New technology is now available as spectacle lenses also enter the digital era. Other terms used to describe digital lenses are “free form” or “high-definition”.
The main benefit of digital lenses is that they are custom made exactly to each persons prescription, and do not suffer the compromises inherent in conventional lens manufacturing. Conventional lenses are partially prepared by lens manufacturers, and when prescription lenses are produced a lab selects from among the premade blanks whichever is most appropriate for the prescription and then grinds the lens accordingly.
However, in an ideal world every prescription requires a completely unique curvature of the lens for best correction. When premaking lenses, manufacturers cannot economically produce every curvature for every prescription, so they produce a dramatically reduced selection of curvatures that are satisfactory for most prescriptions. But satisfactory is far from perfect. Some of the optical distortions and aberrations one experiences with conventional lenses, such as the “fish bowl” effect and distortion at the peripheral edges of the lenses, are because the curvatures are just not perfectly matched to the patients prescription. Due to the larger size of the snooker lens, this is often more of an issue than would be experienced in a standard pair of spectacles.
Digital lenses are produced by a digital lens fabrication process that eliminates the constraints of premade materials. The advanced machines used cut custom curvatures to very accurate specifications, far more so than traditional methods.
The benefits of digital processing are compounded when astigmatism is involved. To correct astigmatism lenses have two prescriptions ground into them at cross directions. Since every prescription requires a unique curve, lenses that correct astigmatism require two unique curves. Conventional lenses that correct astigmatism are still made from the single premade curve selection, so they will err due to rounding in both directions. If the astigmatism is high, it becomes impossible to even come close to proper curvature for both prescriptions with a single premade curve, and wearers end up with lots of distortion and peripheral blur. Digital technology enables perfectly accurate curves for both prescriptions to be fabricated in the lenses, providing high astigmatism patients with better vision than previously possible in conventional lenses.
Who Should Wear Digital Lenses?
Anyone can wear digital lenses,some will get more benefit than others, whereas others will perceive no difference at all. Patients with low prescriptions and negligible astigmatism will experience less of an improvement than those with a higher prescription. I would recommend the digital lens upgrade to anyone with a prescription in excess of + or – 2.00 dioptres.