physics of the eye

14 flashcards · Physics · by inquisitive learner

  1. power

    1f \frac{1}{f} f1​ ; 1u+1v\frac{1}{u} + \frac{1}{v}u1​+v1​

  2. The cornea and lens in the eye form a system that acts as a single thin lens

  3. Rods are more sensitive than cones by a factor of about 1000. They are responsible for peripheral vision and night vision. There are about 120 million rods in the human retina

  4. Cones are responsible for central vision. The cones work best in bright light and are responsible for high-resolution vision There are three types of cones and each type is sensitive to different ranges of wavelength; these correspond to the primary colours - red, green and s.

  5. How are rods and cones photo detectors

    Rods and cones convert changes in intensity and colour into electrical signals, which the brain detects.

  6. Myopia short-sightedness requires a concave lens to correct images focus in front of the retina

  7. Hypermetropia long-sightedness requires a convex lens to correct images focus behind the retina

  8. Astigmatism imperfect curvature of the cornea

  9. Concave lens Parallel light rays diverge from the principal axis Object and image are both on the same side of the lens

  10. Astigmatism Prescriptions A prescription for astigmatism contains three terms: S|C|A, C| A and A.

  11. Astigmatism Prescriptions A prescription for astigmatism contains three terms: S, C and A S is the spherical part of the prescription in dioptres; essentially the short or long sightendness correction C is the degree of astigmatism, measured in dioptres A is the orientation | axis of astigmatism from 0 to 180 degrees;

  12. presbyopia

    impaired vision as a result of aging farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.

  13. Near-sightedness has a negative sign. Far-sightedness has a positive sign. A stronger prescription has a higher magnitude|size.

  14. Convex lens Parallel light rays converge towards the principal axis Object and image are on different sides of the lens