What is Keratoconus?
Let me explain as follows; the cornea is the clear dome over the eye. Theoretically the cornea should be baseball shape but in actuality for most people the cornea is a little bit football-shaped and we call that astigmatism. With Keratoconus the cornea is shaped more like a cone, hence the name Kera meaning cornea, conus shaped like a cone.
One in 2,000 people have Keratoconus so what’s the scenario? The scenario is usually in adolescent years, teenagers and then even people early 20s, mid 20s we’ll notice a sudden drop in their vision. Of all the people that I see coming in for second or third opinions the most common scenario is somebody with a red eye and it just doesn’t clear, but the second most common is probably Keratoconus.
What happens is a teenager or someone in the early 20s will notice their vision is really slipped, usually they’re not comfortable driving and having difficulty in a classroom or a lecture hall, productivity is declining & they usually go to a retail outlet get a pair of glasses. The glasses are better than nothing, but even this is very unsatisfactory. They will find that for example when they’re in the car with other passengers, they’re the last one to be able to see the road signs, having difficulty seeing that lecture hall board etc and then they’ll come in for a second or third opinion.
On examination with Keratoconus what I’ll find are usually several different signs, the first is, with the eye looking down it is cone shape and then there’ll be an indentation of the lower eyelid that happens to go by the name of Munson sign. So when the eyes are looking down I tell patient to your toes you’ll see that very significant indentation of the lower eyelid.
The second is with Keratoconus, there will be iron deposits within the cornea, so if we turn on a cobalt blue light we will be able to see a brown ring at the base of the Keratoconus. So it’s a little bit subtle, a little bit hard to tell but here’s actually iron deposition in patient with Keratoconus. A third thing that I look for, usually it’s in a little bit more advanced, but there’ll be little lines or a little bit of scar tissue and this is referred to as Vogt’s striae.
Most commonly I’ll see the Munson sign, we’re looking down beneath & it’s indented, the iron ring which is called a Fleischer Ring, or the Vogt’s striae, and usually will seek to of the above or three of the above with Keratoconus.
It used to be that those were the ways we made the diagnosis, well now there’s newer technology it’s called Corneal Topography; what happens is just like there are topographic maps, we get a three-dimensional view of the cornea. This just looks like many different colors but actually what happens is there is a color scale for elevation.
When there’s marked Keratoconus it’s very easy to pick up with topography, sometimes it’ll be much more subtle in which case the clinical examination will always do the trick. Now why is this important? Because for patients who have Keratoconus, eyeglasses will be helpful, more helpful than just winging it with nothing, but Keratoconus patients in particular do much much better with contact lenses.
Now the soft lenses are usually marginally helpful but with gas permeable hard lenses, piggyback lenses, what happens? Imagine that the cornea is shaped like a cone those lenses help kind of smash down the cornea a little bit, so the quality of vision is far better. The vast majority of people going the route of one of those type of contact lenses get significant improvement, so a very good quality of vision. If none of those work, the hard lenses is the gas permeable and the piggyback lens is there are Scleral contact lenses which can be utilized as well.
For those where none of the contacts will work there is now a newer procedure that’s been out for the last several years called Corneal Cross-Linking that’s an in-office procedure. Patient lies on their back, this is a schematic, what happens is a medication is placed on the eye called riboflavin, ultraviolet light is shone into the eye it’s an in-office procedure and specifically what happens is we are trying to not only strengthen the cornea, but to flatten it down too. Now what does that achieve? It does not miraculously correct for perfect vision, but in doing so the cornea is strengthened. It is a little bit more baseball shape so it’s much much easier to wear a contact lens and frequently with a corneal cross-linking as a second stage procedure months or a year later, patients sometimes can have Lasik performed but one never never never wants to do Lasik on someone with Keratoconus unless they’ve had that corneal cross-linking.
Now in the unlikely event that none of the above work, then the cornea transplant certainly can be performed. Of the patients with Keratoconus it’s about one in 2000. The vast majority of the patients come teenage years, early 20s, it’s always very upsetting when the vision is slipping, but usually, fortunately, by mid 30s upper 30s it’ll just plateau and it will not be an increase in that Keratoconus.