Surgery of the cornea
FAQ
The actual cause of this disease remains unknown. Most commonly the explanation given is that it may be caused by a combination of genetic factors, environment and the working of hormones. It is hereditary in some 5 to 10% of cases. To date, 6 genes that can be linked to the hereditary nature of this disease, have been discovered. The research is ongoing.
Yes, in the early stages of the disease (while keratoconus has often not been diagnosed yet). At this stage, the refractive error often is successfully corrected using glasses or soft contact lenses.
It is only possible to correct more advanced stages of the disease using the so-called rigid gas permeable contact lenses. Its effect may be illustrated as a combination of a dioptre effect and the effect of “braces”. Its rigidity partially restrains the bulging of the affected part of the cornea. As such, it actually also cures keratoconus to a certain extent.
The development of the disease of the cornea is largely individual. In practice, this means that in some cases, the progression of the disease may come to a stop during a certain phase while in other cases it may progress rapidly from one phase into the next. It is, however, virtually impossible, to completely cure this disease. The process is considered to be irreversible.
Yes, there is a number of patients in whom the condition is monitored on long-term on-going basis, where the condition is not progressing. At the same time, there is a number of patients where keratoconus was only diagnosed at an advanced age, for example it was only discovered during pre-cataract surgery examination. Needless to say, such cases are more of an exception to the rule.
Keratoconus is often labelled a bipartite disease. At the same time, it is applicable that there often is a considerable difference between the degrees to which the two eyes are affected. This may mean that while in one eye the keratoconus is found to be at an advanced stage, the other eye has a relatively normal finding.
CXL stands for Corneal Collagen Cross-Linking. The cornea is saturated using 0.1% riboflavin (vitamin B2) and subsequently irradiated with ultraviolet radiation. In time, the lamella of the corneal tissue becomes reinforced and as such further progression of keratoconus is prevented. While this helps, it is impossible to return the cornea to its normal condition. This is why this method is often combined with another surgery technique (laser procedure or the implantation of corneal segments).
Keratoconus is a disease that originates from the thinning of the cornea. As such, any pressure from inside or outside may result in the condition worsening. Increased physical exertion, working out included, therefore count as a risk factor.
Is it necessary to repeat transplantation of the cornea over the years, for example where a young patient is concerned?
Here, the answer is not 100% clear. The quality of the transplant and it’s functioning within the body is a very complex relationship. Once we forego the rejection of the transplant (a rare occurrence in a healthy individual), we also must take into consideration the common ageing of the implant just as any other tissue. Usually what happens at an advanced age is the failure of the inner-most layer of the cornea – endothelium. We are in a position to transplant this separately, without the need to transplant the cornea as a whole.
In other cases, we have to deal with the progression of the keratoconus beyond the boundary of the transplant. This means that the donor’s disc is fine, but the keratoconus continues into the peripheral part of the recipient’s cornea. This is why regular post-surgery check-ups are essential (at least once a year).
What one may expect having undergone transplantation of the cornea is the so-called combined residual error. Laser correction is recommended no sooner than 24 months after the initial surgery. During this time, we try to improve the shape of the cornea through a technique using incisions into the cornea (astigmatic keratotomy). The more symmetric the cornea, the better result may be expected.
The surgery of the cornea itself is ideally carried out using the “customised procedure” format. This manages to remove eventual persisting irregularities. It is of great advantage for the surgeon of performing such surgery to have past experience using laser as well as performing transplantations.
Corneal Erosion Syndrome is a condition whereby the wholeness of the epithelium is compromised. Sensitive nerve-endings are bared causing pain, tearing, photophobia and the inability to open one’s eyes.
Often, in 40‒60% of cases, the cause is previous trauma (a scratch or a poke of a branch, a leaf or a finger). Another potential cause is the presence of the so-called corneal dystrophy, disturbance of the connection between the basal membrane of the epithelium of the cornea and the layer below it, the so-called Bowman’s membrane.
The treatment basically means preventing the dry eye syndrome (adequate humidity of the air, reduction of air-conditioning, administering of moisturising eye drops). Sometimes, a surgery is needed whereby we remove the entire epithelium, we cleanse the underlying layer under the contact lenses and allow it to heal. In some cases, pricking with a needle helps but nowadays, the more common practice is to roughen the Bowman’s membrane using a laser.
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