EYE GLASS LENSES, COATING & TINTS
Sharing our expertise so you can make the best choices
Types of Eye Glass Lenses
Lenses can be designed to help people see at various distances. It’s important to know your options so you can make the right choices about your lenses.
Single Vision Lenses
Amongst the different types of eye glass lenses, single vision lenses are designed to help people see at one viewing distance. This is the most common type of lens used. A single vision lens can be used to help with either nearsightedness or farsightedness, but it cannot do both simultaneously.
These lenses are designed to help people see at two viewing distances. They are designed with a smaller reading area (good for reading books, magazines, prescription bottles, newspapers), usually in the shape of a sideways ‘D’ near the bottom of the lens. Above this segment is the distance viewing portion. Bifocal lenses do not correct for an intermediate/computer viewing distance (50-60cm). If you are having troubles with this intermediate area, a Trifocal or Progressive Lens may be a better option for you (discussed below).
In addition to offering a viewing area for both near and far objects, the trifocal lens offers clarity for intermediate distances as well (50-60cm). This intermediate area can include computer screens, the dashboard of your car or viewing items on a grocery shelf. Each of these different viewing zones is demarcated with a visible line on the lens.
This is another type of eye glass lenses that offers clarity for your full visual range, all distances including intermediate, near, and far. However, unlike Trifocal lenses, there is no line demarcating the different viewing areas. Instead, they offer a smooth transition for focusing on objects in the distance to nearby objects. A gradual change in lens power occurs allowing clear distance vision through the top portion of the lens, clear intermediate vision through the middle portion of the lens, and clear near vision through the lower part of the lens.
Computer Vision Lenses
These types of eye glass lenses are specialized to relieve eye strain, vision blur, redness, and other symptoms of discomfort associated with computer use. With the increased amount of time spent working and relaxing in front of a screen, they are designed to correct your vision for an intermediate distance (50-70cm away) and can be combined with a ‘blue blocking’ lens coating (ideal for regular computer use). Another option are computer progressives (AKA an office lens), where the top of the lens is for computer use and the bottom of the lens is for near use (reading or looking at the keyboard).
These lenses are designed to have a flatter curvature compared to conventional lenses. This makes the lenses have a slimmer profile while reducing distortion created from not looking through the center of the lens. This results in better peripheral vision by widening your field of view. These lenses are a great option for patients with stronger prescriptions for farsightedness and nearsightedness because they reduce the magnification and minification effects created by such prescriptions. The magnification effects created by a strong farsighted prescription lens can create a “bug-eyed” look on the wearer.
High Index Lenses: These lenses are designed to be noticeably thinner and lighter compared to glass, CR-39 (hard resin), and other plastic lenses. They allow the wearer to avoid having “coke-bottle” lenses. There are different types of high index lenses, most of them are classified by a number. In general, the higher the number, the thinner and lighter the lens is. Aspheric + High Index Lenses: Combining these two lens options creates a lens that is noticeably lighter, slimmer, and thinner.
High-Index includes 1.60, 1.67, and 1.74. These lenses are thinner than mid-index, glass, or plastic lenses.
Mid-Index includes 1.54, 1.56, and 1.57. These lenses that are thinner than glass but not as strong as CR-39.
Polycarbonate Lenses: These lenses are thin and light with enhanced impact resistance compared to plastic lenses (10x more). They are commonly used in safety eyewear, sports eyewear, and children’s lenses. However, they can scratch easily therefore a scratch-coating is advised.
Coatings and Tints