Two-photon retinal theranostics by adaptive compact laser source

Abstract

To avoid a devastating effect of eye vision impairment on the information flow from the eye to our brain, enormous effort is being put during the last decades into the development of more sensitive diagnostics and more efficient therapies of retinal tissue. While morphology can be impressively imaged by Optical Coherence Tomography, molecular-associated pathology information can be provided almost exclusively by auto-fluorescence-based methods. Among the latter, the recently developed Fluorescence lifetime imaging ophthalmoscopy (FLIO) has the potential to provide both structural information and interacting pictures at the same time. The requirements for FLIO laser sources are almost orthogonal to the laser sources used in phototherapy that is expected to follow-up the FLIO diagnostics. To make theranostics more effective and cheaper, the complete system would need to couple at least the modalities of low power high repetition rate FLIO and precision high-pulse energy adjustable repetition rate phototherapy. In addition, the intermediate power high repetition rate for two-photon excitation would also be desired to increase the depth resolution. In our work, compact fiber-laser-based on high-speed gain-switched laser diode has been shown to achieve adaptable / independently tunable repetition rate and energy per pulse allowing coupled fluorescence lifetime diagnostics via two-photon excitation and phototherapy via laser-induced photodisruption on a local molecular environment in a complex ex-vivo retinal tissue.

Revealing Inflammatory Indications Induced by Titanium Alloy Wear Debris in Periprosthetic Tissue by Label-Free Correlative High-Resolution Ion, Electron and Optical Microspectroscopy

“…The fastest decay time of the autofluorescent molecules surrounding wear debris was shown on the bright fluorescent spots in yellow (region 2), which could either be fluorophore aggregates or, more likely, accumulated molecules inside the cell compartments. Detailed FLIM analysis with two-component fitting revealed lifetimes and their relative amplitudes of τ 1 = 0.45 ns (a 1 = 85%) and τ 2 = 1.7 ns (a 2 = 15%) which are in fairly good agreement with the measured lifetime components of lipopigment lipofuscin [ 44 , 45 ]. To further prove the presence of lipofuscin, fHSI was applied, using a log-normal spectral fitting algorithm ( Figure 3 D).…”

Supplementary document for Method for real-time controlled tissue theranostics using a single adaptable laser source - 5390444.pdf

“…It has been shown recently that FLIM can be done also by a two-photon excitation typically using Ti:sapphire femtosecond lasers, not changing fluorescence lifetime decays [1,2]. The same has been confirmed in one of our recent studies using the custom-designed MOPA GS fiber laser, but at much longer, ps pulse regimes, more qualified for the localized tissue treatment [3]. In this study, we test the diagnostics capabilities of a newly designed tunable laser system that has been found particularly applicable for the customized treatment (Fig.…”