📖 Glossary of Eye Terms
Welcome to the Kardia Eye Resource Center Glossary of Eye Terms. This glossary provides clear, easy-to-understand definitions of common ophthalmology and optometry terminology. Whether you’re a patient, student, or healthcare professional, this resource is designed to help you better understand the language of eye care.
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Select a letter below or scroll through the glossary to explore hundreds of eye care terms arranged alphabetically.
Accommodation
The eye’s ability to change focus from distant objects to near objects by altering the shape of the natural crystalline lens.
Accommodative Esotropia
A type of crossed eyes (esotropia) that develops because of focusing effort, usually in children with significant farsightedness.
Age-Related Macular Degeneration (AMD)
A disease affecting the macula that gradually reduces central vision and is a leading cause of vision loss in older adults.
Amblyopia
Commonly called “lazy eye,” amblyopia is reduced vision caused by abnormal visual development during childhood.
Amsler Grid
A simple grid used to detect changes in central vision caused by macular diseases such as age-related macular degeneration.
Angle Closure
A blockage of the eye’s drainage angle that can rapidly increase eye pressure and cause acute angle-closure glaucoma.
Anisocoria
A condition in which the pupils are different sizes.
Anisometropia
A difference in refractive error between the two eyes that may lead to amblyopia if untreated in childhood.
Anterior Chamber
The fluid-filled space between the cornea and the iris that contains aqueous humor.
Anterior Uveitis
Inflammation affecting the front portion of the uvea, commonly involving the iris.
Aphakia
The absence of the eye’s natural crystalline lens, usually after cataract removal without lens implantation or following trauma.
Applanation Tonometry
A method of measuring intraocular pressure by gently flattening a small area of the cornea.
Arcus Senilis
A gray or white ring around the edge of the cornea commonly associated with aging.
Artificial Tears
Lubricating eye drops used to relieve symptoms of dry eye disease.
Asthenopia
Eye strain or visual fatigue often associated with prolonged near work.
Astigmatism
A refractive error caused by an irregular curvature of the cornea or lens, resulting in blurred or distorted vision.
Aqueous Humor
The clear fluid produced inside the eye that nourishes the cornea and lens while maintaining intraocular pressure.
Bacterial Conjunctivitis
A bacterial infection of the conjunctiva that commonly causes redness, discharge, and eyelid crusting.
Bell’s Palsy
A temporary weakness of the facial nerve that may prevent complete eyelid closure and contribute to dry eye symptoms.
Best Corrected Visual Acuity (BCVA)
The clearest vision achievable using the most accurate glasses or contact lens prescription.
Biomicroscopy
Examination of the eye using a slit lamp microscope to evaluate the anterior and posterior segments.
Binocular Vision
The ability of both eyes to work together to produce a single three-dimensional image.
Blepharitis
Inflammation of the eyelid margins, commonly associated with bacteria, dandruff, or meibomian gland dysfunction.
Blepharospasm
Involuntary spasms or excessive blinking caused by abnormal eyelid muscle contractions.
Blind Spot
The normal area in the visual field corresponding to the optic nerve where no photoreceptors are present.
Blood-Retinal Barrier
A specialized barrier that helps protect the retina by regulating the movement of substances from the bloodstream.
Bowman’s Layer
A tough layer of tissue located beneath the corneal epithelium.
Canaliculus
A small drainage channel that carries tears from the eyelids into the lacrimal sac.
Cataract
Clouding of the eye’s natural crystalline lens, leading to blurred vision, glare, and reduced contrast.
Central Corneal Thickness (CCT)
The thickness of the central cornea, commonly measured during glaucoma evaluations and refractive surgery assessments.
Central Retinal Artery Occlusion (CRAO)
A sudden blockage of the central retinal artery causing painless, severe vision loss. It is considered an eye emergency.
Central Retinal Vein Occlusion (CRVO)
A blockage of the main retinal vein that may cause sudden blurred vision and retinal hemorrhages.
