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ELSA offers return to surface ablation
This variation of LASEK can be used safely for corrections of up to 8 D of myopia, surgeon says.
Excimer laser subepithelial ablation can be used to correct myopia up to 8 D, according to a surgeon who procedure.
Excimer laser subepithelial ablation (ELSA) is a variation of the procedure called laser epithelial keratomileusis (LASEK), said Chris P. Lohmann, MD, of the University Eye Clinic in Regensburg, Germany.
For various reasons, including flap complications, postoperative infections and keratectasia associated with LASIK, surface laser ablation procedures are becoming more popular again, Dr. Lohmann presented at the recent meeting of the German Ophthalmic Surgeons in Nuremburg, Germany.
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ELSA explained
LASEK was introduced by Camellin in 1999, said Dr. Lohmann. LASEK involves the creation of an epithelial flap, which is then repositioned after laser ablation of Bowman’s layer and anterior stroma.
This technique has the potential to eliminate or at least reduce many disadvantages of PRK (postoperative pain, slow vision recovery and corneal haze) and LASIK (flap complications, interface problems and the possibly attenuated long-term biomechanical stability of the cornea) while combining their advantages, Dr. Lohmann said.
As the name LASEK is confusing for surgeons and patients because of its similarity to LASIK, he said calls his procedure ELSA.
In ELSA, the epithelium is rolled back, and the laser treatment is delivered to the surface of the stroma. The epithelium is restored after the ablation, reducing the amount of postoperative pain.
A number of technique variations are used by different surgeons to accomplish this.
Dr. Lohmann said he makes a calibrated depth incision of 70 µm and then applies alcohol, a 20% ethanol solution. He uses a freshly opened flask of alcohol because of the quick evaporation rate.
He applies the alcohol solution for 30 seconds and then uses a special spatula to lift the incised edges of the epithelial flap.
“This epithelial flap can be rolled back like a carpet,” he said.
“We’ve treated some 900 patients over 2.5 years, and we’ve had problems in a few cases,” Dr. Lohmann said. “You just have to keep your nerves and apply alcohol again for 10 to 15 seconds. Then rinse it off again, and the epithelium can be removed quite easily.”
Dr. Lohmann uses disposable instruments distributed by Geuder.
“It’s easier to use disposable instruments today,” he said. “The advantage of disposable instruments is not only that of sterilization, but I believe they are also beneficial in that you always have a sharp blade. This creates a very nice margin like a capsulorrhexis. This factor also has impact upon later success.”
Postoperative pearls
After the laser ablation, the epithelial flap is returned, and a contact lens is applied. Dr. Lohmann tries to dry the epithelium as much as possible before applying the contact lens. This reduces the pain patients experience if the epithelium below the contact lens slips away, which can happen if either there is too much water below the contact lens or below the epithelial flap.
“Following the application of the contact lens, I simply press the contact lens onto the eye trying to eliminate water so the flap won’t move,” Dr. Lohmann said.
In the patients who still report postoperative pain, two potential sources are the alcohol and the contact lens. Dr. Lohmann surveyed all patients who reported pain postoperatively, and of the 10% to 15% of patients who reported postoperative pain, many reported it occurred in the first 4 hours. He attributed this to the alcohol.
The remaining reports of pain involved a foreign-body sensation from the contact lens. To address this, Dr. Lohmann said it is important to have smooth edges on the epithelial flap and a good repositioning of the epithelium, so that it covers the entire wound.
The type of contact lens used is very important, he added. The lens should have a high silicone content and high oxygen permeability. He uses a soft bandage contact lens (PureVision, Bausch & Lomb) applied for 3 days.
Expanded range
Initially, Dr. Lohmann and colleagues used ELSA to correct up to 6 D of myopia. But he has since raised the limit to 8 D of myopia because the initial results were so good.
“Pain was much less than expected, and corneal haze occurred in very few cases,” he said.
An examination of patients between 6.25 D and 8 D of myopia showed that all eyes are in the desired range of correction, stability is just as good as in patients with less than 6 D of myopia, and 90% of patients are within 0.5 D of the desired correction, he said.
No patients lost more than 2 lines of best corrected visual acuity. Stability is excellent after 1 year, he added.
A study in which Dr. Lohmann participated and that was presented via poster at a meeting in Rome reported the 1-year results of 100 consecutive eyes treated with ELSA for up to –8 D of correction. The setting was the University Eye Clinic, University of Regensburg, Germany.
The mean preoperative spherical equivalent was 5.19 ± 1.84 D, with a range from –1.1 D to –8 D. Surgeons used epithelial microincision, alcohol exposure and epithelial flap preparation. The 20% ethanol solution was applied to the cornea for 25 to 30 seconds. The laser ablation was performed with a Bausch & Lomb Keracor 117 excimer laser. Postoperatively, a PureVision soft bandage contact lens was applied for 3 days.
The 1-year follow-up exam included 88 eyes. No serious complications occurred. The mean spherical equivalent after 1 year was 0.25 ± 0.49 D with a range of +1 D to –1.75 D. In the study, 81% of eyes were within 0.5 D of desired refraction, and 93% were within 1 D of desired refraction.
Uncorrected visual acuity was 20/25 or better in 95% of eyes and 20/20 or better in 75% of eyes. No eye lost more than one line of best corrected visual acuity. In almost all eyes, haze was not present or only minimally present.
An ELSA enhancement was performed in nine eyes.
The study concluded that moderate myopia to –8 D could be treated safely and effectively with ELSA. For the correction of low to moderate myopia, ELSA could represent not only an alternative to PRK, but also to LASIK, the authors said.
Dr. Lohmann said that ELSA is characterized by fewer complications than LASIK. Beginning LASIK surgeons have to overcome a learning curve with the microkeratome, which is not used in ELSA. And ELSA is safer in patients with dry eye and for contact lens wearers, he said.
By offering ELSA, the patient can decide what procedure should be done, “and that’s precisely the way it should be,” Dr. Lohmann said.
For Your Information:
- Chris P. Lohmann, MD, can be reached at the University Eye Clinic, Franz Josef Strauss Allee, Regensburg 8400 Germany; (49) 94-1-944-9201; fax: (49) 94-1-944-9202; e-mail: lohmann@eye-regensburg.de.
- Geuder AG can be reached at Hertzstrasse 4, D-69126 Heidelberg, Germany; (49) 6221-3066; fax: (49) 6221-303-122; e-mail: info@geuder.de; Web site: www.geuder.de.