Replacement schedules range from every single day to twice yearly. Lenses for astigmatism, bifocals and eye color change are available as disposables. Disposable lenses are thinner than most traditional lenses, and allow more oxygen to reach the cornea. They, in general, are better for eye health for a variety of reasons. These include:
- The risk of infection is greatly reduced by having clean, sterile lenses on a more frequent basis.
- Lens cleaning is much easier, so less solution is needed.
- If lenses are lost or torn, replacements are readily available.
Daily wear lenses are designed to be removed from the eye every day. They are NOT designed for overnight wear. Both disposable and traditional soft lenses may be designated for daily wear.
Lenses that are FDA approved for overnight wear are termed "extended wear". These lenses must be used with caution, because what an individual eye will tolerate varies, and the risk of complications is higher. These lenses must still be removed on a regular basis. Extended wear lenses are designed for traditional wear and disposable replacement.
Toric lenses are available for patients who have astigmatism and cannot achieve acceptable visual outcomes from spherical soft lenses. Toric lenses have astigmatism correction built into the lens that "offsets" the "football" shape of a cornea. These lenses are available as disposable and traditional types, and are even available in colors.
RIGID GAS PERMEABLE
Also termed "RGP", these lenses are made of firmer plastics than soft lenses, and have many benefits. The adaptation period for these lenses is typically longer that what is required for soft lenses, but RGP's also usually provide very crisp vision, and high oxygen availability to the cornea. Patients with astigmatism who aren't suited for soft toric lenses and those with corneal irregularities tend to do very well with these lenses.
Monovision is a fitting technique that can be used with any lens type for those people who need a bifocal in their glasses. A patient's dominant eye is fit with a lens for full distance vision, and the other eye is fit with a lens for near vision. This option can be especially successful for patients who are just beginning to experience near vision changes.
Multifocal lenses can be an option for patients who aren't satisfied with the visual outcome of the monovision fitting technique. Because the lens for each eye has correction for both near and distance vision, in many cases the eyes blend better as a team, and visual function can be more comfortable.