A bifocal lens only allows you to have two vision distances (near and far) while progressive lenses give you all your range of vision from distance, intermediate and near in a smooth progression. Most people like the newer technology of the progressive because it allows for more natural vision and cosmetically they look nicer because there is no line. The upside to standard lined bifocals is that the peripheral vision is sometimes better.

There are lens implants, which give focus at all distances. There are limitations and you should consult with your surgeon about them. See similar questions...

A progressive lens make a progressive change from distance vision to near vision providing an infinite range of powers in between. An additional advantage of progressive lenses is the lack of a bifocal line. See similar questions...

Yes, not all frames are doable with Bifocals or Progressive. The lens height of the frame should be at least 30mm. We want to make it easier for you to identify which frame can or can't be done with Bifocal or Progressive by putting a check or cross mark on the item page. If you need more advise, please don't hesitate to contact our Customer Service Department. See similar questions...

Normally, the division is 60% of the lens height for distance and 40% of the lens height for reading. But of course, you are very much welcome to inform us your preference in division. Please include a note on the order form or call us as soon as you place your order, we will make sure to note it on our end. See similar questions...

interlaced picture is divided into two halves, the odd and even scan lines. These are "halves" are displayed odd, even, odd, even, etc., at a rate of 60 frames per second. So, in reality at any given time you are only seeing half of the picture (although because the frame rate is so high, your eyes don't notice it.) Interlaced scanning sometimes results in screen flicker and visible scan lines. Standard analog TV signals are interlaced signals. See similar questions...

In addition to a correction for nearsightedness, farsightedness, and/or astigmatism, a bifocal contains an addition for near vision. There are two focal powers. See similar questions...

Progressive rate springs have a variable spring rate. What this means is that the spring gets firmer as it gets compressed. The harder you push into a corner the stiffer the spring becomes. A specific rate springs features the same rate all the time, it does not matter what pressure is applied on the springs. Progressive rate springs tend to have better characteristics on the street where as a specific rate springs shines on the track. See similar questions...

A television image is created when a device known as the CRT (cathode ray tube) scans a constant stream of electrons across the inside of the picture tube. Each image is created with a series of horizontal lines. In interlaced scanning, the CRT starts with the top line and scans every other line all the way to the bottom of the image. The CRT then returns to the top and scans all remaining lines. This process constructs a complete image 30 times per second. See similar questions...

Progressive" is an political term used loosely to identify activists of the left, favorable to sound and fair economic and social policies, equality of chances, and the defense of personal rights. The European Tribune is broadly progressive, but welcomes all contributors regardless of political self-identification, provided that they be respectful of the mission of this site, provide principled disagreement and don't engage in trollish behavior. (click to see the definition of a troll) See similar questions...

With conventional auto-focusing, auto-focus is driven by electromagnetic force of a DC-motor, gear and shaft mechanism. However, Ultrasonic Oscillation Energy operates the HSM lens and creates high-torque drive. Since this motor has no reduction gears, it has much quicker response to start and stop compared to DC- motor lenses. See similar questions...

The lens is the part of the eye that helps focus light on the retina. The retina is the eye's light-sensitive layer that sends visual signals to the brain. In a normal eye, light passes through the lens and gets focused on the retina. To help produce a sharp image, the lens must remain clear. See similar questions...

A lens implant (intraocular lens or IOL) is a man-made, clear plastic lens approximately 6 mm in diameter which is placed inside the eye at the time the cataract is removed. It replaces the natural lens and remains permanently within the eye. The lens has small spring-like arms called haptics that prevent the lens from moving out of place. See similar questions...

Crystalens™ is an accommodating lens which allows for continuous vision at all distances. In contrast, standard (single vision) lens implants provide vision at a fixed distance and do not have the ability to change. Most people with standard lenses must wear glasses for near vision and may need to wear them for intermediate or arm’s length distance as well. Your ability to see at approximately arm’s length will be greatly enhanced with the Crystalens™. See similar questions...

Variblee rate springs defelct at different amounts per inch. An example would be: 200 lbs. = 1 inch deflection, 600 lbs. = 2 inch deflection, 1000 lbs. = 3 inch deflection, and so on. Varible coils have a soft initial spring rate and a much firmer spring rate to handle more weight, decrease sway, and improve handling. See similar questions...