By Roibeard O' hEineachain

CANNES--Excellent un-corrected and corrected vision has been achieved in myopic patients using the new ZYOPTIX® customised ablation system, Jorge Alio, MD will tell the 5th ESCRS Winter Refractive Surgery Meeting here.

That conclusion comes from the early results of a study in which 30 patients (aged 20 to 51 years) with myopia ranging from -1.0 D to -12 D and cylinder of -5.0 D or less underwent treatment with the ZYOPTIX system in one eye, and normal planoscan LASIK in the other. By the time of his report they will have been followed for up to three months, said Dr. Alio, Director, Instituto Oftalmologica de Alicante, Spain.

Previous to surgery the patients' un-corrected visual acuity ranged from 20/400 to 20/30 and all had best-corrected visual acuity of 20/20 or better. At the latest evaluation , UCVA was 20/40 or better in 86.7% and 20/20 or better in 26.7%. In all eyes BCVA was 20/40 or better and 73.3% saw 20/20 or better, he told EuroTimes in an interview.

Dr. Alio noted that the difference between the visual outcomes in the two treatment groups was statistically significant (P<0.5) customised as regards UCVA, but not BCVA. In the customised ablation group 83%and 36% had an UCVA of 20/40 and 20/20, respectively, compared to 55% and 33% in the planoscan group. The respective values for BCVA were 88 % and 77 % for the customised ablation group and 87% and 62% for the planoscan group.

All eyes in the study underwent a thorough vision quality assessment using the ray-tracing C-scan programme and the integral diagnostic unit of the ZYOPTIX customised ablation system. The latter included Orbscan II, which provides a topographic map of the corneal surface, and Bausch and Lomb's Wavefront analyser, which measures the aberrations present in the optical system of the un-treated eye, he noted, adding:

"This is a Hartman's Shack's analyser which works on the basis that reflected rays of a diode laser will form a deformed wavefront when passing through imperfect optical systems. This idea was originally utilised in astronomy to sharpen images of the stars when received blurred from the interference effect of the atmosphere."

Dr, Alio and his associates entered the measurements of the Orbscan and the wavefront analyzer, together with ultrasonic pachymetry and manifest refraction data, into a programme which calculates the treatment file of each patient. Other parameters included were optical treated zone, maximum ablation depth and central ablation. The final treatment calculation was saved on a floppy disk and entered into the Technolas 217Z machine, which includes special modifications for the ZYOPTIX system, such as a built-in "robot" and a place to hold the treatment card.

"The treatment card modifies the shape and distribution of the laser beam into a modified truncated Gaussian beam with a maximum smoothing and maximum thermal effect. We used manifest refraction as our target correction."

When making the flap Dr, Alio and his associates used a Hansatome microkeratome in all eyes, with a depth of 160 microns and a suction ring diametre of 9.5 mm, he said, adding:

"ZYOPTIX is a promising technique of customised ablation for correction of higher order aberrations of the eye. However we do think that a further hardware and software development is required to reach the desired aim of aberration-free vision."

Also included in the study were Dr. Mohamed Fakhry, MD, Tamer Salam, MD, Amhed Shalaby, MD, and Jose Belda, MD.