Doctor's Answers (4)
The risk of a person getting corneal ectasia, in general, is very low after LASIK. A prospective study of almost 38000 patients (https://www.ncbi.nlm.nih.gov/pubmed/20153899) at the Singapore National Eye Centre found 8 cases of this complication out of all the cases done.
There are some factors which may somewhat increase the risk of ectasia slightly but where it is still generally considered safe to have laser refractive surgery done.
1. These include high spectacle degrees (eg 700 degrees and above, but with enough corneal thickness). In these cases, 'LASIK Xtra' or LASIK with simultaneous crosslinking is often offered. Many doctors would avoid epiLASIK in these patients with high spectacle degrees because there is a higher risk of post-operative haze or scarring.
2. Some other patients may have somewhat thin corneas (but no other signs of keratoconus or corneal weakness), and relatively low spectacle degrees. If the calculated residual corneal thickness is somewhat thin (eg less than 300-350 microns), and the spectacle degree is not too high, then epiLASIK would be a viable option to potentially give a stronger eye than any other laser refractive surgery.
It is important to bear in mind that doctors would not offer any laser refractive surgery in the first place, if they really thought a patient had a high chance of getting ectasia. These would be patients who show signs of corneal weakness, or what is called Forme Fruste Keratoconus.
In your case, if your doctor offered you both epiLASIK and LASIK, then both should be fine.
If you are very worried about the risk of corneal ectasia regardless of what the doctor says (ie your priority is to minimise the risk of ectasia as much as possible regardless of healing time and post-op comfort), then yes, epiLASIK would give you a theoretically stronger cornea with a theoretically lower risk of ectasia as compared with LASIK.
On the other hand, if you regard fast recovery and minimal pain as strong priorities and are still considering LASIK, you can consider seeing another doctor for another opinion. The most important factors are the shape and thickness of your cornea, and your spectacle power. Whichever doctor you seek a definitive opinion from needs to have these details as well as examine your eyes first, and then discuss your concerns and the various options.
That's a very relevant question. There is no absolutely complication free option, and even the safest option of no laser treatment / collagen cross-linking alone may leave you with a residual risk of corneal ectasia, albeit miniscule.
Between the two options you detailed, there is a theoretical advantage to performing EpiLASIK as there would be more residual tissue that would theoretically contribute to corneal stability.
However if the overall findings suggest that the risk of ectasia is low, then the relative speed of healing / visual recovery would tilt the discussion towards Femto-LASIK / KXL.
At the other extreme, if the risk of ectasia is significant, I would recommend you consider collagen cross-linking, and subsequent implantable collamer lens to correct your refractive error.
Ultimately, you will have to weigh up the relative advantages of each treatment option prior to deciding. You should decide this together with your ophthalmologist with consideration of your specific examination findings.
If you are assessed to be at risk of corneal ectasia, no matter how low, it definitely pays to be more vigilant about the type of procedure you undergo.
The type of machine that made the assessment may read differently from another machine. However, once any one machine flags out a suspicion, a responsible LASIK surgeon should certainly discuss your options with you.
In fact even scans that turn out to be normal is not a 100% guarantee for surgical outcome free of ectasia, which basically is warpage of the cornea.
The risk of ectasia can be reduced by cross linking, both in LASIK as well as epiLasik. However, in general, if your eye power is higher than around 500deg myopia, especially if the astig is also quite high, epilasik is not so great as you may be at risk of cornea haze post op. In general, epilasik also does not work so well for higher astig as it is less predictable than lasik.
You may want to consider Smile as well. In terms of ectasia risk, smile should be safer than lasik, with less downtime compared to epilasik. It can also combine with cross linking. But again it still thins the cornea.
Another option that I usually recommend for those with eyes at risk of ectasia is the ICL. As this operation does not thin the cornea, there is practically zero risk of inducing ectasia. Many of my patients in this situation accept this proposal, and hence we get away with the worry of ectasia.
Last but not least, please avoid rubbing your eyes. Eye-rubbing is notorious for inducing both astigmatism and ectasia, particularly in young eyes.
All the best for your eye treatment!
Dr Daphne Han
As with all cases of surgery, risks and complications must be managed to an acceptable degree. A surgeon would have to help the patient weigh the benefits vs the likelihood of complications before deciding on going ahead with surgery.
Fortunately, the overall risks of post-laser refractive surgery corneal weakening or corneal ectasia are very low. However, we are aware that certain types of cornea shapes or thickness may place that patient at a higher risk of corneal ectasia than the general population.
When this occurs, the surgeon has the option of choosing a treatment that has a lower risk of causing corneal ectasia. In your case, advanced surface ablation (e.g. epi-LASIK, PRK, LASEK) is preferred over LASIK for this reason. Collagen cross-linking is also offered to mitigate the risk of corneal ectasia.