Digital Eyeglass Lenses
Digital Eyeglass Lenses
There are really two ways to make lenses for a pair of eyeglasses: conventional lenses and digital eyeglass lenses. The Conventional way is to take a stock lens off the shelf that has a standard curve on the front, and grind down the backside of the lens until it approximates the correction that the doctor has prescribed. The upside of this method is it can be done “in about an hour.” The downside of this method is that it doesn’t account for the fact that that standard curve on the front of the lens may not work with your prescription being ground into the back side of the lens. And, because the stock lens is a standard curve that is meant to work okay for any eyeglasses, there is no optimization for the three-dimensional position of your eye behind the lens in the frame you have chosen as there would be with digital eyeglass lenses.
These problems create unwanted peripheral distortions and aberrations that are noticeable anytime the wearer looks off-center such as when reading, driving, playing sports, etc (basically, when living). Because the stock lenses used as a starting point for this method are limited, the manufacturers only stock a limited range that will minimize these effects when used with the most common prescriptions. However, this means that these unwanted effects increase as a wearer’s prescription either increases or differs from the standard prescriptions for which the stock lenses were selected.
Digital eyeglass lenses on the other hand, use a computer controlled generator that creates a personalized lens with the correct prescription throughout the lens accounting for both the wearer’s prescription (the thing you get from your doctor) and the position of wear measurements (taken by an optician, including: the distance between the bridge of your nose and each eye; the distance from the lens to your eye; the vertical distance from the bottom of the frame to the center of your pupil; the tilt of the frame toward or away from your face; and the amount the frame wraps around your face).
Digital eyeglass lenses are optimized to minimize peripheral distortion and aberration. The downside of this method is that it costs more in both time and money because the lenses must be created in laboratories that invest hundreds of thousands of dollars in the machines for creating these lenses. The upside is that these digital, free-form lenses are personalized to your prescription, lifestyle, and fitting measurements. This personalization minimizes the peripheral distortions and aberrations that interfere with reading, driving, playing sports, etc (again, basically living).
So, are digital eyeglass lenses right for you? While everyone will benefit from them, the benefits of these lenses increase with increases in prescription, astigmatism, or with progressive lens designs. Generally if your prescription is more than plus or minus 1.00, you have astigmatism, or you wear progressive lenses, then you will benefit from digital eyeglass lenses, otherwise you can probably get by with conventional lenses.