Terms Related to the Eye

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.



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