What is it?
Your eyelid is a thin fold of skin, lined with a row of eyelashes. Each eye has an upper and lower eyelid, and they can be opened and closed by special muscles.

Eyelid

What does it do?
The eyelids are vital to keeping your eyes healthy. By completely covering the front of your eye, they are able to block debris or impurities that may otherwise cause damage or infection.

Just as importantly, your eyelids help to prevent the surface of your eyes from drying out. They do this by regularly spreading tears when blinking, keeping the cornea moist.

2. Sclera

What is it?
You might better know the sclera by its more common name – the “white of the eye”. As its nickname suggests, this is the white part of your eye that surrounds the iris.

Sclera

What does it do?
The sclera helps to support and protect the structure of your eye. It’s made up of tough tissue, which ensures your eyeball keeps its shape.

Thanks to the sclera’s hardiness, the eyeball is less susceptible to injury than if it were surrounded by a softer tissue. It also provides support to the inside of your eye, by providing a surface for some of the ocular muscles to attach to.

3. Tear Duct

What is it?
The nasolacrimal duct is known to you and me as the tear duct. It’s the area found in the corner of your eyes, closest to the nose.

Tear duct

What does it do?
Your tear ducts carry excess tears away from the surface of your eyes. These tears are carried through to an area inside your nose called the nasolacrimal duct.

This explains why when you’re crying or suffering from watery eyes due to an allergy, you can sometimes taste the salt from your tears in your mouth. It’s also the reason why you might find your nose goes runny from crying.

4. Lacrimal Gland

What is it?
The lacrimal glands are shaped a bit like an almonds, found in the upper part of your eye sockets. You’ve got two lacrimal glands, one located just above each eye.

Lacrimal gland

What does it do?
The basic function of your lacrimal glands is to produce tears. The secreted tears are collected on the conjunctiva of your upper eyelid.

Tears help to nourish and moisten your cornea (the outer layer of your eye’s surface). They also keep your eye clean, and lubricate it to avoid irritation.

5. Conjunctiva

What is it?
The conjunctiva makes up the lining inside your eyelids. It almost entirely covers your sclera, and is nourished by tiny blood vessels that are almost invisible to the naked eye.

Conjunctiva

What does it do?
The conjunctiva acts as a vessel for your tears to be spread over the surface of your eye. This is important for ensuring your eyes are properly lubricated.

Conjunctivitis, also known as pinkeye, is a common condition associated with the conjunctiva. It occurs when the conjunctiva becomes inflamed, usually due to some sort of infection.

6. Pupil

What is it?
The pupil is the small black hole found in the centre of your eye. It is surrounded by the colourful iris, and leads directly to the inside of your eye.

Pupil

What does it do?
The pupil acts as an entry point for light to enter your eye. Surrounding muscles in the iris, called the pupillae, adjust the pupil’s size automatically depending on light conditions.

In light conditions, your pupil will probably be around 3mm in diameter. In total darkness, this diameter can extend to over 6mm. This allows more light into your eye, allowing you to see more clearly in dimmer environments.

7. Iris

What is it?
The colourful ring found in the middle of your eye is called the iris. It’s made up of tiny pigment cells called melanin, which determine the colour of your eyes.

Iris

What does it do?
Your iris surrounds the pupil, and contains muscles that are able to alter its size. During light conditions, your iris causes the pupil to lessen in size. In darkness, the iris enlarges in order to allow more light to enter your eye.

The iris also acts as a wall that separates the anterior chamber (between cornea and iris) from the posterior chamber (between the iris and crystalline lens).

Inside Your Eye