Adie’s Pupil: A pupil that fails to react to the bright light normally due to impaired function of the nerve. There is no substantial interference to vision.

Amaurosis Fugax: Temporary blindness in one eye that may result from a Transient Ischemic Attack (TIA) or an impending stroke.

Amblyopia: Also known as lazy eye; a visual impairment due to the lack of inputs from the eye to the brain during childhood.

Amsler Grid: Square grid with a dot at the centre used to diagnose Macular Degeneration (MD)

Aphakia: Condition where the natural lens of the eye is missing, usually resulting from cataract extraction surgery.

Arcus Senilis: Grey or white ring that forms in the periphery of the cornea. There is no substantial interference to vision.

Astigmatism: Impaired vision due to irregular shape of the cornea.

Aqueous humour: Clear gelatinous fluid present between the cornea and lens, and maintains the pressure inside the eye

Bell’s Palsy: Condition which causes temporary paralysis of certain muscles on one side of the face, which can prevent blinking of the eye on the affected side.

Blepharitis: Inflammation of the eyelids causing red and itchy eyelids and formation of dry crusts on the eyelashes.

Cataract: Clouding of the natural lens of the eye that affects vision

Chalazion: Small cyst in the eyelid caused by blocked oil glands.

Choroid: Region between the sclera (white of the eye) and the retina that consists of the blood vessels and connective tissues

Ciliary body: Tissue that produce aqueous humour.

Ciliary muscle: Helps change the shape of the lens for focusing the image.

Conjunctiva: Thin transparent membrane that coats the inner surface of the eyelid and the white part of the eyeball (the sclera)

Conjunctivitis: Infection or inflammation of the conjunctiva.

Cornea: Dome-shaped clear membrane that covers the outer surface of the eye.

Corneal Oedema: Fluid collection in the cornea, often causing impairment of vision.

Corneal Erosion: Spontaneous loss of the outermost layer (epithelium) of the cornea which can cause sensitivity to light and blurring of vision

Corneal Ulcer: Open sore in the outer layer of the cornea often caused by infection.

Central Retinal Artery Occlusion: Blockage of the main artery supplying blood to the retina.

Central Retinal Vein Occlusion: Blockage of the main vein in the retina.

Central Serous Retinopathy: Vision abnormality caused by build-up of fluid under the retina.

Cyclophotocoagulation: Procedure used to destroy the ciliary body, the part of the eye that produces fluid

Dacryocystitis: Inflammation of the tear sac (nasolacrimal sac) adjacent to the nose.

Dermatochalasis: Excess skin on the eyelids, usually from loss of elastic tissue in the skin; also known as baggy eyes

Diplopia: Double vision

Drusen: Yellow deposits under the retina; increases the risk of age-related macular degeneration

Ectropion: Age-related abnormal outward turning of an eyelid.

Entropion: Abnormal inward turning of an eyelid causing redness and irritation.

Epiretinal membrane: Abnormal growth of thin transparent tissue on the surface of the macular area; also called macular pucker.

Esotropia: Condition where one or both eyes are turned inwards.

Exophthalmos: Extrusion of eyeballs from their sockets.

Exotropia: Condition where the eyes are turned outwards.

Fluorescein angiography: Test that uses a special dye and camera to observe the flow of blood in the retina and choroid.

Fuchs’ dystrophy: Progressing disease characterised by the death of cells lining the cornea and maintaining its transparency.

Glaucoma: Damaged optic nerve caused by increased fluid pressure inside the eyes.

Hemianopia: Loss of vision in half of the visual field (in one or both eyes); often caused by brain injury or stroke.

Hyphema: Pooling of blood in the anterior chamber of the eye.

Intraocular pressure: Fluid pressure inside the eye.

Iris: Coloured part of the eye located between the cornea and lens which is responsible for the amount of light that reaches the retina.

Iridotomy: Procedure which involves making a puncture through the iris.

Iritis: Inflammation of the iris.

Keratitis: Inflammation of the cornea.

Keratectomy: Removal of a portion of the cornea.

Keratoconus: Condition, in which the cornea takes a cone-like shape.

Keratomileusis: Procedure that corrects the curvature of the cornea.

Lens: Transparent flexible disc that helps focus light on the retina.

Long-sightedness: Condition which affects a person’s ability to see objects close to them; also known as hyperopia.

Macula: Yellow central portion of the retina responsible for central high-resolution vision.

Macular edema: Fluid and protein deposition on or under the macula.

Metamorphopsia: Vision impairment, in which grid of straight lines seems wavy and parts of the grid may seem blank.

Micropsia: Vision impairment in which objects appear to be smaller than normal.

Neovascularization: Growth of small abnormal leaky blood vessels in the eye.

Nystagmus: Fast movement of the eyeballs either up and down, side to side or around.

Ocular migraine: Vision loss usually lasting less than an hour; often accompanied by or following a migraine headache.

Optic disc: Circular area behind the eye where the optic nerve connects to the retina.

Optic nerve: Nerve that connects the eye to the brain and passes on the information of the image to the brain.

Optic neuritis: Inflammation of the optic nerve resulting in visual disturbances.

Optical coherence tomography: Non-invasive imaging test that takes cross-sectional images of the retina.

Papilledema: Swelling of the optic disc due to elevated fluid pressure in the brain.

Photodynamic therapy: Treatment for wet age-related macular degeneration (wet AMD)

Pinguecula: Noncancerous growth of the conjunctiva, which is slightly raised from the surface of the sclera.

Presbyopia: Age-related condition where the eye’s lens loses its ability to change shape and focus on nearby objects.

Pterygium: Noncancerous growth that starts at the conjunctiva, covers the sclera, and grows onto the cornea; also known as Surfer’s eye

Ptosis: Drooping of the eyelids caused by muscle weakness.

Retina: Light-sensitive layer at the back of the eye.

Retinopathy: Disease caused by damage of blood vessels of the retina.

Retinal detachment: Pulling away of the retina from its supportive tissue.

Rubeosis iridis: Growth of new abnormal blood vessels on the surface of the iris.

Sclera: White of the eye.

Scotoma: Area of diminished vision within the visual field.

Short–sightedness: Condition which affects a person’s ability to see distant objects, while close objects can be seen clearly; also known as myopia.

Strabismus: Abnormal alignment of the eye.

Stye: Small painful lump (collection of pus) at the base of the eyelashes usually caused by bacteria.

Trichiasis: Abnormal inward growth of eyelash.

Uvea: Middle layer of the eye beneath the sclera, and consists of the iris, ciliary body, and choroid.

Uveitis: Inflammation of the uvea.

Vitreous humour: Clear gel-like material that lies between the lens and the retina.

Vitrectomy: Surgical removal of vitreous humour from the eye.

Vitreous detachment: Separation of vitreous humour from the retina.