerve. This reactivation results in a painful and potentially serious infection of the eye...
What is herpes simplex keratitis?
Herpes simplex keratitis (HSK) is a condition of the eyes caused by the herpes simplex virus (HSV), primarily HSV-1, which also causes cold sores. It affects the cornea, the transparent front part of the eye,...
What is hereditary retinal dystrophy?
Hereditary retinal dystrophies (HRDs) are a diverse group of genetic disorders that cause progressive retinal degeneration, resulting in vision impairment and, in severe cases, blindness. The retina, a thin layer of tissue at the back...
What is hereditary optic neuropathy?
Hereditary optic neuropathies are a collection of genetic disorders that cause progressive damage to the optic nerve, resulting in vision loss. The most common types of these conditions are Leber's Hereditary Optic Neuropathy (LHON) and...
What is gonococcal conjunctivitis?
The bacterium Neisseria gonorrhoeae, which is also responsible for the sexually transmitted infection gonorrhea, causes gonococcal conjunctivitis, a severe and potentially blinding eye infection. This condition can affect people of all ages, but it is especially...
What is Globe Rupture?
Globe rupture is a severe and often vision-threatening ocular condition that occurs when trauma compromises the integrity of the eye's outer membrane. This condition is typically caused by blunt or penetrating trauma to the eye, resulting...
What is glaucoma?
Glaucoma is a group of eye conditions that harm the optic nerve, which is essential for clear vision. Abnormally high intraocular pressure (IOP) is a common cause of this damage. Glaucoma is a leading cause of blindness...
Definition of Functional Lacrimal Duct Obstruction
Functional lacrimal duct obstruction (FLDO) is a condition in which tears cannot drain properly through the nasolacrimal duct, resulting in excessive tearing (epiphora) and recurring eye infections. In contrast to anatomical obstructions, which involve...
What is fungal keratitis?
Fungal keratitis is a serious and vision-threatening infection of the cornea, the transparent front part of the eye, caused by a variety of fungi. This condition is frequently caused by eye trauma, particularly from organic matter...
What is pleomorphic adenoma of the lacrimal gland?
Pleomorphic adenoma of the lacrimal gland, also known as benign mixed tumor, is the most common benign epithelial tumor in the lacrimal gland. This condition primarily affects the eye's orbital region, which...
What is Pinguecula?
Pinguecula is a non-cancerous growth that develops on the conjunctiva, the clear, thin tissue that covers the white part of the eye (sclera). This condition is distinguished by a small, yellowish bump that usually appears on the...
What is pigmentary glaucoma?
Pigmentary glaucoma is a type of secondary open-angle glaucoma caused by pigment granules dispersed throughout the eye. These granules, which normally reside in the iris, escape into the aqueous humor and can clog the trabecular meshwork....
What is photophobia?
Photophobia, which comes from the Greek words "photo" (light) and "phobia" (fear), is an ocular condition characterized by an abnormal sensitivity to light. Individuals with photophobia feel discomfort or pain when exposed to light, which can range...
What Is a Foreign Body in My Eye?
A foreign body in the eye is any object or substance that enters the eye from outside and may cause irritation, injury, or infection. Common examples include dust, sand, metal shavings, wood...
What is eyelid squamous cell carcinoma?
Eyelid squamous cell carcinoma (SCC) is a malignant tumor that develops from squamous cells in the eyelid's epidermis. It is the second most common form of eyelid cancer, after basal cell carcinoma. Eyelid SCC...
What is eyelid sebaceous gland carcinoma?
Eyelid sebaceous gland carcinoma (SGC) is a rare and aggressive cancer that originates in the eyelid's sebaceous glands. These glands produce the oily substance that lubricates the eyes. SGC typically presents as a painless,...
What is an Eyelid Laceration?
An eyelid laceration is a cut or tear in the eyelid tissue that can range in severity from a minor superficial injury to a deep, complex wound involving multiple layers of tissue. Accidents, sports injuries,...
What is eyelid edema?
Eyelid edema, also known as eyelid swelling, is a condition in which fluid accumulates in the connective tissues around the eye. This condition can affect one or both eyelids, and its severity ranges from mild puffiness...
What is phacomatoses?
Phacomatoses, also known as neurocutaneous syndromes, are a group of hereditary disorders distinguished by the presence of lesions on both the skin and the nervous system. These conditions are usually genetic, with abnormalities in the development and...
What is the definition of phacoanaphylactic endophthalmitis?
Phacoanaphylactic endophthalmitis, also known as lens-induced uveitis, is an uncommon but severe inflammatory condition of the eye. It occurs as an immune response to lens proteins exposed to the intraocular environment, usually as...
What is Peter's Anomaly?
Peters anomaly is a rare congenital eye disorder that causes abnormalities in the development of the eye's anterior segment. It is named for Dr. Albert Peters, who first described the condition in 1906. This condition primarily...
What is persistent fetal vasculature?
Persistent fetal vasculature (PFV), also known as persistent hyperplastic primary vitreous (PHPV), is a congenital ocular abnormality caused by the failure of the fetal hyaloid vascular system to regress. This system, which includes the hyaloid...
What is Periorbital Cellulitis?
Periorbital cellulitis, also known as preseptal cellulitis, is an infection of the eyelid and surrounding skin that occurs anterior to the orbital septum. It primarily affects the soft tissues surrounding the eye, resulting in swelling, redness,...
What is Eyelid Dermatitis?
Eyelid dermatitis, also known as eyelid eczema, is an inflammatory skin condition that affects the sensitive skin of the eyelids. Symptoms of this condition include redness, swelling, itching, and, in some cases, flaking or crusting of...
