Adie's Pupil - a pupil that does not react normally to bright light due to impaired nerve function; usually does not interfere substantially with vision

Amaurosis Fugax - temporary loss of vision in one eye; may be a sign of a transient ischemic attack (TIA) or an impending stroke

Amblyopia - the inability of an eye to see normally due to lack of input from the eye to the brain during childhood; also termed"lazy eye"

Aphakia - the absence of the eye's natural lens, usually after cataract surgery

Arcus Senilis - a hazy ring at the edge of the cornea where the iris meets the white of the eye; does not impair vision

Bell's Palsy - paralysis of the muscles on one side of the face due to nerve damage; usually temporary, but can interfere with blinking and protection of the eye

Blepharitis - inflammation of the eyelid; can cause irritation, discharge and even blurred vision

Chalazion - a bump in the eyelid caused by a clogged oil gland; may require surgical removal

Conjunctivitis - inflammation or infection of the conjunctiva, the mucous membrane covering the white of the eye

Corneal Edema - swelling of the cornea, often causing blurred vision

Corneal Erosion - spontaneous loss of a part of the surface"skin" of the eye-causes pain, light sensitivity and occasionally blurriness, and often occurs on awakening

Corneal Ulcer - a localized inflammation or infection of the cornea extending beneath the surface layer-must be treated immediately to prevent permanent damage

Central Retinal Artery Occlusion - blockage of the main blood supply to the eye often; causes blindness

Central Retinal Vein Occlusion - blockage of the main vein transporting blood away from the retina; causes hemorrhage in the retina and usually results in permanent vision impairment

Central Serous Retinopathy - spontaneous leakage of fluid into the retina, often in young, healthy people - cause is unknown

Dacryocystitis - infection in the tear sac adjacent to the nose-causes pain, swelling, tenderness and tearing

Dermatochalasis - excess or baggy skin on the eyelids, usually from loss of elastic tissue in the skin

Diplopia - double vision; usually caused by misaligned eyes

Drusen - discolored spots in the retina - can be an early sign of macular degeneration

Ectropion - loosening of the eyelid causing it to turn outward, away from the eye

Entropion -"collapsing" of the eyelid, causing the edge of the lid to turn inward, toward the eye-often results in discomfort due to eyelashes rubbing against the eye

Epiretinal Membrane - wrinkling of the surface of the retina; can cause blurriness or distortion in vision - severe cases can be treated with surgical removal

Esotropia - having an eye that turns inward

Exophthalmos - bulging forward of the eyes, sometimes caused by thyroid problems

Exotropia - having an eye that turns outward

Fuchs' Dystrophy - a deterioration of the cells in the cornea that maintain the cornea's clarity; often has no visual effect but may require a corneal transplant if severe

Hemianopia - the loss of one half of the visual field (left or right); usually affects both eyes and is often caused by brain injury, especially stroke

Hyphema - bleeding inside the eye, often due to an injury

Herpes Simplex - a cause of serious corneal infection - the same virus that causes cold sores

Herpes Zoster -"shingles" - the same virus that causes chicken pox, which can return and affect many areas of the body, including the eye

Iritis - inflammation inside the eye, primarily in the front of the eye - causes redness, pain, blurred vision and sensitivity to light in most cases

Keratitis - inflammation in the cornea-may cause scratchiness, pain, blurred vision and light sensitivity

Keratoconus - a progressive change in the shape of the cornea, creating a"cone" - like configuration and causing blurred vision - severe cases may require a corneal transplant

Macular Oedema - swelling in the centre of the retina caused by fluid leakage; results in blurred vision and visual distortion

Neovascularization - growth of new abnormal blood vessels - can occur at several locations in the eye

Nystagmus - oscillating movements of the eye

Ocular Migraine - a visual disturbance usually including an arc of zigzag light and blurry vision - disappears spontaneously and does not usually include a headache

Optic Neuritis - inflammation of the optic nerve, resulting in blurred vision or other visual disturbances - can be caused by multiple sclerosis

Papilledema - swelling of the optic nerve where it enters the eye - can be caused by increased fluid pressure around the brain

Pinguecula - a thickening of the white of the eye; often caused by chronic irritation

Pterygium - growth of tissue from the white of the eye over the cornea - may interfere with vision if it nears the centre of the cornea

Ptosis - droopiness of the eyelid - may result from nerve or muscle damage, and sometimes requires surgical correction

Retinal Detachment - separation of the retina from its normal location covering the inner surface of the back portion of the eye

Rubeosis - growth of abnormal blood vessels on the iris

Scotoma - a blind spot

Strabismus (Squint)- any misalignment of the eye

Stye - an acute inflammation of a gland at the base of an eyelash, caused by bacterial infection.

Trichiasis - abnormal eyelash growth, usually pointing toward the eye

Uveitis - inflammation of the interior of the eye

Vitreous Detachment - separation of the vitreous gel from the back of the eye - a common occurrence which can result in sudden floaters and occasionally causes a tear in the retina