Refractive index of spectacle lens
It is generally believed that the higher the refractive index, the better the spectacle lens. Such spectacle lenses are relatively thin, and of course, the price is a bit expensive. When the refractive index increases, the direction of the light entering the lens will change greatly, the focus will move to the lens, the focal length will be smaller, and the diopter will become larger. In order to keep the diopter unchanged, it is necessary to reduce the curvature of the lens, that is, to reduce the curvature of the mirror surface, so that the thickness of the lens can be reduced. This is why the larger the refractive index, the thinner the lens is. Under the same premise of other things, the larger the refractive index, the thinner the lens, the lighter and more beautiful the lens, and the higher the price, but the larger the refractive index is not the better.
The advantages of metal frames
Its advantage is that the lens is fixed firmly, not easy to fall off. But the weight of the glasses increased slightly compared to the other frames. Full-frame glasses give people a sense of calm. The frame can cover the thickness of the lens very well, suitable for people with high degrees.
The mission of Harmony Eyecare is to create an unforgettable eye care experience for every patient by providing unmatched customer service, comprehensive patient education, and superior product quality. Providing the highest quality lenses and craftsmanship, their state-of-the-art, the professional lab provides the latest lens technology and generous warranties. There are plenty of options with price designer frames to fit every budget.
Prescription glasses are more comfortable to wear than other glasses for visually impaired people. For example, there exist bulky protective glasses designed to be worn over existing eyeglasses. There are protective glasses with prescription lenses for the visually impaired, for example. You can consider wearing prescription glasses while driving at night. When driving at night with these glasses, you will feel safer and more comfortable. Even if you feel like you're a skilled, capable driver. Driving glasses can be an investment. But that being said, it's better to invest in night-driving glasses now than to pay the price later.
Kirkland Signature™ HD Digital Progressive Lenses
They use the latest lens manufacturing technology to provide high-definition vision at any distance. Giving you sharper vision in all conditions, all lenses have anti-reflection treatment, and they have superior scratch resistance and superior quality. The lenses help provide a greater reading area and less distortion than standard lenses. And they give each lens a cosmetically attractive appearance.
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.
What Is Bifocal Lens?
Bifocal lenses are divided into two parts to accommodate two different prescriptions in one lens. One is for distance prescription and the other is for near vision prescription. Bifocal glasses are used to correct the presbyopia eye condition.
Bifocal lenses are with lines separating two different prescriptions. With bifocals, you don’t get the single-vision lens look with them as you do with progressive lenses. If you don’t need to see through two prescriptions, bifocal glasses are an excellent option. Bifocal glasses come with the following features:
- Two vision zone. (One for near vision and the other one for distance vision.)
- Has a distinct line separating the powers.
However, with bifocal glasses, you may have trouble reading computer screens and causing a greater risk for computer vision syndrome.