How Refractive Error Causes Blurry Vision
Many of our patients require a vision correction in the form of glasses or contact lenses in order to see clearly. The terms nearsighted, farsighted, and astigmatism are terms used to describe refractive error. Nearsightedness is another term for Myopia. It means a patient will have the ability to see clearly at a close distance, i.e. reading a book, looking at a smart phone, but will see blurry far away. These prescriptions are written as a negative value. On paper, it would look something like this: -2.00sph.
Farsightedness is another term for Hyperopia. This is not as straight forward as Myopia since patients with hyperopia often have some difficulty seeing both far and near. However, hyperopic patients find it easier to see clearly at far distances than up close. These prescriptions are written as a positive value. On paper, it would look something like this: +3.00sph.
Astigmatism refers to an imperfection in the curvature of the eye which causes distortion in vision. The shape of the eye is not always perfectly round like a basketball. Sometimes the eyeball has an oval shape, more like a football. Astigmatism is a more common than people realize. It usually causes blurred vision for both far away and up close. A prescription for astigmatism requires three values. On paper, it would look something like this: -0.50-0.75×180.
What can be done about Astigmatism?
Regular astigmatism is corrected with glasses and even soft contact lenses. Many more soft contact lens options are available today than ever before. There are even daily disposable contact lenses for astigmatism. In rare conditions, astigmatism is considered irregular because it is caused by a disorder of the cornea. In these cases, the astigmatism may progress much quicker than regular astigmatism. Patients with irregular astigmatism will not see clearly in glasses or soft contact lenses. These patients require specialty hard contact lenses for clear vision.
How can I find out if I have Astigmatism?
At your annual exam, the optometrist will perform a refraction to determine whether you require glasses to see clearly. The doctor will also be able to tell you if you have astigmatism or not. If needed, a special test called topography can be done to provide a map of the corneal curvature. You will also be able to discuss whether contact lenses or LASIK is an option for you. Astigmatism that is left untreated, especially in children, can lead to vision problems which may inhibit a child’s ability to learn and participate in extracurricular activities. It is important to have your eyes evaluated once a year by your local eye doctor. Schedule an Eye Exam today.
Meghan Schiffer, OD