August 2010

 

COVER FEATURE

 

Challenging refractive cases

Treating post-LASIK ectasia with corneal crosslinking


by Enette Ngoei EyeWorld Contributing Editor

   
keratoectasia

Dr. Stonecipher's patient returned in 2007 for additional treatment but showed signs of keratoectasia Source: Karl G. Stonecipher, M.D.

For patients who develop ectasia following LASIK surgery, there really aren't too many treatment options, according to Parag A. Majmudar, M.D., associate professor of ophthalmology, Rush Medical Center, Chicago. "I don't think Intacs work very well, especially the Intacs (Additional Technology, Des Plaines, Ill.) that are available in the United States, which are different from the other range available in other countries," he said.

Moreover, in a situation where the cornea continues to become ectatic, Intacs alone will not provide a long-term solution, Dr. Majmudar added. In his opinion, there's no other solution for ectasia other than collagen crosslinking. That's the procedure that's been shown to stop the progression of ectasia, and in the future, as the cornea remodels to improve the overall curvature, it will allow the patient to function better with a soft contact lens instead of a hard lens, he explained.

In the following case study, Karl G. Stonecipher, M.D., medical director, TLC, Greensboro, N.C., and Raleigh, N.C., discusses a patient who developed ectasia after LASIK surgery and was treated with Intacs and collagen crosslinking.

A 42-year-old female presents for refractive surgery in September 1996. Her preoperative refraction was: 12.5 + 1 x 080 20/25 13.0 + 1 x 085 20/25 Thin flap LASIK was performed with a mechanical microkeratome and a residual stromal bed of 260 microns was left in both eyes. The patient tolerated the procedure without complications. She returned with uncorrected visual acuity (UCVA) of 20/20 in the right eye and 20/30 UCVA in the left eye 6 months later. A modified monovision of 0.5 D was planned with the first surgery and the residual ametropia was a problem for the patient. The flap of the left eye was lifted and an enhancement of 0.5 D was performed on the left eye without incident. The patient's postoperative course was unremarkable for 10 years. She returned in 2007 requesting additional intervention in the left eye however the patient showed signs of keratoectasia (Figure 1). The patient showed signs of progression and was referred for riboflavin cross-linking with single segment Intac implantation in 2007. The procedure was successful and stabilization was obtained. Her last manifest refraction showed: 0.25 Spherical 20/20 +0.75 + .75 x 022 20/25 Brian S. Boxer-Wachler, M.D., director, Boxer Wachler Vision Institute, Los Angeles, who is experienced in performing corneal collagen crosslinking for the treatment of ectasia and keratoconus, weighed in on the case. "First of all, nowadays we know that performing LASIK on somebody who is such a high myope probably isn't the best procedure for them. I would be doing a Visian ICL. Of course back in 1996 that wasn't available," he said.

In terms of the cause of the ectasia, because this occurred 10 years after the LASIK, procedure, Dr. Boxer-Wachler said that the ectasia is less likely related to the LASIK and may just be the patient's own keratoconus that was going to develop anyway. "In my experience, patients that have ectasia for LASIK usually develop that fairly quickly, within a year or 2, if it's actually caused by the LASIK," he explained.

Regardless, he said that corneal crosslinking is the proper procedure to perform on somebody who has ectasia. This is how he would have treated it exactly and the results are similar to what he's experienced, he added.

Dr. Boxer-Wachler said he would use a single segment Intac as well and also pointed out the importance of the orientation of the Intac. Some surgeons don't like to use Intacs because they haven't had good results from them, he said.

His experience in seeing patients that have been treated elsewhere and referred to him is that sometimes the Intacs are not in the orientation that he would have recommended them to be placed to get the optimum result and that can give surgeons a bad experience, he said.

"The Intacs may be placed in a way that make the cornea shape worse instead of making the cornea shape more normalized," he explained.

So while some surgeons prefer to perform corneal crosslinking alone without Intacs, Dr. Boxer-Wachler said that he and colleagues conducted a study that found the combination of Intacts and corneal crosslinking to have a synergistic effect on the cornea. Published in the January 2007 issue of the Journal of Cataract and Refractive Surgery, Dr. Boxer-Wachler and colleagues sought to determine whether corneal collagen cross-linking with riboflavin (C3-R) augments the effect of inferior-segment Intacs in the treatment of keratoconus.

The retrospective nonrandomized comparative case series included 12 eyes of nine patients who only had inferior-segment Intacs placement without C3-R (Intacs-only group) and 13 eyes of 12 patients who had inferior-segment Intacs placement combined with C3-R (Intacs with C3-R group).

The two groups were matched pre-op. All patients had inferior-segment Intacs placed with the incision in the steep axis of manifest refraction. Corneal collagen cross-linking with riboflavin was performed following the insertion of the Intacs segments. The outcome measures were topographic keratometry values and the lowerupper (LU) ratio. Preoperative data were compared to results 1 day post-op and measurements at the last post-op visit.

Results of the analysis showed the Intacs with C3-R group had a significantly greater reduction in cylinder than the Intacs-only group (P<.05). In addition, steep and average keratometry were reduced significantly more in the Intacs with C3-R group (P<.05). There was also a greater reduction in LU ratio in the Intacs with C3-R group (P<.05). Dr. Boxer Wachler and colleagues therefore concluded that the addition of C3-R to the Intacs procedure resulted in greater keratoconus improvements than Intacs insertion alone.

The future of treatment for patients with ectasia

Corneal Cross-Linking article summary

Dr. Majmudar, who is involved in clinical trials for collagen crosslinking using a transepithelial approach, said there is no question in his mind that the procedure is going to be the future of treatment for patients who have ectasia.

In the clinical trials he is involved, if the patient's corneal thickness is above 400 microns, the cornea is loaded with riboflavin, but no epithelium removal is done. "We're making sure there's enough penetration of the riboflavin in to the cornea and then we're applying the standard treatment with the ultraviolent light for 30 minutes," he said.

Patients typically have a few days of irritation or discomfort and once the initial process is resolved then their vision for the first month or two typically is a little bit lower because of remodeling of the cornea. The cornea becomes a little steeper and then patients typically tend to improve over time, he said.

He and colleagues are seeing that at 6 months or a year, the patients do have better overall vision. It's a relatively non-invasive procedure and typically, most patients don't have any complication, Dr. Majmudar said. There's always the potential issue of infection, especially in the "epithelial-off " method where is removed because the barrier to the infection to the epithelial layer cells is removed. So far, that's the biggest issue, he said.

"Down the road, nobody has 40-50 years of follow-up because this procedure internationally has only been done about 8-10 years. And we in the United States have very limited experience because it's not FDA [Food and Drug Administration] approved and you can only do it as part of a clinical trial," he added.

Eventually though, Dr. Majmudar noted that corneal crosslinking may be combined with other types of laser enhancement like PRK to not only stop the ectatic process but to also provide immediate visual rehabilitation. So there's hope there that patients can get good improvement in their visual acuity not just stopping the progression, he said.

Editor's note: Drs. Majmudar and Boxer Wachler have no financial interests related to their comments.

Contact information

Boxer Wachler: 310-860-1900, bbw@boxerwachler.com
Majmudar: 847-275-6174 or pamajmudar@yahoo.com

Treating post-LASIK ectasia with corneal crosslinking Treating post-LASIK ectasia with corneal crosslinking
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