EYE PHYSIOLOGY

GROUP MEMBERS; Lama, arjome

Castro, Lourdes

Calion, Yvonne

Soriano, Amy

Tapay, Windy

*VISION

* Basic Anatomy

*the EyE is…

- very complex organ

- approximately 1 inch (2.54 cm) wide

-1 inch deep and 0.9 inches (2.3 cm) tall.

*Three different layers

*1. external layer

-formed by the sclera and cornea

*2. intermediate layer

-divided into two parts: anterior (iris and ciliary body) and posterior (choroid)

*3. internal layer /sensory part of the eye

-the retina

*Three chambers of fluid:

*1. Anterior chamber

-(between cornea and iris)

*2. Posterior chamber -(between iris, zonule fibers and lens)

*3. Vitreous chamber

-(between the lens and the retina).

*The first two chambers are filled with aqueous humor whereas the vitreous chamber is filled with a more viscous fluid, the vitreous humor.

* Aqueous Humour

The aqueous humour is a jelly-like substance located in the anterior chamber of the eye.

* Choroid

The choroid layer is located behind the retina and absorbs unused radiation.

* Ciliary Muscle

The ciliary muscle is a ring-shaped muscle attached to the iris. It is important because contraction and relaxation of the ciliary muscle controls the shape of the lens.

* Zonules

The zonules (or "zonule fibers") attach the lens to the ciliary muscles.*Different parts of the

eye

* Cornea

-a strong clear bulge located at the front of the eye.-has a radius of approximately 8mm.-contributes to the image-forming process by refracting light entering the eye.

* Fovea

The fovea is a small depression (approx. 1.5 mm in diameter) in the retina.This is the part of the retina in which high-resolution vision of fine detail is possible.

*Hyaloid

The hyaloid canal divides the aqueous humour from the vitreous humour.*Different parts of the

eye

*Optic Nerve

-second cranial nerve and is responsible for vision.Each nerve contains approx. one million fibres transmitting information from the rod and cone cells of the retina.

* Lens

-a flexible unit that consists of layers of tissue enclosed in a tough capsule.

* Papilla

* -"blind spot“

* Sclera

The sclera is a tough white sheath around the outside of the eye-ball.-"white of the eye". *Different parts of the

eye

* Pupil

-the aperture through which light the images we "see" and "perceive" - enters the eye.

-formed by iris

* Retina

-The retina contains photosensitive elements (called rods and cones) that convert the light they detect into nerve impulses that are then sent onto the brain along the optic nerve.

* Iris

-the coloured part of the eye.

* -function is to adjust the size of the pupil to regulate the amount of light admitted into the eye.

* Vitreous Humour*Different parts of the eye

* Macula: light-sensitive cells

*Extrinsic Muscle

Muscle Primary Function

Medial rectus moves eye towards nose

Lateral rectus moves eye away from nose

Superior rectus raises eye

Inferior rectus lowers eye

Superior oblique rotates eye

Inferior oblique rotates eye

*Intrinsic Muscle• iris sphincter

• Iris dilator muscles

• ciliarymuscle