In the previous article, we discussed “Why should pilots not wear polarized sunglasses?”. In this article, let’s talk about “Which are better bifocal or progressive lenses?”.
Single Focus Lens
Single vision is the most commonly used prescription lens. This lens type has a single field of view or a prescription ability of the entire lens and can be used to correct myopia (nearsightedness) or hyperopia (supervision). Some people need glasses to keep their distance and read. Instead of having a pair of single-vision glasses for each pair of glasses, bifocal or progressive glasses may be a more convenient choice. Unlike single vision, bifocal and progressive lenses are multifocal lenses with multiple focal points, such as distance and near distance. People whose prescription for spectacles list the numbers in the 'ADD' section require bifocals, progressive glasses, or reading glasses because your glasses need to add ADDitional to the distance prescription to see close distances.(https://www.koalaeye.com/collections/progressive-glasses)
Bifocal lenses have two observation areas separated by visible lines, a larger observation distance area, and a smaller reading area. It may take some time for people who are wearing bifocal glasses for the first time to get used to the lenses. This is mainly due to learning how to move the eyes between the observation distance area and the reading area. Some people will also find that there will be an 'image jump' phenomenon at the visible line between the distance and the reading area, especially for those with limited mobility, who must look down when walking. The best way to get used to bifocals is to wear them as much as possible.
Standard progressive lenses are multifocal lenses with three observation areas, farsightedness, intermediate vision, and nearsightedness. Unlike bifocals, there are no visible lines between each viewing area. They have a seamless, invisible design, where the optical power changes 'gradually' throughout the lens. Many people confuse 'bifocal' or 'trifocal' with 'progressive' but remember that bifocals and trifocals have visible lines in the lens, while progressive lenses do not. Because progressive lenses have no lines in the lens, they are more popular multifocal lenses than bifocal lenses.
The main observation area of the progressive lens is a far distance, the smaller area at the bottom of the lens is used for myopia, and the middle area in the middle is smaller. Standard progressive glasses are very suitable for general purpose glasses, focusing on hyperopia activities (such as driving and walking) and sufficient area in the lenses for nearsighted activities (such as reading and computer use). The left and right sides or 'convex corners' of the lens are deliberately blurred to achieve an invisible design. The clearest line of sight in the gradual process is from the center to the top of the lens.
People who wear new advanced glasses usually have an adjustment period. For novices, please gradually adapt to the glasses. In the first 2-3 weeks, increase the wearing time every day to adapt to the lens. For example, wear it for 1-2 hours on the first day, then add 2 hours a day until you feel comfortable. Before driving, please try it at home. Remember, you need to turn your head and move your eyes to find the 'sweet spot' for the activity you care about.
For experienced wearers, even under the same prescription, a new incremental pairing is required, and some adjustments are usually required. Progressive lens design, frame shape, and many other factors will also affect the adjustment time.
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