Preliminary Results In-vitro and In-vivo on Intraocular Micro Surgery with Deep Ultra-violet Laser Scalpel

¹Yasukawa T., ²Dietz H., ³Dick M., ¹Yafai Y., ⁴Kacza J., ¹Wiedemann P., ¹Schastak S.,
¹Universität Leipzig, Klinik und Poliklinik für Augenheilkunde (Leipzig)
²Fachhochschule Merseburg, FB Informatik und angewandte Naturwissenschaften (Merseburg)
³Asclepion-Meditec AG (Jena)
⁴Universität Leipzig, Veterinär-Anatomisches Institut (Leipzig)

Purpose: To develop a new deep ultra violet (DUV) laser scalpel for precise, "cold" and tractionless cutting of the retina.
Method: In this work we designed and tested a laboratory prototype of a scalpel for surgical treatments of the retina based on DUV laser ablation. A hollow core wave guide is used in combination with a short length of a special fused silica optical fiber to guide the laser beam. To achieve a very small cut width a fused silica fiber (core diameter 600 µm) has been tapered down to a diameter of about 150 µm.
Results: To cut the retina in vitro and in vivo from rabbit eyes in contact we used light intensities between 0.4, 0.3, 0.2, 0.1 and 0.07 J/cm² at the wavelength of 193 nm. It was not possible to cut the retina in non contact technique because of absorption of the laser light in a thin film of liquid between the scalpel and the tissue. Full-depth dissection of rabbit and also porcine retina ex vivo was achieved at the intensities of 0.4 to 0.07 J/cm² and a repetition rate of 50 Hz, with a linear cutting rate of 6 mm/sec. Although the retina was completely cut, a heat necrosis of the choroid has not occurred. The cutting experiments with a Nd:YAG laser scalpel at l = 213 nm and at the above intensities will be prepared.
Conclusions: We are currently in the process of testing the dissection of retinal tissue during retinotomy, and the formation of holes in the trabecular meshwork in glaucoma surgery.

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