Depending on the individual’s vision and type of work, there are several options the type of lenses for computer glasses. Single vision, bifocal, trifocals, and progressive lenses are the main types of lenses prescribed for computer glasses. Most often, a separate pair of glasses is needed for computer work, in addition to the patient’s dress glasses (general purpose glasses).
Single vision glasses provide the appropriate correction for the working distance between the screen and the computer user’s eyes. This option allows users to have the same power the whole way across the lens and the whole screen can be seen with a minimum head movement. For presbyopic patients, the disadvantage of this option is that both distant objects and reading materials that are closer than the computer screen will appear blurry. When they look up, things at distance are blurry and when they want to read small print, they cannot pull things closer to see because the lenses only focus at armslength.
Bifocal glasses can be prescribed so that the focus of the upper part is set for the distance of the screen (armslength) and a lower area is set to focus at the regular reading distance. The disadvantage of this option is that distance is blurry. If distance viewing is desired, the computer bifocals must be removed and those who need a correction for distance will need to put on their regular glasses.
Trifocal lenses have the top part for distance, the bottom part for near vision, and a third for armslength (sits above the bottom part). The disadvantage of using trifocal lenses the small viewing area of the trifocal and the need for head movement.
Progressive lenses have basically the same three distances of focus as a trifocal, but there are an infinite number of focus points in between each of them. The disadvantage of progressive lenses is the distortion in peripheral vision (where they eliminate the lines), a small intermediate area, and a lot of head movement is required to use the lenses.
Occupational lenses or readables (the Sola Access or the Zeiss Business, Shamir Office, Essilor Prio) that are a modified type of progressive lenses work the best for presbyopic computer users. They have three different zones of vision. The center is the largest and focuses the computer distance. If the chin is raised slightly and reading material is pulled closer, there is a comfortable power at the bottom for smaller print and focuses at the regular reading distance. If the head is dropped and the patient looks out through the top, the lens focuses out to about 10 feet, room-type vision. They do not have the lines blurred out and there is no distortion off the side.
They address all of the disadvantages of the other types of lenses and are the most functional lenses. Most people working on computers need to focus at many distances for other tasks while doing their work. They are not intended for driving because they do not have a true distance focus in the lens. Distance viewing would require removal of the computer glasses and looking at distance without glasses or with the general use glasses.
If two pairs of glasses are not an option, there are clip-on magnifiers available that clip-on like clip-on sunglasses. Also, there are frames available that have a magnetic sunclip. It is possible to buy a second clip that has the armslength correction in it to focus on the computer. Caution should be used concerning buying ready made magnifying or reading glasses off the rack in stores to use as computer glasses. The perceived advantage of buying off the rack is price. The problem is that they are single vision lenses (they correct the vision at only one distance), the correction is exactly the same in each eye (few people have the exact same correction in each eye), and there is no option available for prism, a tint, a UV coating, and an anti-reflective coating.
There is no one type of computer glasses that fits all or is the best for everybody. Visual ability, personal preferences of the computer user, the type of work, the distance between the computer user’s eyes and the monitor, and lighting in the workplace are all factors that should be taken into consideration when selecting and prescribing computer glasses. Each of the options listed above can be beneficial for computer users, if properly fitted and corrected maximally. It is very important that the selection of computer glasses is made based on consultation with an eye doctor (optometrist or ophthalmologist) who is knowledgeable with occupational lenes..