Keratoconus is an eye disease in which the clear part of the eye (the cornea) gets thinner and becomes misshapen, bulging forward in a cone shape. This results in blurred vision which may be corrected early on with glasses, but contact lenses are the most common keratoconus treatment.
Keratoconus is a progressive disease which generally becomes apparent during a patients late teens or early 20s. Its cause is unknown and there is no cure for keratoconus.
The symptoms of keratoconus include:
- Blurred vision.
- Sensitivity to bright light.
- Problems caused by glare when night driving.
- Distortion of vision.
Keratoconus symptoms first appear during puberty or a person’s early 20s and will most likely change as the disease progresses.
It’s worth noting that keratoconus is prone to misdiagnosis, especially in the early stages. Common misdiagnosis is astigmatism or myopia. So it is important to see a keratoconus specialist if you have any of the typical symptoms.
The cause of keratoconus remains unknown. However research suggests an imbalance of protective enzymes in the cornea may lead to collagen weakness, causing the cornea to bulge out.
There is evidence that Keratoconus runs in families. Also, excessive childhood eye rubbing and allergies are associated with keratoconus.
The treatment for keratoconus is dependent on the severity of the condition. Glasses or soft contact lenses can help people with mild keratoconus. However, as the disease progresses there will probably be a need for other treatments .
Keratoconus treatments include:
1. Glasses for keratoconus
With the right prescription, people with mild keratoconus can often achieve highly functional vision using glasses. However, it is important to get the correct lens prescription from a keratoconus optometrist.
2. Soft contact lenses for keratoconus treatment
Soft contact lenses may help in mild forms of keratoconus. These soft hydrogels let oxygen pass through to the eye. Because they are soft, these lenses are comfortable to wear.
3. Rigid Gas Permeable contact lenses
Rigid Gas Permeable lenses are the mainstay of keratoconus treatment. These hard contact lenses have multiple benefits for keratoconus patients. Not only do they allow oxygen to pass through to the eye, but in addition they significantly improve vision. This is because the lens tends to arch over the irregularly shaped cornea, presenting a smooth refracting surface which improves focus and clarity.
4. “Piggyback” contact lens systems
The “Piggyback” contact lens system utilises both soft and Rigid Gas Permeable lenses. The system uses a gas permeable lens fitted on top of a soft contact lens. The main advantage is that it offers the optics of a Gas Permeable lens with the comfort of a soft contact lens.
They are an effective keratoconus treatment, but best suited for patients who find commonly prescribed hard contact lenses uncomfortable.
5. Hybrid contact lenses
Hybrid contact lenses are made of two polymers (plastics). They have a central rigid zone which corrects vision and a peripheral soft zone which provides stability and comfort. These lenses are an ideal for sport because they are more comfortable to wear.
6. Scleral contact lenses
Scleral contact lenses provide the improved optics of gas permeable lenses, but with superior comfort. Indeed, scleral lenses are larger than gas permeable lenses. They rest on the white part of the eye (the sclera) and arch over the more sensitive cornea, which is what makes them more comfortable to wear. These lenses are also more stable on the eye surface, not moving as much with each blink.
7. Corneal cross linking as a keratoconus treatment
Corneal cross linking is a minimally invasive outpatient procedure designed to strengthen the cornea. This treatment can successfully slow or halt the bulging and misshaping of the cornea that causes poor vision in people with keratoconus.
The procedure works by using specially formulated riboflavin (vitamin B2) eyedrops which create a biochemical reaction with ultraviolet light. This creates new bonds between collagen fibres in the cornea making it stronger.
Corneal cross linking works best during the early progressive phase of keratoconus – before the shape of the cornea has become too irregular.
8. Laser eye surgery + corneal cross linking
Laser eye surgery combined with corneal crosslinking is now a surgical option for some keratoconus patients. Corneal cross-linking is done first. This helps strengthen and stabilize the cornea. Depending on the outcome of this procedure, laser eye surgery may then be possible.
Patients are only recommended to get laser eye surgery combined with corneal crosslinking if contact lenses are too uncomfortable.
The aim of this combined procedure is two-fold: first, to make the surface of the cornea more regular, and therefore improve vision; and second, to stabilise the condition and stop the keratoconus from getting worse.