We at KR Spectacle Shoppe love Progressives (Progressive lenses that is) and we have no plans to make a political statement here. Progressive lenses have a continual progression of power allowing for many various focal points giving vision at all distances from far to near. Some professionals are now calling Progressive Lenses Continual Lenses instead of the standard term. For the simplicity of this discussion we will continue to use the term Progressives Lenses.
Historically eyeglasses had only one focal point but in 1784 Ben Franklin invented the first Bifocal glasses. Having Bifocals gave the viewer two focal points in one pair of glasses and that has helped many for over 200 years. If the bifocal prescription becomes stronger with a new RX then the arm’s length vision no longer works through the Bifocal. This problem has left many viewers with only a close near vision area and a distance area but no middle vision field. The solution to this problem became available in the 1940’s with the invention of the Trifocal lens. This lens has two lines offering a third focal point. Finally, the viewer has arm’s length vision with the addition of an intermediate zone. These types of lined (Bifocal and Trifocal) lenses causes an image jump at the line(s) when the eyes move from the distance vision area to the intermediate (Trifocal part in the middle) to the bottom where the bifocal part is at. Many managed to adjust to this difficulty.
Some people really didn’t like the Bifocal line showing so in the early 50’s Younger Optical came up with the first no-line lenses. This type of lens was called a Blended Bifocal. This lens traded a line for a blurry area. That really wasn’t easy to get used to either. Because it was based on a Bifocal with two focal points it didn’t work for the intermediate area.
The industry knew that we still needed a lens without the image jump and without the restricted focal points. Some of the first Progressives Lenses came to the American marketplace in the late 1970’s. We had lenses by American Optical, Zeiss, Sola and Varilux. The first lens design came to be called a hard design. Some of the designs like the Varilux II, Hoya GP Wide, and Sola XL were somewhat successful. Early Progressive Lenses of the hard design had many problems. Wearers didn’t like the horrible distortion when looking away from the central areas of the lens. And looking side to side caused much swim and dizziness. The intermediate and near areas were very narrow. We had to tell the customer to keep wearing it and you will get used to it. Those were difficult times for the consumer as well as the dispensing Optician. Over the next 30 years the industry continued to find better ways to design the molded front surface Progressives even changing to a softer design but they all continued to have some of the dizziness, narrow field and side distortion.
Over the last decade optical industry has moved further away from the front molded Progressive Lenses to what is usually called Digital HD (high definition) or Free-Form Lenses. With personalized Free-Form Lenses, the front side of the lens has a continual curve just like single vision lenses. All the special curves for an individual prescription are processed on the back side of the lens including the continual addition of the intermediate and near reading area. A software program writes and sends the job to a CNC (Computer numerical control) machine for processing. Each prescription is designed with the frame information considered for optimal vision through the lenses no matter where the viewer is looking. With this Free-Form technological improvement, the side to side blur and the swim is virtually gone. Personalized lenses have made having the glasses you want not just a dream but totally available to the consumer no matter what type or size of eyeglass frame is chosen.
The only limitation with Free-Form Lenses is that for some the intermediate and near reading area is not as wide as one would hope. For individuals with high plus (far sighted) prescriptions the lenses can still be too thick and too heavy. To address the problem some lens manufactures were using old frontside molded lenses and putting half of the prescription magnification on the front with the other half on the back. The hope was to correct the side to side blur with adding complicated curves on the backside. The concept did make the lenses thinner but didn’t give the results that were expected leaving distortion areas with a narrow near field of vision. This combination of old and new technology didn’t really have the success the industry had hoped. As a result, most of those types of lenses were discontinued.
Younger Optical has designed a new front side molded lens to support and enhance backside high definition Free-Form Progressive Lenses. It is called
Camber. Camber Lenses are flatter and thinner for high plus prescriptions. This new Camber personalized lens design gives the wider intermediate and near area that so many are asking to wear.