Search

Despite widespread government and public interest, there are significant barriers to translating basic science discoveries into clinical practice. Biophotonics and biomedical optics technologies can be used to overcome many of these hurdles, due, in part, to offering new portable, bedside, and accessible devices. The current JBO special issue highlights promising activities and examples of translational biophotonics from leading laboratories around the world. We identify common essential features of successful clinical translation by examining the origins and activities of three major international academic affiliated centers with beginnings traceable to the mid-late 1970s: The Wellman Center for Photomedicine (Mass General Hospital, USA), the Beckman Laser Institute and Medical Clinic (University of California, Irvine, USA), and the Medical Laser Center Lübeck at the University of Lübeck, Germany. Major factors driving the success of these programs include visionary founders and leadership, multidisciplinary research and training activities in light-based therapies and diagnostics, diverse funding portfolios, and a thriving entrepreneurial culture that tolerates risk. We provide a brief review of how these three programs emerged and highlight critical phases and lessons learned. Based on these observations, we identify pathways for encouraging the growth and formation of similar programs in order to more rapidly and effectively expand the impact of biophotonics and biomedical optics on human health.

The influence of spherical aberrations on laser-induced plasma formation in water by 6-ns Nd:YAG laser pulses was investigated for focusing angles that are used in intraocular microsurgery. Waveform distortions of 5.5[Lambda] and 18.5[Lambda] between the optical axis and the 1/[e.sup.2] irradiance values of the laser beam were introduced by replacement of laser achromats in the delivery system by planoconvex lenses. Aberrations of 18.5[Lambda] increased the energy threshold for plasma formation by a factor of 8.5 compared with the optimized system. The actual irradiance threshold for optical breakdown was determined from the threshold energy in the optimized system and the spot size measured with a knife-edge technique. For aberrations of 18.5[Lambda] the irradiance threshold was 48 times larger than the actual threshold when it was calculated by use of the diffraction-limited spot size but was 35 times smaller when it was calculated by use of the measured spot size. The latter discrepancy is probably due to hot spots in the focal region of the aberrated laser beam. Hence the determination of the optical-breakdown threshold in the presence of aberrations leads to highly erroneous results. In the presence of aberrations the plasmas are as much as 3 times longer and the transmitted energy is 17-20 times higher than without aberrations. Aberrations can thus strongly compromise the precision and the safety of intraocular microsurgery. They can further account for a major part of the differences in the breakdown-threshold and the plasma-transmission values reported in previous investigations.

The fundamental difference between time-resolved and coherence-gated imaging modalities in scattering media is analyzed in terms of their optical transfer functions. The effectiveness of coherence gating for multiple-scattering rejection is shown by imaging a 100-[[micro]meter]-thick razor blade hidden in the scattering phantoms (i.e., Intralipid suspensions) with different scattering coefficients. We found that the imaging contrast is limited by multiple scattering and speckle effects in high-scattering media, and the measured effective penetration depth of optical coherence tomography is approximately equal to six mean free paths under the experimental conditions of a numerical aperture of less than 0.1 and a scattering anisotropy of approximately 0.8. Key words: Coherence-gated imaging, time-resolved imaging, low-coherence interference, imaging contrast limits, multiple scattering effects, tissue optics.

