Definitions

Choroid
The vascular shell or tunic of the posterior segment of the eye, providing nutrition to the retina.

Ciliary Body
The vascular tissue where the aqueous fluid is produced.

Ciliary Muscles
The smooth muscles which attach the ciliary body to the lens via the zonular ligaments

Conjunctiva
A fine tissue which lines the inner surface of the eyelids, both surfaces of the third eyelid, and reflects onto the globe where it attaches at the limbus.

Cornea
The cornea is the clear tissue in front of the eye. It is the "window" of the eye. The cornea consists of a surface layer called the epithelium, the stroma which makes up most of the corneal tissue, a tough layer called Descemet's membrane, and the endothelium on the inner surface.

Gland of the Third Eyelid
A tear secreting gland located on the inner surface of the third eyelid. It is responsible for the production of approximately 30% of the aqueous portion of the tear film.

Iris
The iris is the coloured part of the eye. It consists of dilator and constrictor muscles and vascular tissue. The pupil is the opening in the centre of the iris, and is the diaphragm of the eye. When the pupil dilates, more light enters the eye.

Lens
The lens is the structure within the eye which allows the image to focus on the retina.

Lens Capsule
A fibrous covering of the lens.

Lids
The upper and lower eyelids provide protection for the eye, and the glands within the eyelid margin (meibomian glands) secrete an oily substance which helps stabilize the tear film.

Limbus
The limbus is where the cornea meets the sclera

Nictitans
Also called the third eyelid, the nictitating membrane helps protect the eye, helps spread the tear film over the cornea, and is involved in tear production.

Non-Tapetal Fundus
That part of the retina lacking a tapetal layer.

Optic Disk
The structure in the fundus where all the nerve fibres from the retina meet to form the optic nerve.

Optic Nerve
the main sensory nerve running from the eye to the brain.

Posterior Chamber
The space between the iris and the lens, filed with aqueous fluid.

Retina
The nervous tissue in the eye, upon which the image is cast, and converted to an bio-electrical signal. The rods and cones are involved in this biochemical transformation, and the generated signal travels via the ganglion cells, and the nerve fibre layer to the optic nerve and onto the visual centers in the brain.

Sclera
The fibrous shell or tunic of the eye.

Tapetal Fundus
That part of the retina bearing a tapetum, a mirror like structure just behind the retina which acts as a light amplifier.

Vitreous
A jelly like material which fills the posterior segment of the eye.

Zonular Ligaments
The ligaments connecting the ciliary muscle to the perimeter of the lens, stabilizing the position of the lens.