The Eye

BYDr. Abdulazim Ghoraba

DINA ABDEL-AZIM GHAZY GHORABALECTURER OF MEDICAL SCIENCE

Structure of the Eye

External Structures1- The Orbit 2-The Muscles of the Eye 3-The Eyelids 4-The Conjunctiva 5-The Lacrimal Apparatus

Internal Structures1- The Eyeball2-Sclera3-Choroid 4-Ciliary body5-Iris6-Retina7-The lens

1- The Orbit Contains the eyeball. Cavity is lined with fatty tissue

that cushions the eyeball and has several openings (FORMINA) through which blood vessels and nerves pass.

2-The Muscles of the Eye: Six short muscles provide support

and rotary movement of the eyeball

3-The Eyelids Protect the eyeballs from intense light, foreign particles, and impact

4-The Conjunctiva Acts as a protective covering for the

exposed surface of the eyeball5-The Lacrimal Apparatus Produces, stores, and removes tears

that cleanse and lubricate the eye.

It consists of :

1. The Lacrimal Gland 2. The Lacrimal Canaliculi3. The Lacrimal Sac4. The Nosolacrimal Duct

6- The Eyeball: Organ of vision

The Outer Layer1-ScleraThe outer layer known as the "white" of

the eye consists of the cornea, which bends light rays and helps to focus them on the surface of the retina

2- CorneaAnterior transparent Portion of the

eye’s fibrous Outer surface

The Middle Layer:1-Iris

Colored membrane attached to the ciliary body. It has a circular opening in its center, the pupil, and two

muscles that contract to regulate the amount of light admitted by the pupil

2-Choroid Pigmented vascular membrane that prevents internal

reflection of light 3-Ciliary body

Smooth muscle forming a part of the ciliary body that governs the convexity of the lens. The ciliary body secretes nutrient fluids that nourish the cornea, the

lens, and surrounding tissues

The Inner Layer

1-Retina Contains photo receptive cells that

translate light wava focused on its surface into nerve impulses

7-The lens

Sharpens the focus of light on the

retina (accommodation)

Pathway of the light waves from the cornea of the eye to the cerebral cortex of the brain

Pathology Of The Eye 1- CataractAn Opacity of the crystalline lens or its

capsule Most often occurs in adult past middle age 2- Chalazion

A small hard Painless Cyst 3-Glucoma

A disease characterized by increased intraocular pressure which result in atrophy

of the optic nerve and blindness

Pathology Of The Eye 4- Macular Degeneration

Vision Errors

Astigmatism

HyperopiaHypermetropi

a

Myopia

Examination of the Eye

1- Ophthalmoscopy

2- Snellen Eye Chart

Individual with Normal vision can read line 8 of a full- sized chart at 20 feet (6.10 m)

Types of Eye Movements

YouTube - How Light Enters the Eye.url

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