Purpose: Central serous chorioretinopathy (CSC) is a disease presenting with detachment of the neurosensory retina and characteristic focal leakage on fluorescein angiography. The spontaneous remission rate is 84% within 6 months. In this study, the efficacy of selective retina therapy (SRT) was examined in patients with therapy refractory persistent acute CSC defined by symptoms for at least 6 months and persistent subretinal fluid (SRF) despite eplerenone therapy. Material and methods: This is a prospective, monocentric observational study in 17 eyes (16 patients, mean age 42 years, 2 female). SRT was performed with the approved R:GEN laser (Lutronic, South Korea), a micropulsed 527-nm Nd:YLF laser device, with a train of 30 pulses of 1.7 μs at 100-Hz repetition rate at the point of focal leakage determined by fluorescein angiography (FA) at baseline (BSL). Visits on BSL, week 4 (wk4), and week 12 (wk12) included best corrected visual acuity (BCVA, logMar), central retinal thickness (CRT) on spectral domain optical coherence tomography (SD-OCT), and FA. Statistical analysis was performed by pair-by-pair comparisons of multiple observations in each case with Bonferroni correction for multiple testing. (IBM SPSS Statistics 25®). Results: Mean CRT at BSL was 387.69 ± 110.4 μm. CRT significantly decreased by 106.31 μm in wk4 (95%-KI: 21.42–191.2; p = 0.01), by 133.63 μm in wk12 (95%-KI: 50.22–217.03; p = 0.001) and by 133.81 μm (95%-KI: 48.88–218.75; p = 0.001) compared to BSL. Treatment success defined as complete resolution of SRF occurred at wk4 in 7/17 eyes (35.3%) and at wk12 in 10/17 eyes (58.8%). Re-SRT was performed in 7/17 eyes (41.2%) after an average of 107.14 ± 96.59 days. Treatment success after Re-SRT was observed in 4/6 eyes (66.6%, 12 weeks after Re-SRT). Mean BCVA did not change significantly from BSL to any later timepoint after adjusting for multiple testing. Notably, eyes with treatment success showed better BCVA at all timepoints and gained more letters compared to failures. Conclusion: Single or repetitive SRT may be an effective and safe treatment in 2 of 3 patients suffering from acute persistent CSC after 6 months of symptoms or more. We observed complete resolution of SRF in around 60% of eyes 12 weeks after first SRT treatment and also 12 weeks after Re-SRT treatment in eyes with persistent or recurrent SRF. Results on the long-term course after SRT are still pending. [ABSTRACT FROM AUTHOR]

PURPOSE: To evaluate a new non-ablative and adjustable procedure for laser ablative refractive corneal surgery in hyperopia using the injection of a biocompatible liquid filler material into a stromal pocket. METHODS: A total of 120 stromal pockets were created using a clinical femtosecond laser system in 96 rabbit corneoscleral discs and 24 whole globes. Pockets were cut at a depth of 120 or 250 µm below the epithelial surface. Hyaluronic acid was injected manually into the pocket. To determine the refractive changes, three-dimensional optical coherence tomography images and a specifically developed picture recognition Matlab (The Mathworks) routine were used. RESULTS: After injection, a steepening of the anterior and flattening of the posterior corneal surface was observed, which led to hyperopic correction. The two main factors determining the amount of correction were the pocket depth and the injected volume. After the pocket was homogeneously filled, an initial refractive increase was observed, followed by a linear relation between the injected volume and the refraction increase. CONCLUSIONS: This possible clinical protocol for controlled refraction correction of hyperopia suggests a potential readjustable clinical application. [[J Refract Surg. 2020;36(6):406–414.] [ABSTRACT FROM AUTHOR]

Correction of hyperopia requires an increase of the refractive power by steepening of the corneal surface. Present refractive surgical techniques based on corneal ablation (LASIK) or intrastromal lenticule extraction (SMILE) are problematic due to epithelial regrowth. Recently, it was shown that correction of low hyperopia can be achieved by implanting intracorneal inlays or allogeneic lenticules. We demonstrate a steepening of the anterior corneal surface after injection of a transparent, liquid filler material into a laser-dissected intrastromal pocket. We performed the study on ex-vivo porcine eyes. The increase of the refractive power was evaluated by optical coherence tomography (OCT). For a circular pocket, injection of 1 μl filler material increased the refractive power by þ4.5 diopters. An astigmatism correction is possible when ellipsoidal intrastromal pockets are created. Injection of 2 μl filler material into an ellipsoidal pocket increased the refractive power by þ10.9 dpt on the short and þ5.1 dpt on the long axis. OCT will enable to monitor the refractive change during filler injection and is thus a promising technique for real-time dosimetry. [ABSTRACT FROM AUTHOR]