Eye & Neuro-Ophthalmology Glossary

Pus Collection

A walled-off collection of pus from infection. Orbital abscess is a serious complication of sinusitis requiring urgent drainage.

Angiotensin-Converting Enzyme

A blood test marker. Elevated ACE levels can support a diagnosis of sarcoidosis, an inflammatory condition that can cause uveitis and optic nerve disease.

Herpes Antiviral

An antiviral medication used to treat herpes simplex and herpes zoster (shingles) infections of the eye and surrounding structures.

Carrying Signals to the Brain

Carrying signals toward the brain. The optic nerve is the eye's afferent pathway - it carries vision information from the retina to the brain.

Eylea (Anti-VEGF)

An anti-VEGF fusion protein injected into the eye for wet AMD, diabetic macular edema, and retinal vein occlusions. Brand name: Eylea.

Anterior Ischemic Optic Neuropathy

Sudden vision loss from reduced blood flow to the front of the optic nerve. Divided into arteritic (from GCA, emergency) and non-arteritic (NAION, more common) types.

Top or Bottom Half Loss

A visual-field defect that affects the top or bottom half of vision in one eye. Classic for ischemic optic neuropathy.

Sudden Brief Vision Loss in One Eye

A sudden, temporary loss of vision in one eye that comes and goes - often described as a curtain coming down. A warning sign of a possible stroke or carotid artery disease.

Lazy Eye

Reduced vision in one eye that didn't develop properly in childhood, even with glasses; not correctable in adulthood without earlier treatment.

Age-Related Macular Degeneration

A progressive condition affecting the macula, the leading cause of vision loss in people over 50. Occurs in dry (atrophic) and wet (neovascular) forms.

Anti-Neutrophil Cytoplasmic Antibodies

Blood test antibodies associated with vasculitis (blood vessel inflammation). ANCA-positive vasculitis can cause scleritis, retinal vasculitis, and orbital inflammation.

Low Red Blood Cells

A condition with too few red blood cells or hemoglobin. Severe anemia can cause retinal hemorrhages, cotton-wool spots, and optic disc swelling.

Vessel Bulge

A weakened, bulging area in a blood vessel wall. Microaneurysms - tiny outpouchings in retinal capillaries - are the earliest sign of diabetic retinopathy.

Absent Sweating

Lack of sweating on one side of the face. Combined with miosis and ptosis, it forms the classic triad of Horner syndrome.

Pupils of Unequal Size

Pupils that differ in size. Can be benign or signal a nerve problem; the difference in light vs. dark helps localize the cause.

Anti-Muscle-Specific Kinase

Antibodies against the MuSK protein at the neuromuscular junction. Anti-MuSK positive myasthenia gravis often causes prominent facial and bulbar weakness.

Anti-Vascular Endothelial Growth Factor

Medications injected into the eye that block VEGF, slowing abnormal vessel growth and reducing fluid leakage. Used for wet AMD, DME, and vein occlusions.

Acetylcholine-Blocking

Blocking the neurotransmitter acetylcholine. Anticholinergic drugs or side effects can dilate pupils, reduce tear production, and blur near vision.

Blood-Thinning Treatment

Treatment with medications preventing blood clots. Important in managing retinal vein occlusions, carotid disease, and embolic artery occlusions.

Mood-Regulating Drug

Medications for depression and anxiety. Some (amitriptyline, venlafaxine) are also used to prevent migraines. Side effects can include dry eye and blurred vision.

Allergy-Blocking Drug

Medications blocking histamine to relieve allergy symptoms like itching, redness, and swelling. Available as eye drops (olopatadine, ketotifen) or oral tablets.

Blood Clot-Preventing Drug

Medications (aspirin, clopidogrel) that prevent platelets from clumping to reduce stroke and heart attack risk. Important in managing retinal vascular disease.

Germ-Killing Agent

Substances applied to tissue to kill or prevent growth of microorganisms. Povidone-iodine is the standard antiseptic used before eye injections and surgery.

Virus-Fighting Drug

Medications used to treat viral infections. In ophthalmology, antivirals like acyclovir and valacyclovir treat herpes simplex and herpes zoster eye infections.

Afferent Pupillary Defect

A defect in the visual signal pathway from eye to brain, detected by the swinging flashlight test. Often called a Marcus Gunn pupil.

Eye Without a Lens

An eye with no lens, usually after cataract removal without an implant. Pseudophakia means the eye has an artificial intraocular lens after cataract surgery.

Tendon-Related

Relating to an aponeurosis (flat tendon). Aponeurotic ptosis is the most common type of age-related droopy eyelid, caused by stretching of the levator tendon.

Alpha-Agonist Eye Drop

An eye drop that lowers eye pressure and can also be used as a diagnostic test for Horner syndrome (the affected pupil dilates with this drop).

Aquaporin-4

A water channel protein in the brain and spinal cord. Antibodies against AQP4 are the hallmark of NMO and help distinguish it from MS.

Eye Fluid (Front Chamber)

The clear, watery fluid filling the space between the cornea and the lens. It nourishes the front of the eye and maintains pressure as it drains.

Insufficient Tear Production

A form of dry eye where the lacrimal gland does not produce enough tears, as opposed to evaporative dry eye where tears evaporate too quickly.

Arc-Shaped

Having an arc or curved shape. An arcuate scotoma is an arc-shaped blind spot following the nerve fiber pattern, characteristic of glaucoma.

Artery-Vein Connection

Relating to both arteries and veins. Arteriovenous malformations or fistulas near the eye can cause proptosis, redness, and vision changes.

