At The River’s Edge Optical we know you have many spectacle lens styles available to you. We are the experts and you trust us; we do not take that lightly. Our responsibility is to educate you on the best available options for your spectacle prescription, frame selection and budget. There may be a lot of terminology you are not familiar with when it comes to lenses. Listed below are the current lens styles available:
Single Vision Lenses
Single Vision Lenses, as the name implies, have only one power which can be set for distance, intermediate or near focus. In a younger patient, this lens will actually work for all distances. For anyone requiring a bifocal/multifocal prescription, the lens will be more limited in function as it only has one focus distance.
Bifocal lenses have two distinct powers in the same lens and are used by patients so they do not have to switch between two pair of spectacles. Typically they are used in a condition called presbyopia, in which the eye loses the ability to focus from distance to near. In some cases, even children will be fit into a bifocal if they have a condition where the eye has difficulty focusing from far to near. The bifocal lens has two distinct divisions with the top of the lens set for the distance vision and the bottom for near (reading). In some cases, the top of the lens can be made for intermediate distance (computer) and the bottom for near. The transition point where the two powers meet results in a clearly visible “line”, which is commonly associated with the bifocal. Lined bifocals come in many different sizes and shapes from flat tops, curve tops and round. They even make a blended bifocal, in which the line is less visible. The result is still the same and there are still only two distinct powers in the lens.
Trifocal lenses have three distinct powers and are used for patients that need three working distances in one lens such as driving, computer and reading. Like the bifocal, they are used for patients with presbyopia. The distinction between the two is the trifocal has a middle lens which focuses for intermediate distances. The top of the lens is set for the distance, the middle portion for arms length and the bottom for near (reading). The transition point where the three powers meet result in a visible “line” because the change in powers is immediate. Trifocals, just like bifocals, are available in many different flat top widths.
Progressive Lenses- (Invisible Multifocal)
A progressive lens is the most commonly used lens today for patients that require a lens that provides distance, intermediate and near powers at the same time. As with the bifocal and trifocal, it is used to correct Presbyopia. But unlike the latter two, it does so with a lens design that has no visible lines. The way this is achieved is that the change in power is progressive rather than abrupt. The advantages to the progressive is that it offers all distances in one lens in a cosmetically appealing way.
Digital Progressive Lenses
The most advanced technology in lens design is the digital progressive lens. Recent advances in lens manufacturing and computer-controlled surfacing equipment have made possible new high definition eyeglass lenses that correct for aberrations in the lenses made the traditional way. These lenses are designed to provide sharper vision in all lighting conditions with wider viewing areas for the wearer than traditionally designed progressive lenses.
Computer Lenses- Near Variable Focus
The near variable focus lenses are the most common computer lenses we use today. They are designed so that the top of the lens is used for view across your desk, middle part of the lens is intermediate distance (computer) and the bottom of the lens is for near (reading). The lens does not have any visible lines similar to the progressive above. The near variable focus lenses are solely intended for close work or desk work and are not to be used for distance viewing. The advantage of this lens design is that the patient can look straight ahead at a desktop computer without having to tilt their head back as they would in a bifocal, trifocal or progressive lens.
Double Bifocal / Quadra focal
The double bifocal is a lens design that has two bifocals built into the lens. One is inferior and the other is superior. It is used by patients that require both a distance and near power, but also require to read up above their heads, such as an airline pilot reading the gauges overhead. The Quadra focal lens is similar to the double bifocal listed above with the exception that a flat top trifocal is used on the bottom portion of the lens and a flat top bifocal is used on the top. This allows the patient when looking down to have both intermediate and near vision, straight ahead to have distance vision and when looking overhead to have reading vision.