All About Contact Lenses
What are the most common types of contact lenses?
There are a lot of different contacts. They basically fall into two categeories. Hard lenses or gas permeable lenses (is the official term) and soft lenses. Soft lenses are bigger and they tend to be flexible. You can fold them in half with your fingers. The hard lenses are rigid. If you fold them in half they will actually break. They will crack. Each has their own advantages and disadvantages.
What are the advantages or disadvantages of soft contact lenses?
Soft lenses are considerably more comfortable than the gas permeable kind for a lot of people. Also, with soft lenses you can often get a disposable lens, so you can open a new lens in the morning, put it in your eye, throw it away at bedtime. Then you never have to clean lenses, store lenses, have a lens case or lens solution. It is very convenient in terms of comfort and ease of life. Soft lenses have their drawbacks. Compared to a gas perm lens, a soft lens has a higher risk of causing an eye infection although that risk is still very low. Soft lenses often are not as good in people who have dry eyes because they tend to suck up moisture. Soft lenses often don't provide quite as good a quality of vision as the gas permeable lenses particularly in people with higher levels of astigmatism.
What are the advantages or disadvantages of hard contact lenses?
Hard lenses have several of their own advantages and disadvantages. The advantages are, generally, very good quality vision. Also they are very useful if you have certain hereditary conditions that cause distortions of the eye, because their hardness can flatten the eye out and reshape it. Hard lenses can actually be used to temporarily correct near sightedness in some people; while you are sleeping overnight it flattens the eye out and then you can see without it during the day. Hard lenses tend to be better in people who have significantly dry eyes because they suck up less moisture. Now, they have their disadvantages as well. Hard lenses are definitely less comfortable for most people then soft lenses, and they can crack or break. They also tend to be more expensive so if you lose one it's a bigger hit out of pocket. Hard lenses aren't disposable so that means you need to have solutions to clean them, solutions to store them, a lens case, and a pair of glasses if the hard lenses are not working properly and bothering your eyes. So, you need more paraphernalia if you are a hard lens wearer. Another disadvantage of hard lenses is that they tend to mould your eye into a slightly different shape while you wear them, so when you take them out your eye surface is slightly distorted which changes your vision. When you put your glasses on your vision is not quite clear; you call this 'spectacle blur'. Then, over the space of ten or twenty minutes or an hour the eye bounces back to the correct shape and your vision's clear again. In the meantime things can be a little bit blurry.
Can I wear contact lenses if I need bifocal vision correction?
If you are over the age of forty and need bifocals, you can get bifocal contact lenses. Either bifocal soft lenses or bifocal hard lenses. They give you good far away and good up close vision.
How long should I wear my contact lenses?
Contact lenses can be taken out every night. We call that daily wear lenses - you wear them for the day. Alternatively, certain kinds of contacts can be slept in overnight. We call those extended wear, because you can wear them for a week, or sometimes even two weeks. Disposable contact lenses are very convenient. Open a fresh pack, put it in in the morning. At night before you go to bed, pop them out and throw them in the trash.
What are the advantages or disadvantages of daily-wear lenses?
What makes a lense a daily-wear lense is it doesn't allow as much oxygen to the eye as the extended-wear types. At night when you close your eyes, your eyes are no longer exposed to the oxygen in the air and so the amount of oxygen in your eyes goes way down. A contact lense is a further barrier to your eye getting oxygen if you sleep with it on. The extended wear lenses are made to be very oxygen permeiable, so they let a lot of oxgen through. Daily wear lenses generally are not. So, it is very important that when you are wearing a daily-wear lense that you don't go to sleep or close your eyes much, because that will really deprive your eye of oxygen. If your doctor's prescribed daily-wear lenses for you, don't sleep in them. Don't have a few beers and fall asleep on the couch overnight, get your lenses out befor you go to sleep.
What are the advantages or disadvantage of extended-wear contact lenses?
The advantage of the extended wear is you don't have to hassle with them as often. You put them in, you forget about them for a week, and then you take them out. The disadvantages though is that they can be less comfortable because as the week goes on some proteins can build up on the lenses. And more importantly, extended-wear lenses increase your risk of getting a serious eye infection. Whenever you sleep in a contact lens, you're increasing your risk of getting an infection or your cornea and those can be very serious, and on rare cases even blinding. And so my recommendation is, if possible, avoid sleeping in your contact lenses. Avoid extended-wear lenses unless you really have a good reason for taking extra risk of an eye infection. The kind of people who may want to wear extended-wear lenses are people who work all night sometimes. For example, maybe you drive all night, or perhaps you have irregular hours and it's hard to get the lenses in and out, or maybe you're woken up in the middle of the night for emergencies and need to be ready to go. If you like camping or you're going to be out in the wilderness for a while and don't want to hassle with your contacts, extended-wear lenses could be a good option for you.
What are the advantages or disadvantage of disposable contact lenses?
