Comparative study of laser damage threshold energies in the artificial retina

Short-pulse duration retinal lasers: a review

The development of lasers for biological use was an important medical advance in the 20th century with numerous evidence-based therapeutic applications to retinal disease, including capillary leakage at the macula. Although the role of photocoagulative laser in the treatment of macular oedema has diminished, there is evidence for a modified role in clinical management, particularly for extrafoveal leakage. Additionally, it may reduce the frequency of required intravitreal injections and assist in visual stabilization when used as an adjunct. The tissue destructive effect of photocoagulative lasers has motivated the development of safer macular lasers and the search for novel therapeutic applications, including treatment of drusen and regeneration of dysfunctional retinal pigment epithelium.

Label-free second harmonic and hyper Rayleigh scattering with high efficiency

We present a method to perform hyper Rayleigh scattering from aqueous solutions and second harmonic scattering measurements from unlabeled interfaces of liposomes and nanoparticles in dilute solutions. The water and interfacial response can be measured on a millisecond timescale, thus opening up the possibility to measure label-free time dependent transport processes in biological (membrane) systems.

In vitro model that approximates retinal damage threshold trends

Without effective in vitro damage models, advances in our understanding of the physics and biology of laser-tissue interaction would be hampered due to cost and ethical limitations placed on the use of nonhuman primates. We extend our characterization of laser-induced cell death in an existing in vitro retinal model to include damage thresholds at 514 and 413 nm. The new data, when combined with data previously reported for 532 and 458 nm exposures, provide a sufficiently broad range of wavelengths and exposure durations (0.1 to 100 s) to make comparisons with minimum visible lesion (in vivo) data in the literature. Based on similarities between in vivo and in vitro action spectra and temporal action profiles, the cell culture model is found to respond to laser irradiation in a fundamentally similar fashion as the retina of the rhesus animal model. We further show that this response depends on the amount of intracellular melanin pigmentation.