In hands of experts, surface ablation has many variations

Leading surgeons shared their surface ablation surgical techniques and explained why they perform the procedure the way they do.

Surface ablation is a blanket term that encompasses a wide variety of refractive surgical techniques. Excimer laser refractive surgery started on the surface of the cornea in the late 1980s, and interest in surface ablation has recently had a resurgence.

Daniel S. Durrie

Now, surgeons have a range of options for performing surface ablation, with a wide variety of surgical approaches to choose from and more pharmaceutical alternatives for postoperative management of pain. Ocular Surgery News interviewed four refractive surgeons with extensive experience in surface ablation to learn the personal variations in their techniques and the reasons they do what they do.

Several of the surgeons we interviewed noted that they have been performing surface ablation since the early days of laser refractive surgery and have never abandoned it. Marguerite B. McDonald, MD, performed the first PRK on a human eye in 1987, and although her practice was interrupted last year by Hurricane Katrina, she said she intends to return to performing surface ablation as soon as she can.

Daniel S. Durrie, MD, said he, too, never left surface ablation behind.

“I’ve been doing surface ablation since we first started doing laser refractive surgery in 1989, so it’s been something that I’ve never quit,” Dr. Durrie said. “I’ve done all the techniques: LASEK, butterfly LASEK, epi-LASIK, subepithelial separation. I’ve used brushes, I’ve used alcohol, all different things to remove the epithelium. I have always done it, so the technique I use now has really evolved over a long period of time, over the past 15 years.”

In addition to Dr. Durrie and Dr. McDonald, OSN also spoke to William B. Trattler, MD, and Kerry D. Solomon, MD, regarding their preoperative, intraoperative and postoperative choices in surface ablation.

Preparing the surface

As with any refractive procedure, proper patient selection is important for success with surface ablation, Dr. Trattler said.

William B. Trattler

“The most important thing about epi-LASIK is proper patient selection,” Dr. Trattler said. “If the patient has a scar, the epikeratome may dive into the stroma when you hit the scar, and that could lead to a stromal incursion. You want to be careful about patient selection.”

Once the patient is selected, the surgeon must be sure that the ocular surface is in good shape for surgery. Preparative regimens can be minimal or extensive, including drugs and nutritional supplements.

Three of the four surgeons we spoke to said they prescribe a regimen of artificial tears or Restasis (cyclosporine ophthalmic emulsion 0.05%, Allergan) to ensure the ocular surface is optimal for surface ablation and there are no signs of dry eye.

“Most of our patients have wavefront-derived treatments, so we have them use artificial tears, often preservative free, four to six times a day to make sure that the ocular surface is pristine,” Dr. Solomon said.

Both Drs. Trattler and McDonald said they prescribe Restasis. Dr. McDonald has patients begin Restasis on the day they book their surgery, ensuring about 2 weeks of treatment.

“You want to identify dry eye patients and treat them preoperatively,” Dr. Trattler said. “Because of that, I use Restasis pretty extensively in a large number of patients. This is how you can get them ready for surgery; get their ocular surface as healthy as possible before surgery.”

Some surgeons also favor nutritional supplements for selected patients. For those with severe dry eye, Dr. Trattler said he prescribes oral omega-3 fatty acids and inserts punctal plugs preoperatively.

Drs. McDonald and Trattler both said they also prescribe vitamin C preoperatively, which according to a study by Aleksander Stojanovic may help to reduce postoperative haze.

“They get vitamin C 500 mg, twice a day, 1 week before and 1 week after the surgery,” Dr. McDonald said. “Just before Katrina hit, I was about to change that to 3 weeks.”

Dr. Trattler said he prescribes vitamin C 1,000 mg per day for the week before surgery.

Immediately preop

Marguerite B. McDonald

Dr. McDonald said she has an aggressive pain-control regimen for her patients. It begins 30 minutes before surgery, when they receive 80 mg of oral prednisone.

“In our research, we’ve discovered that oral steroids taken in high doses exactly 30 minutes before the laser fires will vastly decrease postop pain for surface ablation,” she said.

At the same time, each patient receives a drop of Alphagan P (brimonidine tartrate ophthalmic solution 0.15%, Allergan) to constrict the blood vessels.

