What options do I have to correct my myopia if I am at risk for post-LASIK ectasia?Eye Health LASIK
I recently went to SNEC for a pre-LASIK assessment and was told by the consultant that the shapes of my corneas are associated with a borderline risk of developing post-LASIK ectasia, but otherwise my eyes are healthy. A month later I did a follow-up scan with the Pentacam and the results were consistent. I was told that none of the LASIK options offered by SNEC would be suitable for me. I have 3.00+ degree myopia and very mild astigmatism. What other options do I have to correct my myopia save from spectacles, contact lenses, and ortho-k?
Post-LASIK ectasia is one of the rare complications that can happen after any kind of laser refractive surgery, whether PRK/TransPRK/epiLASIK, LASIK or SMILE. In a predisposed eye with pre-existing weakness of the stromal collagen layer, even the small extra weakening caused by laser treatment can cause it to 'decompensate' and bulge forwards from the normal eye pressure. As you know, we routinely look for cases which are at higher risk and recommend these patients against going for laser refractive surgery.
I would agree with Dr Chan that sometimes we see very obvious cases that should not have any kind of laser refractive surgery. Then there are also borderline cases, where the patient may come across different opinions from different doctors.
This situation is not unique to suitability assessment for LASIK. For example, there are also borderline cases when we screen people to see whether they have glaucoma-we call this group of patients glaucoma suspects.
Generally speaking, cases that are obviously unsuitable for LASIK can still be considered for Implantable Collamer Lens (ICL) surgery, provided criteria such as adequate anterior chamber depth are met. ICL surgery does not cause significant corneal weakening, and has also been used in selected cases of frank keratoconus that were previously stabilised through crosslinking.
Borderline cases need to be considered on a case by case basis, with the increased risk clearly communicated to the patient. It is important to note that these 'borderline'/grey area cases may not develop ectasia. The increased risk comes from the statistics that go into the development of various indexes. Although these statistics are real data and need to be considered, they originate from large groups of people and do not necessarily apply to any one particular individual.
Therefore, occasionally borderline cases may be offered procedures that weaken the cornea less, such as PRK/epiLASIK (without flap), with or without crosslinking.
It is also important to understand that there are many variations in the way crosslinking is applied to the cornea. In the typical 'LASIK Xtra' procedure, only a mild kind of crosslinking is performed that is a fraction of the usual 'dose' applied to cases of frank keratoconus.
As such, LASIK Xtra (with a flap) is not offered to the group of patients who are obviously unsuitable due to a high risk of ectasia. LASIK Xtra is usually offered as an option in cases where there is a high spectacle degree to be corrected or where the cornea is predicted to be quite thin after the procedure, or in selected borderline cases where the risk is considered very low. In other words, LASIK Xtra is done in essentially normal corneas. We do not know how much of a risk reduction LASIK Xtra would provide for people who are at high risk, hence most doctors do not offer it for cases that they would not have done anyway for ectasia risk reasons.
To summarise, your options for refractive correction would include ICL surgery (provided the other eligibility criteria are met), and possibly PRK/epiLASIK +/- crosslinking depending on further testing and evaluation. The major factors that could potentially make PRK/epiLASIK feasible would be the corneal topographic characteristics (to determine 'borderlineness'), corneal thickness, as well as degree to be corrected.
Dr Por Yong Ming
MBBS, FRCSEd, FRCS, MRCOphth, MMed
38 IRRAWADDY ROAD
#09 - 26/27/28/29 Singapore 329563
In my clinic, patients with borderline LASIK suitability test results using cornea topography and tomography (i.e. cornea mapping) are usually carefully counselled before options presented for consideration.
The possible options, depending on the post-LASIK ectasia risk profile, are: LASIK-EXTRA, LASEK, LASEK-EXTRA and ICL (implantable contact lens).
SMILE-EXTRA had been tried out before too, although currently it is still much rarer than the other options, due to limited experience in the medical community. ICL disturbs the cornea the least amongst the various options, although it has its own set of suitability criteria such as depth of the front of eye etc.
EXTRA refers to accelerated cornea collagen cross-linking in conjunction with a refractive laser procedure, using a combination of UV-A light by the Avedro machine, and vitamin B solution.
The process of cross-linking improves the biomechanical strength of the cornea, and was initially created to treat ectasia that arise from the cornea disease called keratoconus, by Professor Theo Seiler, a Swiss/German ophthalmologist, whom I am very fortunate to have trained with.
