Abstract
Purpose: :
To test a novel, compact Thulium fiber laser with tunable wavelength for creation of variable thickness thermal lesions in the cornea.
Methods: :
A tunable Thulium fiber laser was used to create variable thickness thermal lesions in fresh rabbit corneas, ex vivo. The laser wavelength was tunable in the range of 1873–1904 nm (near a major water absorption peak in tissue) corresponding to a variable optical penetration depth ranging from approximately 400 µm at a wavelength of 1873 nm down to 100 µm at a wavelength of 1904 nm. The corneas were separated into three treatment arms corresponding to laser irradiation with three different wavelengths: full–thickness lesions (1873 nm), partial thickness (1890 nm), and superficial(1904 nm). For each cornea, laser parameters were equivalent and kept fixed. The laser power at the tissue surface measured 5.5 W, with an exposure time of 25 ms, yielding an energy per pulse of 138 mJ for a single pulse exposure. The laser spot diameter was 650 µm, resulting in a fluence of 42 J/cm2. After treatment, corneas were submitted to OCT evaluation and histology to detect the depth of the lesion.
Results: :
the lesion depth proportion to whole cornea thickness is 67.9% with 1873nm wave–length laser, 64.9% with 1890nm laser and 27.8%with 1904nm laser.
Conclusions: :
This is a preliminary test of a compact, tunable Thulium fiber laser for creating variable depth thermal lesions in the cornea. With further development, this laser may have potential use in laser thermal keratoplasty.
Keywords: refractive surgery • laser • cornea: clinical science