Preventing Lens Movement Midday Fogging

by Dr. Charles McBride, McBride Optometrists, Beaverton, OR

Scleral lens movement virtually guarantees mid-day fog, that hazy murkiness that replaces the clear insertion fluid under a scleral lens. I forget who recently coined the term chamber fog, but I like it better than mid-day fog. This is especially true when related to lens movement; indeed, the haziness can develop quickly and there is no ambiguity about the fog being under the lens or on the outer lens surface.

Fortunately, preventing lens movement is usually straightforward and can be accomplished by lowering the outer haptic or “toe” of the lens. Many of us use the word “tightening” for this, but I bet I’m not the only one who has come to appreciate the precise meaning behind the moving of lens material around by a certain number of microns.

How many microns the outer haptic needs to be lowered to prevent lens movement depends on the amount of movement, but I would suggest somewhere in the neighborhood of 20-80um all the way around the lens to begin with.

With a lens that no longer moves with each blink, one can get to tackling all of the other little quirks that come with scleral lens design. Happy fitting!  

Gaudi Dashboard: Before and After a 50um Adjustment in the Haptic Zone

Dr. McBride has received no remuneration from EYEXY, including for the writing of this blog.