Anatomy of the eye

The eyes are organs of vision that perceive light. Different kinds of light-sensitive organs have been found in different animals. The simplest eyes do nothing more than recognise whether the objects around them are dark or light, while the most sophisticated eyes can distinguish shapes and colours. The visual fields of some sophisticated eyes overlap allowing better depth perception (binocular vision), as in humans, and others are positioned to minimise overlap, as in rabbits and chameleons.

Anatomy of the eye

Forward Chamber
The cavity at the front of the eye, between the lens and the cornea, is called the anterior chamber. It is filled with aqueous humor, a water-like fluid. This fluid is produced by the ciliary body and is pumped back into the bloodstream through pores in the corner of the anterior chamber. The aqueous humor is recycled every 100 minutes.

The cavity at the front of the eye, between the lens and the cornea, is called the anterior chamber. It is filled with aqueous humor, a water-like fluid. This fluid is produced by the ciliary body and is pumped back into the bloodstream through pores in the corner of the anterior chamber. The aqueous humor is recycled every 100 minutes.

Front Chamber Corner
It is located at the junction of the cornea, iris and sclera. The angle of the anterior chamber extends 360 degrees to the perimeter of the iris. Pores allow the aqueous humor to drain into the bloodstream from the eye.

Radial Body
An anatomical structure located behind the iris (very difficult to see) that produces the aqueous humor that fills the front of the eye and thus maintains intraocular pressure. It also allows the lens to focus/adjust.

Conjunctivitis
A thin membrane, usually transparent, located on the sclera of the eye. The sclera is the white wall of the eye or the white part of the eye. The conjunctiva also coats the inside of the eyelids. Cells in the conjunctiva produce mucus, which helps lubricate the eye.

Cornea
The transparent, external «window» and main focusing element of the eye. The outer layer of the cornea, known as the epithelium. Its main purpose is to protect the eye. The epithelium is made of clear cells that have the ability to regenerate quickly. The inner layer of the cornea is also made of transparent tissue, which allows light to pass through.

Hyaloid Tube
A narrow channel that starts from the optic disc to the back surface of the lens. It provides an embryological function before birth but none afterwards and usually disappears.

Iris
Inside the anterior chamber is the iris. It is a part of the eye, which is responsible for the colour of each person's eyes. It works like the diaphragm of a camera, by dilating (mydriasis) and contracting (myesis) the pupil to allow more or less light into the eye.

Daughter
The dark hole in the centre of the coloured iris that controls the amount of light entering the eye. The colored iris works like the iris of a camera, opening and closing to control the amount of light entering through the pupil.

Flashlight
The part of the eye just behind the iris that creates the precise focus of light rays onto the retina. In people under 40, the lens is soft and flexible, allowing good focusing at different distances. In people over 40, the lens begins to become less flexible, making it more difficult to focus on objects close to the eye. This is called presbyopia.

Macular stain
The part of the retina that is the most sensitive and is responsible for central vision. It is located near the optic nerve, just inside the back of the eye. This area is also responsible for colour vision.

Optical Disc
The place at the back of the eye where the nerves, along with the artery and vein, enter the eye. This entry point corresponds to the «blind spot», as there are no cones or rods in this area. Normally, a person is not aware of this blind spot, as the rapid movements of the eye help the brain to receive impulses from other parts of the retina around the blind spot, which fill the «gap». The optic disc is the area that the ophthalmologist checks in glaucoma patients when the optic nerve begins to atrophy due to increased intraocular pressure. Under fluoroscopy, there is a wobble in the optic nerve area called an optic disc.

Optic Nerve
The optic nerve is the structure that takes information from the retina as electrical signals and transmits it to the brain, where this information is converted into a visual image. The optic nerve consists of a bundle of about one million nerve fibres.

Retina
The membrane at the back of the eye that contains the photoreceptors. The photoreceptors react to the presence and intensity of light, sending the stimulus to the brain via the optic nerve. In the brain, a multitude of nerve impulses are received by the photoreceptors in the retina and converted into an image.

Tough guy.
The white, hard wall of the eye. Few diseases affect this layer. It is covered by the epidermis (a fibrous layer between the conjunctiva and the sclera) and the conjunctiva. The oculomotor muscles are attached to it.

Hyaline Body
It is a jelly-like substance that fills the inside of the eye. Normally it is clear. Initially, it is firmly attached to the retina. Over the years, the vitreous becomes fluid and can detach from the retina. Often small masses or threads of vitreous create shadow symptoms called myopes (flies). Most of the time they are benign symptoms, but they can also become precursors of a retinal tear or retinal detachment and should be carefully checked by an ophthalmologist.