Taking Advantage of Technology
Patients requiring spectacle correction with multifocal lenses have benefitted significantly from advanced technologies which were unimaginable even a decade ago. The first prototype was designed in 1907 by Owen Aves, a British optometrist. However, while the concept was attractive, the technology was not available to make this design practical. The first commercially available lens, designed by Bernard Maitenaz, was manufactured in France during the 1960s. Although a certain measure of success was achieved, many patients had difficulty with this form of correction because the variable power of the lens caused objects to appear distorted and straight lines to be “bent”. Recent computerised lens manufacturing techniques have made it possible to generate complex lens curves which have markedly reduced the visual distortion and “swim effect” which often resulted in patients becoming nauseous or “seasick”. This benefit has been achieved by customising the lens design, which depends on a variety of factors. For example, a lens which is used for extensive close work would differ from one for a truck driver whose main consideration is distance vision. Furthermore, the design is affected by the nature of the distance prescription, frame shape and size, the tilt of the frame on the face and the level of adjustment for reading. While advanced technology designs improve visual performance, they also increase the risk of flaws during the manufacturing process. Quality control therefore becomes imperative. Unless sufficient care is taken in the prescribing, manufacturing, aligning and dispensing of these sophisticated lenses the potential benefits will be lost.
with DR ALAN BURROW Dip Optom F.B.O.A. (HD) D.C.L.P. D. ORTH FBCO M.SC Med GCT OPTOMETRIST