Artery Inflammation-Related

Caused by inflammation of arteries. Arteritic AION (from giant cell arteritis) is more severe than the non-arteritic form and requires emergency steroids.

Joint Inflammation

Joint inflammation. Rheumatoid arthritis, juvenile idiopathic arthritis, and reactive arthritis can all cause eye inflammation (uveitis, scleritis, dry eye).

Unusual Presentation

Not following the usual or expected pattern. Atypical features in optic neuritis (e.g., bilateral, no pain, severe loss) prompt testing for NMO or MOGAD.

Self-Tissue Transplant

A transplant using the patient's own tissue. Conjunctival autografts use healthy conjunctiva from one area to cover a defect in another.

Self-Attacking Immune Response

A condition where the immune system mistakenly attacks healthy tissue. Many neuro-ophthalmic conditions (NMO, MOGAD, myasthenia gravis) are autoimmune.

Non-Sex Chromosome

Relating to chromosomes other than X and Y. Autosomal dominant or recessive inheritance patterns determine how genetic eye conditions are passed down.

Avastin (Off-Label Anti-VEGF)

An anti-VEGF antibody originally for cancer, widely used off-label as a lower-cost eye injection for wet AMD, DME, and vein occlusions.

Dual-Focus Lens

Eyeglass lenses with two distinct zones - typically distance on top and near on the bottom - to correct both far and close vision.

On Both Sides

Affecting both eyes or both sides. Bilateral involvement of the optic nerve is more suggestive of NMO or MOGAD than of typical MS.

Both-Eye

Involving both eyes together. Binocular diplopia (double vision that disappears when one eye is closed) indicates a nerve or muscle problem.

Outer Vision in Both Eyes

Loss of the outer (temporal) half of vision in both eyes, classically from compression at the optic chiasm by a pituitary tumor.

Protective Eye Barrier

A selective barrier formed by tight junctions in retinal vessels and RPE cells that controls what passes from the bloodstream into the retina. Its breakdown causes edema.

Branch Retinal Artery Occlusion

Blockage of a smaller branch artery in the retina, causing sudden painless loss of a portion of the visual field.

Glaucoma Eye Drop (CAI)

A topical carbonic anhydrase inhibitor eye drop that lowers eye pressure by reducing aqueous humor production. Brand name: Azopt.

Beovu (Anti-VEGF)

An anti-VEGF antibody fragment for wet AMD, designed for longer treatment intervals. Brand name: Beovu. Carries a small risk of intraocular inflammation.

Branch Retinal Vein Occlusion

Blockage of a smaller branch vein in the retina, causing blurred vision and hemorrhages in part of the visual field.

Eyeball-Related (or Brainstem-Related)

In ophthalmology, “bulbar” usually means relating to the eyeball - for example, the bulbar conjunctiva is the membrane covering the white of the eye. In neurology, the same word means relating to the lower brainstem (medulla); bulbar weakness in myasthenia gravis affects swallowing, speech, and facial muscles.

Calcium Deposits

Abnormal deposition of calcium in tissue. In the eye, calcification can occur in the lens (cataract), cornea (band keratopathy), or optic nerve head (drusen).

Tiny Blood Vessels

The smallest blood vessels connecting arteries to veins. In the retina, capillary damage from diabetes causes microaneurysms, leakage, and vision loss.

Laser Clearing After Cataract Surgery

A short laser procedure that clears a cloudy membrane that can form behind the lens implant after cataract surgery, restoring clear vision.

Pressure-Lowering Drug Class

Medications that reduce fluid production in the eye or brain. Used as eye drops (dorzolamide, brinzolamide) or pills (acetazolamide) for glaucoma and IIH.

Thin Flexible Tube

A thin tube inserted into the body. In ophthalmology, used for procedures like nasolacrimal duct probing/stenting and some glaucoma surgeries.

Brain-Related

Relating to the cerebrum. Cerebral blood vessel disease, tumors, or strokes can affect the visual pathways and cause vision changes.

Brain & Spinal Fluid

Relating to the fluid surrounding the brain and spinal cord. Cerebrospinal fluid analysis (via lumbar puncture) helps diagnose MS, infections, and IIH.

Conjunctival Swelling

Swelling of the thin membrane covering the white of the eye, like a water blister; can occur with allergy, thyroid eye disease, infection, or trauma.

Optic Nerve Crossing

The X-shaped junction where the optic nerves partially cross so each side of the brain receives visual information from both eyes. Lesions here cause characteristic visual field loss.

Vascular Layer Behind Retina

A blood vessel-rich layer between the retina and sclera that supplies oxygen and nutrients to the outer retina.

Ciliary Body-Related

Relating to the ciliary body, a ring of tissue behind the iris that produces aqueous humor and controls the lens shape for focusing.

Cystoid Macular Edema

Macular swelling with a characteristic cyst-like pattern, often after eye surgery or with inflammation.

Central Nervous System

The brain and spinal cord. Many neuro-ophthalmic conditions involve the CNS because the visual pathway extends from the eyes through the brain.

Blood Clotting

The process of blood clot formation. In ophthalmology, laser photocoagulation uses heat to seal leaking vessels or destroy abnormal tissue.

Structural Protein

A protein providing structure to connective tissues. Collagen cross-linking is a treatment for keratoconus; collagen vascular diseases can affect the eyes.

Immune Defense Cascade

A system of blood proteins enhancing the immune response. Overactivation contributes to tissue damage in NMO and geographic atrophy (advanced dry AMD).

Eye Surface Membrane

The thin, transparent mucous membrane covering the white of the eye and lining the inner eyelids. It produces mucus and tears to lubricate the eye.

