Physiological Optics Lecture 13: Spectacle Magnification
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Questions and Answers

What is the ratio between the corrected and uncorrected image size known as?

  • Optical correction ratio
  • Relative spectacle magnification (correct)
  • Ameteropia conversion factor
  • Absolute spectacle magnification

    • In axial ametropia, if the correcting lens is placed at the anterior focal point of the eye, what is the value of the relative spectacle magnification (RSM)?

  • Equal to unity (correct)
  • Less than unity
  • Depends on the type of ametropia
  • Greater than unity

    • For axial myopia, if the correcting lens is worn nearer to the eye than the anterior focal point, what is the effect on the relative spectacle magnification?

  • It remains unchanged
  • It decreases
  • It increases (correct)
  • It becomes negative

    • What effect do contact lenses have on axial myopia?

    <p>They have a magnifying effect on image size</p> Signup and view all the answers

    What does the relative spectacle magnification compare in clinical use?

    <p>Emmetropic image size with ametropic image size</p> Signup and view all the answers

    What is the term used for the ratio between the corrected and uncorrected image size?

    <p>Relative spectacle magnification</p> Signup and view all the answers

    What happens to the relative spectacle magnification in refractive hypermetropia?

    <p>It is greater than unity</p> Signup and view all the answers

    What is the relative spectacle magnification produced by aphakic spectacle correction approximately?

    <p>1.33</p> Signup and view all the answers

    What effect does wearing correcting lenses nearer to the eye than the anterior focal point have on relative spectacle magnification in refractive ametropia?

    <p>It approaches unity</p> Signup and view all the answers

    How does the image magnification affect the perception of distance in aphakic spectacle wearers?

    <p>Objects appear closer than they really are</p> Signup and view all the answers

    What does reducing the Relative Spectacle Magnification (RSM) to 1.1 or 1.0 overcome?

    <p>Distance misjudgment</p> Signup and view all the answers

    What effect does spectacle correction in aphakia have on standard tests of visual acuity?

    <p>Enhanced performance</p> Signup and view all the answers

    What happens to the image size in refractive myopia?

    <p>It is diminished</p> Signup and view all the answers

    Where are spectacles usually worn in front of the cornea for aphakic patients?

    <p>12–15 mm</p> Signup and view all the answers

    What is the typical relative spectacle magnification for contact lens correction in aphakia?

    <p>1.1</p> Signup and view all the answers

    What does refractive ametropia refer to?

    <p>Differences from emmetropic image size in refractive error</p> Signup and view all the answers

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