Zyoptix ablation refinement uses two-step approach to achieve best visual results

By Ana Hidalgo-Simón MD, PhD

ALICANTE - Correcting residual refractive errors can be a good opportunity to smooth over previous aberrations and improve visual quality for your patients, according to two Spanish ophthalmologists.

José I Belda MD, PhD and Jorge L Alió MD, PhD told the VII Congress of the Mediterranean Ophthalmological Society that the microkeratome cut, the ablation itself and the process of wound healing all contribute to the creation of new aberrations following refractive surgery.

They and colleagues at the Instituto Oftalmológico de Alicante looked at the problem of aberrations as two different issues: high order aberrations and spherocylindrical aberrations.

"When performing refractive therapy (Zyoptix or Planoscan), we sometimes induce spherocylindrical aberrations or operate on patients who had previous aberrations. If our aim is to achieve the best visual result for the patient, we can't possibly resolve both types of aberrations in a single operation," they explained.

Dr Alió and Dr Belda developed a new surgical approach which consists of two steps: regular LASIK surgery (Planoscan) followed by Zyoptix as a secondary procedure to correct high order aberrations and create a more regular cornea. The new approach has been christened ZAR (Zyoptix Ablation Refinement).

They reported a pilot study using this approach in 18 patients (36 eyes) with residual myopia after standard LASIK. The second intervention was aimed at correcting the residual refractive error, but included analysis and treatment of aberrations at the same time.

All second interventions were performed three months after initial surgery. The ZAR technique was used in one eye and standard LASIK enhancement procedure was performed in the other eye. Follow-up consisted of visits at 24 hours, one week and then one, three and six months after surgery. Contrast sensitivity analyses were performed before and after ZAR.

Patients' age averaged 30.6 years within a range of 23 to 46 years. Eleven were females and seven males. Mean spherical error after first surgery was
-1.09 D ± 1.48 D (range 0.5 D - 3.00 D), and mean astigmatism was -1.00 D ± 0.87 D (range 0.0 D -4.00 D).

The safety index was 1.16 and none of the eyes lost lines of BCVA. One patient retained the same BCVA, 12 eyes gained one line and five eyes gained two lines of BCVA, he reported.

Twelve eyes (66.6%) reached an UCVA of 20/20, and another six eyes (33.3%) reached an UCVA of 20/16 or better. The efficacy index was 1.22. Predictability was also very good. All 18 eyes were within 1 D of the expected outcome and 15 eyes (83.3%) were within 0.5 D of attempted correction.

"I am confident that these eyes are stable. During the six months follow-up, none of the eyes showed any change in their spherical equivalent of 1 D," Dr Belda said.
Contrast sensitivity analysis before and afte r second surgery showed a significant difference (p<0.001) in favour of ZAR. Further analysis of this data showed that not only the quantity, but also the quality of visual acuity was improved following ZAR.

Mean preoperative contrast sensitivity was 3.3 dB ± 1.6 dB (range 1 dB to 6 dB), and 5.1 dB ± 1.6 dB (range 3 dB to 7 dB) after surgery.
Based on these results, Dr Belda said that ZAR appeared to be a predictable, efficient and safe technique to correct residual refractive errors with less central depth ablation - and subsequently better corneal tissue preservations.

"The additive effects of ZAR in treating high order aberrations matches the expectations of wavefront-oriented excimer correction. Both quality and quantity of visual acuity power improved after the ZAR.

"We will consider using this system to correct aberrations in patients who, although not having residual refractive problems, are not happy with the visual results of LASIK therapy," he remarked.

A larger trial to confirm the results of this pilot study has already been performed, and the data is currently being analysed.

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