Neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers are among the most commonly used lasers with a wide variety of applications from biomedicine to manufacturing. The ubiquity of these lasers increases the likelihood of accidental ocular injury resulting in permanent visual impairment. We performed dosimetry studies to determine retinal damage thresholds and hemorrhagic lesions in the porcine eye with Qswitched Nd:YAG lasers. The Yucatan miniature pig model exhibited similarities in ocular anatomy to human eyes. The Nd:YAG laser, tuned to 1064 nm with a pulse width of seven nanoseconds, delivered laser energy to the retina. Retinal imaging modalities including fundus photography, real-time video, confocal scanning laser ophthalmoscopy (cSLO), and spectral domain optical coherence tomography (SD-OCT) provided visualization of retinal morphology at multiple time points. Retinal damage thresholds were grouped into three categories: minimum visible lesion (MVL), contained hemorrhagic lesion (CHL), and vitreal hemorrhagic lesion (VHL). Probit analysis determined the effective dose for 50% probability of damage (ED50) for each lesion category. The threshold to produce a MVL was 0.193 mJ based on 24-hour assessments of the retina. The one-hour hemorrhagic lesion thresholds were 0.408 mJ and 1.52 mJ for CHL and VHL, respectively
It has recently been shown that bone marrow cells can differentiate into various lineage cells including neural cells in
vitro and in vivo. Therefore it is an attractive therapeutic intervention to apply autologous bone marrow-derived stem
cells that may offer neuroprotection to laser-induced retinal injuries. The purpose of this study is to develop a method
with which to visualize bone marrow stem cells dynamics in mouse retinal circulation. We have used a physiological
method, confocal scanning laser ophthalmoscope (SLO), to track the highly enriched stem/progenitor cells circulating in
the retina. Stem cells were enriched by immunomagnetic depletion of cells committed to the T- and B lymphocytic,
myeloid and erythorid lineages. CellTrackerTM Green-labeled stem cells were injected into the tail veins of mice with
laser-induced focal retinal injuries. Bone marrow stem cells labeled with CellTrackerTM Green were visible in the
retinal circulation for as long as 1 hour and 30 minutes. These studies suggest that stem cell-enriched bone marrow
cells may have the ability to mobilize into laser-induced retinal injuries and possibly further proliferate, differentiate and
functionally integrate into the retina.
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