SENSORY SYSTEM IN THE EYES

By: Afida Zahara Adzkiya (03)Alifah Farah Gusmaniar (05)

Indah Puspita Aziz (15)Ridha Astri Indryana (24)

9.4

THE PARTS OF THE EYES

Part of Eye Protector • Eyebrow

= to hold sweat from the forehead that will flow to the eyeball.

• Eyelash= to hold and protect the eye from dust and filter very

striking sunlight.

• The Eyelid= to protect the eyeball from dust and excessive light.

• The Tear Gland= to keep the eyeball surface from drying, clean the

eyeball surface from dust, also destrong germs that enter into the eyes.

THE PARTS OF THE EYES

Retina (most inner layer)

Choroid (middle layer)

Sclera (outer layer)

next

Sclera• Sclera has white color, except the front part that is

transparant. The sclera is a strong layer.

• The function of sclera is:• Keep the shape of eyes (aquous humor = between cornea and eyelens,

vitrous humor = between eyelens and retina).• Protecting the part of in eyes.

• The front part of sclera is modified be a transparant part called cornea. The function is to going on the light that enter the eyes.

• Cornea is covered by transparant layer called conjunctiva.

Choroid• Choroid has blackish brown color until black. The function is

to prevent reflection of ray. Besides in this layer there are many blood vessels.

• The part of choroid:• Iris (rainbow layer), that determines eye color of somebody.• Pupil, that control the size of pupil that controls the entering light.• Eyelens, focussed the fall of light to the retina with accommodation

power.

• The function of choroid is:• Preventing light reflection that enter the eyeball.• Suply the required food and oxigen for retina.

Retina

• This layer contains receptor that is sensitive to light (yellow spot / fovea).

• Kinds of receptor cell:• Bacilus cell, is receptor cell that sensitive at the low

light (dark).• Conus cell, is receptor cell that sensitive at the high

light (terang), also has function to cathch the light. There are three kinds of conus cell: red cell, green cell, blue cell.

Seeing Procces

Object PupilEyelens

(accommodation power)

Oksipital (Cerebrum)

Nerve RetinaYellow spot

Disorders of disturbances in eyes

• Myopia is a condition which the eyes cannot see far object because the eyelens is very convex (too long).

• The myopic eyes can be helped by using concave (negative) lens glasses.

Myopia

• Hypermethropia is a condition which the eyes cannot see near object because the eyelens is too flat (too short) so the image of the object falls behind the yellow spot.

• The hypermethropic eyes can be helped using convex (positive) lens glasses.

Hypermethropia

• Presbyopia is disturbance that is commonly suffered by old people because the eyelens moving muscle loosen, so power accommodation decrease

• The presbyopia eyes can be helped using double lens glasses, they are concave (negative) lens in upper part and convex (positive) in the lower part.

Presbyopia

• Xerophtalmia is the drying of eye cornea membrane because of lack of vitamin A continously.

Xerophtalmia

Color blindness• Color blindness is disturbance in which the eyes

differentiate certain colors red, blue, and green. The colour blindness is a hereditary disease, cannot be cured, and commonly is inherited to a son.

• Astigmatism is disturbance in the eye, that cause sigh to blur because the corned is not flat.

• Astigmatism can be helped by using cylindrical lens glasses.

Astigmatism

Cataract

• Cataract is disturbance in the eye because the eyelens is dirty so it blocks the entering of light to retina.

• Commonly it attacks old people (55 years old above).

• Cataract can be overcame by operation

• Squint-eyed is disorder because of inharmonius work of the right and left eye muscles, so viewing direction of both eyeballs are not the same.

Squint-eyed