The Human Eye

STRUCTURE & PARTS OF THE EYES

The eye is an organ that allows you to see. The cornea, iris, pupil, and lens focus light rays from an object onto the retina to form an image. The retina then sends this image on to the brain.

The eye is made up of different parts. Each part performs a special function. An understanding of the different parts of the eye will help you take good care of your eye.

Parts of the Eyes             Functions

1. The eye brow               Prevents sweat from running down into the eyes.

2. The eye lashes             Protects the eyes from dust and dirt.

3. The eye lids                 They can close to protect the eye from foreign objects.
4. The eye balls   These are the organs of sight, It is connected to the brain by the sensory nerve called optical nerve.      
5. Cornea  A protective layer. It keeps dust and dirt from passing through the pupil of the eye.
6. The Iris           It is the coloured part of the eyes. It surrounds the pupil. It can increases or decreases the size of the pupil.
7. The Pupil          the hole in front of the eye ball through which light rays pass into the eye.
8. The lens           a glass – like part of the eye. It focuses the light rays into one spot on the retina thus forming the image.
9. The Retina       A light sensitive spot where image is formed.
10. Aqueous humour           both keeps the eye ball round.
11. Vitreous humour           they enable the eye to maintain its shape.
12. Tear gland                   Pours out tear over the front of the eye. The tear washes away any dust which enters the eyes.

CARE OF THE EYES

1. Use good light when reading or doing any fine work such as sewing. Poor light strains the eyes.
2. Do not rub the eye when you have something in it.
3. Do not wash your eyes with disinfectant unless on doctor’s advice.
4. Do not borrow another person’s face towel for wiping your eyes.
5. Do not watch television in a completely dark room.
6. Do not sit too close to the television screen.
7. Eat food rich in vitamin A such as carrot, Green vegetables and red palm oil.
8. If you have to wear glasses, do so according to the opticians’ instruction and keep it clean always.

LACK OF PROPER CARE FOR THE EYES CAN LEAD TO

1. Straining on the eyes.
2. Eye Infection
3. Poor sight( long or short sightedness or blindness)
4. Need to wear glasses
5. In serious cases, major injury to the eyes could result in blindness

EVALUATION

1. State two ways by which we can care for our eyes
2. State the functions of the following:
3. The retina
4. The lens
5. The iris

COMMON EYE DEFECTS

1. Long Sightedness (Hypermyopia): Results in an inability to see objects that are too near.    But objects that are far can be seen.
2. Short Sightedness (Myopia): Results in inability to see objects that are far away. But objects that are near can be seen.
3. Night Blindness: Result in inability to see in the dark.

REMOVAL OF FOREIGN OBJECTS FROM THE EYES

Foreign objects such as flying insects, soap, dirt, etc. get into the eyes. Do not rub or scratch the eyes. Get a clean bowl of cold water and deep your eyes into the bowl and blink the eyes at intervals. If the object remains there, see the doctor.

GENERAL EVALUATION

1. State three eye defects
2. Mention two hair infections
3. State two ways we can care for the hair
4. Mention five career opportunities in Home economics
5. List five parts of the eyes

WEEKEND ASSIGNMENT

1. _____ is a light sensitive part of the eye where images are formed (a) Retina (b) Pupil (c) Aqueous humous (d) Tear gland (e) Lens.
2. ______ part of the eyes has the ability to increase or decrease the size of the pupil (a) Lens (b) Retina (c) Pupil (d) Iris.
3. The ability to see distant objects alone is called______ (a) River blindness (b) Night blindness (c) Short sightedness (d) Long sightedness.
4. Carrot, Green vegetables and Red palm oil are sources of (a) Vitamin K (b) Vitamin A (c) Vitamin E (d) Vitamin D.
5. The eyes is a sense organ for (a) taste (b) talking (c) sight (d) feeling

THEORY

1. State three common eye defects and explain one of them.
2. State two parts of the eyes and their functions.

READING ASSIGNMENT

Read on: “The structure, functions, parts and care of the eyes” from Home Economics for Junior Secondary Schools, by Elizabeth U. Anyakoha, Page 16-18.