Clear Front Window

The clear, dome-shaped front surface of the eye that bends light as it enters, providing about two-thirds of the eye's focusing power.

Central Retinal Artery Occlusion

Blockage of the main artery to the retina - an 'eye stroke' causing sudden, severe, painless vision loss. An ocular emergency.

C-Reactive Protein

A blood marker of inflammation produced by the liver. Elevated CRP, along with ESR, helps diagnose and monitor giant cell arteritis.

Central Retinal Vein Occlusion

Blockage of the main vein draining the retina, causing sudden painless vision loss, swelling, and hemorrhages.

Cerebrospinal Fluid

The clear fluid surrounding and cushioning the brain and spinal cord. Changes in CSF pressure or composition can affect the optic nerve and vision.

Optic Disc Hollowing

Enlargement of the cup (central depression) of the optic disc. Increased cupping is a hallmark sign of glaucoma damage.

Focusing Muscle Paralysis

Temporary paralysis of the ciliary (focusing) muscle using drops. A cycloplegic refraction reveals the true prescription by eliminating the eye's compensation.

Cyst-Like

Resembling cysts - small fluid-filled spaces. Cystoid macular edema shows a petal-shaped pattern of fluid pockets in the macula.

Tear Sac Infection

Infection of the lacrimal (tear drainage) sac, usually from a blocked nasolacrimal duct. Causes painful swelling near the inner corner of the eye.

Nerve Insulation Damage

Loss of the myelin sheath insulating nerve fibers, slowing or blocking signal transmission. The central process in MS and related conditions.

Corneal Basement Membrane

A thin, tough membrane between the corneal stroma and endothelium. Descemet's membrane tears or detachment can cause corneal swelling and vision loss.

Lens Power Unit

The unit measuring optical power of a lens or the refractive error of an eye. Higher diopters mean stronger correction is needed.

Double Vision

The medical term for double vision - seeing two images of one object. Can be from one eye (monocular) or both eyes (binocular).

Diabetic Macular Edema

Swelling in the macula caused by leaking blood vessels in people with diabetes. Treated with injections or laser.

Glaucoma Eye Drop (CAI)

A topical carbonic anhydrase inhibitor eye drop for glaucoma. Often combined with timolol (Cosopt) for greater pressure lowering.

Tiny Deposits Under the Retina

Tiny yellow deposits under the retina; a hallmark of dry age-related macular degeneration. Optic disc drusen are a separate finding on the optic nerve - usually benign, but they can occasionally cause gradual visual-field loss.

Color Vision Deficiency

Impaired color perception, often an early sign of optic nerve disease. Red desaturation (red appears washed out) is tested at the bedside.

Altered Taste

Distortion or loss of the sense of taste. Can occur with facial nerve (Bell's) palsy and certain medications.

Inherited Tissue Degeneration

A genetically inherited condition causing progressive tissue deterioration. Corneal dystrophies cause deposits or clouding; retinal dystrophies cause photoreceptor loss.

Carrying Signals from the Brain

Carrying signals away from the brain to the muscles or pupil. Eye-movement nerves and the pupil-constriction pathway are efferent systems.

Electrical Activity Testing

Tests measuring the electrical responses of the visual system (ERG, VEP, EOG). Used when structural imaging is normal but function is impaired.

Hormone System

Relating to the hormone-producing gland system. Thyroid eye disease, diabetes-related eye changes, and pituitary tumors are endocrine causes of vision problems.

Severe Eye Infection

A serious infection inside the eye, usually from bacteria entering after surgery or injury. Requires emergency antibiotic injection into the eye.

Inner Cell Lining

The single layer of cells lining the inner surface of the cornea. These cells pump fluid out of the cornea to keep it clear; they do not regenerate.

Sunken Eye

Abnormal recession of the eyeball into the orbit. Can result from orbital fracture, tissue atrophy, or Horner syndrome.

Sunken-Looking Eye

A sunken appearance of the eye, classically after an orbital fracture that enlarges the eye socket. The apparent sunken eye in Horner syndrome is actually an illusion caused by the drooping upper eyelid (pseudoenophthalmos), not true posterior displacement of the globe.

Inside-the-Eye Perception

Visual phenomena originating within the eye itself, such as seeing floaters, blue-field entoptic phenomena (white blood cells in retinal vessels), or phosphenes.

Excessive Tearing

Overflow of tears onto the face, caused by either overproduction of tears (reflex tearing) or blocked tear drainage (nasolacrimal obstruction).

Surface Cell Layer

A layer of tightly packed cells lining body surfaces. In the eye, epithelium covers the cornea, conjunctiva, lens, and retinal pigment layer.

Electroretinogram

A test measuring the retina's electrical response to light. Helps diagnose inherited retinal diseases, toxicity, and unexplained vision loss.

Epiretinal Membrane

A thin sheet of scar tissue on the retinal surface that can contract and distort vision. Also called a macular pucker.

Inward Eye Turn

A form of strabismus where one eye turns inward. Can be present from infancy or develop later from nerve palsy or uncorrected farsightedness.

Inward Eye Turn

A form of strabismus where one eye turns inward (crosses).

Erythrocyte Sedimentation Rate

A blood test measuring how quickly red blood cells settle. Elevated ESR indicates inflammation, important for diagnosing giant cell arteritis.

Tear Evaporation-Related

Relating to tear film drying through excessive evaporation - the most common form of dry eye, usually caused by meibomian gland dysfunction.

Bulging Eye (Same as Proptosis)

Another term for forward bulging of the eyeball, classically caused by thyroid eye disease (Graves orbitopathy).

