Thin Corneas, High Prescription....PRK?
- Asked by KCM
- 2 years ago
Hi, Just looking for some thoughts on this.... I've gone to 4 different offices for consultations, looking to see if I'm a candidate. My eyes are -7.25, and -7.50, corneal thickness of 475. I've gotten 2 no's and 2 yeses. Only for PRK, obviously no LASIK. Why the difference in opinion? I don't have any eye problems, contacts are fine, no dry eyes. It would just be nice to be free from it all. Oh, I turned down ICL, btw. Does anyone have and advice/thoughts/comments? Thanks!!
PRK for Thin Corneas with a High Prescription
I think you are getting about half "yes" and about half "no" because you are really a borderline candidate.
PRK removes about 14 microns (amount of corneal tissue) per diopter (-1.00 prescription) of treatment for a standard 8.5 mm ablation zone with a normal blend. This would leave you with about 375 microns of residual bed (amount of corneal tissue/thickness). Most surgeons like to leave at least 400 microns of residual cornea plus enough for a re-treatment if necessary. I am not sure this is possible in your case. It might be possible to leave you with 400 microns with a smaller treatment zone or no blend zone. Either of these things increase the chance of glare and halos and you would have no room for re-treatment.
I am going to add myself to the chorus of surgeons who recommend that you consider ICL.
ICL vs PRK
You are certainly not a LASIK candidate. PRK or LASEK are possible but you will face higher risk of corneal ectasia than most people, particularly if re-treatment is needed. ICL is a viable option which is unaffected by corneal thickness. However, there are other risks with ICL as it is intra-ocular surgery. I think you should find a surgeon who is comfortable doing both ICL and PRK/LASEK and discuss the pros and cons of each then make an informed decision.
PRK for thin corneas
I do not consider you a LASIK candidate with your correction. Understanding that, you may be a candidate for PRK or the ICL. The quality of the vision may be slightly better with the ICL than PRK, but the difference is minimal. The potential risk of serious complications is hugely less with PRK than the ICL as long as the curvature of your cornea is adequate. Good luck.
Recent PRK Reviews
Intraocular Contact Lens vs PRK For Patients With Thin Corneas
One of the benefits of nearly 20 years of experience with Laser Vision Correction(Lasik and PRK) in the United States and over 15 million procedures performed worldwide, is we have learned alot. Surgeons now know, down to the micron, how thin a cornea can be made with a laser before visual complications arise. The patient who posed this question is truely on the borderline between being able to have PRK or not. If I were this patient, I would reconsider the Intraocular Contact Lens(ICL) option. An ICL procedure is a surgical process whereby a plastic lens(the materials have been used for decades, so no worries there) is inserted into the eye in front of the human lens, thus, serving a similar purpose as a traditional contact lens, but without the day to day care and hassle. Obviously, this procedure is more involved than PRK or Lasik, but, in this scenario, it would allow for a great visual outcome without using any corneal tissue. This is a good idea in this patients case for many reasons, the main one being to preserve corneal tissue in case any touchups are needed in the future. ICL surgery is a bit more involved than PRK or Lasik, and, as a byproduct, more expensive as well, but it is a terrific procedure that gets terrrific results.
Thin cornea and LASIK vs PRK vs LASEK
you are not a borderline candidate. i will explain the math, so the confusion of conflicting answers goes away
your corneas are 475. you cannot have LASIK, because after wasting over 100 microns of tissue to cut the flap, you'd still need to remove almost 100 microns to get rid of your prescription.
the math looks like this:
475 initial - 125 flap - 100 laser ablation (removal of tissue) = 250 = minimum safe residual limit for LASEK
that means you won't be able to get enhanced if necessary, and you are at increased risk for keratoconus
so whoever told you that you could have LASIK, is, objectively, not the most conservative surgeon around
don't get PRK, i stopped performing PRK over a decade ago because it's very painful and has long recovery
instead, you should get an Advanced Surface Ablation, which is a LASEK or epiLASEK, where no flap is made, so we aren't wasting 125 microns of corneal tissue, which allows us to laser safely, see below:
475 initial - 0 (no flap made) - 125 (removed to correct your Rx) = 350 which is WAY more than 250 limit
this means you can be safely enhanced, and are NOT at risk for KC
i would not get an ICL if I were you, this is too risky to propose for anyone less than -10 Rx
i would also not get an intracorneal stromal inlay, they don't work great, and are somewhat experimental
i hope this helps you and others actually understand the objective numbers that are relevant to this common question of what procedure is right for people with high Rx or thin corneas--the answer 99% of the time is an Advanced Surface Ablation in my opinion (and not ICL or LASIK)
PRK and thin corneas
Many factors are considered for candidacy and corneal thickness is only one factor. 475 is certainly on the thinner side. Other factors include topography (shape of the cornea) age, residual corneal thickness, pupil size, and available technology such as femtosecond lasers (IntraLase) to create flaps.
Thin corneas and high myopia
You have definitely done the right thing by getting multiple consultations. The fact that you have gotten different answers from different places shows that you are a borderline candidate for laser vision correction. A safer option may be Intacs corneal inserts which can reduce your nearsightedness without removing tissue from your already thin corneas.
These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.