 I'm Dr. David Meyer, I'm the Director of Contact Lens Services at the Moran Ice Center in Salt Lake City. Today we're going to spend a few minutes talking about corneal topography. Now the reason this is important is because it's critical in diagnosing and managing keratoconus. I have an image here of patients with a very classic presentation of keratoconus. This type of patient often comes in complaining a very blurry vision at all ranges. They often times complain of ghosting or double images that very often times cannot be corrected with glasses alone. After the topography is taken it's very important to be able to analyze it not only to see the degree of the keratoconus but where the ectasia occurs and the best way to manage the condition. For example, here we have an image of the right and the left eye. This is an axial image of the front surface of the cornea. As you can see there's a scale here that shows the relative curvatures of the cornea from flat to steep. The steeper numbers tend to be represented in reds and yellows and the flatter numbers tend to be in blues and purples. Now the reason this right eye is pretty classic for keratoconus is for a number of reasons. Number one you see an area that is very steep and it occurs inferior nasally in that quadrant. That's a very common quadrant to have a lot of steepening in someone with keratoconus. You can see that in one area where the topographer is measured at, this patient's cornea measures about 54 diopters steep and that is obviously very irregular. Most patients vary anywhere from about 40 to about 45 diopters relatively on their front surface of their cornea. This patient has one area of very steep cornea at 54 and you can see surrounding that it flattens out and you have a very flat area in just superior to the visual axis. This is a very irregular pattern. This is someone who has keratoconus and the challenge will be whether it's glasses or contacts to try to minimize ghosting double images and in a case like this a gas permeable contact lens would be the ideal way to reduce these symptoms. Now for the left eye we have a very similar finding. You have a larger area that's very steep. In fact one of the areas measures 63 diopters which is very steep. Another characteristic of keratoconus is that the steepening pattern is not symmetric. You can see here that it's one large area inferior to the visual axis as opposed to someone with regular astigmatism who has a very symmetrical pattern. And the challenge again in this case is the fit of contact lens that not only provides good vision but is also comfortable and doesn't create lots of bearing which can cause scarring and increase the patient's discomfort. Most apographers come with many other features including pachymetry to look at the thickness of the cornea, posterior float which is a measure of the inside surface of the cornea and other measurements to get an even better idea of how the cornea is abnormally shaped and the best way to fit a contact lens. This is just a very standard pattern and a standard display that most apographers have. Again I'm Dr. David Meyer. This video has been about corneal topography and keratoconus. Thank you for watching.