Cornea Genetic Eye Institute, Cedars-Sinai Medical Center, 444 S San Vicente Blvd, #1102, Los Angeles, CA 90048, USA. rabinowitzy@cshs.org
PURPOSE: To determine the efficacy of INTACS insertion using a femtosecond laser in the treatment of keratoconus and to compare it to the technique using a mechanical spreader. METHODS: INTACS were inserted in 10 eyes using the mechanical spreader to create the channels and subsequently on another 20 eyes using the femtosecond laser. Uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), manifest refraction, and corneal topography were measured prior to surgery, at 6 months (femtosecond group), and 1 year (mechanical group). Pre- and postoperative data were analyzed to determine changes in the above parameters. RESULTS: Both groups showed significant reduction in average keratometry (K), spherical equivalent refraction, BSCVA, UCVA, surface regularity index (SRI), and surface asymmetry index (SAI). The laser group performed better in all parameters except change in SRI. Results of the laser versus the mechanical spreader were as follows: reduction in spherical equivalent refraction (3.98 vs 2.96), change in average K (2.91 vs 2.52), improvement in UCVA (4.13 vs 3.63), improvement in BSCVA (3.92 vs 1.63), change in SRI (0.37 vs 0.64), and change in SAI (1.00 vs 0.70). Statistical analysis, however, did not reveal any statistically significant differences between the two groups for any single parameter studied. The biggest improvement in the laser group versus the mechanical group was BSCVA (P=.09). Overall success, defined as contact lens or spectacles tolerance, was 85% in the laser group and 70% in the mechanical group. CONCLUSIONS: Inserting INTACS using the femtosecond laser to create the channels is as effective as using the mechanical spreader.
However if the improvement can be slight, it is to be underscored that the insertion with a femtosedond laser is less risky.
Thanks for the comparison of the two methods with that study, do you know what method Dr Colin (the inventor) uses or prefers?
I have heard that vision fluctuates with intacs, mostly in the first 6 months as things settle (I thought i'll just add that for Chris here).
Dr. Rabinowitz uses the intralase to make the channel unlike Dr. Wachler who does it manually. Dr. Mark Swanson does it both ways but for him the only difference is he has to charge more to do the intralase, but prefers the manual way.
Dr Wachler normally uses one intac segament, which he finds works more than well, then using two.
The thicker the Intac the greater degree of flattening occurs. So very steep corneas would get better results with 4.5 as opposed to the 3.5 segments. However generally, mild to moderate cases in KC get's better results.
It does look like the laser way has the edge over the manual way in the results (which is the main thing), may be in the near future all Intacs will be done that way if the results keep showing this advantage and the advantage can be futher improved on, over-all its on what's seen to happen with a particular surgery in if it was done (Intacs placed) optimumly.
1°) As far as I know, no matter visual resultats, the insertion with a femtosecond is always safer than the manual way The problem is that femtosecond is very expensive and all hospitals or clinics do not have it so sometimes they keep using the manual way. 2°) The other big issue is how many time do INTACS "hide" keratoconus and the cornea remains stable after insertion (without C3R). It depends from the patient. The girl who was operated by Professeur Colin eight years ago and who had the first INTACS in the world is always stable whereas her other eye (which is without INTACS) evolved a lot. However, it is not proved that INTACS slow KC evolution, it is probably that they hide this evolution until the day it is too important.
I have read several papers about this and the improvement with the femtosecond laser is not huge but still noticeably in every test. The paper told us that the difference is very small but the change in BSCVA (3.92 vs 1.63) is very important to me.
And as you mention there is less chance of extrussion and other risks. I will have my intracorneal rings implant soon and I will make sure it is done with the femtosecond laser, any improvement is welcomed.
My son had intacs placed by Dr. Boxer Wachler and was given one intac in one eye and two in the other. This was dictated by the corneal topography being different in the second eye, I think there were two areas requiring flattening, sort of in a dumb bell shape, as I recall.
I was just reading the regression thread, and Dr. BW also strongly urged the patient to stay on antioxidant formula vitamins for life, as well as to continue with flax seed oil supplements.