Results 1 to 7 of 7

Thread: calculation of spectacle tools for prescription in toric lens

  1. #1
    OptiBoard Novice
    Join Date
    Aug 2011
    Location
    Singapore
    Occupation
    Optometrist
    Posts
    8

    calculation of spectacle tools for prescription in toric lens

    I need help in solving this question. Hope somebody could help with this.

    Q: Which spectacle tools, calibrated for glass of refractive index 1.52 must be employed in order to produce the prescription -2.00DS/+1.00DCxH in toric form with a -8.00 sphere curve in glass of refractive index 1.65?

  2. #2
    Master OptiBoarder OptiBoard Silver Supporter
    Join Date
    Jul 2008
    Location
    Cincinnati
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    637
    Is this two different Rx's?

  3. #3
    Master OptiBoarder lensgrinder's Avatar
    Join Date
    Jul 2005
    Location
    Raleigh, NC
    Occupation
    Lens Manufacturer
    Posts
    504
    Quote Originally Posted by Optometry student View Post
    I need help in solving this question. Hope somebody could help with this.

    Q: Which spectacle tools, calibrated for glass of refractive index 1.52 must be employed in order to produce the prescription -2.00DS/+1.00DCxH in toric form with a -8.00 sphere curve in glass of refractive index 1.65?

    First you need to determine the laps based on the power and sphere curve you have.

    You can use the nominal power formula with each major meridian of power(-2.00 and -1.00)





    Your base curve is the flatest curve on a toric surface so you have 6.00 base curve and 7.00 cross curve. These are the curves you want to cut with this sphere curve. to produce that power.

    Since your index is 1.65 and your tooling index is 1.52 you can use the refractive power formula.






  4. #4
    ABOM Wes's Avatar
    Join Date
    Nov 2007
    Location
    Earth
    Occupation
    Optical Laboratory Technician
    Posts
    3,194
    Brent, are you assuming the -8.00 sphere curve is representing surface power? Would you need further calc if he meant -8.00 curve in 1.52 or 1.53 tooling? I don't think the op made that post completely clear.
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

    “As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein

  5. #5
    Master OptiBoarder lensgrinder's Avatar
    Join Date
    Jul 2005
    Location
    Raleigh, NC
    Occupation
    Lens Manufacturer
    Posts
    504
    Quote Originally Posted by Wes View Post
    Brent, are you assuming the -8.00 sphere curve is representing surface power? Would you need further calc if he meant -8.00 curve in 1.52 or 1.53 tooling? I don't think the op made that post completely clear.
    Wes, you are right. I did not convert the -8.00 to the refractive power. I would assume the -8.00 is in 1.52 or 1.53. I will go with 1.52 since that is what he/she wrote.


    [latex]refractive = -10.00[\latex]
    Now use this value to determine laps needed











  6. #6
    OptiBoard Novice
    Join Date
    Aug 2011
    Location
    Singapore
    Occupation
    Optometrist
    Posts
    8
    yes, the answer is correct!!!! thank you very much! appreciate this

  7. #7
    OptiBoard Novice
    Join Date
    Sep 2014
    Location
    turkey
    Occupation
    Optical Laboratory Technician
    Posts
    2
    How can i find tool base and tool cyl for given details?

    Rigth eye

    sph 11
    cyl 2.25
    customer wants 60 mm diameter
    base for blank 13.89
    blank index 1.502
    blank radius 32.45
    blank diameter 67
    tool index 1.530

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Lens Calculation?
    By ilan1204 in forum General Optics and Eyecare Discussion Forum
    Replies: 5
    Last Post: 06-09-2009, 01:52 PM
  2. Very Toric lens needed
    By chip anderson in forum General Optics and Eyecare Discussion Forum
    Replies: 6
    Last Post: 04-09-2009, 08:53 PM
  3. Plus lens and toric; how thick?
    By Leon from Sweden in forum Ophthalmic Optics
    Replies: 6
    Last Post: 10-28-2007, 04:25 PM
  4. Toric lens rotating.
    By cookies in forum General Optics and Eyecare Discussion Forum
    Replies: 2
    Last Post: 04-29-2006, 02:17 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •