Posted by Jairo, Manager on 2/17/2019 to Progressive Lens Technology and Tips
What is a Progressive Lens? and How do I use a Progressive Lens?
Progressive lenses are lenses that allow you to see at different focal lengths. Progressive lenses have three main focal lengths: distance vision, intermediate vision, and close up vision.
Progressive lenses are the best solution to the problem of having to change eyeglasses to view at different distances.
1. Distance Vision:
The top part of the lens is specifically for distance vision. We define distance vision as a focal length minimum of 20 feet. 20 feet is the magical "distance" because it is when our eyes are not converging and are parallel. This part of the progressive lens is the widest, with some lenses providing beyond a 165 degree viewing angle, depending on the patient's prescription and optimization done by the progressive lens design. When accessing the distance portion of your progressive lens, one must look at eye level or above, which means that if you want to look at something that is below eye level, one would move your chin down until the object comes into focus.
2. Intermediate Vision:
The intermediate part of the lens is specifically for intermediate vision. We define intermediate vision as a focal length of arm's length away (30 to 36 inches). The intermediate portion of the progressive lens is accessed exactly 4 millimeters below eye level. The progressive lens narrows in the most at the intermediate level, so you will have to point your nose to the object you would like to be in focus. The most common function of the intermediate is for computer use and for desk related tasks. Limitations would arise if your computer monitor is at eye level (and couldn't be lowered) or if you couldn't adjust the elevation of your chair to fine tune the focal length.
3. Near Vision:
The near part of the lens is specifically for close range. We define near vision or close-up vision as 16 to 18 inches away. The lens at this range is wider than the intermediate, but narrower than the distance portion of the progressive lens. This part of the lens is perfect to look at your watch, to navigate your phone, and to read a book. On most progressive lens designs, the near vision starts when the lens offers 85% of the full reading power of your prescription. Depending on the length of the progressive lens corridor, 85% of the full power is accessed at 14 to 16 millimeters below the optical center of the lens. Expect for everything beyond 16 to 18 inches to not be in focus. It is normal for your watch to be crystal clear and then to look at your shoes while standing and notice that the shoes are blurry. From that point of view, you can get your shoes into focus by either raising your foot or by lowering your chin towards your chest until the shoes come into focus (because you would then be looking at the shoes via the intermediate portion of the lens, not the near part).
Progressive lenses are a great solution to the inconvenience of having to carry around three separate eyeglasses that have prescriptions for three different focal lengths. It is also great for people that have been blessed with great distance vision and don't wear distance correction. Usually, this is a condition that occurs in everyone called Presbyopia. People with presbyopia are often annoyed from having to take their reading glasses off and on, and off and on, ALL DAY LONG!! Progressive lenses allows them to have the glasses on and gives them use of both of their hands again. We've helped many people become much more productive by suggesting progressive lenses even though they see wonderful far away.
Have you tried our Progressive lens technology? If you haven't, give us a call or email us a question. We love helping people see better!