Chemosis
Swelling of the conjunctiva caused by allergy, inflammation, infection, or trauma.
Choroid
The vascular layer between the retina and sclera that supplies oxygen and nutrients to the outer retina.
Choroidal Nevus
A benign pigmented lesion beneath the retina that is sometimes referred to as an eye freckle.
Ciliary Body
A structure behind the iris responsible for producing aqueous humor and controlling accommodation.
Color Vision
The ability to distinguish different colors through the function of cone photoreceptors.
Conjunctiva
The thin transparent membrane covering the white part of the eye and lining the inside of the eyelids.
Conjunctivitis
Inflammation of the conjunctiva, commonly caused by infection, allergy, or irritation. Often referred to as “pink eye.”
Contact Lens
A medical device placed directly on the eye to correct vision or manage certain eye conditions.
Contrast Sensitivity
The ability to distinguish an object from its background, particularly under low-light conditions.
Cornea
The clear front surface of the eye that helps focus incoming light.
Corneal Abrasion
A scratch on the surface of the cornea that commonly causes pain, tearing, and light sensitivity.
Corneal Edema
Swelling of the cornea that may cause blurred vision and halos around lights.
Corneal Ulcer
An open sore on the cornea, usually caused by infection. It is a potentially sight-threatening emergency.
Cup-to-Disc Ratio (CDR)
A measurement of the optic nerve used to evaluate and monitor glaucoma.
Dacryoadenitis
Inflammation of the lacrimal (tear) gland, often caused by infection or autoimmune disease.
Dacryocystitis
An infection of the lacrimal (tear) sac, usually caused by blockage of the tear drainage system.
Dacryostenosis
Blockage or narrowing of the tear drainage system, resulting in excessive tearing.
Day Blindness
Difficulty seeing in bright light, also called hemeralopia.
Demodex Blepharitis
Blepharitis caused by infestation of Demodex mites along the eyelid margins and eyelashes.
Descemet’s Membrane
A thin layer of the cornea located between the corneal stroma and endothelium.
Diabetic Macular Edema (DME)
Swelling of the macula caused by leakage from retinal blood vessels in patients with diabetes.
Diabetic Retinopathy
Damage to the retinal blood vessels caused by diabetes, which may lead to permanent vision loss if untreated.
Diplopia
The perception of double vision.
Direct Ophthalmoscopy
An examination technique using a handheld ophthalmoscope to view the retina and optic nerve.
Distichiasis
An abnormal extra row of eyelashes that may rub against the surface of the eye.
Drusen
Yellow deposits beneath the retina commonly associated with age-related macular degeneration.
Dry Eye Disease
A chronic condition in which the eyes do not produce enough healthy tears or tears evaporate too quickly.
Ectropion
Outward turning of the eyelid, usually affecting the lower eyelid and causing excessive tearing and irritation.
Emmetropia
The normal refractive state in which distant objects are focused clearly on the retina without corrective lenses.
Endophthalmitis
A severe infection inside the eye that requires immediate treatment to prevent permanent vision loss.
Endothelium
The innermost layer of the cornea responsible for maintaining corneal clarity by pumping fluid out of the cornea.
Entropion
Inward turning of the eyelid that causes the eyelashes to rub against the eye.
Epiblepharon
An extra fold of skin causing the eyelashes to turn inward and contact the eye.
Epiphora
Excessive tearing caused by overproduction of tears or blockage of tear drainage.
Epiretinal Membrane (ERM)
A thin layer of scar tissue that forms on the surface of the retina and may distort central vision.
Episcleritis
Inflammation of the episclera, a thin layer between the conjunctiva and sclera, usually causing mild redness and discomfort.
Esophoria
A tendency for one eye to drift inward that is normally controlled by the brain’s fusion mechanism.
Esotropia
A form of strabismus in which one or both eyes turn inward.
