What are Multifocal lenses?
Technically multifocals refer to all lenses with two or more focal distances. For example: bifocals, trifocals and progressive lenses all fall within this group of lenses. In South Africa we refer to progressive lenses as multifocals or varifocals. So if you hear your Optometrist talk about multifocal or varifocal lenses it means the following:
Progressive lenses are line-free multifocals that have a seamless progression from far to intermediate and near viewing distances
Until recently multifocals have been associated with a lengthy adjustment period due to peripheral distortions. Great strides have been made with progressive lens designs and these days it should only take a few days to get used to them. With complicated or high prescriptions it may be a bit more challenging but shouldn’t take longer than 3 weeks.
Free Form Progressive Lenses
Free form is a computer aided design and manufacturing process. With an extremely accurate calculating system, the lenses can be customized according to the size and type of prescription as well as the frame dimensions and fit. The result is less peripheral distortion which means a wider field of view and quicker adaptation.
Office Multifocal Lenses
Progressive and Bifocal wearers have to lift their heads about 20 degrees when they are working on a computer because they must use the intermediate and lower lens areas. This may cause neck and shoulder pain as well as eye strain. Single vision wearers don’t have this problem but are limited with regards to the focal or working distance of the glasses.
To solve this problem, intermediate to near “office” lenses were developed. These lenses have a wide intermediate area in the upper half of the lens and a wide reading area at the bottom of the lens. Two options of intermediate vision are usually available: computer distance or slightly further then the computer. This allows the wearer to have a natural head position when working on the computer as well as more flexible viewing distances than single vision reading glasses.
A new lens has been developed by BBGR called, Progressive Indoor. This lens has a wide computer field of view as well as distance and reading vision. It differs from a traditional multifocal in that the computer screen area on the lens has the widest field of view where the distance and near vision fields are narrower. A traditional multifocal has wide distance and near fields with a narrower computer field. With this lens your computer vision will be comfortable all day and you will also be able to view presentations, walk around the office with your glasses on and read documents.