Outward Eye Turn

A form of strabismus where one eye turns outward.

Leaked Protein Deposits

Yellowish deposits of protein and fat leaked from damaged retinal blood vessels. A common sign of diabetic retinopathy and macular edema.

Fluorescein Angiography

Fluorescent dye injected into a vein with photographs taken as it circulates through retinal blood vessels, revealing leaks and blockages.

Vabysmo (Bispecific Antibody)

A bispecific antibody targeting both VEGF and Ang-2 for wet AMD and DME, often allowing longer intervals between injections. Brand name: Vabysmo.

Essential Nutritional Fat

Building blocks of fats important for cell function. Omega-3 fatty acids from fish oil have anti-inflammatory effects beneficial for dry eye.

Food and Drug Administration

The U.S. agency that approves medications and medical devices. FDA-approved indicates a treatment has met rigorous safety and efficacy standards.

Irregular Heart Rhythm

An irregular, often rapid heart rhythm. Atrial fibrillation is a major risk factor for embolic stroke and retinal artery occlusion.

Scar Tissue Formation

Development of excess connective (scar) tissue from injury or chronic inflammation. In the eye it can distort the retina or block drainage.

Yellow Eye Dye

An orange-yellow dye placed on the eye surface or injected through a vein. It glows under blue light and helps reveal scratches, infections, and blood-vessel leaks.

Center of Sharpest Vision

A tiny pit at the center of the macula packed with cone photoreceptors, providing the sharpest vision for reading and face recognition.

Press-On Prism Lens

A thin, flexible press-on prism applied to eyeglass lenses to redirect light, used as a temporary treatment for double vision.

Exam of the Back of the Eye

An eye exam where the doctor uses a light to look at the back of the eye through the pupil to view the optic disc, retina, and blood vessels.

Back of the Eye

The inside back wall of the eye that the doctor views during a dilated exam, including the retina, optic disc, and blood vessels.

MRI Contrast Dye

A contrast agent injected during MRI that highlights areas of active inflammation or blood-brain barrier breakdown. Enhancement suggests active disease.

Nerve Cell Cluster

A cluster of nerve cell bodies. Retinal ganglion cells collect visual signals from the retina and transmit them through the optic nerve to the brain.

Giant Cell Arteritis

Inflammatory disease of blood vessels, mainly temporal arteries. Can cause sudden vision loss and requires urgent high-dose steroids.

Ganglion Cell Layer

The retinal layer containing ganglion cells whose axons form the optic nerve. Loss of ganglion cells is a hallmark of glaucoma.

Drainage Angle Exam

An exam using a special lens to view the drainage angle of the eye, used in glaucoma evaluation to distinguish open-angle from angle-closure forms.

Bacterial STI

An STI that can cause severe, sight-threatening conjunctivitis (gonococcal ophthalmia), particularly dangerous in newborns.

Inflammatory Nodule

A nodule of chronic inflammation formed when the immune system walls off substances it cannot eliminate. Seen in sarcoidosis and tuberculosis.

Autoimmune Thyroid Disease

An autoimmune condition causing overactive thyroid. Graves' orbitopathy (thyroid eye disease) causes eye bulging, double vision, and eyelid retraction.

Loss of Half of Vision

Loss of half of the visual field in each eye, usually from a problem behind the eyes in the brain.

Bleeding

Blood leaked from damaged vessels. In the eye, hemorrhages appear as dots, blots, or flame-shaped patches on the retina, signaling vascular disease.

Tissue Microscopy

Microscopic examination of tissue samples (biopsies) to identify disease. Temporal artery biopsy histopathology confirms giant cell arteritis.

Same Side of Both Eyes

Affecting the same side of the visual field in both eyes. A homonymous hemianopia means the right or left half of vision is lost in each eye, classically from an occipital-lobe stroke.

Eye Fluid

A clear fluid inside the eye. Aqueous humor fills the front chamber; vitreous humor is the gel filling the back. Both help maintain eye shape and pressure.

Extremely Rapid Onset

Developing extremely quickly, often within hours. Hyperacute conjunctivitis (especially gonococcal) is a sight-threatening emergency.

Excessive Clotting Tendency

A state in which the blood clots more easily than normal. Hypercoagulable disorders increase risk of retinal vein and artery occlusions.

Visible Eye Redness

Visible redness of the eye from dilated surface blood vessels. In clinical notes the same finding is often called “conjunctival injection.”

High Blood Fats

Elevated levels of fats (cholesterol, triglycerides) in the blood. A risk factor for retinal vein and artery occlusions and corneal arcus.

Farsighted

Having farsightedness, where distant objects are clearer than near ones. Small, hyperopic eyes have a higher risk of acute angle-closure glaucoma.

Upward Eye Misalignment

A form of strabismus where one eye sits higher than the other.

Antimicrobial Eyelid Cleanser

Hypochlorous acid is a gentle antimicrobial spray used for eyelid hygiene in blepharitis and dry eye. It reduces bacteria and inflammation without irritation.

Pus in the Eye's Front Chamber

A visible layer of white blood cells (pus) settling at the bottom of the anterior chamber. A sign of severe intraocular inflammation or infection.

Abnormally Low Eye Pressure

Dangerously low intraocular pressure, usually below 5 mmHg. Can cause maculopathy, choroidal folds, and vision loss after glaucoma surgery or trauma.

Downward Eye Misalignment

A form of strabismus where one eye sits lower than the other.

Indocyanine Green Angiography

An imaging test using a different dye to visualize the choroidal blood vessels beneath the retina, useful for deeper layer conditions.