Exophthalmos
Forward protrusion of one or both eyes, commonly associated with thyroid eye disease.
Exophoria
A tendency for one eye to drift outward when binocular vision is disrupted.
Exotropia
A form of strabismus in which one or both eyes turn outward.
Extraocular Muscles
The six muscles responsible for moving the eyes in different directions.
Farsightedness (Hyperopia)
A refractive error in which nearby objects are more difficult to see clearly than distant objects.
Fixation
The ability to maintain steady visual focus on a single target.
Flashes
Brief streaks or flickers of light often caused by traction on the retina from the vitreous gel.
Floaters
Small moving spots or strands that drift across the visual field due to changes in the vitreous gel.
Fluorescein
A bright orange dye used to detect corneal injuries, evaluate tear drainage, and perform retinal angiography.
Fluorescein Angiography (FA)
An imaging test that uses fluorescein dye to evaluate blood flow within the retina and choroid.
Follicular Conjunctivitis
A form of conjunctivitis characterized by small lymphoid follicles on the inner surface of the eyelids.
Foreign Body
Any object that enters or becomes lodged on the surface or inside the eye.
Fovea
The central portion of the macula responsible for the sharpest central vision.
Fuchs Endothelial Corneal Dystrophy
A progressive corneal disease affecting the endothelial cells, leading to corneal swelling and blurred vision.
Fundus
The interior surface of the eye, including the retina, optic nerve, macula, and retinal blood vessels.
Fundus Photography
Color photographs of the retina used to document and monitor retinal and optic nerve diseases.
Fusion
The brain’s ability to combine images from both eyes into a single three-dimensional image.
Geographic Atrophy
An advanced form of dry age-related macular degeneration characterized by progressive loss of retinal cells.
Glare
Difficulty seeing due to bright light, commonly experienced with cataracts, corneal disease, or refractive errors.
Glaucoma
A group of eye diseases that damage the optic nerve, often associated with elevated intraocular pressure.
Goldmann Applanation Tonometry
The gold-standard method for measuring intraocular pressure.
Gonioscopy
A specialized examination used to evaluate the drainage angle of the eye.
Graft Rejection
An immune response against a transplanted cornea that requires prompt treatment.
Graves’ Eye Disease
An autoimmune condition associated with thyroid disease that may cause eye bulging, double vision, and eyelid retraction.
Gritty Sensation
A feeling that something is in the eye, commonly associated with dry eye disease or blepharitis.
Hemeralopia
Difficulty seeing in bright light, also known as day blindness.
Hemianopia
Loss of one-half of the visual field, usually caused by neurological disease.
Herpes Simplex Keratitis
A viral infection of the cornea caused by the herpes simplex virus.
Herpes Zoster Ophthalmicus
Shingles affecting the eye and surrounding tissues.
Heterochromia
A condition in which the irises are different colors.
Hordeolum (Stye)
An acute bacterial infection of an eyelid gland causing a tender red lump.
Humphrey Visual Field (HVF)
A computerized visual field test commonly used to diagnose and monitor glaucoma and neurological disorders.
Hyperopia
Farsightedness, a refractive error in which near objects are more difficult to focus.
Hyphema
Blood within the anterior chamber of the eye, usually following trauma.
Hypopyon
A collection of inflammatory white blood cells in the anterior chamber, often indicating severe infection or inflammation.
Intraocular Lens (IOL)
An artificial lens implanted during cataract surgery to replace the eye’s natural lens.
Intraocular Pressure (IOP)
The pressure inside the eye. Elevated IOP is a major risk factor for glaucoma.
Iris
The colored portion of the eye that controls the size of the pupil.
Iridocyclitis
Inflammation involving both the iris and ciliary body.
Iridotomy
A laser procedure that creates a small opening in the iris to improve aqueous humor flow.
Irregular Astigmatism
Astigmatism caused by an uneven corneal surface, often due to keratoconus or corneal scarring.
