Astigmatism

Astigmatism usually occurs when the front surface of the eye, the cornea, has an irregular curvature. Astigmatism usually occurs when the front surface of the eye, the cornea, has an irregular curvature. In astigmatism, the front surface of the cornea is curved more in one direction than in the other. This abnormality may result in vision that is much like looking into a distorted, wavy mirror. The distortion results because of an inability of the eye to focus light rays to a point.

Symptoms

Distortion or blurring of images at all distances Headache and fatigue

Squinting and eye discomfort or irritation

Astigmatism can be corrected by hard contact lenses or eyeglasses

Diagram of Astigmatism

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Short sightedness

The medical term for short-sightedness is referred to as myopia. It is a visual defect that results in the eye being too long from front to back, or from the cornea being too steeply curved. When light comes into the eye, it is focused onto the retina. A clear image is obtained if the light is properly focused on the retina. This is normal vision. Near sightedness can be corrected by eyeglasses with concave lenses.

Diagram of short sightedness

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Far sightedness

Hyperopia (farsightedness) is the condition of the eye where incoming rays of light reach the retina before they converge into a focused image.

Description

When light goes through transparent but dense material like the materials of the eye's lens system (the lens and cornea), its velocity decreases. If the surface of the dense material is not perpendicular to the incoming light, as is the case with the curved surfaces on lenses and corneas, the direction of the light changes. The greater the curvature of the lens system, the greater the change in the direction of the light.When parallel light rays from an object go through the lens system of the eye, they are bent so they converge at a point some distance behind the lens. With perfect vision this point of convergence, where the light rays are focused, is on the retina. Far sightedness can be corrected with eyeglasses with convex lenses.

Diagram of far sightedness

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Glaucoma

Definition - What is Glaucoma?Glaucoma is a group of eye diseases causing optic nerve damage. In glaucoma, eye pressure plays a role in damaging the delicate nerve fibers of the optic nerve. When a significant number of nerve fibers are damaged, blind spots develop in the field of vision. Once nerve damage and visual loss occur, it is permanent. If the entire nerve is destroyed, blindness results. Early detection and treatment by your ophthalmologist are the keys to preventing optic nerve damage and vision loss from glaucoma. Glaucoma can be treated by laser surgery or eye drops and prescription drugs.

Diagram of Glaucoma

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Cataract

DefinitionA cataract is a clouding of the eye's lens. Most cataracts are related to age. Most people do not even realize they have a cataract, because cataracts grow very slowly and may not impede vision early on. After a number of years vision will likely be affected. The lens can then no longer transmit a clear picture to the retina where it can be processed and sent through the optic nerve to the brain. Surgery is the only treatment. You should not consider surgery until the cataract is fully developed

Diagram of Cataract

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Ways to take care of your eyes

1. Avoid working at night and in artificially lighted rooms.

2. Always make sure your workplace is well lit.

3. People with eyeglasses should visit their optometrist regularly.

4. Eat a lot of fruits and vegetables.

5. When using the computer take little breaks every 15 minutes to give your eyes a rest.

6. Use safety goggles when doing things such as playing sports and welding

7. Make sure you get adequate rest.

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Four instruments to help you see are:

1. Eye glasses

2. Hard contact lenses

3. Magnifying glass

4. Intra ocular lenses

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