Saturday, February 28, 2009

Lesson for the day

I do not have any new pictures to put up just yet, so I thought I would give you all a lesson on eyes. Today's topic is ASTIGMATISM :) First off, many people thing it is called, a 'stigmatism', but it is all one word, astigmatism.

Astigmatism is a vision condition that causes blurred vision due either to the irregular shape of the cornea, the clear front cover of the eye, or sometimes the curvature of the lens inside the eye. An irregular shaped cornea or lens prevents light from focusing properly on the retina, the light sensitive surface at the back of the eye. As a result, vision becomes blurred at any distance. Astigmatism is a very common vision condition, it occurs in about 70% of the population. Most people have some degree of astigmatism. Slight amounts of astigmatism usually don't affect vision and don't require treatment. However, larger amounts cause distorted or blurred vision, eye discomfort and headaches.

Astigmatism frequently occurs with other vision conditions like nearsightedness (myopia) and farsightedness (hyperopia). Together these vision conditions are referred to as refractive errors because they affect how the eyes bend or "refract" light.

The specific cause of astigmatism is unknown. It can be hereditary and is usually present from birth. It can change as a child grows and may decrease or worsen over time.

A comprehensive optometric examination will include testing for astigmatism. Depending on the amount present, your optometrist can provide eyeglasses or contact lenses that correct the astigmatism by altering the way light enters your eyes.

Most astigmatic corneas have two curves – a steeper curve and a flatter curve, as seen in the picture above. This causes light to focus on more than one point in the eye, resulting in blurred vision at distance or near.
The picture here is of how the light should look like falling on to the retina creating clear vision.
Hope this taught you something! Have a great weekend.

1 comment:

Laura said...

Thanks for the eye lesson!! Very informative :) Happy to say I learned something this weekend.

Can't wait to see you in a bit for Norah Kate's party!