Bif: “Boy, do I feel dizzy!” Calli: “You been drinkin’ again?” Bif: “No.” Calli: “Get in an accident?”
Bif: “No.” Calli: “ Are ya sick?” Bif: “No, I jus got my new glasses.”
Have you heard of the new digital lenses that are available? For the first time in 50-60 years the way lenses are ground to make the prescription is different.
The power of a lens is due to three things: one, front lens curvature, two, lens density and three, back lens curvature.
Originally the main curvature was ground on the front lens surface. Later it was found that putting the main curvature on the back surface reduced lens distortion dramatically.
Then new materials came out that were denser than before, and allowed lenses to be thinner. The problem was that the main curvature, or base curve, was the same throughout the whole of the lens surface, whether front or back. This caused various types of distortion, even though the prescription, per se, was correct. A variation lens model came out that allowed lenses to change curvature moving from the optical center to the periphery, but there were still some adaptations to get used to.
Recently, as computers came to be more precise and powerful, optical labs were able to streamline lenses. This is similar to how the car industry streamlined the look of cars and trucks, because computer graphics allowed more curvature to design than before.
Lenses can now be ground using a laser, instead of a large polishing tool. In doing so, the lens thickness and curvature can be adapted to give a very similar view from center to lens edge, with less distortion. This is especially important with high astigmatism corrections.
No line bifocal lenses have also seen substantial improvement. Previously, the gradual change in power to make the bifocal was formed on the front surface of the lens. Due to new laser technology the new lenses have this change, at least in part, on the back surface.
By so doing, it opens up the viewing area with less distortion towards the periphery. I relate it to looking through a hole in a screen door-the closer you are to the hole, the better the view. I’ve personally worn this lens and was surprised at how much wider the comfortable viewing area was in the lens.
If you’ve had problems before with lens distortion, whether from single vision or bifocal, you may want to consider trying this improved technology.
Dr. Scott Borgholthaus is owner of Vision Haus Optometry in Cheney. He is a member of the Optometric Physicians of Washington and has been in private practice for over 27 years.
Dr. Borgholthaus would love to answer and/or include any questions or comments in future columns. Please send questions or comments to email@example.com.