Refractive Power of Lenses
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Questions and Answers

What is the approximate percentage of the general population affected by amblyopia?

  • 1%
  • 5%
  • 7%
  • 3% (correct)
  • What is the term used to describe the process of increasing the curvature of the lens to focus on near objects?

  • Strabismus
  • Myopia
  • Emmetropia
  • Accommodation (correct)
  • What is the shape of the lens when the ciliary muscle is relaxed?

  • Irregular
  • Convex
  • Spherical
  • Flattened (correct)
  • What is the maximum additional refractive power added to the eye in young individuals due to accommodation?

    <p>12 diopters</p> Signup and view all the answers

    What is the term used to describe the condition where parallel light rays are brought to a focus on the retina?

    <p>Emmetropia</p> Signup and view all the answers

    What is the purpose of the lens ligaments?

    <p>To hold the lens under tension</p> Signup and view all the answers

    What happens to the lens when the ciliary muscle contracts?

    <p>It becomes more convex</p> Signup and view all the answers

    What is the minimum distance from the observer at which parallel light rays are brought to a focus on the retina?

    <p>6 m</p> Signup and view all the answers

    What is the unit of measurement for the refractive power of a lens?

    <p>Diopters</p> Signup and view all the answers

    What is the refractive power of the human eye at rest?

    <p>60 diopters</p> Signup and view all the answers

    Where does the refraction of light occur in the eye?

    <p>At the anterior and posterior surfaces of the lens and the anterior surface of the cornea</p> Signup and view all the answers

    Why do we perceive an inverted image on the retina as right side up?

    <p>Because of the connections of the retinal receptors</p> Signup and view all the answers

    What is the result of turning retinal images right side up by means of special lenses?

    <p>The objects viewed look upside down</p> Signup and view all the answers

    What is the condition characterized by an eyeball that is too long?

    <p>Myopia</p> Signup and view all the answers

    What is the term for the uncorrectable loss of visual acuity that is not directly due to organic disease of the eye?

    <p>Amblyopia ex anopsia</p> Signup and view all the answers

    What percentage of children under 6 years of age are affected by Strabismus?

    <p>4%</p> Signup and view all the answers

    What is the term for the condition where one eye turns inward, outward, upwards, or downward?

    <p>Strabismus</p> Signup and view all the answers

    What is the condition characterized by a misalignment of the eyes?

    <p>Strabismus</p> Signup and view all the answers

    At what age is it crucial to institute treatment for strabismus in children to prevent permanent loss of visual acuity?

    <p>Before age 6</p> Signup and view all the answers

    What is the result of visual images not falling on corresponding retinal points in children?

    <p>Suppression scotoma</p> Signup and view all the answers

    What is the consequence of suppression persisting in children with strabismus?

    <p>Permanent loss of visual acuity</p> Signup and view all the answers

    What is the term for the weak eye with poor vision in a child with strabismus?

    <p>Amblyopic eye</p> Signup and view all the answers

    What is the type of phenomenon that suppression scotoma is in children with strabismus?

    <p>Cortical phenomenon</p> Signup and view all the answers

    What is the result of vision in one eye being blurred or distorted due to refractive error in children?

    <p>Amblyopia ex anopsia</p> Signup and view all the answers

    What is the main reason for the recession of the near point with advancing age?

    <p>Steady decrease in the curvature of the lens</p> Signup and view all the answers

    What is the purpose of the contraction of longitudinal muscle fibers in the ciliary body?

    <p>To pull the whole ciliary body forward and inward</p> Signup and view all the answers

    What is presbyopia, and how is it corrected?

    <p>A condition of loss of accommodation, corrected by wearing glasses with convex lenses</p> Signup and view all the answers

    What is the approximate distance of the near point at age 10?

    <p>9 cm</p> Signup and view all the answers

    What happens to the edges of the ciliary body when the longitudinal muscle fibers contract?

    <p>They come closer together</p> Signup and view all the answers

    What is the function of the circular muscle fibers in the ciliary body?

    <p>To exhibit a sphincter-like action</p> Signup and view all the answers

    What happens to the visual axes when an individual looks at near objects?

    <p>They converge</p> Signup and view all the answers

    What is the approximate distance of the near point at age 60?

    <p>83 cm</p> Signup and view all the answers

    What is the reason why individuals who need maximum visual sensitivity and dim light can avoid waiting 20 minutes in the dark?

    <p>Because they wear red goggles in bright light</p> Signup and view all the answers

    What are the three attributes of color?

    <p>Hue, intensity, and saturation</p> Signup and view all the answers

    What is the sensation produced by the absence of light?

    <p>Black</p> Signup and view all the answers

    What can be produced by mixing various proportions of red, green, and blue light?

    <p>The sensation of white, any spectral color, and even the extra spectral color, purple</p> Signup and view all the answers

    What are the primary colors?

    <p>Red, green, and blue</p> Signup and view all the answers

    What happens to the rods in the peripheral portions of the retina?

    <p>They adapt</p> Signup and view all the answers

    What is the purpose of wearing red goggles in bright light?

    <p>To allow the cones to function reasonably well</p> Signup and view all the answers

    What is the compensatory color that, when properly mixed with a color, produces a sensation of white?

    <p>A color with opposite hue</p> Signup and view all the answers

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