Bifocal lenses contain two distinct optical powers in one spectacle lens, usually for distance and near vision. They are a traditional way of correcting presbyopia when distance correction is also needed.
Design
The upper part of the lens is set for distance, while a visible segment at the bottom provides near power. Wearers look through the appropriate portion depending on the task.
- Segments can be round or D-shaped, with various sizes
- The dividing line is visible but often becomes less noticeable with use
- Intermediate distances such as computer screens may not be optimally covered
- Lens coatings and materials can be chosen to reduce weight and reflections
Advantages and Considerations
Bifocals offer clear distance and near zones without the peripheral distortions seen in some varifocals, but they do not provide a continuous range of focus. Some people prefer or adapt more easily to this clear separation.
- Particularly helpful for tasks requiring quick switching between near and distance
- May be less suitable for frequent intermediate work unless designed accordingly
- Driving and steps should be approached with care while adapting
- Regular review ensures segment height and powers stay appropriate
