advanced surface treatment
The Benefits of Advanced Surface Treatment
Discarding the epi-LASIK flap is key to a more patient-friendly procedure.
BY H.L. "RICK" MILNE, M.D.

I have recently come full circle in my experience with surface ablation. One or 2 years ago, I began performing epi-LASIK with the Epi-K (Moria, Antony, France) as a replacement procedure for PRK. I had already been performing epi-LASIK on about one-third of my laser refractive surgery patients and enthusiastically predicted that I would soon begin to do fewer LASIK cases and convert more of my practice to surface procedures with Epi-K.

However, after treating and following about 100 eyes, I became somewhat disillusioned with the standard epi-LASIK technique in which the viable epithelial flap is retained. I now perform what I term advanced surface treatment (AST) — essentially epi-LASIK with flap removal — on 95% of my laser refractive surgery patients and LASIK on only about 5%.

In this article, I will describe why I have made this change and how I have adjusted my technique and postoperative comfort regimen to make surface procedures more successful in my practice.

Early epi-LASIK Experience

Visual acuity results in the first 100 eyes I treated with the Epi-K and a retained flap were good, and few enhancements were needed. Patients were more comfortable postoperatively than with PRK and most were able to return to work sooner.

However, two of these initial patients experienced delayed visual recovery. Both developed what looked like map-dot-fingerprint dystrophy across the central cornea. After discussions with colleagues, I came to believe this was the result of epithelial regrowth over or under the still-viable epithelial flap. While this eventually resolved in these cases, the patients endured 3 to 6 months of reduced acuity before the epithelium returned to its normal thickness. Thus, my enthusiasm for epi-LASIK began to wane.

However, I remained interested in surface ablation for three primary reasons.

First, because surface ablation eliminates the potential for flap-related complications, it is quite appealing to anyone (patient or surgeon) with a "safety-first" mindset. Second, surface procedures make laser vision correction possible for patients with thin corneas or tear dysfunction. Third, several studies have already shown better results from wavefront-guided surface procedures compared to wavefront-guided LASIK.

At the 2005 American Academy of Ophthalmology meeting, I saw a presentation by Raymond Stein, M.D., F.R.C.S.(C), Toronto, who suggested removing the epithelial flap. At first, it made little sense to me to make a nice epithelial flap and then throw it away. However, once I actually tried it, I quickly realized that discarding the flap might transform the epi-LASIK experience.

Because the epithelium adjacent to the removed epithelial flap made with the Epi-K is fully adherent and not traumatized by alcohol or brush debridement (as shown in Figures 1 and 2), the cornea re-epithelializes very quickly without pushing dead, devitalized cells to the center. With PRK, we would typically see pseudodendrites in the center of the cornea, lasting 1 or more weeks, but this new technique avoids them entirely.

AST with Epi-K

I now set the Epi-K stop at 9 mm and proceed with epithelial separation as usual. This stop setting effectively creates a free cap in about one-third of patients. In the remainder of patients, there is usually a very small tag or hinge remaining that can be easily peeled off with a blunt instrument after removing the Epi-K head.

Not only have I had none of the dystrophy problems I noted before I began discarding the flap, but the smoothness and speed of the epithelial regeneration is clinically impressive compared to my earlier experience — and certainly faster when compared to PRK or LASEK.

I analyzed outcomes in the first 100 eyes (55 patients) treated with this new technique, looking specifically at whether the epithelium was healed at the first postoperative visit, visual acuity at the first postop visit, visual acuity at 1 month or later and utilization of postoperative pain relief. All eyes were treated with VISX CustomVue with Iris Registration (Advanced Medical Optics [AMO]/VISX, Santa Ana, Calif.). Mitomycin C (0.02% for 15 seconds) was used on any eye in which the ablation depth was greater than 75 μm.

Since I performed this analysis, I have treated another 100+ eyes, although 1-month follow-up is not yet available.

I perform AST procedures on Thursdays, with the follow-up exam scheduled for Monday morning, or approximately day 3.5. Of all the 200+ eyes treated thus far, only four eyes of two patients have not been 100% healed by the first postoperative visit. On Monday morning I am able to remove the bandage contact lens as the patients are comfortable and functional enough to go back to work that day.

In the study cohort (100 eyes), visual acuity at the first postoperative visit averaged 20/40, with a range of 20/20 to 20/70. Binocular visual acuity was, on average, 20/30, with all but two patients 20/40 or better OU. In eyes corrected for near, the average was J2. At the 1-month follow-up visit, all patients were 20/30 or better and none desired enhancement. No eye lost any lines of BCVA.

Figure 1. Epithelial border after alcohol debridement.

The "Christmas Cohort"

I even have a small group of six patients, the "Christmas cohort," who were seen for the first postoperative visit on day 2.5. All of those patients were also fully healed, with no devitalized cells in the central epithelium. I removed their bandage lenses early and we were all able to enjoy our Christmas holidays. Given this experience, I think it is possible that I could move to scheduling the first follow-up visit for day 2.5 for all patients, if desired.

This represents a huge improvement over earlier surface techniques. With PRK, the average healing time is about 5 days and many patients take 7 days or longer to fully re-epithelialize. Interestingly, both patients who were not completely healed by day 3.5 had steeper Ks and a larger epithelial flap hinge that had to be removed mechanically. Although this is anecdotal, I suspect that even such limited amount of mechanical removal may negatively affect epithelial healing, so I try to get as close to a free cap as possible.

Improved Postoperative Comfort

The ability to regain functional vision and return to work relatively quickly is important for patient acceptance of any surface ablation procedure. Even more important, though, is the amount of pain patients experience postoperatively. If you can get rid of the pain, risk-averse patients find surface ablation very appealing.

I have recently taken a more pharmacological approach to my postoperative comfort regimen. It is hard to say whether removing the epithelial flap affects comfort levels. What has made a significant difference is pre-medicating the patient with gabapentin (Neurontin, Pfizer) 100 mg t.i.d. or pregabalin (Lyrica, Pfizer) 75 mg b.i.d. Patients are instructed to take one of these medications the morning before their surgery.

Immediately after the procedure, I hold a frozen Weck-Cel (Medtronic Ophthalmics, Minneapolis) against the bed for 30 seconds to chill the nerve endings, which helps to reduce postoperative pain. I have tried a number of bandage contact lenses and have found that a tight-fitting lens works best, so I use CibaVision (Novartis, Duluth, Ga.) Night & Day lenses with a base curve of 8.4.

Figure 2 Epithelial border after epi-K.

We give all patients a prescription for the gabapentin or pregabalin, as described above. I also prescribe bromfenac ophthalmic solution 0.09% (Xibrom, Ista Pharmaceuticals) q.i.d.; zolpidem tartrate (Ambien, Sanofi Aventis) q.h.s. for 4 days; promethazine HCl 25 mg/meperidine HCl 50 mg (Mepergan Fortis, Wyeth-Ayerst), and Comfort Drops (diluted proparacaine).

I like bromfenac because there is a mild anesthetic effect that lasts for about 45 minutes every time patients use it. Promethazine is a good choice for oral pain relief because it does not cause nausea and has a symbiotic effect with either of the other pain relief drugs. I tell patients to use the narcotic painkiller or the Comfort Drops if they experience any "breakthrough pain" after taking the other medications.

In addition to the pain-reduction cocktail, I use a steroid and fluoroquinolone, both q.i.d. Once the eye heals, usually on day 3.5, I remove the bandage lens and stop all the pain medications, including the NSAID. I decrease the steroid to b.i.d. and continue the antibiotic for 2 more days. I like to get most of the chemicals off the epithelium as quickly as possible.

A Patient-Friendly Procedure

This regimen was used for my first 100 eyes treated with the new AST technique. On the first postop visit (day 2.5 or 3.5), I asked patients whether they used any pain medication other than the gabapentin/pregabalin. Seven of the 55 patients took one narcotic pain pill during the first 24 hours following surgery. On day 2, three of the 55 patients took one pill. No patients took additional pain pills over the weekend.

I also asked whether they used the Comfort Drops at all. Two patients (4%) used drops at least once during the first 24 hours. After that, none of the patients used the drops at all. In addition, patients reported being quite functional over the weekend, with many going out to dinner or to the movies and otherwise engaging in normal activities.

I believe we now have the patient-friendly procedure that my patients and I have been seeking. I now perform surface ablation on almost all (95%) of my laser vision correction patients. My practice has grown by 18% and more of the AST patients are referring friends for surgery than my LASIK patients have for a long time.

The Advanced Surface Treatment procedure with the Moria Epi-K has allowed me to attract patients to my practice who have been afraid to have laser vision correction. These patients want a safer procedure. Now that we can offer them a faster recovery, so they don't have much down- time, and improve comfort after surgery, they are embracing the procedure.

H.L. "Rick" Milne, M.D., is in private practice at The Eye Center in Columbia, S.C. Contact him at 803-256-0641 or hmilne@aol.com.