The basic definition of keratoconus is “a bilateral asymmetric thinning of the cornea that causes keratometric myopia and irregular astigmatism”.
The onset of keratoconus usually occurs when the patient is just in their pre-teens, and sometimes can even develop later on in life. Most patients have a stabilisation of the condition by their late 30s, possibly as a result of the general tendency of the body’s collagen to stiffen with age.
The prevalence of keratoconus is such that one in around 1,200 people are afflicted by the disease. In South Asian populations however, the prevalence is almost four times as high, and earlier ages often see heightened onsets, and quickened progression. In most developed countries, keratoconus is the reason for upwards of a third of all patients that are required to undergo a corneal graft procedure.
There are many theories when it comes to what causes keratoconus, including genetic and environment factors. Most researchers do agree that allergies and eye rubbing can be elements that can potentially increase the disease process.
The exact pathological mechanism that causes keratoconus is unknown, and explanations into the development of the disease are still being researched. Studies into the genetics of men and women that are affected by keratoconus has so far identified gene variants that may be inhibitors for the conditions, but there are none that are solely exclusive to the keratoconus patients, and therefore cannot – with certainty – be said to be causing the disease.
There are some that are seeking a call for a better definition of the condition, and believe that the improvement in definition will aid in the assessment of candidates that are eligible for refractive surgery.
One such advocate is Stephen Tuft FRCS from the Moorfields Eye Hospital, London UK, who believes that when assessing patients for corneal refractive surgery, a surgeon should begin with the assumption that all patients under the age of 40 are keratoconus suspects in the broadest sense.
The most reliable way to identify patients in an early stage of the disease is to see if there is a lack of concordance between the area of maximum curvature and the area of maximum elevation, and between the position of the corneal apex and the thinnest point.
“Overall, I think that measurements such as topography, refractive error and astigmatism should be combined and used towards developing better algorithms to improve discrimination in the diagnosis of keratoconus,” Dr Tuft added.
If you believe you may have symptoms of keratoconus, come in for an eye examination at Hunter Laser Vision, or book a consultation today on 1800-44-20-20.