Keratoconus treatment and RGP Lenses for vision correction and stabilisation
RGP lenses are still the most common form of visual correction for Keratoconus. They have major benefits for the patient visually but there are some significant drawbacks too.
Keratoconus is a disease of the cornea; the cornea is the clear front surface of the eye. In people with Keratoconus the cornea thins and distorts outwards into an irregular ‘cone’ shape.
It is this distortion of the corneal shape that results in reduced vision as the light entering the eye cannot be properly focused onto the retina and this causes blurring and ‘ghosting’ .
Spectacles and soft contact lenses (Hydrogels) are not effective with this type of condition as they cannot correct the severe distortion of light entering the eye through the cornea.
Glasses cannot cope with the multitude of focus points created through the distortions of the cornea and the soft lenses are unable to effect a change in the shape of the cornea to bring back an acceptable level of acuity.
RGP or Rigid Gas Permeable contact lenses are small lenses, normally slightly smaller in diameter than the coloured part of your eye. They are rigid, with little or no flexibility. That is why they are also described as hard lenses.
Rigid lenses keep their own shape when fitted to the eye. A tear film is created between the curved structure of the lens and corneal surface. This combination of cornea, tear film and the Rigid lens forms a single refractive element that acts like an artificial cornea. This artificial cornea has a regular shape and is able to direct light so that it can be focused properly on the retina. Blurring and ‘ghosting’ are reduced or removed and vision is improved.
Unfortunately there are a number of negative points associated with RGP lenses.
Rigid lenses are less comfortable than soft lenses. Pressure from the RGP lens on the cornea can cause discomfort along with the edge of the lens rubbing on the inner surface of the eyelid.
RGP’s are found to be uncomfortable in dry and dusty environments.
Where the curve of the cornea is very steep the lens is balanced on the tip of the cone. This means that the lens is prone to movement and being dislodged and lost.
Corneal scarring can occur with over use leading to the RGP’s not being tolerable any more.
Before this situation occurs it is important to seek alternative solutions like Corneal Collagen Cross-linking.
If you are new to RGP lenses they may take some time to get used to, and it may be necessary to ‘build up’ the time you wear them over a number of weeks.
RGP lenses aren’t the only option and other contact lens solutions can be used if RGPs don’t work for you. These include Scleral lenses, Hybrid lenses and Piggyback solutions.
You will need to see a specialist contact lens fitter like the optometrists at Accuvision for a suitable lens fit.
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John Andrews is witness to some of the leading developments in laser eye surgery and Keratoconus treatment through his involvement in Accuvision Laser Eye Care Clinics. He meets with patients from around the world who travel to Accuvision for its leading edge technology, treatments and the outstanding results they are able to safely deliver.
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