Long-term evaluation shows good results of intracorneal rings in keratoconus cases

Progression rate decreases after implantation, clinician says.

Joseph Colin

Five-year follow-up of intracorneal rings in keratoconus patients shows efficacy in stabilizing the cornea and preventing disease progression.

“Of course we are aware that keratoconus stops progressing with age. It is not easy to evaluate what the impact of ring implantation is in the natural history of the disease. In our study we had no control group. However, our results are extremely encouraging,” Joseph Colin, MD, OSN Europe Edition Editorial Board Member, said in an interview with Ocular Surgery News.

The study was conducted on 105 eyes of 82 patients implanted between 2000 and 2005 with one or two Intacs segments (Addition Technology). Fifty-nine patients were implanted unilaterally and 23 bilaterally. The mean patient age was 31 years, ranging between 16 and 52 years. Keratoconus was grade 2 or 3, and it was asymmetrical in most of the eyes.

Progression of the cone before and after ring implantation was evaluated. Data before implantation were not available for 16 eyes, but progression of more than 1 D at 1 year was reported in 59% of the other eyes.

“Intacs implantation was successful in 91 eyes. We had two cases of extrusion and 12 cases with unsatisfactory results, mainly due to insufficient central corneal thickness. Eight of these cases were converted to keratoplasty,” Dr. Colin said.

Results

Out of 91 eyes, eight showed progression of more than 1 D over 5 years. The 8.8% rate of progression was significantly lower than before implantation. Most patients with progression were in the younger age range, with a mean age of 26.3 years, compared with a mean age of 32.7 years in the non-progression group.

“As expected, the younger the patients, the higher the risk of progression,” Dr. Colin said.

Ring implantation also resulted in a small amount of visual acuity improvement. Mean best corrected visual acuity increased from 20/60 preoperatively to 20/50 at 1 year postoperatively, with just a slight decrease at 5 years. A significant improvement in refractive spherical equivalent, from –7.6 D preop to –3.86 D at 1 year and –3.95 D at 5 years, was reported. Mean keratometry values decreased by 4.6 D at 1 year and 4.0 D at 5 years.

Follow-up

“During the 5 years of follow-up, results were basically stable, which is an important parameter for evaluating the effects of the procedure. In the majority of cases, the disease stopped progressing and patients were happy. We were able to avoid corneal transplantation, which is good because patients were young and, in many cases, allergic. The allergic eye condition is very common in keratoconus patients and may affect the results of keratoplasty,” Dr. Colin said.

On the whole, the outcomes of Intacs are comparable to those of collagen cross-linking, he said. In the last series of 117 eyes of 99 patients published by Seiler and colleagues, a 7% rate of progression was found.

Dr. Colin said that in the case of cross-linking, it is unclear to what extent the natural history of keratoconus contributes to halting disease progression.

“The logical approach may be the combination of both procedures in patients with progressing keratoconus. The combined approach exploits the advantages of both techniques and, hopefully, may lead to synergistic results,” he said. – by Michela Cimberle

Reference:

• Koller T, Mrochen M, Seiler T. Complication and failure rates after corneal crosslinking. J Cataract Refract Surg. 2009;35(8):1358-1362.

• Joseph Colin, MD, can be reached at Hôpital Pellegrin, Place Amélie Raba-Lèon, 33076 Bordeaux, France. +33-5-56795608; fax: +33-5-56795909; email: joseph.colin@chu-bordeaux.fr.
• Disclosure: Dr. Colin is a consultant for Addition Technology.

This study confirms that Intacs implantation is a safe and effective treatment option for keratoconic eyes. Keratoconus is more progressive in younger patients, and this treatment gives us a unique opportunity to avoid or postpone corneal transplantation. Combination with cross-linking might have synergistic effects in halting the progression of the disease.

Results are encouraging, but we need further assessment of the outcomes of Intacs in teenagers and children. We also need to evaluate the results of a larger series in the long term. Another topic for further research is combined treatment with cross-linking.

— Aylin Kilic Uzbek, MD
Kudret Eye Hospital, Ankara, Turkey
Disclosure: Dr. Kilic Uzbek has no direct financial interest in the products discussed in this article, nor is she a paid consultant for any companies mentioned.