“It is a glaucoma drop, but we’re not giving it for glaucoma. We’re giving it because it also vasoconstricts very effectively,” Dr. McDonald said. “We don’t want any pro-inflammatory cytokines leaking out of the blood vessels into the conjunctiva and the sclera that might increase haze, pain and regression later on.”

Chilling regimens

Three of the surgeons we spoke to for this article use some form of intraoperative chilling procedure for pain control. Dr. Durrie said he cools the eye with frozen balanced salt solution “popsicles,” applied both before he removes the epithelium and again after the ablation.

Drs. McDonald and Trattler both said they use chilled balanced salt solution. Dr. McDonald has a special device in the operating room to keep the irrigating solution cold.

“It’s a chilling steel block that gets extremely cold. It has four holes in it so you can keep little bottles of balanced salt solution in there,” she said. “Chilled solution makes a huge difference as far as pain control, so that’s critical.”

Dr. McDonald said she puts a small well on the eye, fills it with the chilled balanced salt solution and allows it to sit. After 20 seconds, she empties and repeats. The third time, she allows it to sit for 30 seconds.

Dr. Trattler also said he uses cold irrigating solution.

“The balanced salt solution is placed into a freezer. It’s taken out just a few minutes before surgery and allowed to thaw partially. You end up with a slush of ice-cold BSS with ice cubes in this little bottle,” he said. He applies the solution before epithelial removal and after ablation.

Dr. Solomon did not describe any chilling protocol. For pain control, he said, “On the day they come in, they get a drop of proparacaine on the table, under the laser. They get a drop of antibiotic on the table, under the laser, right then and there as well.” He then proceeds with epithelial removal using the epi-LASIK blade on the Amadeus microkeratome from Advanced Medical Optics.

Following the cooling routine, Dr. McDonald puts proparacaine drops on the eye for further pain control.

Epithelial removal

Epithelial removal is the part of the surface ablation procedure that makes each one different from the others. It takes many forms: epithelial abrasion with knife or brush in “old-fashioned” PRK, laser removal in transepithelial PRK, alcohol loosening in LASEK, mechanical removal of an epithelial sheet with an epikeratome in epi-LASIK.

Each surgeon we interviewed described a different approach to epithelial removal.

Dr. Durrie said he uses 20% alcohol for 25 seconds to create a controlled 7.5-mm epithelial defect, which is completely covered by the subsequent 9-mm-diameter laser ablation.

Kerry D. Solomon

“I like the fact that I have a smaller epithelial defect, which makes patients heal between 24 and 36 hours earlier than doing a 9-mm epithelial defect,” Dr. Durrie said. “It’s a 44% smaller epithelial defect when you go from 9.5 mm to 7 mm, so it’s no wonder that the patients heal faster.”

Dr. Solomon said he prefers the Amadeus epikeratome instead of alcohol to remove the epithelium. “I think I get very clear edge margins with the Amadeus epi-LASIK head,” he said. “I think without the alcohol being used and with clearer edge margins, we’re getting quicker epithelialization.”

Dr. McDonald said she is opposed to the use of alcohol on the epithelium, “either a little bit in PRK or a lot in LASEK.”

“It is very toxic,” she said. “If you look carefully, some of the patients have iritis the next day.”

For patients undergoing epi-LASIK, Dr. McDonald performs epithelial removal using the Norwood EyeCare epikeratome. In her PRK technique, she strokes away the epithelium with a Took knife.

“I don’t like to use an Amoils brush because that crushes every last epithelial cell, and out come the pro-inflammatory cytokines that drip down into the stroma,” she added. “I don’t want to leave any epithelium on Bowman’s, I want it squeaky clean, but I want to do it in broad strokes.”

Dr. Trattler agreed with Dr. McDonald regarding not liking the Amoils brush, but he said he prefers to use alcohol for epithelial loosening. “I’ve had good experience with alcohol,” he said.

Discarding epithelium

In a relatively new trend in surface ablation, the surgeons we interviewed said they are in favor of discarding the epithelium, rather than replacing it after laser ablation. This is believed to lead to quicker healing, surgeons said.

“There is mounting evidence to suggest that amputating the epithelial sheet [in epi-LASIK] is a good idea,” Dr. McDonald said. “This is anecdotal, but to those of us who do a lot of surface ablation it appears as if occasionally that sheet interferes with or delays healing.”

She said she was about to adopt the practice of discarding the epithelial sheet when her practice was disrupted by Hurricane Katrina.

