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K. M. Joos, R. Prasad, J. Kozub, A. Agarwal, J. Shen; Experimental Retinectomy With a Raman-Shifted Q-Switched Alexandrite Laser System. Invest. Ophthalmol. Vis. Sci. 2009;50(13):198.
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Several groups have identified a wavelength at 6.1 µm produced by an experimental Free Electron Laser as capable of ablating tissue, including retina, with a minimal amount of collateral damage. It is hypothesized that 6.1 µm produced by a portable laser, likewise, would be useful for incising layers such as performing a retinectomy in detached retina with extensive anterior proliferative vitreoretinopathy.
An alexandrite laser system, which provides a high-intensity Q-switched pulse (780 nm, 50-100 ns duration, 10 pulses per second), is wavelength-shifted by a two-stage stimulated Raman conversion process into the 6-7 µm range (Light Age, Inc.). Fifteen fresh cadaver porcine retinas were detached with subretinal fluid or left intact. They were lased with 6.1 µm with a 100 µm diameter spot at 0.6 mJ after removal of the vitreous. Specimens were examined grossly and prepared for histological examination.
The Raman-shifted alexandrite laser produced a smooth Gaussian profile. A narrow spectrum was produced at 6.1 µm making it well-suited for efficient coupling into a hollow-glass waveguide beam delivery system. A full-thickness retinal incision with minimal thermal damage was obtained at a low energy level of 0.6 mJ in detached retinas. However, the depth of the incision did vary from an incomplete incision to a full-thickness incision involving the underlying choroidal layer in attached retinas.
The 6.1 µm mid-infrared energy produced by a portable laser is capable of incising detached retinas with minimal thermal damage. However, the safety and precision of this laser may be enhanced with imaging capability to detect when the desired incision depth has been achieved in real-time if underlying layers are present.
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