Does this Prescription look right?

Discussion in 'Optometry Archives' started by bthuynh, Dec 21, 2004.

  1. bthuynh

    bthuynh Guest

    I just got a prescription for some eyeglasses and contacts and am
    trying to make sense of it. First let me give you the numbers:
    For the Eyeglasses:
    OD Sphere -1.75, no astigmatism
    OS Sphere -4.25, Cylinder -050, Axis 015

    For the Contact lenses:
    OD Sphere -1.75
    OS Sphere -4.50
    B. Curve 87
    Diam: 14.0

    Now from the reading I've done I can figure out what some of these
    numbers mean, but I need help with putting it all together.

    It seems that because I have no astigmatism in my R eye, and because
    the power is less than -4.75 (so no correction factor is needed for
    glasses and contacts), the powers for the contacts and eyeglasses will
    be the same. Is this right?

    But for the left eye, I have read that at powers of -4.75 and above, a
    correction factor starting at 0.25 needs to be added to the contact
    lens Rx. But it seems my L eye power is listed as -4.25. However, the
    astigmatism power is -0.50. Would I be correct in adding these two
    values together, to get a value of -4.75 for the L eye, which the
    optometrist then added 0.25 to arrive at the -4.50 value for the
    contact lenses?

    Thanks for helping this amateur optometry sleuth.
    bthuynh, Dec 21, 2004
  2. bthuynh

    RM Guest

    No. you add 1/2 the astigmatism power to the spherical power to obtain what
    is called the "spherical equivalent" power. It adds up to -4.50 in this
    case. -4.50 is right on the breakpoint where you might consider adjusting
    the contact lens power down by a quarter (to -4.25). For me it depends on
    the patients age, and whether I get the "feel" that they are slightly higher
    or slightly lower than -4.50. I pick up that "feel" from how they respond
    during the refraction. Your doctor just left the contact lens power
    at -4.50 which should be fine.

    RM, Dec 21, 2004
  3. bthuynh

    Guest Guest

    For the left softlens S-4.00 will do.
    When you are young of age you might consider S-4.25 which gives you most of
    the time a bit more vision in the dark or at twilight.
    The S-4.50 is to strong in power.
    Guest, Dec 21, 2004
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