Spectacle Lens Designs
How Spectacle Lens Designs Help Your Eyes
Single Vision Lenses
- When Were They Invented: Thought to have been created as early as the 5th Century BC, single vision lenses were used primarily to magnify images close up. The first mention of lenses used to correct distance vision problems was in 60 AD. This lens was used to view gladiator competitions by a Roman Emperor. Over a thousand years later, the first lens was invented to correct astigmatism by an optician in Philadelphia. Astigmatism is a very common eye condition that requires single vision corrective lenses. Up until the early 1800’s, one suffering from astigmatism had no hope of clear vision.
- What They Are: Single vision lenses are lenses that have been fabricated to correct vision for focal length; either for objects close up, far away or at any specific focal length.
- What They Are Used For: Single vision lenses are used to correct one focal distance problem. Whether worn for correcting blurry distance vision (myopia or nearsightedness), blurry near vision (hyperopia or farsightedness) or fabricated to correct for blurry intermediate distance (about arms length), these lenses can only be produced to address one visual prescription and can only address one visual distance or focal length.
- When Were They Invented: Late 1700’s by Benjamin Franklin as most assume – however, Samuel Pierce is thought of to have produced bifocal lenses at the same time as Mr. Franklin or even several years prior.
- What They Are: Bifocal lenses are used to correct up to two focal distance problems. The most common correction is located in the upper portion of the lens for distance vision and the lower portion of the lens for near vision. The distance portion of the lens has a different lens curvature than the lower portion of the lens that corrects for near vision. At the point where the two curves meet a line is formed. It is this line that coined the term “lined bifocals”.
- What They Are Used For: Bifocal lenses are most commonly used for patients that are either farsighted or nearsighted and develop presbyopia. Presbyopia is an age-related visual condition that occurs naturally around the age of 40. Patients start to find it difficult to read, especially small type. Patients who were either nearsighted or farsighted and previously wore single vision lenses, now need bifocal lenses to correct their previous condition as well as their new condition, presbyopia.
- When Were They Invented: It is documented that trifocal lenses were not commercially available until just before the 1940’s.
- What They Are: Trifocal lenses provide visual correction for three distinct focal distances; the top portion of the lens corrects for distance vision, the middle portion of the lens corrects for arms length distance vision and the lower portion of the lens corrects for near vision (closer than arms length). Like the bifocal lens, the trifocal lens has a visible line where the various focal length curves meet. Unlike the bifocal lens, which has one line between the distance focal length and the near focal length, the trifocal lens has two lines. One line is between the distance and intermediate focal length and a second line is between the intermediate and the near focal length. (insert pics – Bifocal and trifocal lenses with the lines shown). These 2 lines can cause a visual jump of images and adjustment to this can be difficult.
- What They Are Used For: Trifocal lenses are used for patients who previously wore bifocal lenses for early presbyopia. As the patient approaches their mid-sixties, not only do they need correction for near- and far- sightedness, but they also need additional correction in order to see clearly beyond reading, i.e. at arms length to see the computer or read a car’s speedometer.
Progressive Multifocal Lenses
- When Were They Invented: Invented by a french engineer in 1959, the progressive multifocal lens was first commercially available in the early 1960’s. This new lens offered many advantages as the design eliminated the “line” associated with bifocals and trifocals. More importantly, the progressive multifocal lens eliminated the perception of image jump which is most commonly associated with the abrupt change in prescription from distance to near correction in lined bifocals and trifocals. The other distinct advantage of progressive lenses was variable focal length correction. This allowed users to see images clearly at virtually any focal length versus a bifocal lens that only allowed two focal lengths (near and far) or trifocal lenses that allowed only three focal lengths (near, intermediate and distance).
- What They Are: Progressive lenses are a true multifocal lens which allows the wearer, who requires various corrective prescriptions for near, far and in between, to have one lens with varying corrective powers. The lens enables the wearer to see clearly at any distance, near or far and every other focal distance in between, all with one sophisticated lens design.
- What They Are Used For: Progressive lenses are perfect for any wearer that has presbyopia. Whether that be a 43 year old who has had problems seeing in the distance and now finds it difficult to read, or the 80 year old who has problems seeing in the distance, seeing the computer screen at arms length and reading the fine print on a medicine bottle. These lenses are advanced and take time to learn how to use, but they are truly a technological advance over the older technologies and science behind bifocal and trifocal lenses. In recent years, specialty progressive lenses have been developed for task-specific uses. For example, computer lenses utilize progressive lens technology for the specific focal distances when working on a computer. This particular lens design is worth mentioning because it has an adapted design specific for work functions revolving around the use of a computer. The lens allows the wearer to have optimal vision at arms length (typically the distance at which the computer monitor is set up on a desk), with the lower portion of the lens specifically designed for closer than arms length use. The typical application is to have the majority of the lens designed for computer distance and the lower portion of the lens designed for reading. This particular application allows the wearer to see the computer screen clearly while also allowing them to read clearly at close range (typically about 12 to 16 inches).
SOLA Access Lens
The Computer Solution
Computers users primarily need two clear vision ranges
- Intermediate to see screen
- Near to see keyboard
Access provides only these vision ranges and because of this the viewing zones are the largest possible
- Less head movement
- More comfort
- Less fatigue
- Access “frees” you from the limitations of current reading glass solutions
- Provides up-close and intermediate viewing zones
- See clearly and comfortably out to 7 feet
- Made to each patients prescription and PD
- No more compromises means freedom for the patient
- Smooth continuous viewing up to 7 feet, no lines
- Hold your reading materials where comfortable
- See and feel better
- There are many specific hobbies and occupations whose primary viewing zones are less than 7 feet
- Using the Access Lens the patient will feel more relaxed and be able to function more effectively because they are not battling limited vision when participating in these hobbies and/or occupations
The SOLA Access lens design provides the wearer with clear vision over the full near vision range. This means that the wearer will have the ability to read and view a keyboard clearly as well as look across their desk at a computer screen or person sitting across from them. This is why SOLA Access should be your first choice for all patients who want the best near vision lenses.