When discussing soft contact lenses, permanent lenses (if they still/ever existed) are a thing of the past and are not better than temporary lenses in any way.
But let’s define what we’re talking about a little better. The terms ‘permanent’ and ‘temporary’ are not terms commonly used in the contact lens industry. In fact, they are not used at all.
By permanent, if the thinking is a lenses that you continue to wear indefinitely, without ever replacing them for new ones, these types of lenses went extinct with the dinosaurs. The longest replacement soft contact lens I can think of in recent history was a yearly replacement. But even that was ages ago. Soft contact lenses that were made to last longer than 1 year either never existed, or existed so long ago that I’ve never heard of them.
If the term temporary lens is used to refer to a lens that is replaced at regular intervals, these are typically referred to as yearlies, quarterlies, monthlies, bi-weeklies, or dailies, depending on their design and intended usage.
There is a reason why contact lenses are now being made to be replaced on a more and more frequent basis. Here are just some of the main reasons:
The more often you replace a contact lens, the more comfortable the experience. Lenses that you re-use day in and day out, become less and less comfortable as the lens accumulates deposits that cannot be cleaned off, and as the surface smoothness wears down. A lens fresh out of the pack is always more comfortable than a lens that’s been worn for a month or longer.
The most common way contact lenses get contaminated is during the handling, cleaning, and storing process. Lenses that you re-wear for a long period of time are lenses that you’ve handled many many times, and as they age, become increasingly more likely to become contaminated. This depends on proper hand washing before touching the contacts, proper cleaning and rinsing technique, having the proper cleaning solution, the cleanliness of the case, etc. But a daily contact lens that is fresh from the sterile packaging, and that is thrown away every day, almost completely circumvents the risk of contamination.
Lenses that are replaced on a daily basis are immensely more convenient as you do not have to spend any time cleaning and storing the contacts. You also don’t have to worry about you cleaning solution stocks, and if you’re travelling, you can just bring as many lenses as you need, and leave behind that case and big bottle of solution.
Another convenience factor is that it mitigates the downside of losing a lens. If you were wearing a yearly lens and lost it for some reason or another, I imagine you’d be pretty inconvenienced. On the flip side of that, if you’re wearing a lens that is thrown out daily and you lose a lens, it’s really no skin off your back.
For all the reasons above and more, contact lens manufactures are shifting increasingly towards shorter and shorter replacement times. In certain markets, contact lens wearers wear almost exclusive daily lenses. In others places, monthlies are still the dominant modaility.
For soft contact lens wearer, it is not recommend to be in a lens that is designed to last more than a month before being replaced.
Hard Contact Lenses
There are contact lenses that are still being worn today that are designed to replaced every year or more, and they are called hard contact lenses or rigid gas permeable (RGP) lenses. These lenses have very limited use today as the advances in soft contact lenses have rendered them almost obsolete. However, if you happen to have a very complex prescription, or an eye condition called keratoconus, RGPs may be your only option for contact lenses.
Ortho K Lenses
Another type of contact lenses that are not designed to be replaced frequently are lenses called Ortho K (OK) lenses. These lenses are worn for a different purpose than soft contact lenses or RGPs. They are worn overnight instead of during the day, and their purpose is temporarily change your prescription.
When you wear Ortho K lenses, it causes a temporary change in the shape of your cornea. This change neutralizes your nearsightedness temporarily. The strength of your nearsightedness will determine the length of the effect of the Ortho K lenses. If your prescription is very small, you may only need to sleep with your Ortho K lenses every 2nd or 3rd night to maintain the effect. If you have a strong prescription, you will have to sleep with them every single night.