Having a difficult time reading the restaurant menu? Newspaper print looking a little small? As we age, many people develop something called presbyopia which makes it harder to see things that are close to us. Corrective lenses are the best method to combat the results of presbyopia. However how do you understand which type of lenses is right for you?
Bifocal Lenses
Bifocal lenses have actually been around given that the late 18th century and were produced when Benjamin Franklin cut two lenses in half (each with different corrective powers) and glued them together. Modern day bifocal lenses are still comprised of two parts. The top of the lens is made for seeing things at a distance, while the bottom part of the lens is produced viewing things close up, making concentrating on books or menus much easier. The two areas of the lens are typically separated by a visible line. The segment of the lens committed to fixing near-vision can be in several shapes including a half-moon, a round sector, a narrow rectangular area, or the full bottom half of the bifocal lens.
With just two zones of vision, bifocal lenses do not account for the intermediate zone of vision. Because this intermediate watching area has to do with 18 – 24 inches from the face, it can be hard to view things like a computer screen while using bifocal lenses.
Trifocal Lenses
In an effort to remedy the problem of doing not have an intermediate watching area, trifocal lenses were developed. Trifocal lenses use correction for near and far vision, however also allow a person to see clearly at an intermediate level (about the length of your arm). Trifocals help remedy the intermediate zone by including a 2nd little lens segment directly above the area used to correct near vision. This leads to a total of 3 power zones, hence the name trifocal. This intermediate sector permits the user to better see things like the computer or the car instrument panel on the control panel. Similar to bifocal lenses, trifocal lenses also include noticeable lines on the lenses.
Progressive Lenses
With no visible lines on the lens, progressive lenses provide a smooth shift from distance through intermediate vision to near vision. Progressive lenses also use vision correction for all the in-between vision zones. So rather of just having two or three different seeing zones, progressive lenses use vision correction that advances in power from the bottom to the top of the lens. This progression of correction eases eye strain by providing the most natural vision correction. Some people also call these no-line glasses or no-line bifocals.
Modern innovation has continued to enhance the style of progressive lenses. Some progressive lenses on the market today, like Varilux lenses, are now designed to represent the difference in prescription for both the right and left eyes. These lenses likewise help minimize blurred peripheral vision, which can be evident in other progressive lenses and cause motion sickness.
If you think you are experiencing presbyopia or any other vision issues, talk with your eye doctor about which lenses are right for you. You have an option!