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INTACS (Addition Technology) could offer a safe and effective way to improve visual acuity in patients suffering from post-Lasik keratectasia, according to George Kymionis MD, PhD.
“Our research shows that intracorneal ring segments implantation improved uncorrected visual acuity and best spectacle-corrected visual acuity in patients suffering from post-Lasik ectasia,” Dr Kymionis told EuroTimes.

In a prospective study, which was awarded the Best Poster prize at the 7th ESCRS Winter Refractive Surgery meeting in Rome, researchers examined 10 eyes of seven patients with post-Lasik corneal ectasia (two men and five women) aged 33 to 46 years.

The investigators diagnosed ectasia by several means, including slit lamp appearance of corneal thinning, unstable topographical steepening and progressive corneal thinning seen with ultrasonic pachymetry. Other criteria included decreased visual acuity, unstable refraction and posterior corneal steepening.

Two Intacs segments of thickness depending on the residual refraction of the patients were inserted in each eye. Follow-up ranged from six to 24 months. Patients were assessed for uncorrected visual acuity, best spectacle-corrected visual acuity, refractive outcome and topographic findings after Intacs implantation.

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Intacs were successfully implanted in all eyes. Spherical equivalent error was statistically significantly reduced after Intacs implantation from a mean of - 4.81 D before surgery to a mean of - 0.96 D afterwards.

Pre-Intacs uncorrected visual acuity was 20/100 or worse in all eyes while at the last follow-up examination, nine (90%) of 10 eyes had uncorrected visual acuity of 20/40 or better.

Three eyes maintained the pre-Intacs best spectacle-corrected visual acuity while the remaining seven eyes experienced a gain of one to two lines. Overall, best spectacle-corrected visual acuity had improved one line at the last follow-up visit.
Dr Kymionis said that Intacs were initially used for correction of low myopia and offered the advantage over Lasik of preserving corneal tissue while maintaining clarity in the central optical zone.

“Several studies have demonstrated the efficacy of Intacs in correcting low myopia, while in keratoconic eyes, Intacs implantation has resulted in an increase in topographic regularity and in UCVA. We wanted to see if similar results could be achieved for post-Lasik ecstatic eyes,” he said.

Dr Kymionis noted that one eye with an advanced stage of ectasia (spherical equivalent refraction: 13.75 D), showed a decrease in BSCVA from 20/50 to 20/80 and an increase in topographic irregularity between the third and sixth postoperative month. The patient underwent Lasik with an attempted correction of -12.5 D.

“We decided to move the segments and to advance them to bring them in contact and minimise the irregular astigmatism. Three months later, the patient had a remarkable increase in BSCVA to 20/32, while a significant increase in the topographic regularity was found, which remained stable at the last follow-up 10 months later,” he said.
Dr Kymionis said that the researchers had been “very surprised” at the significant improvement of this particular patient.

“I think these findings support the unpredictability of the effects of Intacs in the advanced stages of post-Lasik ectasia and close follow-up of these patients is clearly necessary to control and manage the possibly unpredictable results,” he said.

He said his experience has shown that even in cases where biomechanical factors in the cornea have been disturbed by prior surgery, the placement of Intacs may still provide favourable outcomes. The availability of a noninvasive, painless, rapid recovery procedure as an intermediate layover is very promising, he commented.

He warned, however, that further study with a much longer follow-up needed to be done to establish whether there were any long-term complications arising from Intacs use in such instances.

“It’s definitely something that needs to be looked at. Since long-term stability is a critical issue for any surgical intervention in ectatic corneas, it will be interesting to evaluate how Intacs affect corneal ectasia over a more extended follow-up period,” Dr Kymionis said.

Dr Kymionis and colleagues have no relevant financial interest in the product mentioned in this article.

George Kymionis MD, PhD
Crete, Greece
Email: kymionis@med.uoc.gr

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