EXPLAIN THE CAUSE, FEATURES, PHYSIOLOGICAL BASIS, AND CORRECTION OF ASTIGMATISM скачать в хорошем качестве

EXPLAIN THE CAUSE, FEATURES, PHYSIOLOGICAL BASIS, AND CORRECTION OF ASTIGMATISM

It is a type of refractive error in which the eye does not focus light evenly on the retina. This results in distorted or blurred vision at all distances. OR It is a type of refractive error wherein the refraction Varies in the different meridian. CAUSE ( Etiology) Irregular curvature in the Anterior surface of the cornea. Irregular curvature and also the position of lens/ IOL. The refractive power is not uniform in all meridians of both lens or cornea. The principal meridians are the meridians of greatest and least refracting power. GENETICS: Astigmatism often runs in families and can be present at birth EYE INJURIES: Trauma or surgery that change the shape of the cornea can cause Astigmatism. KERATOCONUS: A progressive eye disease where the cornea becomes thin and cone-shaped, leading to severe Astigmatism. LENS-INDUCED: This can occur due to conditions like Cataracts that distort the shape of the lens. FEATURES, Blurred or distorted Vision at any distance. Eyestrain OR discomfort particularly after prolonged reading or computer use. Headaches due to eye’s effort to correct the blurred vision. Difficulty with night vision. Squinting to try to improve focus. Difficulty in driving at night. PHYSIOLOGICAL BASIS: The physiological basis of Astigmatism lies in the optical principles governing the eye’s ability to focus light on the retina. In a normal eye, the cornea and lens are smoothly curved, allowing light to focus precisely on the retina. IN ASTIGMATISM: The irregular shape of the cornea or lens causes light to focus on multiple points, either in front of, behind, or on the retina. Astigmatism is often classified into two types based on the curvature: CORNEAL ASTIGMATISM: The cornea is more curved in one direction than the other.( irregular cornea) LENTICULAR ASTIGMATISM: Due to an irregularly shaped lens. CORRECTION: Astigmatism can be corrected using several methods, Eyeglasses Contact lenses, cylindrical lenses and Spherocylindrical lenses in spectacles SUMMARY: Astigmatism results from an irregular curvature of the cornea or LENS, which can be caused by genetic factors, eye injuries, surgeries, or certain eye conditions like kerataconus. It is often hereditary and may develop early in life, although it can also arise later due to trauma or medical procedures. Proper diagnosis and correction with glasses, contact LENSES, or surgery can help manage the condition. Refractive surgery, Photorefractive keratectomy ( PRK)