Astigmatism

Definition Astigmatism is the defects in the curvature of the cornea. If the curvature of the cornea and lens is mismatched, this will allow the light inside eye in different angles. This condition leads eye discomfort, headaches and blurred or fuzzy vision. There are several types but three most common types are as follows: Myopic: The one or two principal medians are near sighted. Should both the meridians be near sighted, they are myopic in changing degree. Hyperopic: one or two principal medians are far sighted. Should both the meridians be farsighted, they are hyperopic in changing degree. Mixed: One principal meridian is near sighted and the other is farsighted. Risk factors It occurs in both children and adults. Risk may be higher if a person has any of the following: Family history of astigmatism and eye disorders such as keratoconus Thinning or cone shaped of your cornea Excessive near sightedness, which creates blurry vision at a distance Excessive farsightedness, which creates blurry close-up vision A history of eye surgery, such as cataract surgery (surgical removal of a clouded lens) Causes It is mainly caused by the irregular shape of the cornea, which is called corneal astigmatism. It might be from the birth or later in life due to injury, disease and surgery in the eye. The exact cause is unknown. In a few cases, it is caused by the shape of the lens inside the eye which is called lenticular astigmatism. Symptoms Symptoms include: Blurred or distorted vision Eyestrain or discomfort Headaches Difficulty with night vision Squinting Diagnosis and test Astigmatism is commonly diagnosed by comprehensive eye examination. This examination undergoes for measuring how the eyes focus light and it determines the power of the lenses required for better vision. The tests may include: Visual acuity test: This assessment text will be conducted by asking the patient to read the letter from the chart at a particular distance to examine how well patient can see the letters. Keratometry: It is the instrument used to measure the curvature of the cornea by focusing the light on the cornea and it calculates the reflection of the light. From the results of reflection, it is possible to determine the curvature of the cornea surface. These measurements are used to determine the proper fit for the contact lenses. Refraction: For refraction test the instrument called refractor is used. This machine contains multiple corrective glass lenses of different strengths. To conduct the test patient should read a chart through the lenses which having different strengths on the optical refractor. At the end of the test doctor will finds a lens that fits the patient’s vision. Treatment There are some several options available to get back clear visions. Contact lenses: Some people will get better vision with contact lenses rather than eyeglasses. It provides cleaner vision and a broader view. Though it is wears directly on eyes it needs proper care and cleaning of the lens to keep your eyes safe. Eyeglasses: Mostly people use eyeglasses to improve their vision. The cylindrical lens which is present in the eyeglasses will compensate astigmatism. It provides additional power to the certain parts of the lens. Orthokeratology (Ortho k): It involves fitting the suitable lenses to reshape the cornea. The patient wears contact lenses for a short period of time and removes after overnight. People with moderate astigmatism will get a temporary clear vision in their daily activities. Orthokeratology doesn’t give permanent cure. If the patient stops wearing lenses, they may get back into their original condition. Laser and other refractive surgery procedures: Astigmatism can also be treated by reshaping the cornea by using two techniques such as LASIK (laser in situ keratomileusis) it removes tissue only from the inner layer of the cornea or PRK (photorefractive keratectomy). It removes tissue from the superficial and inner layers of the cornea. Prevention There is no prevention for astigmatism. But the regular preventive care will detect the problem early and keep the corrective lenses up to date. Adults should undergo periodic eye tests: Every 2-4 years between ages 40 and 55 Every 1-3 years from 55-65 Every 1-2 years after 65 More frequently if recommended by your physician.