Keratoconus is a condition of the cornea, the clear part at the front of the eye, which causes it to become softer and thinner than those of normal eyes. Under the influence of the internal eye pressure, the cornea then changes shape. As the cornea is the main part of the eye that focuses light, this shape change distorts the image that forms on the retina, at the back of the eye, even if you are wearing glasses.
The picture shows more advanced keratoconus, where this shape change is obvious, even to the naked eye, In mild to moderate keratoconus, this sort of shape change is not easily seen but it still causes issues with focusing light.
Keratoconus can start as early as 9 years of age but usually in the early 20s. It is usually active (as in: progress or get worse) for up to 10 years after which it tends to stabilize.
Contact lenses are used to restore a better shape/focus. Most people with keratoconus have to rely on contact lenses to regain functional vision. Up until recently, it was the only way to manage the condition.
Corneal Collagen Cross-Linking (CXL) has now brought hope to keratoconus as this is the only surgical intervention that has shown that the progression of keratoconus can be halted.
What are my options?
Traditionally, the only way Keratoconus has been managed in the past is in the use of contact lenses.
Contact lenses form a new, stable, regular optical surface which then allows proper focussing of light onto the back of the eye. This has traditionally been achieved using Rigid Gas Permeable contact lenses (RGPs). Normal contact lenses, such as disposables, can help in cases of low cones, where central distortion is not too bad, but tend to be of little use for central keratoconus.
Contact lenses only help when they are being worn. If you have to wear them all waking hours, then tolerance to wear becomes an issue for some people. People without keratoconus can swap to glasses if their lenses are irritating them or if they lose or damage them. People with keratoconus cannot do that, so work and driving become an issue if lenses cannot be worn all the time.
These are small, hard lenses made out of plastic that is permeable to oxygen. They mask the underlying distortion and function as the new refractive surface of the eye. In some cases, wearers may find comfort an issue, especially if they have to be worn all waking hours.
Do RGP lenses stop the progression of keratoconus? No. It was once thought that RPGs “pushed back” or “retarded” the cone. However, although some “reshaping” of the cornea may take place, it will return to its original shape once RGP wear is discontinued.
In early/mild cases and for low cones, regular soft lenses can still give very good vision. You do not automatically have to resort to RGP lenses if you have keratoconus. If you can see as well as you want to in soft lenses and are happy with them, then continue as you are until the situation changes.
Once the condition progresses to a certain point, specialist soft lenses, are then required to cope with the higher levels of distortion.These cannot mask distortion in the same way as an RGP lens, as they drape over the cornea with no underlying tear “pool”. Some soft lens types are made as thick as possible to attempt to mask distortion. These can have the disadvantage of lower wear times due to the restriction of oxygen flow through the lens.
Other lenses, such as the KeraSoft IC, are specifically designed to make the cornea much more regular. These convert the irregular corneal astigmatism caused by keratoconus to regular astigmatism. These lenses are closer to regular soft contact lenses in thickness.
The advantage of soft lenses is that they can be worn comfortably all day and virtually eliminate the issue of dust finding its way under the lens, This is very useful in dusty conditions.
Alternatively, there is the ClearKone® hybrid contact lenses offer all the benefits of rigid gas permeable (RGP) and soft contact lenses without any of the disadvantages for an overall GREAT contact lens experience.
Other contact lens types
These include, large RGPs, semi limbal piggy backing (wearing an RGP on top of a soft lens) and scleral (a very large lens that covers most of the white of the eye as well).
- CXL (Corneal Collagen Cross-Linking)
- Intra Corneal Rings (INTACs, Ferrara Rings)
- Intra Ocular Implants (IOL)/Implantable Contact Lenses (ICL)