Idiopathic Intracranial Hypertension

Elevated skull pressure without a tumor or other identifiable cause, causing headaches and optic nerve swelling (papilledema).

Internal Limiting Membrane

The thin membrane at the innermost surface of the retina, sometimes peeled during surgery to treat macular holes or epiretinal membranes.

Caused by the Immune System

Caused by the body's own immune response rather than infection. Many forms of optic neuritis and uveitis are immune-mediated.

Weakened Immune System

Reduced ability to fight infections, from disease (HIV), medications (chemotherapy), or transplant. Raises risk of opportunistic eye infections.

Immune System Adjuster

Medications that modify or regulate immune function rather than broadly suppressing it. Used for chronic inflammatory eye diseases.

Immune System Suppression

Treatments that reduce immune system activity. Used when the immune system attacks the body's own tissues, as in uveitis, NMO, and myasthenia gravis.

Immune-Based Treatment

Treatment that uses the immune system to fight disease, especially cancer. Checkpoint inhibitor immunotherapy can cause uveitis and other eye inflammation as a side effect.

Implanted Device

A device surgically placed inside the body. Eye implants include glaucoma drainage devices, sustained-release steroid implants (Ozurdex), and retinal prostheses.

Inside the Eye's Vitreous Gel

An injection given directly into the vitreous gel inside the eye, used for anti-VEGF and steroid treatments of retinal disease.

Intraocular Lens

An artificial lens implanted during cataract surgery. Different types correct distance, astigmatism, or provide multifocal correction.

Intraocular Pressure

Fluid pressure inside the eye. Elevated IOP is the major risk factor for glaucoma, measured using a tonometer.

Laser Hole in the Iris

A laser-made hole in the iris that relieves angle-closure glaucoma by letting fluid pass directly from behind the iris to in front of it. This equalizes the pressure that was pushing the iris forward and blocking the eye's drainage angle.

Iris Inflammation

Inflammation of the iris, a form of anterior uveitis. Causes pain, redness, light sensitivity, and a small pupil. Often treated with steroid drops.

Reduced Blood Supply

Insufficient blood flow and oxygen to tissue. In the eye, ischemia can damage the retina, optic nerve, or visual pathways in the brain.

Cornea + Conjunctiva Inflammation

Combined inflammation of the cornea and conjunctiva. Includes keratoconjunctivitis sicca (dry eye) and epidemic viral keratoconjunctivitis.

Cornea Disease

Any non-inflammatory disease of the cornea. Band keratopathy (calcium deposits) and bullous keratopathy (corneal swelling) are common forms.

Corneal Transplant

Surgical replacement of damaged corneal tissue with healthy donor cornea. Types include full-thickness (penetrating) and partial-thickness (lamellar).

Tear-Related

Relating to the tear glands and drainage system. The lacrimal gland produces tears; the lacrimal sac and nasolacrimal duct drain them into the nose.

Incomplete Eyelid Closure

Inability to fully close the eyelids, exposing the cornea. Caused by facial nerve palsy, thyroid eye disease, or scarring. Risks corneal damage.

Laser-Assisted In Situ Keratomileusis

Refractive surgery using a laser to reshape the cornea, correcting nearsightedness, farsightedness, or astigmatism.

Cornea-Sclera Border

The border zone where the transparent cornea meets the white sclera. It contains stem cells essential for corneal healing.

Swollen Lymph Nodes

Enlargement of lymph nodes, which can indicate infection, inflammation, or cancer. Preauricular lymphadenopathy accompanies viral conjunctivitis.

Lymphatic System Cancer

A cancer of the lymphatic system that can involve the eye and orbit. Primary intraocular lymphoma masquerades as chronic uveitis.

Central Retina

The small, central part of the retina responsible for sharp, straight-ahead vision used for reading and recognizing faces.

Macula Still Attached

A retinal detachment where the macula (central vision area) remains attached. Macula-on detachments are treated more urgently to preserve central vision.

Macula Disease

Any disease or dysfunction of the macula. Includes diabetic maculopathy, toxic maculopathy, and age-related maculopathy.

Structural Abnormality

An abnormally formed structure present from birth or developing later. Arteriovenous malformations in the orbit or brain can affect vision.

Eyelid Oil Secretion

The oily substance secreted by meibomian glands that forms the outer layer of the tear film. Its quality and quantity are assessed in dry eye evaluation.

Brain Membrane Infection

Inflammation of the membranes (meninges) surrounding the brain and spinal cord. Can cause papilledema, cranial nerve palsies, and vision loss.

Distorted / Wavy Vision

Visual distortion where straight lines appear wavy or bent. A key symptom of macular diseases like epiretinal membrane and wet AMD.

Spread from Another Cancer

Cancer that has spread from its original site to another location. The eye and orbit can be targets for metastatic breast, lung, and other cancers.

Tiny Vessel Bulges

The earliest visible sign of diabetic retinopathy - tiny balloon-like outpouchings of weakened retinal capillaries that can leak fluid.

One Millionth of a Meter

A unit of measurement (1/1000 of a millimeter) used for retinal layer thickness on OCT. Normal RNFL is roughly 90-110 microns.

Small / Constricted Pupil

Abnormal constriction of the pupil. A miotic pupil on one side is a key sign of Horner syndrome.

Myelin Oligodendrocyte Glycoprotein

A protein on myelin sheaths in the CNS. Antibodies against MOG cause optic neuritis and other inflammatory conditions (MOGAD).

MOG Antibody Disease

An autoimmune condition caused by antibodies against MOG protein. Can cause optic neuritis with often good recovery but relapse risk.

