How often should a gas permeable lens be replaced?
When should you replace a gas permeable lens
There are fewer and fewer gas permeable lens wearers these days but that still doesn't mean gas perm lenses are outdated. But there's a chance that your gas permeable lenses are outdated or deposited or significantly scratched.
How long you keep your gas perm lenses varies from one person to another but my guess is many people keep some old ones laying around just in case and that might be ok. These lenses are pretty durable but still need care when you are using them.
If you wear the older type hard lens then you might even keep yours even longer but that's not the case for most people. It's pretty rare to find someone wearing the old type hard lens called PMMA. Those aren't gas permeable which is why they aren't prescribed by doctors today.
Here are a couple of things to think about when deciding to replace your lenses:
- If your prescription changed enough to make a difference.
- If the doctor says the lenses should not be worn due to a defect like an edge is broken, or if the lenses are so deposited they cannot be cleaned or polished
- Heavy scratches can effect the performance of how well the lens "wets" and perhaps feels.
- The lens fit is not proper and thus may cause some cornea abrasion or other potential problem.
Standard gas permeable lenses may last years but some of the newer lens treatments may eventually breakdown so the lens may not perform as intended. There is a lens approved for overnight wear of up to 30 days that goes through a special process to make it more permeable to oxygen. This is a lens material manufactured by Menicon. If you have that lens you may be able to have that lens retreated if it's not scratched significantly.
Bottom line for replacing should be determined by your eye care professional but if the lens is bothersome or you suspect a problem which is unexplained you should check with your doctor.
But to answer the question about how long these lenses could last? They could last years if treated and cleaned well.
There is a special type of gas permeable lens used in orthokeratology and the replacement schedule for that lens may be more frequent. Some doctors who use these lenses may recommend annual replacement due to a couple of factors. The inner curves are important for the effect and could wear enough to change how a person sees. Also, buildup of protein could compromise the health of the eye and cause corneal damage.
A very important factor in how long any of these gas permeable lenses last is how well they are treated.
Here are a couple of things to remember about caring for your gas permeable lenses:
- Rub the lenses with the proper gas permeable lens solution. There are a couple of brands like Boston, Optimum and Alcon's Optifree GP solution. You may find some generic labels as well. Other solutions that can be used are Clear Care or Sauflon. Be sure to clean the inner most part of the lens where a large fingertip may not reach.
- If you drop your lens on a hard surface check the edges of the lens by holding the lens up towards a light and look for chips. You can also run your finger gently around the edge to feel for a chip.
- When holding the lens up to a light also check for any discoloration of the lens. If you see a whitish or slight brownish deposit then your lens should be cleaned further and probably should be taken to your eye care providers office. The lens may need polishing or a special solution used for removing deposits
- If the lens falls on a hard surface be careful not to slide the lens over the surface. That might scratch the edges of the lens and make it uncomfortable.
When in doubt you should contact your eye care providers office. It's possible there is a problem with the gas permeable lens if you don't see clearly or it could be your eye that's affected.