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Flapless epi-LASIK shows promising postop results
The procedure produced significantly less pain, photophobia and tearing than PRK, study found.
Our reliance on surface ablation has been evolving, predominantly due to heightened concern about corneal ectasia. No one wants to see an elective surgery patient go on to a potentially devastating complication, nor do we want to face lawsuits stemming from postoperative ectasia.
In light of this, I have taken a “first, do no harm” approach, greatly expanding the role of surface ablation.
A few years ago, I was predominantly a LASIK surgeon, with only about 5% to 10% of my cases being surface ablation. However, once I acquired the Nidek Magellan Mapper corneal topographer, I saw that close to 30% of my patients had an elevated risk of ectasia. The Magellan uses artificial intelligence to compare the patient’s top-bottom symmetry with that of normal eyes and identify irregularities. It is also good at distinguishing between contact lens-induced changes and keratoconus patterns, so it may help me consider as candidates some people I would previously have ruled out for refractive surgery. For any patient flagged by the Magellan, those with thinner corneas or patients whose jobs or hobbies put them at risk of late flap displacement, surface ablation is the safest choice.
My current LASIK technique is wavefront-guided ablation using Bausch & Lomb’s advanced nomogram Zyoptix system with thin flaps made using the femtosecond laser. For surface ablation, I have switched from alcohol-assisted PRK to flapless epi-LASIK with the Moria Epi-K, based on clinical studies I have conducted to determine the best procedure.
In 2005, we retrospectively compared results from our first 150 eyes treated with the Epi-K with a similar number of PRK eyes. In the epi-LASIK cases, the average flap thickness was predictable, at just less than 50 µm. At that time, we were still repositioning the epithelial flap after the ablation.
We found that epi-LASIK produced significantly less pain, photophobia and tearing than PRK in the first 4 postoperative days. Beyond the first week, as the epithelial cells regenerated, there was little difference between the two. Because discomfort had been the biggest disadvantage of surface ablation, this finding was sufficient for me to move to epi-LASIK.
Discarding the flap
Next, we began to question whether the new “flapless” epi-LASIK could further improve the patient’s postop experience.
I conducted a small contralateral eye study (n=13) to compare visual recovery, epithelial regeneration and subjective patient experience with and without the epithelial flap. The mean spherical equivalent was —4.25 D. All patients had bilateral same-day surgery with Alcon’s CustomCornea system and the Epi-K. Mitomycin-C was used in 98% of the eyes.
On the first day after surgery, not only did 46% of the patients have better uncorrected visual acuity in the eye with the flap removed, but there was a five-line difference between the flapless eye and the fellow eye. By the 1-week visit, all subjects either saw better with the eye without a flap (73%) or saw equally well with both eyes (27%). We were twice as likely to be able to remove the bandage contact lens by day 3 or 4 postop in the eyes in which the flap had been removed.
I expected there to be more pain in the eyes without the epithelial flap, but that was not the case. On every single parameter we considered, the flapless group did better. They had substantially faster visual recovery, faster epithelial regeneration, and less pain and discomfort in the immediate postop period, with no increase in haze. We concluded that there was no advantage in replacing the epithelial flap.
The Epi-K makes a smooth, clean edge for the area to be ablated; removal of the epithelial flap eliminates the devitalized cells that slow down healing and visual recovery.
Haze prevention is important, so I use MMC liberally, especially with deep ablations and people who have allergies or asthma. My threshold for using MMC prophylactically is also low for patients in their early 20s, who tend to have a slightly more hyperactive immune system. Postoperatively, all patients should wear UV-blocking sunglasses during the first 3 months to minimize the risk of haze.
There are also several steps that surgeons can take to improve comfort and increase patient satisfaction with epi-LASIK. My full regimen is described in the sidebar below, but some tips for success include pre-treating with Motrin (ibuprofen, Pharmacia) or similar oral nonsteroidal anti-inflammatory drug (unless contraindicated by history of stomach ulcers, etc.) to help blunt the inflammatory cycle. I prescribe it for two to six times a day pre- and postop, based on the patient’s weight. Vitamin C, given pre- and postoperatively, also speeds healing of the epithelial cells.
Some have suggested using the Acuvue Oasys (Vistakon) contact lens as a bandage lens. Whether you prefer Oasys or a different contact lens, it should fit tighter than one would choose for long-term wear. A tight lens with a base curve of 8.3 to 8.4 will prevent it from moving around on the eye and causing discomfort. Dilation also helps to block ciliary muscle spasm and reduce pain in the immediate postop period.
With this regimen and the flapless technique, I am comfortable enough with epi-LASIK that 40% to 50% of my patients have it instead of LASIK.
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Comparing IntraLASIK with epi-LASIK
Most recently, we retrospectively compared our IntraLASIK and epi-LASIK results. In this study, a broad range of myopic subjects was treated with wavefront-guided CustomCornea. Both treatments were safe and effective, but we saw some advantages to epi-LASIK.
In the LASIK group (160 eyes), the lamellar flaps were made with the 60-kHz femtosecond laser. In the epi-LASIK group (58 eyes), the epithelial flaps were made with the Epi-K. Six-week follow-up was available for all patients; 3-month follow-up was available for 25% of the IntraLASIK eyes and 48% of the epi-LASIK eyes.
The two patient groups were typical of the refractive surgery population, with a mean age of 35 years and mean manifest refractive spherical equivalent of –4.39 D (LASIK) and –4.33 D (epi-LASIK), although the upper end of the range for both sphere and cylinder was higher in the LASIK group.
Scatter plots of the attempted vs. achieved corrections for both groups showed a slightly wider scatter for the epi-LASIK group; this difference disappeared by 3 months. At 3 months, in fact, the epi-LASIK results were more accurate, although the difference was small. We were using a new excimer laser with no nomogram adjustment, which probably accounted for the slight overcorrection in both groups.
There was a difference in the binocular 20/20 rates between the two groups. Eighty-six percent of the epi-LASIK patients, compared with 71% of the IntraLASIK patients, were 20/20 at 3 months (Figure 1). All patients in both groups were 20/30 or better.
We also compared postoperative higher-order aberrations in a subset of 10 eyes from each group. Both procedures induced some aberration. Coma and total higher-order aberrations increased more in the LASIK group than in the epi-LASIK group (Figure 2); trefoil was higher in the epi-LASIK group. None of the differences were statistically significant, given the small sample size. Spherical aberration was reduced in both groups compared with preoperative levels. In the future, I would like to conduct contrast sensitivity and driver simulation testing to see if the reduction in spherical aberration has any meaningful impact on night vision.
Both epi-LASIK and IntraLASIK are safe and effective. Patients who are drawn to either of these technologies are safety conscious. In our practice, they understand they will either get LASIK or flapless epi-LASIK, depending on the exam results and their lifestyle. I tell them during the consultation that if I see anything that concerns me, I am going to recommend epi-LASIK.
When we choose a surface procedure, the good news is that our data suggest that at 3 months postop, UCVA with epi-LASIK is better and the aberration profile is also slightly better than in LASIK cases. In the past, fear of pain was the biggest hurdle for patients who were not good LASIK candidates, but today, I can assure my epi-LASIK patients that 90% of them will experience no pain at all. If they are among the 10% who experience some discomfort, we can effectively manage it.
For more information:
- Michael J Endl, MD, can be reached at Fichte-Endl Eye Associates, 2400 Pine Ave., Niagara Falls, N.Y. 14301; 716-282-1114; e-mail: mpderme@aol.com. Dr. Endl receives research assistance and/or serves on speakers’ bureaus for Alcon, Bausch & Lomb and Allergan. He has no financial relationship with Moria.