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Conductive keratoplasty could be a valuable option in hyperopic astigmatism
Significant long-term improvement of near UCVA and correction of cylinder are now possible with CK, a researcher says.
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BARCELONA – Conductive keratoplasty is effective in both hyperopic and hyperopic astigmatic treatment, according to a presentation here.
“We have noted a significant and stable improvement in near vision, and no serious complications. Bearing in mind the good results with astigmatic treatment, the procedure might also become a new and promising enhancement technique,” said Tatiana Naoumidi, PhD, here at the winter meeting of the European Society of Cataract and Refractive Surgeons.
Controlled-release radio frequency energy is delivered deep (450 mm) within the stroma through a 90-mm-wide tip around the circumference of the cornea. The rise in temperature produces a permanent shrinkage of collagen fibrils, resulting in a circumferential tightening at the periphery of the cornea and a steepening in the central, optically active cornea.
Good near vision
“So far, we have treated 35 patients with hyperopic range between +1 D and +3.75 D. Mean uncorrected visual acuity at distance was 20/50 and mean best corrected visual acuity was 20/20. The mean follow-up is 7 months, but in some cases it is up to 1 year,” said Dr. Naoumidi, of Crete University Eye Institute in Greece.
She said that 1 month postoperatively, UCVA at distance improved to mean 20/25 and remained unaltered throughout the follow-up. The cases with 1 year of follow-up showed the same stability of results. No patient lost more than one line of BCVA and two patients gained one line or more.
“The UCVA at near (45 cm) was quite a surprise,” Dr. Naoumidi said. “We were expecting to have the best results right after the treatment, due to the usual myopic shift, but results were actually better at 6 months. This might not only be due to the multifocal effect produced by conductive kerotoplasty (CK), but also to the overcorrection of the first cases, when we were still afraid of undercorrecting.”
While mean acuity for near was J5.63 (range J1 to J9) preoperatively, it was J1.63 (range J1 to J3) 6 months after treatment.
“The mean spherical equivalent of +1.74 D preoperatively was –0.25 D at 1 month, with a very wide range of measurements, from –1.87 D to –0.125 D. At 6 months, it was –0.17 D, and range much closer to 0 in all cases,” she continued.
The best results were obtained in a 45-year-old woman with attempted correction of +1.25 D.
“We applied a treatment of 24 spots and had excellent results. The patient gained two lines of BCVA, she is plano, has a very good near vision and she is very happy,” Dr. Naoumidi said.
Topographic maps showed a remarkable stability of results up to 1 year after the treatment.
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Astigmatic treatment
A new chapter is now opening with the treatment of astigmatism, according to Dr. Naoumidi.
“We have treated 33 cases with hyperopia from +1 D to +4.75 D and astigmatism up to 5.75 D, and have a follow-up of 3 months,” she said. “In some cases astigmatism was irregular, so results are never plano, and don’t look as good as with hyperopic treatment. Nevertheless, CK is a challenging new technique for it.”
She explained that the spherical component is treated first, then more spots are added across the flat meridian (or the minus cylinder axis).
Two cases of customized irregular astigmatic treatment were shown. The first was a 41-year-old woman who had been previously treated with another technique for keratoconus.
“She was +4.25 D at the beginning of CK treatment, with a –2.25 cylinder. We steepened the flatter meridian, and after 3 months she was +1.75 D with –1.00 D cylinder, and had improved three lines of UCVA,” Dr. Naoumidi said.
The elevation of the flat meridian was visible in the topographic maps. Wavefront aberration maps showed that the root-mean-square measurements were almost the same preoperatively and postoperatively, but the coma had decreased.
“This might explain the difference in the quality of vision the patient experienced after the treatment,” she said.
The second case was a 40-year-old man. He had had hyperopic LASIK and complications with striae, poor near vision and night vision with halos.
“CK was performed, applying 22 spots to correct +4.75 D of hyperopia and 3.75 D of cylinder. Sixteen spots were used for spherical treatment and six for the astigmatism. At 3 months he is plano, with –1 cylinder. Postoperative topographic maps look much smoother,” Dr. Naoumidi said.
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For Your Information:
- Tatiana Naoumidi, PhD, can be reached at University of Crete, Department of Ophthalmology, GR-711 10 Voutes, Heraklion Crete, Greece; +(30) 81-0-371-800; fax: +(30) 81-0-394-653; e-mail: tnaoumidi@hotmail.com; Web site: http://www.EyeInstituteCrete.net. Dr. Naoumidi has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.
- Refractec Inc., manufacturer of the ViewPoint CK System, can be reached at 5 Jenner, Suite 150, Irvine, CA 92618 U.S.A.; +(1) 949-784-2600; fax: +(1) 949-784-2601.