Disposable lenses are very convenient for a lot of people because you open a fresh pack in the morning, put it in your eye, and at at the end of the day or night, you take it out and throw it away. You don't have to clean it or mess around with solutions or cases. Now, disposable lenses are not made to be slept in. So the thing to do, at least generally is when it is bedtime, take it out and throw it away. Don't sleep in them unless your doctor has instructed you otherwise. The disadvantage of disposable lenses is they are more expensive and they don't correct astigmatism. So if you have astigmatism, you may find your vision with disposable lenses just isn't good enough.
What are "frequently-replaced lenses"?
Frequent replacement lenses are lenses that are designed to be replaced more frequently, funnily enough. That gives you a fresher, more comfortable lens, more often. The frequent replacement lenses are sort of intermediate, a little more expensive than the long term wear lenses, but cheaper than the disposable. But, they are also a little more intermediate in terms of comfort because you don't have a fresh lens every day, they may not be quite as comfortable, and they are intermediate in terms of maintenance because you have to take them out and clean frequently-replaced lenses everyday.
What should I do if I experience pain or discomfort because of my contact lenses?
If you're a contact lens wearer and you develop pain or irritation, that's serious, because any kind of contact increases your risk of developing serious eye infections. The first thing to do is get those lenses out and don't put them in again until your eye is comfortable. After you take the lenses out, the discomfort may last for an hour or two, but then it should go away. If it persists longer than that, there's more possibility that you've got an infection. Get yourself to an eye doctor or an emergency room as quickly as you can when experiencing discomfort.
Why is oxygen important for eyes?
Oxygen is important to the eye because it's the main defense against eye infections. So when you deprive the cornea of oxygen you're really increasing your risk of an infection.
How often should I clean and disinfect my contact lenses?
There's different ways to clean and disinfect the lense. There's a variety of different solutions that can do it, and the important thing here is to follow your eye doctor's recommendation. Most people get in trouble, by trouble I mean serious eye infections, because they're not following their doctor's recommendation. So there's not one solution that's necessarily better than another or one product better than another, but the important thing is how you use the products. And there's a couple tips that can really keep you out of trouble. One is, if you have a lense case with solution in it, you should dump that solution out every day and put fresh solution in it every night. Even though it's a litte more expensive to change it every day it reduces your risk of an eye infection. During the day leave your case open and let the wells dry out. Because drying out the case kills any germs that were left in the case from the night before. Finally, when you take your lens out of your eye, don't skip the cleaning step. The cleaning step involves putting a liquid on the lense and rubbing it between your fingers. That helps take off a lot of buildup, of protein, other materials and bacteria. Getting rid of that material helps the disinfection work better. So the bottom line is, follor your doctor's instructions and stay out of trouble.
Can contacts lenses cure near-sightedness?
There's a practice called orthokeratology, in which hard contact lenses or gas permeable contacts are used to reshape the eye. It's almost like squeezing a size eight foot into a size six shoe. If you do that for long enough your foot will become squeezed into a smaller shape, your toes will turn inwards. We use the same principle on your eye, by intentionally misfitting a contact lens to your eye, the doctor can cause the eye to temporarily change shape. Then, when you take the lens out, your vision is good, you can see far away again, your near-sightedness is temporarily corrected. It's a way of correcting near-sightedness for people who don't want to have laser surgery. Now unfortunately it's got some disadvantages, the main one is that it's temporary. So, every day you have to wear the contacted lens that's called a retainer lens, to hold your eye into the new shape. If you skip it for a day or two your eye goes back to the way it was. The other disadvantage is that it tends to be a little less comfortable, because these lenses are intentionally misfit. It's like wearing a shoe that's not quite the right size. There's also a limitation in that they can only correct small degrees of near-sightedness. So, if you're nearsightedness is in the moderate or high degrees, they can reduce your near-sightedness, but you still have to wear glasses.
Will contacts damage my eyes or worsen my vision?
Contacts won't weaken your eyes from the point of view of your eyes won't get more near-sighted because you use them. On the other hand, contacts can harm the eye in some ways. In rare cases contact lenses can cause serious eye infections. Contact lenses also tend to cause little blood vessels to grow from the white part of your eye into the clear cornea. Those blood vessels normally shouldn't be there but they're to replace the oxygen that's deprived because the contact lens blocks the air from getting to the eye. And finally contact lenses can cause changes in the outer cell layer of the eye, and in the inner cell layer of the eye we call the endothelium. Blood vessel growth into Cornea* Long term changes to endothelium (inner cell layer) and epithelium (outer cell layer)Robert K. Maloney MD: These long term changes can be deleterious in some people. So, contact lenses in most people are very safe, but they're not absolutely harm-free. The main take-home message is, if you're wearing contacts, you should continue to get regular eye checkups so your eye doctor can check for these conditions and make sure they're not developing.
Why are my contacts lenses hurting or uncomfortable?
There are a variety of reasons for contact discomfort. The longer contact lenses are worn, the greater the chances of eye irritation due to allergies that develop on the eye from protein build-up on the contact lenses. Dust or other environmental factors are also common reasons for increased dryness, pain or discomfort.
