What is corneal ectasia?
Recently, in a newspaper article seen below, LASIK surgery was done on a patient with a condition that is an absolute contra-indication to LASIK. In this condition, degeneration of the cornea structure (pellucid marginal degeneration), the cornea is weak and bulging in the inferior quadrant. After LASIK surgery, this quadrant is further weakened and starts to bulge forward distorting the cornea with a resulting permanent damage to the patient’s vision. This is called corneal ectasia.
Corneal ectasia can also occur when eximer Laser ablation for the correction of a refractive error removes too much cornea tissue. A minimum of 250 microns should be left in the bed of the cornea under the LASIK flap. Unfortunately, mechanical microkeratomes are less predictable and occasionally inadvertently make a thick corneal flap. This results in a thin corneal bed. If not measured and adjustments are not made to the excimer laser ablation, the corneal stromal bed is thinned below the 250 micron limit. This weakened cornea may initially give good results, however the cornea continues to weaken and bulge forward. Fortunately, these conditions if caught early can now be treated with a procedure called corneal collagen crosslinking which strengthens the weakened corneas, sometimes with dramatically good results.
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Corneal ectasia can also occur when eximer Laser ablation for the correction of a refractive error removes too much cornea tissue. A minimum of 250 microns should be left in the bed of the cornea under the LASIK flap. Unfortunately, mechanical microkeratomes are less predictable and occasionally inadvertently make a thick corneal flap. This results in a thin corneal bed. If not measured and adjustments are not made to the excimer laser ablation, the corneal stromal bed is thinned below the 250 micron limit. This weakened cornea may initially give good results, however the cornea continues to weaken and bulge forward. Fortunately, these conditions if caught early can now be treated with a procedure called corneal collagen crosslinking which strengthens the weakened corneas, sometimes with dramatically good results.
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