Understanding Eye Diseases: Myopia, Hypermetropia, Astigmatism, Cataract

        a. Myopia : 

• It is also called “Short-Sightedness” or “Near Sightedness”.
• Myopia is corrected by the use of “Concave Lenses”.
• Myopia is a type of eye disease where light focuses in front of the Retina instead of on the Retina.
• This causes clearly visible of near objects and cannot focus to the for objects properly.
• As concave lenses are diverging lenses it directs light away from the centre of the lens and move the focal point of the light back, so it reaches the retina. Thus when the image is formed in the retina we can see the distant object clearly.

       b. Hypermetropia

• It is also called  “For-Sightedness” or “Long sightedness”.
• Hypermetropia is corrected by the use of “Convex Lens”.
• In hypermetropia a person can see the distant object clearly but unable to focus the near object.
• In this disease the light is focused behind the retina instead of the retina.

        c. Astigmatism

• It is a type of refractive error in which eye does not focus light evenly on the retina.
• It results in distorted or blurred vision at all the distances.
• It is corrected by the use of ‘Cylindrical Lens’.
• In this disease either the corona or the lens has on irregular curvature as a result portion of the image are out of focus thus visions blurred.

        d. Cataract:

• It is a eye problem occurs manly due to Aging.
• It is a clouding of the eye lenses which leads in decrease in vision.
• Risk factors are included diabetes, smoking, tobacco and sunlight.
• It can be eradicated by surgery.