Jackson Cross Cylinder (JCC)
An optical lens used during refraction to refine the axis and power of astigmatism.
Javal Keratometer
An instrument used to measure the curvature of the anterior corneal surface.
Keratitis
Inflammation or infection of the cornea that may threaten vision if untreated.
Keratoconjunctivitis Sicca
The medical term for dry eye disease caused by inadequate tear production.
Keratoconus
A progressive condition in which the cornea becomes thin and cone-shaped, leading to distorted vision.
Keratometer
An instrument used to measure the curvature of the cornea.
Keratoplasty
Corneal transplantation surgery used to replace diseased or damaged corneal tissue.
Keratotomy
A surgical incision made in the cornea, historically used to correct refractive errors.
Keratocyte
A specialized cell located within the corneal stroma responsible for maintaining corneal structure.
Lacrimal Gland
The gland responsible for producing the watery portion of tears.
Lacrimal Sac
A structure within the tear drainage system that collects tears before they drain into the nose.
Lagophthalmos
Incomplete closure of the eyelids, often leading to exposure-related dry eye.
Laser Peripheral Iridotomy (LPI)
A laser procedure used to prevent or treat angle-closure glaucoma.
LASIK
Laser-Assisted In Situ Keratomileusis, a refractive surgery used to correct nearsightedness, farsightedness, and astigmatism.
Lens
The clear natural structure behind the iris that helps focus light onto the retina.
Leukocoria
An abnormal white appearance of the pupil that may indicate serious eye disease such as retinoblastoma or congenital cataract.
Lid Hygiene
Cleaning of the eyelid margins to help manage blepharitis and meibomian gland dysfunction.
Low Vision
Permanent vision impairment that cannot be fully corrected with glasses, contact lenses, medication, or surgery.
Lutein
A carotenoid antioxidant concentrated in the macula that supports retinal health.
Macula
The central portion of the retina responsible for detailed central vision, reading, and recognizing faces.
Macular Degeneration
A disease affecting the macula that gradually reduces central vision, most commonly due to aging.
Macular Edema
Swelling of the macula caused by leakage of fluid from retinal blood vessels.
Macular Hole
A small opening in the macula that can cause blurred or distorted central vision.
Meibography
Imaging of the meibomian glands to evaluate their structure and function.
Meibomian Glands
Oil-producing glands located within the eyelids that help prevent tear evaporation.
Meibomian Gland Dysfunction (MGD)
A common condition in which the meibomian glands become blocked or function poorly, contributing to dry eye disease.
Microaneurysm
A tiny bulge in a retinal blood vessel that is often one of the earliest signs of diabetic retinopathy.
Miosis
Constriction (narrowing) of the pupil.
Mydriasis
Dilation (enlargement) of the pupil, either naturally or with dilating eye drops.
Myopia
Nearsightedness, a refractive error in which distant objects appear blurry while near objects remain clear.
Myopia Control
Treatments designed to slow the progression of childhood nearsightedness, including specialty contact lenses, atropine drops, and orthokeratology.
Nasolacrimal Duct
The drainage channel that carries tears from the lacrimal sac into the nose.
Near Point of Convergence (NPC)
The closest point at which both eyes can maintain single binocular vision.
Near Vision
The ability to focus clearly on objects that are close, such as books or smartphones.
Neovascular Glaucoma
A severe form of glaucoma caused by abnormal blood vessel growth blocking the eye’s drainage angle.
Neovascularization
The growth of abnormal new blood vessels, commonly seen in diabetic retinopathy and retinal vein occlusions.
Nerve Fiber Layer (RNFL)
The retinal nerve fiber layer contains optic nerve fibers and is commonly evaluated using OCT during glaucoma examinations.
Night Blindness (Nyctalopia)
Difficulty seeing in dim lighting or at night.
Nystagmus
Involuntary rhythmic eye movements that may reduce vision and affect balance.
Ocular Hypertension
Elevated intraocular pressure without evidence of optic nerve damage or glaucoma.
Ocular Migraine
A temporary visual disturbance that may include flashing lights, zigzag lines, or blind spots, often associated with migraine.
Ocular Surface Disease
A group of disorders affecting the cornea, conjunctiva, eyelids, and tear film.
OCT (Optical Coherence Tomography)
A non-invasive imaging test that produces detailed cross-sectional images of the retina and optic nerve.
Ophthalmologist
A medical doctor specializing in eye diseases, surgery, and comprehensive eye care.
Ophthalmoscope
An instrument used to examine the retina and optic nerve.
Optic Disc
The visible portion of the optic nerve inside the eye where nerve fibers leave the retina.
Optic Neuritis
Inflammation of the optic nerve that commonly causes pain with eye movement and sudden vision loss.
Optic Nerve
The nerve that carries visual information from the retina to the brain.
Optical Coherence Tomography Angiography (OCTA)
An advanced imaging technique that visualizes retinal and choroidal blood vessels without dye injection.
Optometrist
A healthcare professional specializing in eye examinations, vision correction, diagnosis, and management of many eye diseases.
Orthokeratology (Ortho-K)
Specially designed rigid contact lenses worn overnight to temporarily reshape the cornea and reduce myopia.
Pachymetry
Measurement of corneal thickness, commonly performed during glaucoma evaluations and refractive surgery assessments.
Papilledema
Swelling of the optic nerve caused by increased intracranial pressure.
Peripheral Vision
Vision outside the central line of sight, allowing awareness of objects to the side.
Perimetry
Testing used to measure the visual field and detect peripheral vision loss.
Phacoemulsification
The most common cataract surgery technique in which ultrasound breaks up the cloudy lens before removal.
Photophobia
Abnormal sensitivity to light.
Pinguecula
A yellowish growth on the conjunctiva usually caused by aging and ultraviolet light exposure.
Pinhole Test
A simple vision test used to determine whether blurred vision is likely caused by a refractive error.
Posterior Capsule Opacification (PCO)
Clouding of the lens capsule after cataract surgery, sometimes called a “secondary cataract.”
Posterior Chamber
The small space located behind the iris and in front of the natural lens.
Posterior Vitreous Detachment (PVD)
A common age-related separation of the vitreous gel from the retina that may cause flashes and floaters.
Presbyopia
An age-related loss of the eye’s ability to focus on near objects, usually becoming noticeable after age 40.
Prism
A special lens used to treat certain types of double vision and binocular vision disorders.
Proptosis
Forward displacement or bulging of the eye, commonly associated with thyroid eye disease or orbital disorders.
Ptosis
Drooping of the upper eyelid that may partially block vision.
Pupil
The black opening in the center of the iris that regulates the amount of light entering the eye.
Pupillary Distance (PD)
The distance between the centers of the pupils, used when fitting eyeglasses.
Quadrantanopia
Loss of one-quarter of the visual field, usually caused by neurological disease affecting the visual pathway.
Quality of Vision
A person’s overall visual experience, including clarity, contrast sensitivity, glare, color perception, and depth perception.
Quick Tear Break-Up Time (TBUT)
A clinical measurement used to evaluate tear film stability in patients with dry eye disease.
Radial Keratotomy (RK)
An older refractive surgical procedure that used corneal incisions to reduce myopia.
Reading Glasses
Glasses prescribed to improve near vision, commonly used for presbyopia.
Red Reflex
The reddish-orange reflection from the retina observed during eye examination. It is commonly used to screen for cataracts and childhood eye disease.
Refraction
The process of determining the eyeglass or contact lens prescription needed for clear vision.
Refractive Error
A vision problem caused by the eye not focusing light properly on the retina, including myopia, hyperopia, astigmatism, and presbyopia.