From a Single Cell Clone

Derived from a single cell clone. Monoclonal antibodies (rituximab, eculizumab) are engineered immune proteins used to treat autoimmune eye conditions.

One-Eye

Involving one eye only. Monocular diplopia (double vision in one eye) points to an eye problem like cataract, while binocular diplopia suggests a nerve or muscle issue.

Single-Focus Lens

A lens with one focal point, correcting vision at a single distance. Standard cataract surgery uses monofocal IOLs, usually set for distance.

One Eye Near, One Far

A vision correction strategy where one eye is set for distance and the other for near, reducing dependence on reading glasses. Used in LASIK and cataract surgery.

Magnetic Resonance Imaging

An imaging technique using magnetic fields and radio waves for detailed pictures of the brain, orbits, and optic nerves. No radiation.

Multiple Specialties Together

An approach involving multiple medical specialties working together. Many neuro-ophthalmic conditions require collaboration between ophthalmology, neurology, and other fields.

Myasthenia-Related

Relating to myasthenia gravis, an autoimmune disorder of the neuromuscular junction. Myasthenic symptoms include fluctuating ptosis and double vision.

Dilated / Large Pupil

Abnormal dilation of the pupil. A fixed, dilated pupil can indicate a third nerve palsy, trauma, or pharmacologic dilation.

Spinal Cord Inflammation

Inflammation of the spinal cord, which can occur alongside optic neuritis in NMO and MOGAD. Causes weakness, numbness, and bowel/bladder problems.

Non-Arteritic Anterior Ischemic Optic Neuropathy

Sudden, painless vision loss from reduced blood flow to the front of the optic nerve. Most common acute optic neuropathy in people over 50.

Abnormal New Vessel Growth

Formation of new, abnormal blood vessels in response to oxygen deprivation. These fragile vessels leak and bleed, worsening diabetic retinopathy and wet AMD.

Rho Kinase Inhibitor Eye Drop

A newer class of glaucoma eye drop that lowers eye pressure by increasing fluid drainage through the trabecular meshwork. Brand name: Rhopressa.

Nerve-Eye Related

Involving both the nervous system and the eye. Neuro-ophthalmic conditions include optic neuritis, papilledema, cranial nerve palsies, and visual field defects.

Nerve Tumor Genetic Condition

A genetic condition causing tumors on nerves. NF1 can cause optic pathway gliomas and Lisch nodules on the iris; NF2 can cause vision and hearing loss.

Nerve-Muscle Related

Involving the connection between nerves and muscles. Neuromuscular junction diseases like myasthenia gravis cause fluctuating ptosis and double vision.

From Nerve Damage

Caused by damage to nerves. Neuropathic pain after herpes zoster ophthalmicus can persist long after the rash resolves (postherpetic neuralgia).

Nerve-Protecting

Treatments aimed at protecting nerve cells from damage or death. An active area of research in glaucoma and optic neuropathies.

Brain/Nerve Surgery

Relating to surgery on the brain, spinal cord, or nerves. Some neuro-ophthalmic conditions (pituitary tumors, aneurysms, IIH) require neurosurgical intervention.

Syphilis of the Nervous System

Syphilis infection affecting the brain, spinal cord, or nerves. Can cause pupil abnormalities (Argyll Robertson pupils), optic atrophy, and vision loss.

Neuromyelitis Optica

An autoimmune disorder attacking the optic nerves and spinal cord, associated with AQP4 antibodies. Requires different treatment than MS.

Non-Proliferative Diabetic Retinopathy

Earlier stage of diabetic eye disease where retinal blood vessels weaken and leak, before abnormal new vessels grow.

Involuntary Eye Movements

Involuntary, rhythmic eye movements that can blur vision or make objects appear to move.

Optical Coherence Tomography

A non-invasive imaging test using light waves to take cross-section pictures of the retina and optic nerve, detecting thinning, swelling, and structural changes.

Limited Antibody Bands

Referring to oligoclonal bands - distinct antibody patterns found in cerebrospinal fluid that suggest immune activity in the CNS, supporting a diagnosis of MS.

Anti-Inflammatory Fatty Acid

Essential fatty acids found in fish oil and flaxseed with anti-inflammatory properties. Commonly recommended for dry eye disease and meibomian gland dysfunction.

Optic Nerve Head

The visible portion of the optic nerve inside the eye where nerve fibers exit to carry visual signals to the brain. Also called the optic disc.

Clouding

Loss of transparency in a normally clear eye structure - for example, posterior capsule opacification after cataract surgery or corneal scarring.

Eye Interior Examination

Examination of the interior of the eye using a handheld instrument (ophthalmoscope) that shines light through the pupil to view the retina and optic nerve.

Eye Socket Disease

Disease of the orbit (eye socket). Thyroid orbitopathy (Graves' orbitopathy) is the most common cause, causing bulging eyes and double vision.

Semaglutide (Diabetes Dose)

Brand names for semaglutide, a GLP-1 receptor agonist for diabetes/weight loss. Rapid weight loss from these medications has been linked to increased NAION risk in some studies.

Primary Angle-Closure Glaucoma

Glaucoma where the iris blocks the drainage angle, causing rapid eye pressure rise. Acute angle closure is an emergency.

Corneal Thickness Measurement

A quick, painless measurement of corneal thickness, important for glaucoma risk assessment and LASIK planning.

Small Raised Bumps

Tiny raised bumps on the inner surface of the eyelid, formed by an inflammatory reaction. Giant papillae are characteristic of allergic and contact lens-related conjunctivitis.

