Keratoconus is a progressive condition where the cornea weakens over time. What this means that if nothing is done, keratoconus will continue to get worse with time. As keratoconus gets worse, the cornea changes shape. This shape change causes increasing prescription of the eye followed by worsening vision.
Steeper cornea with keratoconus; image by Madhero88, CC BY-SA 3.0, via Wikimedia Commons
So of course, we would ideally like to prevent this from happening - ie. cure keratoconus. So, are there any cures for keratoconus?
Well, it depends on what you mean by a cure.
- One way to cure keratoconus is to completely reverse the condition and make the cornea go back to being normal.
- Another way to cure keratoconus would be to prevent it from getting worse.
Optimally, of course, things would be great if that first definition of cure could be done.
But unfortunately, there is no perfect “cure" to completely make keratoconus and all of its vision effects go away. But there are ways to prevent the keratoconus from getting worse through a procedure called corneal cross linking.
But let’s look at all the ways keratoconus can be treated.
Reverse Keratoconus To Restore A Normal Cornea
Unfortunately there is nothing that can truly reverse keratoconus. But there are a few workarounds, both with or without surgery.
Corneal Transplant
The most obvious solution is to replaced the weak keratoconus cornea with a normal cornea. This can be achieved with a corneal transplant.
A corneal transplant occurs just like how you would imagine it. The weak keratoconus cornea is surgically cut out and completely replaced with a donor cornea.
Corneal transplants work differently from transplants elsewhere in the body. Our immune system is good at identifying foreign invaders to our own body. This includes transplanted tissue from other people. So typically with transplants, one needs to take anti-rejection medication to prevent the body from fighting off the transplanted organ.
But this isn’t the case with corneas. Because of the lack of blood vessels to ferry immune cells, the cornea is a sort of an “immune-privileged" area. This means that corneas don’t need to be matched like other transplants around the body. It also means that once healed up, eye drops frequently aren’t even necessary to maintain the transplant.
But despite all that, transplants aren’t the optimal solution for keratoconus:
- Transplant surgery isn’t risk free. Other structure in the eye can be damaged during surgery causing other issues. Even without direct injury during surgery, having a transplant increases the risk of developing glaucoma in the long run.
- Following surgery, the new donor cornea may still have a slightly irregular shape and cause some blurred vision and astigmatism.
- The transplant can eventually fail over time, become cloudy and require another transplant to fix. This will happen to about 6% of transplants for keratoconus.
- And lastly, there is even a chance that keratoconus can develop within the new transplanted cornea! This occurs roughly 5% of the time.
Transplants aren’t a fool-proof way to treat keratoconus. As such, today they are reserved for very severe cases of keratoconus; Not for the vast majority of patients with keratoconus.
But wait, there is a way to pseudo-reverse keratoconus. And this method doesn’t require any surgery at all.
Special Contact Lenses
Normal astigmatism (called regular astigmatism), is caused by the eye being shaped more like a football than a basketball. Also check out The Simple Explanation of What Is Astigmatism for a quick run-down of astigmatism. The shape change causing regular astigmatism is symmetric and this allows it to be corrected with symmetric astigmatism-correcting lenses.
But the cone shape the cornea develops from keratoconus tends to be asymmetric. This causes irregular astigmatism. Standard lenses in eyeglasses and contact lenses are incapable of correcting asymmetric irregular astigmatism. This leads to blurry vision (as well as starbursts and glare).
But certain contact lenses take a different approach.
Rigid glass-permeable contact lenses and scleral contact lenses are types of a hard contact lens. Because these contact lenses are rigid or hard, they resist conforming to the irregular shape of the cornea. Instead these contact lenses have a perfect dome shape to mask the irregular cornea shape from keratoconus. This eliminates the vast majority of irregular astigmatism from keratoconus to improve vision.
So in essence, the irregular keratoconus shape of the cornea is reversed (but not permanently since the hard contact lens needs to be sitting on the eye).
Unlike corneal transplant surgery, special contact lenses are a great option for many keratoconus patients; especially those who have moderate to severe keratoconus and are unable to see well out of standard glasses and contact lenses.
Preventing Keratoconus From Getting Worse
A limitation of the hard contact lenses is that they can’t prevent the keratoconus from getting worse over time. The cornea remains weak and the keratoconus can still get worse.
Preventing the keratoconus from getting worse over time is the other definition of a cure for keratoconus. While it doesn’t reverse the damage from keratoconus, it does prevent further vision loss.
To prevent the keratoconus from getting worse, the cornea must become stronger.
The cornea consists of flat sheets of collagen stacked upon each other. But when the cornea becomes weak, there is little resistance holding these sheets together and the cornea can change shape.
Naturally over time, these sheets become linked together. This provides extra resistance preventing the cornea from changing shape. The cornea becomes stronger. But this natural process of cross linking takes decades to occur. In the meantime, a cornea with keratoconus can experience rapid weakening and shape change.
So instead, a procedure exists to rapidly perform this step for keratoconus patients. This procedure is aptly named corneal cross linking. And it is a quick way to strengthen the cornea and prevent the keratoconus from getting worse. Following application of a special eye drop, UV light is applied to the cornea. This interaction between the UV light and the eye drop causes cross linking and strengthening of the cornea.
Aside from being quick, it is also very successful with minimal side effects. Much unlike corneal transplant surgery.
Corneal cross linking is recommended for anyone whose keratoconus is getting worse.
Summary
Corneal cross linking is the best “cure" we have today for keratoconus. While it won’t completely reverse keratoconus and return the cornea back to a normal shape, it will prevent keratoconus from progressing and causing worsening of vision. And when combined with special contact lenses to artificially mask the shape of the cornea, keratoconus patients have a solution to significantly improve their vision.
Like what you just read? Use Social Media?
Stay connected and join the discussion by following Eye Mountain on
Also Check Out: