In the multifocal eyewear industry, most people know that trifocal reading glasses differ from bifocal ones in a third power. A bifocal lens can deal with defected vision at only two distances, while a trifocal lens is capable of providing visual aid at three visual zones. Exactly speaking, the intermediate vision section on a trifocal lens is unavailable in a bifocal lens. Considering presbyopia and nearsightedness compromise, bifocals and trifocals are nearly the same. However, the additional visual help granted by trifocal reading glasses is quite meaningful for a special group of people. In some cases, the intermediate vision is also called computer vision. This actually suggests that the extra vision aid provided by trifocal glasses is closely linked with computer use.
In the recent decades, computer has been an integral part of many people’s lives, including some presbyopic patients in their 50s and even 60s. Computer use is for some people a daily activity. However, the distance between a user’s eyes and the computer screen is different from that of either near vision or distance vision. It is exactly called intermediate vision range. Or it is OK to say that the computer monitor is in the medium visual zone. Without specific vision aid, people can get their eyes easily tired after spending hours on the computer. Computer vision syndrome (CVS) is commonly used to describe the problems caused by excessive computer use with vision aid. Trifocal reading glasses bridge this gap. And progressive trifocal glasses provide more benefits.
In a pair of regular trifocal reading glasses, the lens section for intermediate vision is located in the middle part. The upper section is for distance vision and the lower part is traditionally for reading vision. The reason is that people usually see through the lenses to perform computer tasks in a natural way. Progressive trifocal glasses come in a similar design in the aspect of prescription arrangement. Additional advantages include no visible segment lines and comfortable power transition.
Progressive trifocal glasses provide an additional visual aid for computer work in a similar way as trifocal reading glasses. Improvements include removing visible lines and offering smooth power transition.
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