Defects of human eye

Defects of Human Eye & its correction.

1. Defects of human Eye & their correction Mihir Bhayani B.E. Mechanical, Savitribai Phule University

2. R.S.Academy,Pune Terms Related to Human Eye Accomodation : It is the ability of eye lens to focus both near & distant objects Clearly. Power of Accomodation : it is the max. variation in power of eye lens. Far Point of Eye: It is the farthest point upto which the human eye can clearly see different objects. Near Point of Eye: The minimum distance upto which an object can be seen distinctly is called near point. Persistence of Vision: It is the minimum time for which any object should be seen to capture its image by the human eye.

3. R.S.Academy,Pune Myopia NEAR-SIGHTEDNESS or SHORT-SIGHTEDNESS The person suffering from myopia can see near objects clearly but distant objects seem to be blurry as the image is formed in front of the retina. CAUSES: Increase in curvature of lens Increase in length of eyeball. CORRECTION: It can be corrected by using a suitable concave lens of appropriate focal length which can focus the image backwards on the retina.

4. R.S.Academy,Pune NORMAL EYE Image is formed on retina Retina Retina MYOPIC EYE Image is formed in front of retina CORRECTED EYE Concave lens focusses the image on the retina. Thus image is formed on retina.

5. R.S.Academy,Pune Hypermetropia FAR-SIGHTEDNESS or LONG-SIGHTEDNESS The person suffering from hypermetropia cannot see near objects clearly but distant objects are visible clearly as the image is formed behind the retina. CAUSES: Decrease in curvature of lens Decrease in length of eyeball. CORRECTION: It can be corrected by using a suitable convex lens of appropriate focal length which can focus the image on the retina.

6. R.S.Academy,Pune NORMAL EYE Image is formed on retina Retina Retina HYPERMETROPIC EYE Image is formed behind the retina CORRECTED EYE Convex lens focusses the image on the retina. Thus image is formed on retina.

7. R.S.Academy,Pune Presbyopia Presbyopia  is a natural part of the aging process. It is a type of refractive error along with nearsightedness, farsightedness, and astigmatism. CAUSES: Hardening of the eyes Weakening of ciliary muscles. Decreased flexibility of the eyes. CORRECTION: It can be corrected by using a bifocal lenses consisting of both convex and concave lenses.

8. R.S.Academy,Pune THANK YOU