Scleral Lenses For Keratoconus

For people with Keratoconus the RGP, or Rigid Gas Permeable contact lens is still one of the most effective ways to correct vision. Traditional, or Corneal RGP lenses are small, slightly smaller than the coloured iris, and fit directly onto the cornea. For people who have a problem with the fit of these lenses the Scleral lens may be an alternative.

First some background. Keratoconus is a disease of the cornea, which 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 or the eye that results in reduced vision as the light entering the eye can not be properly focused onto the retina. What happens is that the light, instead of hitting one focus point, is spread out over many points on the retina and this causes blurring and 'ghosting' .

Spectacles cannot be aligned properly to deal with the multiple focus points caused by the irregular shape of an eye with Keratoconus, and hydrogel (or soft) lenses tend to be thin and contour to the same shape as the cornea (although there are some thicker soft lenses that are better at keeping their own shape and therefore go someway towards the benefits of RGP lenses).

RGP lenses work so well because they maintain their own shape and trap a layer of fluid between the lens and the cornea. The combination forms and artificial single surface that acts like a regular shape cornea.

Because RGP lenses are so small the edge of the lens can irritate the inner surface of the eyelid and this can make wearing them uncomfortable.

Also the lenses can pop out quite easily, particularly if the cornea of the eye with Keratoconus is quite steeply curved (think about balancing a saucer on the end of a rugby ball).

Another factor affecting RGP suitability is the environment in which you live or work. RGP lenses can be a problem in very dry and or dusty conditions because dust can get behind the lens or around the edge of the lens quite easily.

An alternative for Keratoconus is a Scleral lens.

This is also a rigid lens but is much larger in diameter than a normal RGP. Where the normal RGP is slightly smaller than the coloured part of your eye and fits only on the cornea, a scleral lens is designed so that the edges sit on the sclera or white part of your eye.

Because of this they tend not to cause irritation of either the eyelid or the cornea.

Of course they have some disadvantages.

They are more expensive and require more complex checks to get the correct fit.

They are also a bit scary to consider putting into your eye as they can be as much as one inch or twenty five millimetres in diameter.

Nevertheless they represent a great alternative when RGP lenses cannot fit properly or where a persons job or lifestyle makes RGP lenses impractical.

Other alternatives include hybrid lenses, a bonded combination of RGP and Hydrogel in a single lens, and Piggy back solutions where RGPs are worn over Hydrogel.

Vision Life is an organisation devoted to helping answer the question what is Keratoconus and how is it treated. We also provide help to people who's lives have been impacted by the disease. Get a free information pack and newsletter at
http://whatiskeratoconus.com

Source: http://articles.submityourarticle.com/scleral-lenses-for-keratoconus-284296

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