Does corneal collagen cross linking with LASIK or ReLEx® SMILE® have benefits?Eye & LASIK
Hi doctors, I am considering going for corneal collagen cross link with my LASIK or ReLEx® SMILE® procedure (still undecided which procedure to choose). Cost is not a concern.
During an eye screening for LASIK earlier this year, I was told that I do not need collagen cross link as my cornea is above average thickness, but I’m still paranoid about thinning of my cornea/keratoconus/corneal ectasia as previously an NUH eye doctor had said my eyeball was elongated, so I was at greater risk for the condition.
So despite my recent normal LASIK eye screening, I still feel that I may be at risk for corneal thinning especially as I have allergies, and like to rub my eyes. I have also read that LASIK weakens the cornea about 20 – 40%, so preventative corneal collagen cross link may help to prevent further corneal thinning, and also prevent regression after LASIK.
In a normal person, does collagen cross linking with LASIK or Relex Smile confer any additional benefits (protective, preventative or otherwise) to my cornea in preventing corneal thinning? Is there a chance that it will improve refractive outcomes, and prevent regression?
Are there any downsides to collagen cross linking in someone who technically doesn’t need it? Really appreciate your advice 🙂
Corneal collagen crosslinking with LASIK or SMILE is relatively new, and the true beneficial effects, if any, may not be quantifiable or known for some years yet.
In essence, after the cornea has been reshaped (through LASIK or SMILE), vitamin B2(riboflavin) is applied to soak the cornea, and then ultraviolet light is shone on the soaked cornea. The entire crosslinking process adds about 3 minutes to the entire refractive procedure.
We do know that after crosslinking, the cornea becomes stiffer (stronger in a way). There is no other extra effect known to be caused by the crosslinking. The corneal stiffening may help to reduce the risk of regression, and may reduce the risk of ectasia.
However, it is important to remember that regression is not caused by one single factor, and crosslinking may only address one of several factors.
There were some initial concerns that combined corneal crosslinking may affect the predictability/accuracy of laser treatments, but studies so far show that results are equally accurate whether crosslinking was done or not. Some cases get a degree of corneal haze after corneal crosslinking, however, the haze almost always disappears by itself after a while. So perhaps the only real downside to having crosslinking done, when you don’t really need it, is the extra cost.
Finally, all myopic/shortsighted eyes are elongated. But most myopic eyes are not at particular risk for developing post LASIK ectasia. The risk comes mainly from corneas that show subtle signs of pre-existing keratoconus, and sometimes from corneas that are thinned a great deal either because of treatments for very high myopia or pre-existing thin corneas.
Collagen cross-linking (CXL) has been used to treat a condition known as keratoconus for many years now. Its purpose is to improve the structural strength of the front portion of the eye known as the cornea.
Keratoconus essentially results in the cornea losing its ability to keep its shape and patients may suffer from increased myopia and astigmatism. Keratoconus may occur naturally or rarely as a consequence of corneal laser vision correction (LVC) such as epi-LASIK, LASIK or ReLEx SMILE.
Due to its effectiveness as a treatment for keratoconus, there has been an increasing trend of laser refractive surgeons now offering CXL at the same time as LVC with the hope that it will reduce the risks of developing keratoconus.
As it is a fairly recent practice, the degree of protection when CXL is done in conjunction with LVC is currently still being studied. Suffice to say it is widely recognised that the cornea structure does strengthen following CXL. The procedure has low rates of complications and side effects, most of which are temporary. Due to the combination of the potential benefits of preventing a serious albeit rare condition and its relatively high safety record many surgeons have adopted CXL into their refractive surgery practice.
Though CXL does not necessarily permit the surgeons to widen their pool of suitable patients or improve the visual outcomes of LVC, its intended benefit is to offer LVC patients an added layer of corneal protection leading to better long term results following LVC.
Certainly with the added treatment comes increased costs. Though the cost of CXL done in conjunction with LVC is far lower than performing CXL as a standalone procedure.
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