Amadeus II achieves precision in lamellar keratoplasty and epi-LASIK

Amadeus II (Ziemer) achieves more precise corneal depth and faster epithelial healing time than other surface ablation treatments for lamellar keratoplasty and epi-LASIK, according to Carlo Lackerbauer from Munich, Germany, presenting at the Zeimer symposium.

Lamellar keratoplasty is used for corneal scars, anterior corneal dystrophies, and reconstruction of the anterior corneal surface. However, there are limitations to this procedure, particularly when it comes to achieving a precise cutting depth and quality of cut.

Lackerbauer conducted lamellar keratoplasty using Amadeus II on 40 fresh porcine corneas. The corneal cutting depth was set at the distributor's indication of 200 µm, 250 µm, 350 µm and 400 µm. In all cases a suction ring of 9.0 was used and the oscillation time for 11,000 rpm was set at 1.5 mm/s. To analyse the cutting depth, Lackerbauer used non-contact corneal pachymetry and an accurate standard deviation of ± 1.12 µm. At the end of the study, scatter-electron microscopy was carried out to demonstrate the smooth interface achieved.

The cutting depth results were all between the range from the distributor, except the 250 µm which was more in the mean with 271 µm (19% deviation). The rest had a 15% deviation, with the best result coming from a smaller cutting head, although Lackerbauer said that more research needs to be done on the influence of cutting head size.

The electron microscopy presented an image of the whole cornea showing a smooth surface and sharp cutting edge between the corneal epithelium and stroma, with a smoother surface noticed in the centre of the stroma. Lackerbauer attributed the high precision cutting edge and quality of cut to the automated guided microkeratome and the optimised automated chamber device. "In my experience, Amadeus II is superior to femto laser systems in lamellar keratoplasty procedures in the cases of central cornea scars, intracorneal deposits or previous amnion-membrane surgery," he said.

In another study, Lackerbauer compared 50 epi-LASIK surgeries using Amadeus II to standard LASIK procedures. "Epi-LASIK is the best surgery for reduced dry eye symptoms, but there is always a question mark around this," he said. Prior to epi-LASIK treatment, histological examinations were carried out which indicated a separated epithelial sheet. During the procedure with Amadeus II, the stratification of the epithelium and cell layer was well conserved. Under electron microscopy, the Bowman's layer showed a smooth surface under magnification of 200, and the bottom side of the epithelial flap showed an equally even surface. A nomogram was used to achieve a perfect epithelial flap work in all cases according to the different keratometric data.

The results of the study showed that the line of precision was similar in both procedures. "What was most interesting for me was finding out that the pain was the same, but the healing time was better with Amadeus II," Lackerbauer explained.

Lackerbauer found that using Amadeus II in epi-LASIK surgery provides a safe and easy treatment of patients with myopic astigmatism of up to -6 D. Efficacy and safety of Amadeus II is similar to other surface ablation treatments, although Lackerbauer believes that Amadeus II results in a shorter healing time and is a less painful procedure compared with Alkohol-LASIK treatment. "As a result of my conclusions, Amadeus II is more efficient in wavefront-guided ablations than mechanical microkeratome-assisted lasers," he said.