ask the labs

Fab Slabs

by Karlen McLean, ABOC, NCLC

SLAB POWER

Q At what power differential should you consider a slab-off lens, and why?

A The normal answer is 2.5 diopters of prism imbalance. But that isn't always the best solution for most patients; you should look in depth at each individual person's needs.

For example, as a licensed optician in Florida, I've worked with many doctors with low vision patients. Many of the patients would complain about eye fatigue and headaches while reading. Some of them had 1-diopter imbalance. We used a slab-off to reduce, if not solve, this problem.

I've seen other cases with low amounts of imbalance at an oblique axis. In essence, I think that when patients have discomfort at reading, you should consider a slab-off.

— John Haskins, president, Slabs Plus, Ruskin, Fla.

SINGLE VISION SLAB

Q Can single vision lenses be slabbed off, and when should a single vision slab-off be considered?

A Yes, we can slab off single vision lenses. Doing so should be determined by the refractionist, but, generally, indications for a single vision slab-off are when anisometropia results in 1.5 diopters of vertical imbalance at near and/or the patient breaks fusion.

— Chris Bowers, operations manager, Walman Optical Co., Minneapolis, Minn.

If you have a question you'd like to have answered in Ask the Labs, send it to Karlen McLean. E-mail: karlen.mclean@wolterskluwer.com. An archive of past Ask the Labs columns can be found on the Eyecare Business Website at www.eyecarebusiness.com.