The Human Eye
Schematic cross section of the human eye
Cornea
The eye is made of various delicate tissues which work harmoniously to give you good quality vision.
In front of the eye is the cornea which is the window of the eye.This tissue is powerful in determining the quality of your vision. An uneven cornea will result in an image that is skewed. The unevenness of the cornea is termed astigmatism.
A hazy cornea will result in an image that is also hazy, so corneal disease is affected by a dry cornea and is relieved by closing ones eyes for a little while. Keratoconus is one of such conditions that affect the shape of the cornea and ultimately the the quality of your vision. Keratoconus induces corneal astigmatism resulting in blurred vision.
The lens
The lens is another structure which funnels light towards the back of the eye to fine tune the image that you eventually perceive.
The lens becomes yellowy with age (a form of cataract), colours appear less bright and you may function better reading with more lighting available for example.
Vitreous
Is the jelly at the back of the eye, the function of which is not clear because it can be replaced with a salty solution after it has been removed during surgery. It is firmly attached to underlying retina in young eyes.
When it detaches completely or partially, it may result in floaters perceived and dark spots in your field of vision and a retinal detachment in patients who are at risk.
Sclera
Sclera gives the eye its white appearance. The outer layer is conjunctiva-commonly affected in pink eye or conjuctivitis. The layer between the conjunctiva and the sclera is called episclera all these layers can be inflamed or diseased.
Iris
The iris gives colour to the eye. It has a round aperture called the pupil.
Pupil
This aperture controlls the amount of light that enters your eye.If there is too much light the pupil becomes smaller .In the dark it becomes larger allowing more light into the eye sensiting your eye in dim lighting.
Retina
This is a light sensitive layer of the eye where images form. The most sensive area of the retina which affords you fine vision and gives you the ability to appreciate detail is the fovea.
Diseases that affect the fovea will create gaps/blanks in your vision like in a macula hole or wavy line in a macular pucker or epiretinal membranes.
Optic Nerve
This is like the main cable transmitting all your visual information to your brain. You see with your brain. Your brain interprets what you see and relates it to your experiences and what you already know. Simply put you can have a healthy eye but a brain injury that interferes with your eyesight.
The optic nerve may be affected by an optic neuritis, glaucoma and dysfunction due to traumatic injuries.
