Eye diseases can range from mild infections like conjunctivitis to severe conditions like glaucoma, affecting vision and overall eye health.
Visual System
Visual information is by far the richest and most important sensory information we receive about our world. With our eyes, we take in at a glance colour, form, texture, movement, direction, size, and location.
Layers of the Eye
The eye is approximately spherical in shape, with a diameter of about 24 mm, or 1 inch. It is composed of three concentric layers (also called coats) with different structures and functions.
Refraction
If the eyeball is elongated from front to rear, the lens does not need to be very curved to allow focusing of near objects, because the light rays will be able to travel further before they must converge on the retina.
Lacrimal System
Collectively, the anatomic structures responsible for the production, distribution, and drainage of tears are known as the lacrimal system.
Eyelids
An eyelid is a thin fold of skin that covers and protects the eye. The Levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision.
Colour Vision
Our ability to discriminate colour is due to the varying sensitivities of three types of cones. They are named blue, green and red for the colour they absorb most strongly.
Aqueous and Vitreous
The eye's anterior and posterior segments are filled with fluids, or humors, that play a vital role in maintaining ocular function. These fluids are called the aqueous humor and vitreous, respectively.