The A-Z Glossary

A

Accommodation – Adjustment of the lens to focus on near/far objects

Acuity (visual acuity) – Sharpness of vision

ALT – Argon laser trabeculoplasty, in which the argon laser is used to make several small holes in the aqueous drainage area to assist in reducing eye pressure

Amaurosis – Blindness

Amaurosis fugax – 'fleeting blindness', usually describing transient marked loss of vision in one eye

Amblyopia (lazy eye) – Vision in one eye has not developed properly

Angiography – A test where dye is injected into the bloodstream to highlight blood vessels

Angle – The zone in the recess of he front chamber where aqueous (see aqueous) drains

Anisocoria – Inequality of pupil size 

Anterior chamber – The front cavity between the cornea and lens/iris 

Anterior uveitis – Inflammation within the front chamber 

Aphakia – Absence of the lens, usually surgical 

Aqueous – Watery fluid filling the front chamber 

Aqueous humour – Fluid in the front of the eye maintaining eye pressure

Astigmatism – Irregular curvature of the eye causing distorted focus

Atrophy – Degeneration or wasting of tissue

Autosomal dominant – A trait that only needs inheritance of 1 copy of the gene to manifest. The gene is located in a non-sex chromosome.

Autosomal recessive – A trait that needs inheritance of both copies of the gene to manifest. The gene is located in a non-sex chromosome.

B

Benign – Non-cancerous tumor

Bilateral – Affecting both eyes

Biopsy – Removal of tissue for examination

Blindness - An inability to see or severe lack of vision.

Blood vessels – Channels that carry blood and oxygen around the body.

C

Cataracts – Cloudy eye lens.

Central vision – Vision from the macula used for detail

Choroid – Part of the middle layer of the eye that supplies blood to the retina

Cone cells – Photoreceptors responsible for colour vision

Cornea – Transparent front surface of the eye

Congenital – A condition you are born with.

Cortex (visual cortex) – Area of the brain that processes vision

Chromosomes – Condensed DNA formed during cell division.

Conjunctiva – A thin, clear membrane covering the inside of the eyelid.

Ciliary body - A part of the eye that allows the lens to change shape and focus.

D

Dilate (pupil dilation) – Widening of the pupil

Distortion – Altered or warped vision

DNA – The genetic information of a cell.

Dystrophy – Degeneration of tissue.

Diplopia (seeing double) – Seeing two images while looking at one object.

E

Edema (oedema) – Swelling caused by fluid buildup

Electroretinogram (ERG) – Test measuring retinal function

Electrooculogram (EOG) - Test measuring electrical potential of the eye.

Enucleation – Surgical removal of the eye

Endothelium – A layer of cells that line the inside of blood vessels.

Epithelium - A thin, continuous layer of cells.

Electrical signals – Nerve cells generate these to transmit information.

F

Field of vision (visual field) – Total area visible without moving eyes

Fibrosis – The formation of connective tissue in response to injury.

Floaters – Visible dots and/or lines in vision.

Fovea – A small pit in the retina that allows for sharp vision.

Fundus autofluorescence imaging (FAF) - A test that illuminates the retina to provide an image of it.

G

Genetic mutation – Change in DNA sequence

Globe – Eyeball structure

Genes – A section of DNA that codes for a protein.

Gene therapy – Altering the genes of a patient to treat a condition.

Genetic counselling – The process of helping people understand and adapt to a genetic condition.

Genetics – The study of genes and heredity.

Genetic testing – Analysis of own DNA, often to identify mutations.

H

Haemorrhage – Bleeding

Hereditary – Passed through genes

Hemianopia – Loss of sight from half of the visual field.

Hyperopia (farsightedness) – Trouble seeing close-up objects clearly.

Hypoplasia – The underdevelopment of tissue.

I

Inflammation – Immune response causing redness/swelling

Intraocular pressure (IOP) – Pressure inside the eye

Iris – The colored part of the eye that adjusts pupil size to let light in the eye.

Inherited – Traits passed from parent to offspring.

K

Keratocyte – Corneal cell

Keratoplasty – Corneal transplant surgery

L

Lens – Transparent structure focusing light

Lesion – Area of abnormal tissue

Laser therapy – A laser is used to reshape the cornea and correct short or farsightedness.

M

Macula – The centre of the retina responsible for central vision.

Magnetic resonance imaging – An imaging technique to used to visualize anatomy and physiological processes

Malignant – Cancerous tumors that grow uncontrollably.

Metastasis – The spread of a cancerous tumor to a different site of the body.

Mutation – Abnormal genetic alteration.

Mitochondria – The part of a cell where energy is produced.

Myopia – Nearsightedness.

N

Neovascularisation – Growth of new abnormal blood vessels.

Neurodegeneration – Progressive nerve damage.

Nystagmus - ‘Wobbling’ of the eyes.

O

Ophthalmology – Study of eye diseases.

Optic disc – Point where optic nerve exits the eye.

Optical coherence tomography (OCT) – Imaging scan of retina.

Opacity – The level of transparency.

Optic nerve - Nerve fibres that carry visual information to the brain.

P

Peripheral vision – Side vision.

Photophobia – Abnormal sensitivity or avoidance to light.

Photoreceptors – Light-detecting cells composed of rods and cones.

Pigment epithelium (RPE) – The layer of cells supporting the retina.

Prognosis – Likely outcome of a condition.

Ptosis – Drooping of the upper eyelid.

Pupil – The black hole in the center of the eye that can change size to let light in.

R

Refraction – Bending of light in the eye.

Retina – Layer at back of eye responsible for light detection.

Retinal pigment epithelium – A single layer of pigmented, hexagonal cells located just outside the light-sensitive sensory retina.  

Rod cells – Photoreceptors for low-light vision.

Retinal ganglion cells – Neurons in the retina that receive visual input and transmit it to the brain. .

S

Scar tissue – Fibrous tissue replacing damaged tissue.

Sclera – White outer layer of the eye.

Scotoma – A blind spot in vision.

Screening – Testing for disease before symptoms.

Stem cells – Unique cells that can divide indefinitely and ‘turn into’ a variety of cell types.

Strabismus (crossed eyes) – Eyes are misaligned and point in different directions.

Stroma – Cells or tissues that provide structural support to tissues and organs.

Synapse – The gap between nearby nerve cells that allows signal transmission between them.

Syndrome – A medical condition characterized by a common group of symptoms.

T

Therapy – Treatment

Tissue – Group of cells performing a function

Tumour – Abnormal growth of cells

Tunnel vision – Progressive narrowing of peripheral vision

Transplant – Moving cells or tissues from one site to another.

U

Ultrasound – Imaging using sound waves.

Uvea – Middle layer of the eye (composed of iris, ciliary body, choroid).

V

Vascular – Relating to blood vessels.

Vitreous humour – Gel filling the eye and providing nutrients to it.

Visual impairment – Reduced vision.

X

X linked inheritance – The gene responsible for the trait is located in an X chromosome. The trait is dominant in males and recessive in females.