Did you know that there are many different types of contact lenses? You wouldn’t be alone if you didn’t. If you have a refractive eye error such as myopia (nearsightedness) or hyperopia (farsightedness), you may rely on prescription contact lenses to see clearly. Alternatively, you may be wearing glasses at this time and wondering if contact lenses are right for you. Conventional contact lenses can resolve many refractive eye errors, but if you have other eye care issues, specialty contact lenses can help.
Specialty contact lenses are an alternative when conventional contacts are not available in the shape, size or design needed to suit your individual requirements. Every eye is different, and by choosing specialty contact lenses, you can be sure to find a variety that fits comfortably and securely and give you the clear vision that you need and deserve.
There are a variety of different types of specialty contact lenses, with some being more common than the others. Here’s what you need to know about the main types.
As their name suggests, bifocal lenses have two different prescription powers. This enables the wearer to enjoy clear vision at all distances without needing to change their lenses or put on a pair of glasses. There is a line of separation in the glasses, with near powers usually being focused in the bottom part of the lens, and far powers being situated at the top. This means that for distance vision you can look straight ahead whilst looking down at a book or screen you would focus through the lower part of the lens.
Bifocal lenses are designed to address the focusing issues caused by presbyopia – a condition characterized by the natural deterioration of vision after the age of 40. This occurs as the lens of the eye becomes less flexible, causing patients to become long-sighted. Bifocal lenses are also a popular solution for patients with astigmatism. This condition is characterized by an imperfection in the curvature of the cornea that causes blurred and distorted vision.
Rigid, gas-permeable lenses (also known as RGP lenses) are contact lenses made from a material that allows oxygen to pass through them and reach the surface of the eye. As their name suggests, they are also rigid in design, giving them greater ability to retain their shape and meaning that they last longer than soft lenses. However, despite being rigid, they are much more modern and comfortable than the old-fashioned, hard lenses which are now virtually obsolete.
Anyone can wear RGP lenses, but they are particularly good for patients for whom conventional contacts aren’t suitable. This includes patients with astigmatism since the rigid nature of the contacts means that they hold their shape on the eye and allow for more stable, clear vision. They are also good for patients who suffer from dry eye disease. This is because rigid lenses can actually stimulate tear production in some cases, and rigid lens materials don’t dehydrate as quickly as soft lenses. They also allow more oxygen to reach the eyes, keeping them healthy and feeling comfortable.
Toric lenses are also particularly valuable for patients with astigmatism. Toric lenses contain a gradually varying degree of strength, accommodating the different amounts of vision in each part of your eye. They also sit comfortably over their elongated shape. Most toric lenses are designed to be thicker at the bottom and thinner at the top. This places greater weight at the bottom of the lens – something which helps to keep the contacts more stable and ensures they remain securely in place. Since the lens doesn’t move, the correct refractive strengths in the lens will always sit over the parts of the eye that need them.
Scleral lenses have a very different design to conventional contacts. Rather than making contact with the entire surface of the cornea, these large-diameter lenses vault over the main corneal surface and instead make contact with the white part of the eye called the sclera. This has several benefits. Firstly, there is enough space between the back of the lens of the eye and the surface of the cornea to accommodate any corneal irregularities. This includes the bulge that is characteristic of the eye condition known as keratoconus. This space also acts as a fluid reservoir, keeping tear film on the eyes and making scleral lenses a good choice for patients with chronic dry eye disease.
If you’d like more information on specialty contact lenses, our knowledgeable team would be happy to help. Please contact Eyes on You in Portland, OR.