Hello and welcome to Case of the Day. I’m Dr. Croley and today we’re gonna discuss a case where a patient came in with a problem called keratoconus. That is an abnormality in the cornea in which the cornea becomes an abnormal shape. The cornea starts to herniate and bulge in an abnormal way, sort of like a tire blowing out and starts to bulge outward; the tire gets thin. That’s what happens with the cornea. The cornea becomes thin in the area and then it allows that part of the cornea to bulge forward which then causes your vision to blur. So someone who has keratoconus, they have an irregular astigmatism.
So regular astigmatism means your eye is shaped sort of like a football cut in half. It’s more rounded on one way and flatter than the other. But it’s symmetrical.
When people have irregular astigmatism, then the relationship is not consistent as abnormal, so now we have a herniated or bulge in certain areas. So then that makes it difficult for glasses to correct that vision in someone like that because it’s not symmetrical astigmatism which is what almost all cases of astigmatisms are. So this is a unique situation where there’s irregular astigmatism. Eventually if irregular astigmatism gets severe enough, then glasses don’t correct a person’s vision with keratoconus.
Keratoconus is a disease that, is a multifactorial etiology, that is, we’re not sure exactly of the cause for keratoconus. There’s some evidence that there’s some enzymes in the cornea that are sort of activating and thinning the cornea out. There’s also an autosomal dominant form of inherited keratoconus.
Also, there’s a study I think is out of Duke University, where the corneal specialist there who has had a clinic for all these keratoconus patients and he was noticing that they’re all sitting here, rubbing their eyes severely not just like this but actually a knuckle on eye and rubbing it, and he thinks there is some evidence that trauma, that is chronically rubbing on the eye with your knuckle causes the cornea to be damaged, loses its integrity, and then causes the thinning and herniation.
So there’s multiple factors about keratoconus and how it is caused. Usually it is bilateral, that is, it’s in both eyes. But I’ve seen in a couple of cases where it’s only unilateral.
If someone has keratoconus, at the point where the glasses won’t correct your vision anymore, then what’s the next step? So there are now contact lenses that have been advanced. In the beginning, to correct the irregular astigmatism, you had to fit a gas perm or a hard type lens over the cornea so that way would vault over that herniation and your tears would fill in the gap and so then it would straighten someone’s vision out so they could have a good vision with a gas perm or hard type contact lens.
Sometimes they get uncomfortable because the cornea would get so steep, that they’d become difficult to wear. So now, there’s some newer generational lenses where actually there’s a soft lens and in the periphery, then in the center is a gas perm blended into that soft lens so now you have a more comfortable soft lens on the peripheral part of your eye. Then the gas perm on the middle to correct the vision.
A plain soft lens does not correct astigmatism from keratoconus very well. Because it drapes over the eye and follows the same structure or curvature of your cornea.
Now there are toric lenses which can be used for a while in some case of irregular astigmatism or keratoconus but typically, eventually if the keratoconus progresses then that doesn’t work.
What are the other treatments as far as keratoconus goes? Well, one treatment now which is brand new, and should be recent, should be anytime approved by the FDA is cross-linking. So basically, the cornea now is thin and its structure is getting less strong. So the textile strength of the cornea is being diminished. Cross-linking is putting a riboflavin vitamin straight into the eye and then a UVA light is then shone on the cornea for about 30 minutes, and that has been shone to strengthen the collagen in your cornea and stop the progression of keratoconus. The studies that have been done look very good, and so that’s gonna be a nonsurgical way of correcting or stopping the progression of keratoconus.
Then you have surgical procedures. One surgical procedure is an Intac where a sort of splint is put inside the cornea and that strengthens the cornea or gives it a support, like the crutch, and helps people maintain better vision.
For sort of final thing is a corneal transplant where that cornea, this tissue in the central part of the cornea is removed and a donor cornea is put in place and then sutured in place. Then there’s other procedures where only the superficial layers are added on which is called DLK. Then there’s also an epikeratoplasty which is where corneal tissues are put on top of the cornea and that has had some sort of mixed success.
So there are multiple ways of treating keratoconus. The exciting thing is when FDA finally approves the cross-linking because then that is gonna help people without surgically doing anything.
So if you have any questions about keratoconus, or any other thing you can always ask us, you can contact us through the website. If not, may God bless you with healthy eyes and great vision.