Refractive Surgery
Surgical procedures such as LASIK, PRK, and SMILE that reduce dependence on glasses or contact lenses.
Retina
The light-sensitive tissue lining the back of the eye that converts light into electrical signals sent to the brain.
Retinal Detachment
A sight-threatening condition in which the retina separates from the back of the eye. It requires urgent treatment.
Retinal Tear
A break in the retina that may lead to retinal detachment if left untreated.
Retinal Vein Occlusion (RVO)
A blockage of a retinal vein that may cause sudden painless vision loss.
Retinoblastoma
A rare childhood cancer of the retina that often presents with a white pupil (leukocoria).
Retinopathy
Any disease affecting the retina, including diabetic and hypertensive retinopathy.
Retinoscopy
An objective method of determining refractive error using a retinoscope.
Rhegmatogenous Retinal Detachment
The most common type of retinal detachment caused by a retinal tear.
Rigid Gas Permeable (RGP) Contact Lens
A durable contact lens that provides excellent vision and oxygen transmission.
Saccades
Rapid eye movements that allow the eyes to quickly shift focus from one object to another.
Saline Solution
A sterile saltwater solution used to rinse certain contact lenses. It is not intended for disinfecting lenses.
Schirmer Test
A test that measures tear production by placing a small strip of paper beneath the lower eyelid.
Sclera
The tough white outer layer of the eye that provides protection and structural support.
Scleritis
A painful inflammatory disease affecting the sclera that often requires prompt medical treatment.
Scotoma
An area of partial or complete vision loss within the visual field.
Secondary Cataract
A common term for posterior capsule opacification (PCO), which may develop after cataract surgery.
Slit Lamp
A specialized microscope used to examine the eyelids, cornea, iris, lens, and other structures of the eye.
SMILE
Small Incision Lenticule Extraction, a minimally invasive laser refractive surgery used to correct myopia and astigmatism.
Soft Contact Lens
A flexible contact lens made of water-containing materials that provide comfortable vision correction.
Spectacles
Another term for eyeglasses.
Stereoacuity
The ability to perceive fine depth differences using both eyes together.
Stereopsis
Three-dimensional depth perception created by binocular vision.
Strabismus
Misalignment of the eyes in which they do not point in the same direction.
Stroma
The thick middle layer of the cornea composed primarily of collagen fibers.
Subconjunctival Hemorrhage
A bright red patch on the white of the eye caused by a broken conjunctival blood vessel.
Superior Limbic Keratoconjunctivitis (SLK)
An inflammatory condition affecting the superior conjunctiva and cornea, often associated with thyroid eye disease.
Suppression
A neurological adaptation in which the brain ignores the image from one eye to prevent double vision.
Symblepharon
An adhesion between the eyelid and the eyeball, usually resulting from severe inflammation or injury.
Synoptophore
An instrument used to evaluate and treat binocular vision disorders and strabismus.
Tear Break-Up Time (TBUT)
A clinical test used to measure the stability of the tear film. Shorter tear break-up times often indicate dry eye disease.
Tear Film
The thin layer of tears covering the surface of the eye that keeps it lubricated, nourished, and protected.
Tear Meniscus
The thin strip of tears along the eyelid margin used to estimate tear volume.
Thyroid Eye Disease (TED)
An autoimmune disorder affecting the tissues around the eyes, commonly associated with Graves’ disease.
Tonometry
A test used to measure intraocular pressure (IOP), an important part of glaucoma evaluation.
Trabecular Meshwork
The drainage tissue located in the anterior chamber angle that allows aqueous humor to leave the eye.
Trabeculectomy
A surgical procedure performed to lower intraocular pressure in patients with glaucoma.
Trachoma
A chronic bacterial eye infection that is one of the leading infectious causes of blindness worldwide.
Trichiasis
A condition in which eyelashes grow toward the eye and rub against the cornea or conjunctiva.
Tropicamide
A commonly used dilating eye drop that temporarily enlarges the pupil during eye examinations.
