Types of contact lenses
With the multitude of designs on offer, it is little wonder that people get overwhelmed. Read on for an explanation of the various types:
Are disposable contact lenses the best choice?
There are many different types of contact lenses to choose from. Even within the ever-popular disposable designs, there are all sorts. These include daily, fortnightly or monthly disposables, torics (for astigmatism) and multifocals.
Comfort and simplicity of use can make us complacent about the fact that we are wearing something on our most precious organs – our eyes.
Multifocal contact lenses for reading
Presbyopia strikes everyone once they get to their mid-forties or so. Lights aren’t bright enough, nor arms long enough to read small print anymore. Reading glasses and multifocals restore clear vision but bring their own set of problems. Until recently, multifocal contact lenses had a low success rate but modern advances in design have resulted in effective multifocal contact lenses with much higher success rates.
Toric contact lenses for astigmatism
Astigmatism is present in most eyes to a small degree. It is simply when the two curves of your cornea (front surface of your eye) are not the same, resulting in a slightly egg-shaped front surface. This isn’t visible to someone looking at your eyes, but it can distort your vision if there is more than a small difference in curvature. Astigmatism is easily corrected with glasses – not so easily with contact lenses (called torics), which can cause inconsistent vision. An experienced practitioner will have a range of options for correcting astigmatism.
RGP (Gas permeable) contact lenses
RGP stands for Rigid Gas Permeable. This means the lenses are hard (rigid) and breathable (oxygen transfers easily across the lens material). They are usually more difficult to fit successfully than soft lenses as they have to be tailored to the individual eye (unlike many soft lenses which can fit a range of eye shapes). RGPs, when fitted properly, provide very clear vision (even on irregular corneas) and provide the necessary oxygen to the eye to allow for long wearing times. What’s not to like? The reason that RGPs are not more popular than their soft, disposable cousins is that they require some getting used to when you first get them.
Another use of RGP lenses is piggy-backing. Piggy back contact lenses consist of a smaller RGP lens sitting right on top on a larger soft lens. This provides the best of both worlds – the comfort of soft and the vision of the hard lens. This is often a less expensive option than a hybrid lens. The soft lens is usually a thin disposable lens in a very breathable material.
Hybrid contact lenses
Sometimes you need the sharp vision that RGPs provide but the comfort of soft lenses. This is where hybrid lenses come in. They have a hard central zone, made from RGP material, with a soft outer skirt. This can greatly improve your tolerance of a lens on your eye. The soft skirt stabilises the lens and makes it feel more like a soft lens in the eye. These lenses are most often used in the treatment of keratoconus, but are also used on very sensitive eyes where contact lenses are required.
Scleral contact lenses for dry eyes
Dry eyes can be an obstacle when it comes to successful contact lens wear. Soft disposable lenses can dehydrate your eyes even more and may not be tolerated, especially in office environments. However, recent advances in technology have resulted in some very comfortable contact lens materials that are well tolerated even by people with drier eyes. Interestingly, a special type of contact lens called a scleral lens, is one of the best treatments for severe dry eyes. These lenses are made from a hard material and vault the sensitive front surface of your eye. They act as a physical barrier to protect the eye and prevent evaporation of your tears.
Custom contact lenses for the difficult eye
If you think you’ve tried them all and practically given up on contact lenses, custom-made lenses may be the solution for you. While disposables often take a one-size-fits-all approach (when is that ever true?) these lenses are tailored to your individual eyes, no matter how unusual they are. Tailoring the right lens for each individual is a job for a contact lens expert. Especially if you have had trouble with contact lenses in the past, getting the right lens for your eye is essential to success.
Contact lenses for keratoconus
Keratoconus is a corneal disease that affects about 1 in 2,000 Australians (at least 10,000 people). The mainstay of successful management is contact lenses – provided they are comfortable and fit properly. In fact, poor contact lens fit is one of the causes of progression of this disease. It is essential to find an expert contact lens practitioner who is experienced in keratoconus and fits patients every week. This helps to keep you out of needing a corneal transplant for longer – preferably for good. Contact lenses for keratoconus include soft custom lenses, RGP contact lenses, sclerals and hybrid contact lenses.
If you do end up needing a corneal graft, it is not unusual to need a special kind of contact lens afterwards, to provide functional vision.
These lenses are tricky to fit and best left to the experts.