Terms Related to the Eye

By:

 Dr. Najam Iqbal Choudhery

Senior Registrar  

Ophthalmology Dept.

KEMU & Mayo Hospital  

Accommodation: The adjustment of the eye for see­ing at different distances, accomplished by changing the shape of the lens through action of the ciliary muscle, thus focusing a clear image on the retina.

Albinism: A hereditary deficiency of pigment in the retinal pigment epithelium, iris, and choroid.

Amblyopia: Reduced visual acuity (uncorrectable with lenses) in the absence of detectable anatomic defect in the eye or visual pathways.

Aniridia: Congenital absence of the iris.

Anisocoria: Unequal pupillary size.

Anophthalmos: Absence of a true eyeball.

Anterior chamber: Space filled with aqueous bounded anteriorly by the cornea and posteriorly by the iris.

Aphakia: Absence of the crystalline lens.

Aqueous: Clear, watery fluid that fills the anterior and posterior chambers.

Astigmatism: Refractive error that prevents the light rays from coming to a point focus on the retina because of different degrees of refraction in the various meridians of the cornea or crystal­line lens.

Binocular vision: Ability of the eyes to focus on one object and then to fuse two images into one

Bitot's spots: Keratinization of the bulbar conjunctiva near the limbus, resulting in a raised spot—a feature of vitamin A deficiency.

Blepharitis: Inflammation of the eyelids (lid margin).

Blepharospasm: Involuntary spasm of the lids.

Blind spot: "Blank" area in the visual field, corre­sponding to the light rays that come to a focus on the optic nerve.

Blindness: In the USA, the usual definition of blind­ness is corrected visual acuity of 20/200 or less in the better eye, or a visual field of no more than 20 degrees in the better eye.

Buphthalmos: Large eyeball in infantile glaucoma.

Canaliculus: Small tear drainage tube in inner aspect of upper and lower lids leading from the puncta to the common canaliculus and then to the tear sac.

Canthus: The angle at either end of the eyelid aper­ture; specified as outer and inner.

Cataract: Opacity of the crystalline lens.

Chalazion: Chronic Granulomatous inflammation of a meibomian gland.

Coloboma: Congenital cleft due to the failure of some portion of the eye or ocular adnexa to complete growth.

Color blindness: Diminished ability to perceive differ­ences in color.

Dacryocystitis: Infection of the lacrimal sac.

Dacryocystorhinostomy: A procedure by which a com­munication is made between the nasolacrimal duct and the nasal cavity to relieve an obstruc­tion in the nasolacrimal duct, or sac.

Diplopia: Seeing one object as two.

Ectropion: Turning out of the eyelid margin.

Emmetropia: Absence of refractive error.

Endophthalmitis: Extensive intraocular infection sparing the outer coat of eye ball

Entropion: A turning inward of the eyelid margin.

Enucleation: Complete surgical removal of the eye­ball.

Epiphora: Tearing due to blockage of tear drainage passage.

Esotropia: A manifest inward deviation of the eyes.

Exenteration: Removal of the entire contents of the orbit, including the eyeball and lids.

Exophthalmos: Abnormal protrusion of the eyeball.

Exotropia: A manifest outward deviation of the eyes.

Evisceration: Removal of the contents of the eyeball.

Fornix: The junction of the palpebral and bulbar con­junctiva.

Glaucoma: Disease characterized by abnormally in­creased intraocular pressure, optic atrophy, and loss of visual field.

Hordeolum, external (sty): Infection of the glands of Moll or Zeis.(acute Staphylococcal infection)

Hordeolum, internal: Meibomian gland infection.(acute Staphylococcal infection)

Hyperopia, hypermetropia (farsightedness): A refrac­tive error in which the focus of light rays from a distant object is behind the retina provided accommodation is at rest.

Hyphema: Blood in the anterior chamber.

Hypopyon: Pus in the anterior chamber.

Hypotony: Abnormally soft eye from any cause.

Keratic precipitate (KP): Accumulation of inflamma­tory cells on the posterior cornea in uveitis.

Keratitis: Inflammation of the cornea. 

Leukoma: Dense corneal opacity due to any cause.

Limbus: Junction of the cornea and sclera.

Macula: Moderately dense corneal opacity due to any cause.

Myopia (nearsightedness): A refractive error in which the focus for light rays from a distant object is anterior to the retina provided accommodation is at rest.

Nebula: Slight corneal opacity due to any cause.

Nystagmus: An involuntary, rapid movement of the eyeball that may be horizontal, vertical, rota­tory, or mixed.

Orbital cellulitis: Inflammation of the tissues sur­rounding the eye.

Panophthalmitis: Inflammation of the entire eyeball.

Papilledema: Swelling of the optic disk due to raised intracranial pressure.

Papillitis: Optic nerve head ischemia or inflammation that is ophthalmoscopically visible.

Peripheral vision: Ability to perceive the presence, motion, or color of objects outside of the direct line of vision.

Phlyctenule: Localized lymphocytic infiltration of the conjunctiva.

Photophobia: Abnormal sensitivity to light.

Phthisis bulbi: Atrophy of the eyeball with blindness and decreased intraocular pressure, due to end-stage intraocular disease.

Poliosis: Depigmentation of the eyelashes.

Posteriorchamber: Space filled with aqueous anterior to the lens and posterior to the iris.

Presbyopia ("old sight"): Physiologically blurred near vision, commonly evident soon after age 40, due to reduction in the power of accommoda­tion.

Pseudophakia: Presence of an artificial intraocular lens implant following cataract extraction.

Pterygium: A triangular degenerative growth of conjunctiva that encroaches cornea.

Ptosis: Drooping of the upper eyelid.

Pupil: The round hole in the center of the iris that cor­responds to the lens aperture in a camera.

Sclera: "The white part of the eye--a tough covering that, with the cornea, forms the external protec­tive coat of the eye.

Scotoma: A blind or partially blind area in the visual field.

Staphyloma: A thinned part of the coat of the eye, causing protrusion of uveal tissue.

Strabismus (heterotropia, tropia): A manifest devia­tion of the eyes.( Squint ).

Sty: See Hordeolum, external.

Symblepharon: Adhesions between the bulbar and palpebral conjunctiva.

Synechia: Adhesion of the iris to cornea (anterior synechia) or lens (posterior synechia).

Tarsorrhaphy: A surgical procedure by which the upper and lower lid margins are united.

Trabeculectomy: The preferred first-line procedure for surgically creating an additional aqueous drainage channel in the treatment of glaucoma.

Trichiasis: Inversion and rubbing of previously normal eyelashes against the globe.

Uvea (uveal tract): The iris, ciliary body, and choroid.

Uveitis: Inflammation of one or all portions of the uveal tract.

Visual acuity: Measure of the acuteness of vision; the finest of detail that the eye can distinguish.

Vitiligo: Localized patchy decrease or absence of pig­ment on the skin.

Vitreous: Transparent, colorless mass of soft, gelati­nous material filling the eyeball behind the crystalline lens.

Zonule: The numerous fine tissue strands that stretch from the ciliary processes to the crystalline lens equator (360 degrees) and hold the lens in place.