Tunnel Vision
Loss of peripheral vision while central vision remains relatively preserved, commonly seen in advanced glaucoma.
Ultraviolet (UV) Light
Invisible rays from the sun that may contribute to cataracts, pterygium, and other eye conditions. UV-blocking sunglasses help protect the eyes.
Ulcerative Keratitis
A serious corneal infection or inflammation that causes an open sore (ulcer) on the cornea.
Uvea
The middle layer of the eye consisting of the iris, ciliary body, and choroid.
Uveitis
Inflammation of the uveal tract that may cause pain, redness, blurred vision, and light sensitivity.
Vergence
Coordinated eye movements that allow both eyes to maintain single binocular vision when focusing at different distances.
Visual Acuity
A measurement of the sharpness or clarity of vision, commonly assessed using an eye chart.
Visual Field
The entire area visible while looking straight ahead, including both central and peripheral vision.
Visual Field Test
A computerized examination used to detect peripheral vision loss caused by glaucoma, retinal disease, or neurological disorders.
Viral Conjunctivitis
A highly contagious infection of the conjunctiva, commonly caused by adenovirus.
Vitreous
The clear gel that fills the back portion of the eye between the lens and retina.
Vitreous Hemorrhage
Bleeding into the vitreous cavity that may cause sudden floaters or blurred vision.
Vitreomacular Traction (VMT)
A condition in which the vitreous pulls abnormally on the macula, causing distortion or blurred central vision.
Vitrectomy
A surgical procedure that removes the vitreous gel to treat retinal disorders, vitreous hemorrhage, or other eye diseases.
Wavefront Analysis
An advanced optical measurement used in refractive surgery and customized lens prescriptions.
Wet Age-Related Macular Degeneration (Wet AMD)
An advanced form of macular degeneration characterized by abnormal blood vessel growth beneath the retina.
White Cataract
A mature cataract in which the natural lens becomes completely opaque and white.
White-to-White (WTW)
The horizontal diameter of the visible cornea, commonly measured during refractive surgery and specialty contact lens fitting.
Xanthelasma
Yellow cholesterol deposits beneath the skin of the eyelids.
Xerophthalmia
Severe dryness of the eye caused by vitamin A deficiency.
YAG Laser Capsulotomy
A laser procedure used to treat posterior capsule opacification (secondary cataract) following cataract surgery.
Yellow Tint Lens
A spectacle lens designed to improve contrast in certain lighting conditions, although benefits vary among individuals.
Zeaxanthin
A carotenoid antioxidant concentrated in the macula that helps protect retinal cells from oxidative damage.
Zonules (Zonular Fibers)
Fine fibers that suspend the natural lens and allow it to change shape during accommodation.
Zoster Ophthalmicus
An eye condition caused by reactivation of the varicella-zoster virus (shingles) involving the ophthalmic branch of the trigeminal nerve.
Zygomatic Bone
The cheekbone that forms part of the orbit and helps protect the eye.
📚 Continue Learning
This glossary is designed to help you understand common eye care terminology. Many of these terms are discussed in greater detail throughout the Kardia Eye Resource Center. Continue exploring our educational resources to learn more about eye anatomy, diseases, diagnostic testing, treatments, contact lenses, eye drops, surgery, and preventive eye care.
Many eye conditions can be detected before symptoms develop. Routine comprehensive eye examinations remain one of the best ways to protect your vision and maintain lifelong eye health.
Medical Disclaimer
The information provided by Kardia Eye Resource Center is intended for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.
Medical terminology is provided to improve understanding of eye health and should not be used to diagnose or treat eye conditions without consultation with a qualified eye care professional.
If you experience sudden vision loss, severe eye pain, flashes of light, a curtain over your vision, chemical exposure, significant eye trauma, or any sudden change in vision, seek immediate evaluation by an eye care professional or visit your nearest emergency department.