FAQ
Can keratoconus cause me to go blind?
It is extremely rare for someone with keratoconus to go blind. Modern management both with contact lenses and/or surgery means the vast majority of keratoconus patients will lead a normal life. However, it is extremely important that the patient plays their part in looking after their eyes. This means keeping contact lenses in good condition, attending regular appointments and following the advice of their eye care professional.
Does keratoconus affect both eyes?
Over 95% of people with keratoconus will have the condition in both eyes. Reasonably often (especially in early keratoconus) only one eye will appear to be affected but corneal topography will confirm the condition in both eyes. For this reason both eyes are always imaged with the corneal topographer at regular intervals.
I have been told I have astigmatism. Does this mean I have keratoconus?
Probably not. Astigmatism is induced when the front of the eye (cornea) is a different curve vertically versus horizontally, somewhat like a rugby ball. Regular astigmatism is normal and can be easily corrected with spectacles or soft contact lenses. Irregular astigmatism is caused by distortion of the cornea from injury, scarring, infection or conditions such as keratoconus or pellucid marginal degeneration. This irregular astigmatism is the main reason spectacles often don't work well for keratoconic patients as the astigmatism changes across the surface of the cornea.
"With-the-rule" astigmatism is when the cornea is flattest in the horizontal direction. "Against-the-rule" astigmatism is when the cornea is flattest vertically.
"With-the-rule" astigmatism is when the cornea is flattest in the horizontal direction. "Against-the-rule" astigmatism is when the cornea is flattest vertically.
Regular astigmatism
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Keratoconus
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Do contact lenses hurt?
There are many different types of contact lenses used for keratoconus. Generally speaking RGP (hard) lenses are less comfortable when first fitted but give superior vision to soft lenses. Most keratoconus patients will adapt to their hard lenses, however if reasonable comfort is not achieved then there is several different options to improve comfort. If you tried contact lenses some time ago and didn't succeed, chances are that there are new options that will suit.
Will contact lenses fix (or worsen) my keratoconus?
No. Contact lenses for keratoconus are designed to provide a good standard of vision while worn. They will not reverse the condition.
As long as the lenses are well fitted and cared for they will not worsen the condition. However, it is extremely important to have regular checks because dirty or ill-fitting lenses do have the potential to cause corneal scarring or infection.
As long as the lenses are well fitted and cared for they will not worsen the condition. However, it is extremely important to have regular checks because dirty or ill-fitting lenses do have the potential to cause corneal scarring or infection.
Are contact lenses for keratoconus expensive?
The fitting of contact lenses for keratoconus is a lot more complicated and time consuming than regular contact lenses and the lenses themselves are usually custom made lenses with very complicated shapes. Because of this the cost is usually quite high. In New Zealand we are lucky enough to have a Ministry of Health subsidy that contributes towards the costs of fitting and lenses.
Why is dye used in the fitting of my lenses?
Sodium fluorescein (NaF) is an orange dye used to assess the fit of RGP lenses on the eye. The dye is made to glow green by using a blue light. The intensity of the glow shows the proximity of the lens to the eye at various points across the cornea. NaF dye is non-toxic and does not cause permanent staining of the eyes or skin.
Can I have laser surgery to correct my keratoconus?
No. Laser refractive surgery (eg: PRK, LASIK etc) reshapes the cornea by removing (ablating) corneal tissue resulting in a thinner cornea. This corneal thinning carries an extremely high risk of causing the keratoconus to rapidly worsen. Keratoconus is a contra-indication to laser refractive surgery.
What is graft failure?
Graft failure (or rejection) is when the donor cornea is rejected by the eye it has been attached to. This can happen at any time but is more common when the graft is new. Symptoms include redness, glare, reduced vision and sometimes ache or pain. Rejection came usually be reversed with prompt intensive steriod therapy (eye drops) but treatment must be intiated with urgency.
What is corneal hydrops?
Corneal hydrops is an acute clouding of the cornea caused by a small break in the back layer of the cornea allowing fluid to enter. The cornea rapidly turns white causing a dramatic drop in vision. This break usually heals up and the fluid eventually gets "pumped" back out, resulting in a clearing of the cornea. However this can take months and often the eye is left with secondary scarring that may require keratoplasty to correct. Hydrops is usually treated with steriod eye drops and sometimes other ocular medications if secondary problems develop.
What is pellucid marginal degeneration?
Pellucid marginal degeneration (PMD) is a corneal condition similar to keratoconus.
PMD results in thinning near the bottom edge of the cornea (inferior limbus) causing the cornea to sag down resulting in significant "against-the-rule" astigmatism. A typical PMD topography is shown on the right.
PMD is very frequently mis-diagnosed as keratoconus by optometrists as it quite similar to keratoconus in it's early stages. Generally the differences are that PMD has thinning much lower in the cornea, has a classic "crab-claw" topography with significant "against-the-rule" astigmatism and tends to present at a later age in patients than keratoconus.
Early PMD patients often do well in spectacles of soft toric contact lens. More advanced cases can be very difficult to manage. Semi-scleral RGP lens are often useful in this challenging cases.
PMD results in thinning near the bottom edge of the cornea (inferior limbus) causing the cornea to sag down resulting in significant "against-the-rule" astigmatism. A typical PMD topography is shown on the right.
PMD is very frequently mis-diagnosed as keratoconus by optometrists as it quite similar to keratoconus in it's early stages. Generally the differences are that PMD has thinning much lower in the cornea, has a classic "crab-claw" topography with significant "against-the-rule" astigmatism and tends to present at a later age in patients than keratoconus.
Early PMD patients often do well in spectacles of soft toric contact lens. More advanced cases can be very difficult to manage. Semi-scleral RGP lens are often useful in this challenging cases.
