Glossary

Adaptive immune system

The adaptive immune response is the second line of defence after the innate immune system and destroys invading foreign bodies (like bacteria and viruses). The adaptive immune response takes several days to weeks to develop.

Age-related macular degeneration (AMD)

AMD is a degenerative disease that affects the macula, the central region of the retina, causing progressive and irreversible loss of vision.

Amsler grid

The Amsler grid is a method used to screen for AMD and monitor vision changes. Patients fixate with one eye at a time on the small dot in the centre of the grid to determine if there is any impairment in their visual field.

Atrophy

Refers to when body tissue or organs become damaged, especially as a result of cell death.

Best-corrected visual acuity (BCVA)

BCVA is a measure of the best possible vision that an eye can achieve using glasses or contact lenses.

Choroid

The choroid supplies oxygen and nutrients to the outer layers of the retina and is the primary route by which waste is cleared from the retina.

Choroidal neovascularisation

This term describes the growth of abnormal new blood vessels that start in the choroid and grow into the retina. There, they leak fluid and blood into the retina, damaging retinal cells and causing vision to distort.

Complement system

The complement system (or complement cascade) is a part of the body’s natural immune system. It is one of the first lines of defence against invading pathogens, like bacteria and viruses. In one of the advanced forms of AMD, geographic atrophy, the complement system can become too active and end up damaging cells in the retina, which contributes to vision loss.

Cornea

The cornea is the transparent outer surface of the eye that covers the iris and pupil, and allows light to enter the eye.

Drusen

Drusen are small yellow deposits of fatty proteins (lipids) that build up under the retina. They are a key method to classify and grade the stage and severity of AMD.

Fovea

The fovea is the part at the centre of the macula. This is the area with the highest visual acuity in the eye.

Fundus

The fundus is the inside, back surface of the eye. It is made up of the retina, macula, optic disc, fovea and blood vessels.

Fundus examination

Fundus examinations are routinely carried out as part of an eye exam to assess the overall health of the retina as many features of AMD are visible by examination of the fundus.

Geographic atrophy (GA)

Geographic atrophy is a term used to describe an advanced form of AMD. It is called geographic atrophy because the areas of damage in the macula look like a map to the ophthalmologist.

Immune system

The immune system is a complex network of organs, cells and proteins that work together to protect the body.

Innate immune system

The innate immune system is the body’s first line of defence against pathogens entering the body.

Iris and pupil

The iris regulates the amount of light that is let into the eye by constricting or expanding the pupil.

Lens

The lens is a transparent structure that sits behind the iris and the pupil. Along with the cornea, the lens helps to refract light onto the retina.

Macula

The macula is a small, pigmented area at the centre of the retina that is responsible for central vision and colour perception.

Ophthalmoscopy

Ophthalmoscopy, or fundoscopy, is used to examine the fundus and is often carried out as part of a routine eye exam.

Optic nerve

The optic nerve consists of a bundle of nerve fibres that is responsible for transmitting visual information from the retina to the brain.

Optical coherence tomography (OCT)

OCT is a test that takes cross-sectional images of the retina and surrounding structures.

Photoreceptors

Photoreceptors are special light-sensitive cells that convert light into electric signals that can travel to the brain.

Retina

The retina is a thin layer of tissue at the back of the eye. The retina converts light to electrical signals that are sent to the brain and processed to create vision.

Retinal pigment epithelium (RPE)

The RPE is a single layer of cells in the outer layer of the retina. It plays an important role in the visual process.

Sclera

The sclera is the white layer of the eye that covers most of the outside of the eyeball. It is made up of collagen and elastin fibre, and protects against things entering the eye and infection, as well as providing structure for the eye.

Vitreous humour

The vitreous humour is a clear, colourless, gel-like substance that fills the space between the lens and the retina. It helps maintain the round shape of the eye.