What is Astigmatism and how do we cure it?
Posted On 5 May 2021
Ocular astigmatism is a disorder in the eye due to which a person has blurred vision of the eye. Usually, ocular astigmatism occurs in the curvature of the eye. But this disorder or imperfection if the eye and vision are treatable. If the cornea or lens of the eye got mismatched curve then you may have ocular astigmatism. Like if an eyeball has curves like an egg instead of a circle, then the vision (distant or near) of the eye is affected badly. This disorder may be occurred by birth or at any age due to many reasons. This is not a disease; simply ocular astigmatism is a disorder that can be treated.
Causes of ocular astigmatism
The cornea and retina are two parts of the inner eye that reflect the light onto the retina so that vision occurs or an image of the object is produced. The cornea is present on the front side of the eye, while the lens is present inside the eye just behind the cornea, and can change its shape to focus on near or distant objects. In a normal eye, the shape of the eyeball is just like a smooth round ball, both the cornea and lens have curves in the same direction so that light could be focused sharply and directly on the retina which is present at the I’m back of the eye.
- Ocular astigmatism is a type of refractive error. If your eye got egg-like shape due to mismatched curves in either or both of cornea and lens then the light will not be able to be directed on the retina in a straight path, it will reflect on the retina in different ways through the cornea and lens, both having different shapes of curves. Now due to multiple paths of reflection of light, a single image will not be formed, there will be multiple images resulting in blur vision. Blur vision can occur in more than one direction i.e., vertical, horizontal, diagonal.
- If the corneal curve is mismatched, then the condition is called corneal ocular astigmatism.
- If the lens curve is mismatched, then the condition of called lenticular ocular astigmatism.
- When your eye gets longer than normal due to a deeper curve in the cornea, the light will be focused on the front of the retina, and ultimately distant objects will be seemed blurry. This condition of ocular astigmatism is called myopia or nearsightedness.
- When your eye gets smaller than normal due to a lesser curve in the cornea, the light will be focused on the back of the retina, and ultimately near objects will be seemed blurry. This condition of ocular astigmatism is called hyperopia or farsightedness.
- Some people get ocular astigmatism due to an injury, surgery, or, after any infection.
- Keratoconus is a condition in which the eye’s front gets thinner and cone-shaped due to which ocular astigmatism is caused.
Diagnosis of ocular astigmatism
Ocular astigmatism does not diagnose sooner, its symptoms appear slowly. You may get a complete check-up from your doctor if you feel any disturbance or changes in your vision. The doctor will check your eyesight by making you read an eye chart or by using different equipment like a phoropter, keratometer, topography, autorefractor, etc.
- If you have a slight eyesight problem then you may not need any proper treatment otherwise it could be treated through contact lenses or glasses to normalized the eyesight.
- If you have a problem with eyesight that is much disturbing for you then the doctor will go for corrective lenses, which means lenses or glasses. Sometimes doctors will prescribe you soft contact lenses, called toric lenses. They help in bending and focusing the light in one direction. If you have a severe case then the doctor will go for gas permeable lenses, for the procedure called orthokeratology.
- Refractive surgery is also a treatment for ocular astigmatism.
- Alpins method astigmatism is also used for its treatment.
Alpins method astigmatism
Alpins method astigmatism is a method to analyze astigmatism. This method is introduced by an Australian ophthalmologist Noel Alpins. If treatment fails to minimize the problem, then doctors may use the Alpins method astigmatism, in this method they use vectors and mathematical tools to correct the problem. This method is also used to sift surgical strategies or for beam settings. According to Alpins method astigmatism, three types of vectors are used to analyze the correctness of astigmatism:
- Target induced astigmatism vector (TIA)
- Surgically induced astigmatism vector
- Difference vector