The Vision Therapy Opportunity, Part Four

By Erich Mack, B.S., ABO, NCLE
Wednesday, April 8, 2015 11:00 AM A recent report from Canada thoroughly examined the efficacy of vision therapy and found an apparent research war over its use.

The Vision Therapy Opportunity, Part Three

By Erich Mack, B.S., ABO, NCLE
Wednesday, April 1, 2015 10:00 AM A successful vision therapy practice has many proven techniques and interesting tools (called orthoptics) at their disposal.

The Vision Therapy Opportunity, Part Two

By Erich Mack, B.S., ABO, NCLE
Wednesday, March 25, 2015 9:00 AM Research has demonstrated vision therapy can be an effective treatment option for, ocular motility dysfunctions (eye movement disorders)...

The Vision Therapy Opportunity, Part One

By Erich Mack, B.S., ABO, NCLE
Wednesday, March 18, 2015 2:00 PM Most of us understand that vision is our keystone sense. It is the most relied on and integrated sense in human cognition.

Converting Prism Into an Order

By Mark Mattison-Shupnick, ABOM
Tuesday, August 26, 2014 11:00 AM The Opticians Handbook received this question about a prism Rx for a patient experiencing vertigo:
"I recently got a prescription where the doctor asked for 1.5 degrees of prism base down at axis 255 right and 1.5 degree base down in the left at axis 255. What should I order? The doctor told me to order 1.1 base down with 0.50 Base Out right and 1.1 Base Down with 0.50 Base In."

Slab-off, Reverse Slab-off and Bi-centric Grinding

By Andrew S. Bruce, ABOM
Tuesday, February 18, 2014 1:00 PM The most common way of correcting vertical imbalance is to induce a vertical prismatic effect in the lower half of one lens. This type of correction is referred to as bi-centric grinding, or slab-off.

Verification of Slab-off

By Andrew S. Bruce, ABOM
Monday, February 3, 2014 10:30 AM There are two ways basic ways to verify slab-off: Comparing the vertical prismatic effects of the two lenses through a lensometer and checking for actual image displacement at the reading level.

A Prism Tutorial, Part 3

By Andrew S. Bruce, ABOM
Tuesday, December 3, 2013 3:51 PM First, it is an effect of the prescription as determined by the doctor, so we cannot fix it, but we can correct for it. Some methods are capable of correcting for more imbalance than others.

Anisometropia and Antimetropia

By Andrew S. Bruce, ABOM
Sunday, November 24, 2013 10:00 AM According to “The Dictionary of Ophthalmic Optics” (Keeney, Hagman, & Fratello), Anisometropia is defined as, “Unequal refractive errors in the two eyes.” 

A Prism Tutorial, Part 1

By Andrew S. Bruce, ABOM
Tuesday, November 19, 2013 1:00 PM Powered lenses are, in effect, prisms either mounted base to base (plus lenses), or apex to apex (minus lenses).

Prism Thinning: A Real World Scenario

By Johnna Dukes, ABOC
Monday, November 5, 2012 3:43 PM This was my formal introduction into Prism Thinning, as a young optician and the results of which I've never forgotten.

Prism 'Only at Near'

By Ed Muller, Mark Mattison-Shupnick
Monday, October 8, 2012 2:28 PM Ever get that request from the doctor? Ed M. just sent me this Rx and we discussed how a FT45 (available from Younger Optics) could be used to deliver the prism at near only. In this Rx, 2.5Δ (prism diopters) Base In is wanted in each lens.

Prism Pearls

By Staff
Monday, August 27, 2012 8:21 PM

The ability to turn eyes in (converge) and yes, turn slightly outward (diverge), is the reason that the ANSI standard for PD and prism allows up to 2/3 prism diopters of "tolerance".

Prism Rx Flat Tops

By Staff
Wednesday, April 11, 2012 6:05 PM When a flat top bifocal lens Rx is ordered with prescribed prism... (flat top bifocal or a progressive for that matter), the amount of prescribed prism is placed in front of the pupil, in line with the visual axis.

The 1,2, 3 of Prism

By Staff
Saturday, November 26, 2011 3:26 AM

Here's some basics about prism in lenses

1. Eyewear with prism, means that the optical centers of the lenses do not occur at the PD. For example, if the left eye has 2 prism diopters Base Out prescribed, the point on the lens that is 2 Base Out is located at the PD.