It is also used to treat post-LASIK ectasia complication. Somewhere along the line other scientists started to offer cross-linking as a preventive treatment during LASIK.
It has been shown that LASIK-EXTRA improves cornea stability after treatment and reduces risk of power regression, with very minimal side effects. My experience with LASIK-EXTRA and LASEK EXTRA have been very positive. Many doctors offering EXTRA believe that it reduces risk of post-LASIK ectasia by around 50%.
Below is the summary of a scientific article on this:
PURPOSE OF REVIEW:
The purpose is to review the literature of combined laser in-situ keratomileusis (LASIK) and accelerated corneal collagen cross-linking (CXL) in context of its indications-contraindications, kerato-refractive, visual and safety outcomes, particularly with reference to preventing the development of post-LASIK ectasia.
LASIK + accelerated CXL has been developed with the rationale that the addition of CXL after LASIK may strengthen the LASIK compromised corneal biomechanics and minimize the complications such as post-LASIK ectasia. Different clinical studies have documented the safety and efficacy of LASIK + accelerated CXL for the correction of myopia or hyperopia and in the patients with low predicted residual bed thickness.
Available literature shows that refractive and keratometric outcomes of LASIK + accelerated CXL are comparable or better than LASIK alone. Less regression has been observed after LASIK + accelerated CXL compared with LASIK alone and no case of post-LASIK ectasia development has been reported among 673 eyes with the follow-up ranging from 3 months to 4.5 years. Future studies with large numbers of patients and longer postoperative follow-ups are needed to establish the efficacy of LASIK + accelerated CXL in preventing the development of post-LASIK ectasia.
I hope all that was not too much medical jargon, and feel free to contact me if you need further advice. Cheerio!
Dr Daphne Han
MBBS, MMed, MRCS, FRCS, FAMS
#09 - 23 TO 27, 30/31 Singapore 238859
Indeed, the purpose of any pre-LASIK assessment is to determine if the patient can safely undergo LASIK and have visual results that can remain stable for a reasonable period of time. The criteria to consider are many and the list, though not exhaustive, include the patient’s refractive error, corneal thickness and corneal shape.
Some cases are frankly either safe or unsafe to have LASIK. However, there is a group of patients who may belong in the grey zone for which there can be variations of interpretation between surgeons. Surgeons do have different levels of risk appetite and hence it can sometimes cause confusion for patients seeking second opinions about their suitability for LASIK surgery.
Be sure that in all your visits, the surgeons goes through in detail the specific pros and cons of the various options and advise you on the appropriate treatment choice for your eyes. Walk away form anyone who tells you that any surgery is “risk-free”.
Should your case truly be unsuitable for LASIK, you may still consider the alternative forms of refractive surgery that include Advanced Surface Ablation, ReLEx SMILE or implantable contact lens. However, all the various techniques have their own set of suitability criteria and will have to considered individually on how they may benefit you.
Dr David Chan
Dr David Chan
MBChB, MMed, FAMS, MRCS, FRCS
290 Orchard Road
#07-09 Singapore 238859
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Its difficult to be more precise in my answer, in the absence of more specific examination findings. However, in general for patients in your situation, there are definitely options available to you!
First and foremost, this would include an implantable collamer lens which will fully correct your myopia and astigmatism. This is an intraocular procedure to place a collamer lens within the posterior chamber of the eye immediately in front of the natural lens.
It provides excellent visual rehabilitation with a minimum of side-effects (that plague laser refractive procedures). As the cornea is not operated on, the risk of developing corneal ectasia remains the same as if you had not performed surgery.
Some patients in your situation are also suitable for laser refractive procedures including epilasik, femto-assisted Lasik and even Smile / ReLEX. These procedures are usually supplemented by a collagen cross-linking procedure using riboflavin-Ultraviolet-A. This is a process called Epilasik-Xtra, Lasik-Xtra and Smile-Xtra respectively.
This additional procedure stiffens the anterior stromal fibers of the cornea which replicates the de novo state of the cornea, reducing the risk of developing post-Lasik corneal ectasia. You should speak to your ophthalmologist for a more detailed discussion with all your medical records and findings in order to get a detailed understanding of your specific requirements.
Good luck and I'm sure that you will find a solution that is most suited for you!
Dr E-Shawn Goh
MBBS, MRCOphth, MMed, FRCOphth, FRCS, FAMS
MOUNT ALVERNIA HOSPITAL MEDICAL CENTRE D
820 THOMSON ROAD
#06 - 57/58/59/60/61/62 Singapore 574623
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