Swelling of the Optic Nerve from Brain Pressure

Swelling of the optic nerve head - usually in both eyes - caused by raised pressure inside the brain. A key sign of idiopathic intracranial hypertension and other dangerous causes of raised intracranial pressure.

Disease-Related

Caused by disease rather than being a normal finding. Pathological myopia (extreme nearsightedness) increases risk of retinal detachment and macular problems.

Proliferative Diabetic Retinopathy

Advanced diabetic eye disease with abnormal new blood vessels on the retina that can bleed or cause detachment.

Swinging Like a Pendulum

A type of nystagmus with equal-speed movements in both directions (like a pendulum), as opposed to jerk nystagmus with fast and slow phases.

Around the Eyeball

The space around the globe of the eye. Peribulbar anesthesia is an injection around the eye used during ocular surgery.

Visual Field Testing

The formal test that maps the entire field of vision in each eye, used to detect glaucoma, optic nerve disease, and brain lesions.

Around the Eye

The area immediately surrounding the eye. Periocular steroid injections deliver medication near the eye without entering it.

Around the Eye Socket

The area surrounding the bony orbit (eye socket). Periorbital swelling or bruising can signal orbital disease, trauma, or systemic conditions.

Flashes of Light in Vision

Brief flashes or sparks of light in your vision, often from vitreous traction on the retina or from migraine.

Light-Sensing Cell

Specialized retinal cells - rods (dim light, peripheral vision) and cones (color, central detail) - that convert light into electrical signals.

Inflamed Pinguecula

Inflammation of a pinguecula, a yellowish raised lesion on the conjunctiva near the cornea. Causes redness, irritation, and swelling.

Vessel Wall Deposit

Buildup of cholesterol, calcium, or inflammatory material in a vessel wall. Plaques can break loose and travel to retinal arteries, causing sudden vision loss.

Primary Open-Angle Glaucoma

The most common glaucoma where fluid doesn't drain efficiently despite an open drainage angle, causing gradual optic nerve damage.

Widespread Muscle Pain

Polymyalgia rheumatica is an inflammatory condition causing severe muscle stiffness and pain. Closely associated with giant cell arteritis - both share elevated ESR/CRP.

Pars Plana Vitrectomy

Surgery removing the vitreous gel to treat retinal detachment, macular holes, vitreous hemorrhage, and epiretinal membranes.

Pre-Procedure Medication

Medication given before a procedure to prepare the patient - such as dilating drops before an eye exam or anxiety medication before surgery.

In Front of the Eye Socket Wall

Located in front of the orbital septum (the tissue dividing the eyelid from the orbit). Preseptal cellulitis is an eyelid infection that has not spread into the orbit.

How Common a Condition Is

The proportion of a population affected by a condition at a given time. Helps patients understand how common their diagnosis is.

Photorefractive Keratectomy

Laser vision correction similar to LASIK but without creating a corneal flap. Surface cells are removed before the laser reshapes the cornea.

Forward-Bulging Eye

Forward bulging of the eyeball, most often from thyroid eye disease or an orbital mass.

Glaucoma Pressure-Lowering Drop

Eye drops (latanoprost, travoprost, bimatoprost) that lower eye pressure by increasing fluid drainage. Usually the first-line glaucoma treatment.

Reticular Pseudodrusen

Small yellowish deposits above the RPE (unlike true drusen which are below it). Associated with a higher risk of progression to advanced AMD.

Aggressive Bacteria

A type of bacteria (Pseudomonas aeruginosa) that causes rapidly progressive, sight-threatening corneal ulcers, especially in contact lens wearers.

Eye With an Artificial Lens

An eye that has an artificial intraocular lens implant after cataract surgery.

Drooping Upper Eyelid

Drooping of the upper eyelid, which can signal nerve, muscle, aging, or aponeurotic causes.

Tear Drain Opening

The tiny opening on the inner edge of each eyelid where tears drain into the nasolacrimal duct. Punctal plugs block these openings to keep tears on the eye for dry eye treatment.

Pupil Not Affected

A nerve palsy that does not affect the pupil. A pupil-sparing third nerve palsy is more likely vascular (e.g., diabetes) than compressive (e.g., aneurysm).

Pupil-Related

Relating to the pupil - the round, central opening of the iris that controls how much light enters the eye.

Posterior Vitreous Detachment

Common age-related separation of the vitreous gel from the retina, often causing new floaters and flashes.

Loss of One Quarter of Vision

Loss of one quarter of the visual field in each eye, from injury to part of the optic radiation in the temporal or parietal lobe.

Lucentis (Anti-VEGF)

An anti-VEGF antibody fragment injected into the eye for wet AMD, diabetic macular edema, and retinal vein occlusions. Brand name: Lucentis.

Relative Afferent Pupillary Defect

Abnormal pupil response on swinging flashlight test, indicating one optic nerve transmits signals less efficiently than the other.

Net-Like Pattern

Having a network or net-like pattern. Reticular pseudodrusen are a specific type of deposit associated with higher AMD progression risk.

Retina Reattachment Procedure

A procedure to reattach the retina. Pneumatic retinopexy uses a gas bubble injected into the eye to push the retina back into place.

Behind the Eyeball

Located behind the globe of the eye, within the orbit. Retrobulbar optic neuritis affects the optic nerve behind the eye and may show a normal-looking disc.

Tear-Related (Retinal Detachment)

A retinal detachment caused by a break or tear in the retina, allowing fluid to seep underneath and separate it from the wall of the eye.

Retinal Nerve Fiber Layer

The layer of nerve cell fibers on the inner surface of the retina. Thinning of the RNFL is an important sign of optic nerve damage, measured by OCT.

