Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy

Jenny Wang; Philip Huie; Roopa Dalal; Seungjun Lee; Gavin Tan; Daeyoung Lee; Daniel Lavinksy M.D.; Daniel Palanker

doi:10.1117/12.2213171

4 March 2016 Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy

Jenny Wang, Philip Huie, Roopa Dalal, Seungjun Lee, Gavin Tan, Daeyoung Lee, Daniel Lavinksy M.D., Daniel Palanker

Proceedings Volume 9693, Ophthalmic Technologies XXVI; 969319 (2016) https://doi.org/10.1117/12.2213171
Event: SPIE BiOS, 2016, San Francisco, California, United States

Abstract

Unlike conventional photocoagulation, non-damaging retinal laser therapy (NRT) limits laser-induced heating to stay below the retinal damage threshold and therefore requires careful dosimetry. Without the adverse effects associated with photocoagulation, NRT can be applied to critical areas of the retina and repeatedly to manage chronic disorders. Although the clinical benefits of NRT have been demonstrated, the mechanism of therapeutic effect and width of the therapeutic window below damage threshold are not well understood. Here, we measure activation of heat shock response via laser-induced hyperthermia as one indication of cellular response. A 577 nm laser is used with the Endpoint Management (EpM) user interface, a titration algorithm, to set experimental pulse energies relative to a barely visible titration lesion. Live/dead staining and histology show that the retinal damage threshold in rabbits is at 40% of titration energy on EpM scale. Heat shock protein 70 (HSP70) expression in the retinal pigment epithelium (RPE) was detected by whole-mount immunohistochemistry after different levels of laser treatment. We show HSP70 expression in the RPE beginning at 25% of titration energy indicating that there is a window for NRT between 25% and 40% with activation of the heat shock protein expression in response to hyperthermia. HSP70 expression is also seen at the perimeter of damaging lesions, as expected based on a computational model of laser heating. Expression area for each pulse energy setting varied between laser spots due to pigmentation changes, indicating the relatively narrow window of non-damaging activation and highlighting the importance of proper titration.

Conference Presentation

Citation Download Citation

Jenny Wang, Philip Huie, Roopa Dalal, Seungjun Lee, Gavin Tan, Daeyoung Lee, Daniel Lavinksy M.D., and Daniel Palanker "Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy", Proc. SPIE 9693, Ophthalmic Technologies XXVI, 969319 (4 March 2016); https://doi.org/10.1117/12.2213171

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