The American physician and signer of the Declaration of Independence Benjamin Rush once said, "Controversy is only dreaded by the advocates of error." If that's true, then he would be proud of refractive surgeons, since they don't shy away from a controversy. Each year at the meeting of the American Society of Cataract and Refractive Surgery, Greensboro, N.C., surgeon Karl Stonecipher moderates a course on refractive controversies, sparking a lively debate. Here, surgeons respond to three controversies discussed at this year's course.

 

Refractive Surgery in Herpes Simplex

Though it's possible for the excimer to induce a recurrence of herpes simplex virus, some surgeons think refractive surgery is possible in select cases.

"I won't do it," says University of North Carolina corneal specialist Craig Fowler. "The reason is Deepinder Dhaliwal, MD, [of the University of Pittsburgh] did work in rabbits in 2001 that showed the excimer laser could induce recurrences of herpes simplex." In the study, the number of herpes simplex virus type-1 positive eye cultures and total herpes simplex virus type-1 shedding days were significantly greater after surface excimer laser ablation and LASIK compared with the untreated control group (p<0.002 and p<0.000001, respectively).1 Dr. Fowler notes that, in the American Academy of Ophthalmology's basic and clinical science guidelines for cornea and refractive surgery, HSV-1 is listed as a relative contraindication for refractive surgery.

A history of herpes keratitis is a relative contraindication for excimer surgery for some surgeons, but an absolute one for others.

Other surgeons, though, point to studies in which the risk of recurrence could be minimized.

"One of the challenges is we always want to do the best job for our patients while avoiding any issues," says Miami surgeon William Trattler. "Though experimental models have shown the excimer laser can induce recurrences of herpes, other models have shown that oral antiviral prophylaxis dramatically reduces the risk of a HSV-1 recurrence.2 I feel comfortable offering PRK or LASIK to patients with previous herpes as long as we perform a careful informed consent and initiate preop therapy with oral antivirals. I use valacyclovir [Valtrex] starting a week ahead of time and continuing on for about six weeks postop." Because of the dry-eye risk in these patients, he'll also start them on Restasis a week to a month before surgery and will place punctal plugs either preop or intraoperatively. He won't offer it to patients, though, if they've got significant scarring and irregular astigmatism from past recurrences.

Louisville, Ky., surgeon Asim Piracha is very conservative with these patients, and will have to be convinced that the patient needs the surgery. "It's not enough that they just want to get out of glasses, it has to be more like they can't tolerate their glasses or contact lenses," he says. "I like to see that they've gone at least six months without a recurrence, and if they have any scarring, vessels or decreased vision, I won't do it. Their corneal sensation must also be OK, and I check it with a cotton wisp. But, if the cornea's normal, there's no loss of vision because of scarring or neovascularization, I'd consider surface ablation with the patient on antivirals. I wouldn't do a flap because there can always be a recurrence and you'd get DLK and possibly a flap melt."

 

How Thin Is Too Thin?

With the specter of ectasia hovering over refractive surgery, more thought is being devoted to the thickness of the residual stromal bed in LASIK, and what the real risks for ectasia are.

Dr. Stonecipher says that a poll of the audience at the most recent controversies course showed that the residual stromal bed had crept up to 300 µm from the usual 250-µm cutoff. For his part, he says using the IntraLase has allowed him to make thinner flaps, increasing the residual stromal bed, and he has been able to leave a bed of 376 µm in more than 6,000 LASIK eyes at his practice.

Minneapolis surgeon David Hardten makes his plan based on how thick his flap could possibly be, and to allow for postop enhancement. "I still use 250 µm as the very minimum thickness, though there's no data to support an exact minimum thickness," he says. "I use an IntraLase set to create a 100- to 110-µm flap, so the thickest possible flap I might get would be 160 µm," he says. "So, when planning surgery, I use that maximum thickness number and plan for at least 280 µm in the residual stromal bed. That would leave me 30 µm in case I needed to do an enhancement." He says he doesn't usually perform intraoperative pachymetry, but he would if "the calculated residual stromal bed thickness ended up being below 300 µm—just to make sure I have more room there than what I thought."

Lexington, Ky., surgeon Lance Ferguson shoots for a residual bed of 270 µm "because my readings may be erroneous and 270 µm leaves me a little tissue if I want to enhance the procedure," he says.

Dr. Trattler tries to stay above the 250-µm residual bed limit, and says he "hopes to be in the 300 range in case the flap is thicker than expected," but puts more emphasis on corneal shape than thickness when trying to avoid ectasia. "For LASIK or PRK, I think shape is the most important risk factor," he says. "If the cornea is shaped normally but a little thin, there's no evidence that that causes ectasia." To cast doubt on the emphasis on thickness as a key risk factor, Dr. Trattler points to a study he performed in his practice of 94 eyes of 71 post-LASIK ectasia patients. Only 10 (11 percent) of the ectatic eyes had corneal thicknesses thinner than 500 µm preoperatively. 

Dr. Trattler performs intraoperative pachymetry on every patient just to be sure he didn't get an inadvertently deep flap, and also because, he says, "that flap information is critical if we're ever going to understand post-LASIK ectasia."

 

Rheumatoid Arthritis Patients

Surgeons approach RA patients with caution, if at all.

"I look very carefully at these patients for controlled dry eye and no significant cataract," says Dr. Hardten. "This is because a lot of them have been on steroids in the past. I make sure that their systemic disease is well-controlled. Just like before cataract surgery in an RA patient, I put them on pre- and postop oral prednisone to try to help reduce the chances of immunologic melt. I published a paper about a patient with an immune melt.3 Anytime you operate on a patient with rheumatoid arthritis, there's the possibility of wound melting." He treats their dry eye with Restasis and sometimes punctal plugs.

Dr. Ferguson will operate on these eyes, but with conditions. "I'll do it if the systemic disease is under control, one eye at a time, separated by six weeks," he says. "They have to have gone three to six months without flare-ups and they should have a history of no ocular manifestations. If there have been any ocular manifestations of it, I'll avoid them. Even on a lens exchange, these limbuses can get so hot and pour out so much collagenase that they'll get a limbal melt."

Dr. Fowler avoids performing refractive surgery on any RA patient. "The idea of 'first, do no harm' is kind of the philosophy behind my approach," he says. "I've had to manage perforations, scleral melts and corneal melts in these patients after the fact, and it only takes your first one to start thinking that it's a real issue."

Dr. Stonecipher avoids certain patients, but doesn't rule out the procedure. "I look at their ocular surface disease," he says. "If they have OSD, I won't even think about it. If I do treat someone, though, I'm more prone to do so in the summer, because it's more humid and I think they heal better then." 

 

1. Dhaliwal DK, Romanowski EG, Yates KA, et al. Experimental laser-assisted in situ keratomileusis induces the reactivation of latent herpes simplex virus. Am J Ophthalmol 2001;131:4:506-7.

2. Asbell PA. Valacyclovir for the prevention of recurrent herpes simplex virus eye disease after excimer laser photokeratectomy.

 Trans Am Ophthalmol Soc 2000;98:285-303.

3. Lahners WJ, Hardten DR, Lindstrom RL. Peripheral keratitis following laser in situ keratomileusis. J Refract Surg 2003;19:6:671-5.