Retinal Pigment Epithelium

A single cell layer behind the retina that nourishes photoreceptors and absorbs stray light. Damage to the RPE plays a role in macular degeneration.

Inflammatory Granuloma Disease

A systemic inflammatory disease causing granulomas in multiple organs. Ocular sarcoidosis is a common cause of uveitis, especially in young adults.

White of the Eye

The tough, white outer coat of the eyeball that provides structural support and protection, continuous with the cornea at the front.

Sclera Inflammation

Painful inflammation of the sclera, often associated with autoimmune conditions like rheumatoid arthritis. Requires systemic treatment.

Blind Spot in Vision

A blind spot or area of reduced vision within an otherwise normal visual field. Can be central (affecting reading) or paracentral.

Sinus Infection

Inflammation of the sinuses that can spread to the orbit, causing orbital cellulitis - a sight- and life-threatening emergency.

Selective Laser Trabeculoplasty

A laser procedure to lower eye pressure in open-angle glaucoma by improving fluid drainage through the trabecular meshwork.

Reducing Steroid Dependence

A treatment strategy introducing another immunosuppressive medication to lower or stop corticosteroids, avoiding their long-term side effects.

Eye Misalignment

Misalignment of the eyes; one eye may turn in (esotropia), out (exotropia), up, or down.

Tissue Framework-Related

Relating to the stroma, the main structural layer of the cornea or iris. Corneal stromal disease causes scarring and loss of transparency.

Under the Brain Membrane

The space beneath the arachnoid membrane surrounding the brain and spinal cord, filled with cerebrospinal fluid. Subarachnoid hemorrhage is a neurological emergency.

Beneath the Retina

The space between the retina and the retinal pigment epithelium, where fluid or blood accumulates in conditions like wet AMD and retinal detachment.

Sympathetic Nervous System

Part of the autonomic nervous system controlling fight-or-flight responses. Disruption of the sympathetic pathway to the eye causes Horner syndrome.

Systemic Bacterial Infection

An STI caused by Treponema pallidum that can affect almost any eye structure, mimicking many diseases - called 'the great imitator.'

Tissue Swelling

Abnormal increase in tissue thickness, often detected on OCT. Retinal thickening typically indicates fluid accumulation or inflammation.

Tissue Loss

Abnormal decrease in tissue thickness, measured on OCT. RNFL or ganglion cell thinning indicates optic nerve damage.

Beta-Blocker Eye Drop

A beta-blocker eye drop that lowers eye pressure by reducing aqueous humor production. One of the oldest and most widely used glaucoma medications.

Eye Pressure Test

The test that measures the pressure inside the eye, used to screen for and monitor glaucoma.

Parasitic Infection

Infection by the Toxoplasma parasite, a leading cause of posterior uveitis. Causes characteristic focal retinal scars (retinochoroiditis).

Drainage Meshwork

Relating to the trabecular meshwork, a sponge-like tissue near the base of the iris through which aqueous humor drains out of the eye.

Glaucoma Drainage Surgery

A glaucoma surgery that creates a new drainage channel for eye fluid, lowering pressure inside the eye.

Pulling / Traction-Related

Caused by pulling forces on the retina from scar tissue or vitreous adhesions. Tractional retinal detachment is a complication of advanced diabetic eye disease.

Short-Lasting

Short-lasting. Transient visual obscurations are brief dim-outs of vision often associated with raised intracranial pressure.

Tissue Replacement Surgery

Replacing damaged tissue with healthy donor tissue. Corneal transplants restore clarity; amniotic membrane transplants promote surface healing.

Injectable Steroid

A long-acting corticosteroid injected around or into the eye to reduce inflammation and macular edema. Also used during vitrectomy to visualize the vitreous.

Antiviral Eye Drop

A topical antiviral eye drop used to treat herpes simplex keratitis (corneal infection). Brand name: Viroptic.

Migraine Medications

Medications (sumatriptan, rizatriptan, etc.) that constrict blood vessels and block pain pathways to treat migraine attacks.

Chronic Bacterial Infection

A bacterial infection (TB) that can cause uveitis, choroidal granulomas, and optic nerve inflammation. Ocular TB can occur without active lung disease.

Blood Vessel Inflammation

Inflammation of blood vessel walls that can narrow, weaken, or scar them. Retinal vasculitis causes vessel sheathing and can lead to ischemia.

Vessel-Narrowing Drug

Medications that narrow blood vessels. Used in eye drops to reduce redness, but prolonged use causes rebound redness and should be avoided.

Vascular Endothelial Growth Factor

A signaling protein promoting new blood vessel growth. In eye disease, excess VEGF drives abnormal vessel growth and leakage in wet AMD and diabetic retinopathy.

Vein-Related

Relating to veins. Venous congestion or occlusion in the retina causes hemorrhages, swelling, and vision loss.

Visual Evoked Potential

A test measuring the electrical signal from eyes to brain. A delayed signal indicates optic nerve damage even when not visible on other tests.

Surgery to Remove Vitreous Gel

Surgery that removes the vitreous gel from inside the eye, used to repair retinal detachment, macular holes, vitreous hemorrhage, and other retinal problems.

Eye's Internal Gel

The clear, jelly-like substance that fills the cavity behind the lens, in front of the retina.

Yttrium Aluminum Garnet Laser

A laser for procedures like capsulotomy (clearing cloudy membrane after cataract surgery) and iridotomy (creating a drainage hole for angle-closure glaucoma).

Shingles Virus

Herpes zoster (shingles) is a reactivation of the chickenpox virus. When it affects the eye area (zoster ophthalmicus), it can cause keratitis, uveitis, and nerve damage.