Allergen - Any substance that causes an allergic response and the onset of symptoms of allergy.

Blepharitis - An inflammation of the eyelids caused by allergy or infection.

Blind Spot - Due to the fact that the optic disc simply carries blood vessels and nerves from the retina into the appropriate areas of the brain, there are actually no receptors here for vision. This is why we have a blind spot and this is on and the same as the optic disc.

Cones - One of two types of light sensitive cells. There are more rods in the eye than cones and they provide us with black and white images, enable us to see at lower illumination and also provide us with our peripheral vision. The cones tend to be positioned more in the centre of the retina and provide colour vision.

Conjunctiva –  A transparent film that lines the surface of the eye and inner side of the eyelids; contains most of the blood vessels that can be seen in somebody else’s eye. When an eye is irritated (such as due to an allergic or toxic reaction) or gets an infection, it is in fact the vessels in the conjunctiva that we can see dilating making the eye appear red.

             - Bulbar Conjunctiva – located under the eyelids.

             - Palpebral Conjunctiva – located underside of the eyelids.

Conjunctivitis - The general term for redness and inflammation of the eye.

Cornea – Located in front of the coloured iris. It is transparent and is one of the few structures in the body that has no blood supply. The cornea is the ‘window’ to the eye and cannot be seen from straight ahead. It is very sensitive having a complex system of nerves running through it. The cornea is where we place contact lenses and is very easily damaged.

Crystalline lens - Helps to focus images along with the cornea - providing one third of the eyes’ total power. It has the ability to change its shape and it is this ability - known as accommodation, that actually enables us to focus at different distances. The structure of the crystalline lens is something like an onion: it has layers which are added to it as we age. This layering of extra tissue on the crystalline lens makes it harden with age. It eventually leads to the condition we know as presbyopia.

Eyelids - have the function of protecting and lubricating the eye, wiping tears across the eye with every blink and, if something gets in the eye, producing excess tears to wash the foreign object away.

Iris – coloured part of the eye. It is a varying level of melanin that creates the variety of different eye colours seen in the population. The main function of the iris is to create the pupil. The iris works like the shutter on a camera, controlling the amount of light that enters the eye.

Histamine - An inflammatory substance produced by the body that is responsible for causing allergy symptoms. It is found widely in the body, and it is the increased release of histamine in response to an allergen that results in most of the characteristic symptoms of allergy.

Lacrimal glands – Responsible for the production of the aqueous component of tears.

Macula area (or fovea) - the most sensitive point on the retina where most of the cells are collected. The macula gives us our very sharp detailed central vision.

Meibomiam glands – Responsible for the secretion of lipids that form the outer part of the tear film and prevent evaporation of the aqueous layer

Melanin – brown pigmentation that creates the variety of different eye colours seen in the population.

Optic Disc - Simply carries blood vessels and nerves from the retina into the appropriate areas of the brain, there are actually no receptors here for vision. This is why we have a blind spot and this is on and the same as the optic disc.

Optic Nerve – Essentially takes the electrical and chemical messages from the retina into the brain.

Presbyopia – Eye condition where the eye struggles to focus clearly on near objects without the help of corrective lenses.

Punctum (Tear duct) – A small opening towards the inside corner of the lower eyelid which serves as a drain for tears. A similar, but smaller, opening is located on the upper lid. As the tear layer refreshes itself, the pumping action of the eyelids carries tears to the punctum where they eventually drain into the nose.

Pupil – the hole or gap in the middle of the iris.

Retina – located at the back of the eye, function similar to the film in a camera. Helps to create the image that we see. It has receptors that convert light into chemical and electrical signals that is then passed onto the brain.

Rods – One of two types of lights sensitive cells. There are more rods in the eye than cones and they provide us with black and white images, enable us to see at lower illumination and also provide us with our peripheral vision. The cones tend to be positioned more in the centre of the retina and provide colour vision.

Sclera - Referred to as the white of the eye; a very tough tissue which helps the eye keep its eyeball shape.

Stye - A red, painful and inflamed section of the eyelid caused by the infection of an eyelash hair follicle.

Superoxide - A form of oxygen that will react / attack susceptible targets such as lipids and proteins. A Superoxide scavenger is something that will mop up the superoxide so it is no longer available to attack other molecules.

Tear duct (Punctum) - A small opening towards the inside corner of the lower eyelid which serves as a drain for tears. A similar, but smaller, opening is located on the upper lid. As the tear layer refreshes itself, the pumping action of the eyelids carries tears to the punctum where they eventually drain into the nose.