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Astigmatism

 

Astigmatism at play - notice the blurry but ghosted image when uncorrected

Astigmatism is one of a family of eye disorders that result in the eye not correctly focussing the light from objects being viewed. The unfocussed images land directly on the retina, the light-receiving layer at the back of the eye, which in turn is perceived as blurry vision.

It’s not a disease of the eye since no part of the eye is destroyed in any way – it’s considered to be a disorder. It’s a disorder because the eye is acting somewhat abnormally, literally “out of order’, rather than being unhealthy.

Members of the eye disorder family are:

•    Farsightedness – medical name hyperopia – where the lens of the eye only focuses to a point that is behind the retina, resulting in blurred vision of near objects.

•    Nearsightedness – myopia – where the lens only focuses to a point in front of the retina, with blurred vision of distant objects, and finally

•    Astigmatism – it has no colloquial name – where this time the eye fails to focus both near and distant objects properly on to the retina, meaning both near and distant objects can appear blurred.

Astigmatism is not well understood, maybe because it has no common name to describe what its effects are, and is not as easily explained in medical terms either.

In astigmatism the cornea, refracts or bends the light from an object, in an irregular way.

Instead of the cornea being spherical like a tennis ball it takes a shape a bit like an egg, which has a tight curvature round its centre but a much longer, smoother curvature from end to end (a bit of an exaggeration in size terms but it illustrates the concept). Consequently the cornea in such a case focuses differently with respect to vertical lines and horizontal lines, with inherent blurred ghosted images.

Detecting astigmatism

It’s no simple matter to detect astigmatism, but it can be readily diagnosed once an optical professional such as an optometrist goes through their normal eye testing procedure.

Mild astigmatism can be thought of as similar in a way to mild colour blindness in that you probably don’t know you suffer from it until you are tested.

Virtually all people will have some form of astigmatism most of which is not relevant, whereas about one third of people that wear glasses will need astigmatism corrected to fully focus their vision.

Symptoms

Apart from blurred vision which may not be appreciated remember if not previously tested for, headaches and eye strain should lead hopefully to an appointment for a much needed eye test.

Treatment

Astigmatism, as with the other eye disorders, can be corrected using spectacles or contact lenses, but the prescriptions are generally more complicated to take account of the different curvatures of the cornea.  It is quite common for patients that have their astigmatism corrected for the first time in glasses to complain of clear but distorted vision.  This is a normal wearing in process that experience spectacle wearers are all too familiar with.

Typically three or four days will acclimatise the brain to accepting this new form of clear vision with no problems.  If after a few weeks you are still uncomfortable with your astigmatism correcting glasses it is probably worthwhile revisiting your optometrist to double check things.

The following Video will explain astigmatism far better than any written words.  The key is that if you think you have astigmatism contact us and we will either see you ourselves or recommend an optometrist, who will look after you with expert care.  Contact Us by <CLICKING HERE>

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About the Author

Dr Jim Kokkinakis (Optometrist) graduated in 1983 from the Optometry School University of NSW. He is currently a Senior Lecturer there and regular speaker to both Optometrists and Ophthalmologists in Australia and Internationally. He has a specialist clinical practice in the Sydney CBD with interests in Eye Strain, Computer Vision problems, Treatment of Eye Diseases and complex Contact lens Fittings.

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