By Chanté Roets - (UOFS) CAS(SA)
First, what are scleral
contact lenses and how do they work?
A scleral contact lens is a large diameter rigid contact lens that is specifically designed to vault over the entire cornea (front of your eye) and rests on the sclera (the white part of the eye).
These lenses effectively replace your irregular cornea with a smooth surface in order to correct your visual problems caused by corneal irregularities.
A scleral contact lens is filled with compatible fluid and the fluid reservoir smoothes out the corneal surface. The fluid reservoir needs to be replaced every day and sometimes more than once and therefore you wear the lenses during the day and take them out before you go to bed.
Scleral lenses help correct vision in the following cases: Keratoconus, Corneal transplant, LASIK, photorefractive keratectomy, radial keratotomy, pellucid marginal degeneration, trauma, dry eyes, and any Irregular cornea.
At Spectacle Warehouse we do fit these incredible specialised scleral contact lenses!
The examination is more complex than a normal eye test or a normal soft contact lens fitting.
Scleral examination: First we take topography maps of the curvature of the cornea in order to determine how high the lens must vault over the cornea. Then we pick a trial lens suitable for your corneal curvatures and put it on the eye. It will not be a perfect fit just yet. This will just be to determine what parameters must be changed when ordering your own scleral lenses. After putting the lens on the eye we take a topography map again over the lens to see if the weight is distributed evenly over the sclera. We also take an Oculor Coherence Topography (OCT) scan with the lens on the eye. The OCT scan allows us to objectively assess the central and peripheral lens fit, and to customise the lens design. A slitlamp microscope examination is also done to see if the lens is not obstructing blood flow in certain blood vessels, and to note if the lens is vaulting the entire cornea. After all this is done, only then do we perform a refraction over the scleral lens to determine what the final optical power should be. Now we can design and order your scleral lenses.
If you've been told in the past that you cannot wear contact lenses because of an irregular cornea or other problems, you may want to get a second opinion. Not everyone fits these lenses. Our optometrists do.