transition glasses are also called photochromic glasses. Their lenses are composed of a special compound product that automatically adapts and changes at varying light levels. Using photochromic technology, transitions glasses have the capability to detect lighting conditions such as being indoors or outside in bright, direct sunlight. The lenses within a pair of transition glasses will be clear when worn indoors and quickly become darker when outdoors to shade and filter out ultraviolet rays. Here are some helpful tips on how to buy transition glasses. 1. Determine your usage needs and under what conditions you will be wearing transition glasses. 2. Research the different types of lenses available for transition glasses. Although many styles require a prescription there are also some types of transition glasses available without a prescription. 3. Realize that some types of transition glasses will provide better shading when driving than others. The reasoning for this is due to the fact that most windshields on newer model vehicles are tinted and have the capability to block out some of the sun's harmful ultraviolet rays. 4. Consider transitions glasses if you wear regular glasses during your workday. This would be a good option if you like the convenience of wearing just 1 pair of glasses for reading when working at your desk and shading from bright sunlight when you are outside. 5. Understand that there are transition glasses available for individuals with special needs due to increased sensitivity to sunlight as a result of illness or medication. Transitions glasses can provide protection against ultraviolet rays as well as decreasing levels of sensitivity. 6. Recognize that transitions glasses are available for individuals of all ages including children and young adults. If you have children that wear regular glasses, transition glasses would be an option to provide protection both indoors and outside. 7. Do some comparison shopping for transition glasses by visiting several stores or eye care centers. Try on different styles and types so that you will make an informed purchase and select the right type for your needs. Sources: http://www.wikihow.com/Buy-Transition-Glasses
A good pair of transition eyeglasses should turn dark completely within 40 seconds when they are exposed to UV light directly and can fade back to half clear within 2 minutes as soon as they are away from UV light. The photochromic lenses should be completely clear without any color tint when they turn clear completely. What's more, The two photochromic lenses should have the same state in color and there is no bubble and flaw in the lenses. A good pair of transition eye glasses can benefit you a lot. Hope you choose a good one.