Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Medical Contact lenses

  1. Jul 22, 2008 #1
    have absolutly no idea where to put this but ill put it here

    My eyesight is something like +6.25/+6.50

    Now the eye man (optomotrist?) said that they only make contact lenses that go up to +6. I was wondering why this is?

    Also why can't long sighted people have laser eye sugery? Is there any other types of surgery they can have?

  2. jcsd
  3. Jul 23, 2008 #2
    Are you sure your optometrist didn't mean that he can't get your prescription in a particular brand? Most of the Acuvue brand lenses and Frequency 55, will go up to a +8.00. Proclear Sphere by Cooper Vison goes up to +10.00 Something doesn't sound right if he says he can't get any lenses in your RX......:confused:

    As for why lasik is so difficult for hyperopia, this article may help you understand it better:
    http://www.usaeyes.org/faq/subjects/hyperopia.htm" [Broken]
    Last edited by a moderator: May 3, 2017
  4. Jul 23, 2008 #3


    User Avatar

    Staff: Mentor

    If the prescription is +6.25/+6.5 at the plane of eyeglasses, the contacts would have to be much higher in magnification (since they are closer to the focal plane of the retina). I wonder if that's what the Optometrist is referring to. I don't know if they refer to contact lens magnification in terms of the equivalent eyeglass Rx or not, though...
  5. Jul 23, 2008 #4


    User Avatar
    Gold Member

    If you are near-sighted, your lens focuses to a point in front of the retina, and the surgeon can re-shape your cornea a bit to flatten the curvature so that the point of focus is farther back in the eye. For far-sighted people, no equivalent surgical correction is possible. You could explore the possibility of having your natural (internal) lenses replaced, but this is normally only done by ophthalmologists in the case of cataracts when lens clarity is compromised by damage, old age, etc.
  6. Jul 23, 2008 #5
    Even if you took the vertex distance into account, it would only add +.50 diopters to the contact lens RX for a total of +6.75/+7.00. That RX is still available in those brands I mentioned.
  7. Jul 23, 2008 #6


    User Avatar
    Gold Member

    The RX may be available, but fitting and tuning those contacts is a real bear!! Most patients could not function fully with them, and would have to resort to well-fitted eyeglasses for critical uses.
  8. Jul 23, 2008 #7


    User Avatar
    Science Advisor
    Homework Helper

    You can have laser surgery to increase the curvature, but since it involves cutting away at the thin edge of the lens the the range of correction is a bit bit more limited.

    Of course anyone who wants to have lumps cut out of their eyes as an alternative to wearing glasses deserves it!
  9. Jul 23, 2008 #8
    If I were he and I was really serious about wanting contacts, then I would ask the optom. more questions. His optom. may not have an account with any of the companies that sell lenses with his parameters. If that is the case, find an optom. who specializes in fitting contacts and can order some to fit him. Our practice (pediatric ophthalmology)fits many high hyperopes in soft contacts with out problems. We fit all ages from aphakic babies who need lenses that are in the +20.00 and higher to teenagers who average +4.00 to+8.00 range. The teens would rather die than have to go back to glasses and love their contacts.
  10. Jul 23, 2008 #9


    User Avatar
    Gold Member

    When you are making small corrections, axial shifts can be tolerable and contacts are a reasonable option. When you are making large corrections, axial shifts can be very disturbing, making driving and other activities pretty risky. Very small shifts can cause enough visual impairment to make an activity that might have been OK with glasses be dangerous with contacts.
  11. Jul 23, 2008 #10


    User Avatar
    Homework Helper

    This is the procedure i received. The surgery lasted about 10 mins. I was +5.00 on both eyes, and now i have 20/20 vision. The exact procedure i received is called Lasik. There are variations of this same procedure.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook