Without a doubt one of the most tense scenarios in ophthalmic practice. The most common is that during a routine test, in which vision did not reach 20/20 (100%), even with glasses, an eyecare professional informs a worried parent that his or her kid might be suffering from keratoconus, and setting up an appointment with an ophthalmologist who handles that problem is the recommended next step.
Keratoconus is a disease of the frontal part of the eye, its external cover, called cornea. This cornea is a transparent lens through which light crosses on the way to the retina(Image 1). Like every lens, it has a certain power, and focuses light at a certain distance, like a magnifying glass. In order for a lens to correctly focus light, its surface needs to be regular, and smooth.
The cornea is made up of a tissue called collagen, organized in a very uniform way, and without water, which results in its transparency. In ideal conditions, it has the form of a soccer ball cut in half, that is, half a sphere.
In some people, typically young, with allergies, who rub their eyes, or receive a lot of sun (although it can also happen in the absence of these risk factors), it is the case that the cornea is inflamed for long periods and this collagen starts to change, to be deformed. After a certain period, the surface turns irregular, as if it had a “bump”. If the causes of this weakening are not corrected, the bump grows and grows, creating a bulge on the magnifying glass, which interferes with the normal focusing of light. This is called keratoconus, because the cornea starts looking like a cone (Image 2).
The patient perceives this as blurry vision, and at the beginning of the process, a simple pair of glasses is enough to compensate, which is the reason as to why early keratoconus usually goes undetected. It isn’t until this bulge is big enough not to be able to be compensated by glasses, that people usually come for a check up.
At this point, my answer to the worried parent is that the single most important factor from now on is to make sure that the low vision is indeed due to keratoconus, and not to one of the other multiple afflictions that can offend the eye. To eliminate doubt, we obtain a tridimensional map of the cornea with a special camera (“Corneal topography”), which represents it like a mountain, and allows us to adequately see if it has a typical bulge (Image 3).
If this was the case, the next step is to eliminate all of the factors that are contributing to the disease, control the allergies and ocular inflammation with medical treatment, and avoid eye rubbing at all costs.
Keratoconus has a very important characteristic, which is the fact that it stops worsening at a certain age. It is a problem of young people that tends to permanently stabilize during young adulthood. When I first see a person with keratoconus, I cannot know if he or she has already reached the age of stability, or it will still worsen. If I have for example, a corneal map from a year ago, I obtain a new one today, and observe no differences upon comparison, I can conclude that we are not facing a progressive keratoconus. This is the best case scenario, and we do not need to intervene, other than to follow up every certain amount of time, to make sure it is still stable. Therefore, if this is my first time seeing a particular patient, the recommended action is to wait a short period before taking a new photo, and do not intervene surgically in an immediate fashion.
If however, I have evidence of progression, either because a new map shows it, or because the patient notes obvious loss of vision in the past few months, the surgical intervention should take place as soon as possible. The surgery for keratoconus, called “corneal collagen cross-linking”, utilizes a combination of vitamin B and ultraviolet light to strengthen the collagen in the cornea, and stop disease progression.In subsequent entries I will explain the details of the procedure.
When we see a patient with such a big keratoconus that the cornea already developed scars, or the vision cannot be corrected in any way, the only possible treatment to improve the function is a corneal transplant, with everything that this surgery involves, in terms of costs and aftercare.This is the reason that makes early diagnosis so important, in the stages in which a procedure of half an hour and a pair of spectacles is all we need to solve the problem.
I hope this information is helpful, thanks for your attention. If you have any questions, do not hesitate to send them through any of our channels.
Dr. Victor Flores.