There are different manufacturers that produce different types of bifocal contact lenses, meaning that it may take you a bit of research and experimenting to find which type works the best for you. Some lenses however, are made with a unique design, known as concentric. Similar to concentric circles, there are two adjustments - one in the middle the other around the outside. Once you clean them they should last you for a long time before they need to be cleaned again. One of the best attributes to extended wear contact lenses is the fact that they are very comfortable. They are easy to put in your eyes, and most people don t even notice that they are wearing any contact lenses at all. Throughout the day, you may need to use rewetting drops or saline solution to keep moisture in your eyes. Sometimes, contacts can dry your eyes out, and make them feel very uncomfortable. When you put some drops or saline in them though, the dryness will normally subside. You should always keep some rewetting drops or saline with you at times, just in case your eyes start to dry out. Toric lenses are for those who have astigmatism, spherical is for short sightedness, and the correction of long sightedness, and multi-focal contact lenses are used in the correction of presbyopia. All three designs have their distinct purpose, and you should always ask your optician before you rush out and buy one. To ensure that your contacts remain healthy, you should always replace them as required by the manufacturer or type of contacts you are using. Most types of contacts need to be replaced every 2 weeks, and replaced with a fresh pair. If you are using daily disposable lenses, you should always throw them away before you go to sleep, then wake up to a fresh new pair in the morning. Along with inspecting your contact lenses you ll need to keep them clean. You can clean your contacts after you have inspected them, by putting a few drops of your solution in the palm of your hand and gently rubbing your contact around. This will help to remove any dirt or debris that you find on the contact, and keep them clean.