LASIK permanently thins and weakens the cornea, which may lead to progressive steepening (bulging). "Ectatic changes can occur as early as 1 week after LASIK, or they can be delayed up to several years after the initial procedure. In many cases, [corneal transplant] is eventually performed to manage this complication... The continuously growing popularity of refractive surgery procedures, namely LASIK, has caused increased concern regarding the serious complication of keratectasia." (Meghpara et al, 2008)
Source from: http://lasikcomplications.com/ectasia.htm
What is ectasia? (Posted: jan 2005)
Ectasia is a bulging of the corneal. Ectasia is also called iatrogenic keratoconus or secondary keratoconus because it is basically a surgically induced version of the naturally occurring disease keratoconus. Ectasia is a very serious long-term complication of LASIK.
What causes ectasia and which surgery(-ies) is it associated with? (posted: jan 2005)
Ectasia is specifically associated with LASIK because LASIK penetrates the cornea much more deeply than other procedures (due to the thick stromal flap) and therefore can result in excessive thinning and structural compromise of the cornea.
Ectasia is caused by biomechanical weakening or destablisation of the cornea due to excessive removal of tissue and distruption to the structure of the cornea. In LASIK, a flap of tissue is created which, studies have shown, never again bonds to the tissue under the flap (called the residual stroma) strongly enough to contribute to its corneal stability. This means that the residual stroma alone will determine the strength and stability of the cornea and therefore it is imperative that certain limits with respect to the amount of stroma left under the flap are respected. However, opinions about what those limits are - the limits that would protect a patient from ectasia - vary.
Factors known to contribute to ectasia risk include: (a) when a patient's corneal thickness is not sufficient to undergo surgery (or a retreatment) safely but surgery (or a retreatment) is performed anyway; (b) the microkeratome cut a thicker flap than it was programmed to (a regular occurrence, according to studies); and (c) the patient had a form of keratoconus - forme fruste keratonus - prior to surgery and this was not detected during screening.
What is the progression and the potential results to the patient? (posted: jan 2005)
Ectasia is typically diagnosed some time in the first two years after surgery but has been known to first be diagnosed later than that. It is a progressive condition and depending on patient particulars and what measures are taken, may progress rapidly or slowly, but typically it will progress over a period of years.
The patient with ectasia may experience progressive myopia; effects similar to irregular astigmatism such as ghosting and other distortions; and fluctuating vision.
How is ectasia diagnosed? (posted: jan 2005)
Ectasia is diagnosed with corneal topography. It can also be seen in confocal microscopy or Artemis VHF digital ultrasound.
How can ectasia be treated? (posted: jan 2005)
There are both surgical and non surgical treatments to mitigate the symptoms of ectasia and attempt to prevent its progression. Gas permeable contact lenses may stabilise it in some patients. INTACS are increasingly being used to treat ectasia; sometimes only one of the ring segments is used. Many cases of ectasia require a corneal transplant (lamellar or penetrating keratoplasty).
Where can I get more information about ectasia? (UPDATE - June 2007)
Click here for LaserMyEye Encyclopedia entry, which may have additional articles and links.
Please also see the http://www.asklasikdocs.com/ site. They have extensive information about ectasia. Look for the Ectasia forum, the Information on Ectasia forum and the support group link.
Source from: http://www.lasermyeye.org/patients/learning/ectasia.html
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