“I haven’t given up completely on keeping the sheet for epi-LASIK,” she said. “We don’t know for sure whether that’s any worse than throwing it away.”

Dr. Solomon said that, because he discards the epithelium, he does not consider his procedure to be epi-LASIK, although he uses the epi-LASIK head on the Amadeus microkeratome.

“I set the machine for free cap, so really I’m doing epithelium removal for PRK using the Amadeus epi-LASIK head,” Dr. Solomon said. “I’m discarding the epithelium and letting it heal.”

Dr. Trattler said he also amputates the flap because of the strides made recently in prevention of haze and glare after surface ablation.

“We know that one of the main reasons to keep the epithelium is to reduce the risk of haze,” Dr. Trattler said. “In the lower myopes, the risk of haze is low to begin with. In the higher myopes, I’m using mitomycin C (see sidebar). The epithelial flap isn’t that important in my opinion.”

Experts say use mitomycin C 'sparingly' The use of mitomycin C varies among surgeons, but all surgeons interviewed for this article stressed the need for care and caution with the powerful antimetabolite. All those interviewed use the same concentration, 0.02%, but indications and application time varies. “My advice is to use it sparingly,” said Daniel S. Durrie, MD. “You don’t need to use it for everybody.” He said he uses it only in patients below the age of 30 years with myopia of more than 6 D. Kerry D. Solomon, MD, said he uses mitomycin C (MMC) for patients with myopic corrections of more than –5 D. “I have an 8-mm circular sponge that I moisten with the MMC,” he said. “I place that sponge on the cornea so I’m not getting mitomycin everywhere else.” He leaves it on for 15 to 20 seconds and then irrigates it off with copious balanced salt solution. William B. Trattler, MD, said he uses the drug in patients with 7 D or more of myopia. “We apply MMC with a round, 8-mm sponge, like a corneal protector sponge,” Dr. Trattler said. “It’s soaked with MMC and placed on the eye wet, but not dripping.” Dr. Trattler said he allows the sponge to sit for 12 seconds because a study by Parag Majmudar showed that 12 seconds is as effective as 2 minutes. Marguerite B. McDonald, MD, said she has not yet used MMC in epi-LASIK, but she did use it in PRK for patients with myopia above –6, hyperopia above +3, or cylinder above 3 D, and for any patient who had previous corneal surgery except previous PRK. “I put it on a round Weck-cel sponge that was squeezed almost dry. I didn’t want any run-out onto the limbal stem cells because it’s extremely toxic,” she said. In regard to epi-LASIK, she added a caution: “If you’re putting this sheet of cells soaked in mitomycin C back on the stromal surface, that’s way too much exposure. That’s dangerous.”

Postoperative regimens

Each surgeon described a different postop regimen to lessen pain and speed healing. Several said they start with a bandage contact lens.

Drs. Solomon and McDonald both use Vistakon’s Acuvue SofLens66. Dr. Trattler uses the Acuvue Oasys.

Dr. McDonald said she was about to switch to the Oasys.

“I had been using SofLens66 bandage contact lenses, but I was about to switch to the Acuvue Oasys, which has been shown in unpublished clinical trials to be extremely comfortable and stay on the eye very well,” she said. “Other surface ablaters are quite enthused about it.”

Dr. Trattler said the Oasys “does a great job of lowering pain for patients, a really comfortable lens.”

Dr. Trattler also said he puts punctal plugs in all patients “to make sure we have a nice layer of tears to help the ocular surface.”

“Every patient needs a punctal plug postoperatively if they don’t already have one,” he said.

Drs. Durrie and McDonald both said cold ice packs are important immediately after surgery. Dr. McDonald suggested using those found in drug stores, but Dr. Durrie said bags of frozen vegetables can work as well.

“I encourage people to use a bag of frozen vegetables or an ice pack to keep their eye cold for the first 24 hours because it dramatically improves the comfort,” he said.

Dr. McDonald said, “They get ice packs for 10 minutes afterward, and I am convinced that that makes a difference.”

Medications

Medication regimens for pain control and infection prevention also vary from surgeon to surgeon. Several of those we spoke to use some combination of steroid and nonsteroidal anti-inflammatory drugs.

