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Anatomy and Physiology

Overview of Anatomy and Physiology:

Eyes are the most complex organs and very precious which require complete care. Eyes work from wake up till you sleep, and collects all information into brain like colors, shapes, etc, eyes are connected to brain through optic nerve. Eye is designed in a way to gather information of the surroundings.

Eye section is divided into three segments:
1. Protective segment- orbit, lids and sclera
2. Anterior segment- aqueous humor, iris, cornea, crystalline lens and cilitary muscles.
3. Posterior segment- retina and vitreous humor.

The visual pathway to the brain are optic nerves.

Orbit or socket

It is situated in front of skull, has wider opening in front and narrowed near optic nerve.

Lid
(Upper and Lower lids)- It gives additional protection to eye.

Sclera

The outer thick protective layer, referred as white of the eye, contain white tissue which covers almost 95% of eye and maintain shape of the eye.
Cornea is the front portion of sclera, which is transparent and allows light to enter eye.
It has a powerful refracting surface.

Choroid

It is second layer of the eye, which lies between Sclera and retina. It also contains blood vessels that provide nourishment to the outer layer of the retina.

Lens

It is transparent, has biconvex structure. It is encased in thin transparent covering.
Lens function is to refract and focus incoming light onto the retina.

Retina

The innermost layer in the eye.
Images are converted into electric impulses that are sent to the brain through optic nerve.

Macula

It is located in the back of eye and in the center of retina.
It produces the sharpest vision.

Iris

It is the part of eye that give it color.It consist of muscular tissue that respond to surrounding light.

Pupil
It is present in the center of the iris, it becomes larger/smaller depends upon the brightness of light.

Vitreous Humor

The largest section inside eyeball, is filled with colorless gelatinous mass at the back of eye.

Aqueous Humor

The smallest section inside eyeball, is the clear, water-like material in front of eye.

Conjunctiva

It is the mucus membrane of the eye, begins at the edge of the cornea, inside surface of eyelid and sclera. It lubricate the eye

Photoreceptor of Retina-Rods and Cones

It is highly concentrated on fovea (area of retina which lack rods)

Rod cell

  1. It is made up of rod shaped cells.
  2. It is light sensitive.
  3. It does not distinguish color.

Cones cell

  1. It is made up of cone shaped cells.
  2. It is not as light sensitive as rods
  3. It distinguish color.

Physiology

Physiology of eye

The main function of eye is to collect light and turn it into electric signal. It is transferred to brain through optic nerve and brain turns it to visual image.

Light enters eye through object and passes primarily through cornea (acts like a camera lens). The intensity of light is adjusted by iris (act as camera diaphragm), accordingly pupil’s size is adjusted and further passes through lens behind vitreous humor, focus on macula (central area of retina) and change it into electric signal which is transmitted to visual cortex (in brain that controls sight) by optic nerve and gives visual image.