This video shows the use of a lensometer, a device used to check the prescription in glasses. This device can be tricky for the novice technician to use, as you must align the glasses well and move two dials at the same time to hone in on the prescription.
Here are the steps:
1. Place glasses on platform and secure
2. Turn axis and focus nobs so that the SMALL lines are straight and focused
Write down the number. This is your sphere.
3. Turn the focus nob until the fat lines become focused, and look at the new number on the focus nob. The DIFFERENCE from your prior sphere value is the CYLINDER value. If you changed from +1.00 to +4.00, then your cylinder is +3.00. If you changed from +1.00 to -1.50, then your cylinder is -2.50. In other words, the cylinder can be a positive or negative number, depending upon the direction you have to turn the focus nob.
4. Check the degrees on the axis dial. This is your cylinder axis.
If you want to check the bifocal add:
5. Move the glasses so that the bifocal segment is being read.
6. Turn the focus nob again until the fat lines again become focussed.
The amount of change needed to refocus the fat lines will give you your bifocal power.
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thanks a lot for the information. please kindly send me in my E Mail Address all more about lensomater technique in reading the amount of prism induce in the lens. thanks
Went back into the wonderful field of optical again and thank-you for the refresher class on the use of the lensometer. Was very helpful. :) Just hoping to remember how to check prisms. THANKS AGAIN
THE ADD(BIFOCAL) POWER IS PROBALY A 2.25 ON THIS LENS. THE BIFOCAL POWER SHOULD BE CHECKED FROM THE BACK OF THE LENS, IE; FRONT VERTEX POWER FOR THE ADDED PORTION.
These videos are the God’s gift and sure Timothy Root’s gift to ophthalmic Residents. Definitely it is the bible for better eye knowledge. Thank you Timothy Root
I hope that you can make a video illustrating Keratometry Readings for calculation of intraocular lens (Non automatic keratometer) .
Thank you from Russia, Kursk state medical uniVersity
Thank you guys so much for showing me how to use the Lensometer! I just started an optician apprenticeship, and really needed to know how to understand how to use this thing:) You guys made it super simple and easy to understand:) Thanks again!
The one basic thing missing was telling the student about focusing for either plus or minus cylinder. It would also be nice to show how to measure for prism. Maybe you could do that at some point in time. You really have nice video presentations and I really enjoy your site.
Hi Tim Root
Congratulations on getting the number 1 google spot for lensometer. Hope all is well and BP doesn’t crush your dream of the beach front gulf coast home in Florida.
Jake Moore
Great video. I’m linking to it from a new site I just started for optician apprentices. It may be useful to also show what it would look like without a cyl and axis as well as what a prism would look like. Thanks!
Tu informacion esta barbara me ayudo muchisimo a refrescar mi memoria,podrias enviarme, algun ejemplo mas con prisma y si es un multifocal.Muchisimas gracias.
laura
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:) Just hoping to remember how to check prisms. THANKS AGAIN