Dr. Solomon said that immediately after surgery his patients receive bottles of the preservative-free NSAID Acular (ketorolac tromethamine, Allergan), the anti-infective Zymar (gatifloxacin ophthalmic solution 0.3%, Allergan) and a drop of the topical steroid FML (fluorometholone ophthalmic suspension 0.1%, Allergan)

“They have the Acular and tetracaine for comfort, they have FML and Acular for inflammation, and they have Zymar for antibiotic prophylactic,” he said.

Dr. Solomon said he recently began prescribing tetracaine, and it has been “a wonderful thing.” Initially he instructed patients to use only two to four drops a day, but he now tells them to use it as often as needed.

“It’s made a huge difference. Patients are comfortable with the larger epithelial defect that’s necessary with customized surface ablation,” he said. “It takes 3 to 4 days, sometimes 5 days, for the epithelium to heal, so I think it’s important for patients to be comfortable.”

Dr. McDonald also allows patients to use tetracaine up to every hour as needed, along with Acular LS (ketorolac tromethamine, Allergan) four times a day for the first 3 days.

She said she has become aggressive with the use of oral steroids and is a “minimalist” with topical steroids. The oral prednisone that was given 30 minutes before surgery is continued, with patients taking 80 mg for 2 days and then halving the dosage each day after that for a total of 6 days.

“I have to say most doctors are afraid of giving a little steroid,” Dr. McDonald said. “I’m a corneal transplant surgeon. I use lots of oral steroids, and I’m very comfortable with it. Healthy young people can tolerate a few days of oral steroids, and it makes all the difference in the world for their pain control.”

Dr. McDonald said she prefers not to prescribe topical steroids postoperatively because they can cause complications such as pressure spikes and cataract formation. In addition, she said, the patient does not achieve a stable postop refraction until the topical steroids are discontinued.

“Basically, you’re just prolonging the period before they stabilize,” she said. “You don’t get much out of long-term topical steroid treatment except complications.”

She also prescribes Zantac (ranitidine HCl, GlaxoSmithKline) 150 mg twice a day, she said, and Pred Forte (prednisolone acetate ophthalmic suspension 1%, Allergan) or prednisone four times a day for 1 week. Dr. McDonald’s patients also use Celluvisc (carboxymethylcellulose sodium 1%, Allergan) until the bandage contact comes off and extra strength acetaminophen for pain.

“This is a lot of medicine, but it’s a lot of pain,” she said.

Dr. Trattler said he primarily uses Xibrom (bromfenac, Ista Pharmaceuticals) and Acular and also, like Dr. McDonald and Dr. Solomon, uses tetracaine to control pain.

Dr. Durrie said that, because of the faster healing time with the 7.5 mm epithelial defect, he does not see the need for much pain medication. He prescribes the topical NSAID Nevanac (nepafenac sodium, Alcon) four times a day for up to 48 hours for those in need of pain control.

“I like to give them tools to fight the pain,” Dr. Durrie said.

Tips and tricks

Dr. Trattler noted that surgeons are constantly discovering new ways to improve their results. One recent innovation for him, he said, is to perform surgery on Wednesday so patients can recover in time for work on Monday.

“They have Thursday and Friday and can recover over the weekend,” he said. “Then Monday, it’s the beginning and they’re ready to go. Psychologically speaking, it’s helpful.”

For more information:

• Daniel S. Durrie, MD, can be reached at 5520 College Blvd., Suite 200 Overland Park, KS 66211; (913) 491-3330; fax: (913) 491-9650; e-mail: ddurrie@durrievision.com.
• Marguerite B. McDonald, MD, FACS, can be reached at 2820 Napoleon Ave., Suite 750, New Orleans, LA 70115; 504-896-1240; fax: 504-896-1251; e-mail: margueritemcdmd@aol.com. Dr. McDonald is a paid consultant to Visx/AMO.
• Kerry D. Solomon, MD, can be reached at Medical University of South Carolina, Storm Eye Institute, 167 Ashley Ave., Room 221, PO Box 250676, Charleston, SC 29425; 843-792-8854; fax: 843-792-6347; e-mail: solomonk@musc.edu. Dr. Solomon is a consultant for Allergan.
• William B. Trattler, MD, can be reached at 8940 N. Kendall Drive, #400, Miami, FL 33176; 305-598-2020; fax: 305-274-0426; e-mail: wtrattler@gmail.com.

• Katrina Altersitz is an OSN Staff Writer who covers all aspects of ophthalmology.