Dataset Information

The Photosensitivity of Rhodopsin Bleaching and Light-Induced Increases of Fundus Reflectance in Mice Measured In Vivo With Scanning Laser Ophthalmoscopy.

ABSTRACT: To quantify bleaching-induced changes in fundus reflectance in the mouse retina.Light reflected from the fundus of albino (Balb/c) and pigmented (C57Bl/6J) mice was measured with a multichannel scanning laser ophthalmoscopy optical coherence tomography (SLO-OCT) optical system. Serial scanning of small retinal regions was used for bleaching rhodopsin and measuring reflectance changes.Serial scanning generated a saturating reflectance increase centered at 501 nm with a photosensitivity of 1.4 × 10-8 per molecule ?m2 in both strains, 2-fold higher than expected were irradiance at the rod outer segment base equal to that at the retinal surface. The action spectrum of the reflectance increase corresponds to the absorption spectrum of mouse rhodopsin in situ. Spectra obtained before and after bleaching were fitted with a model of fundus reflectance, quantifying contributions from loss of rhodopsin absorption with bleaching, absorption by oxygenated hemoglobin (HbO2) in the choroid (Balb/c), and absorption by melanin (C57Bl/6J). Both mouse strains exhibited light-induced broadband reflectance changes explained as bleaching-induced reflectivity increases at photoreceptor inner segment/outer segment (IS/OS) junctions and OS tips.The elevated photosensitivity of rhodopsin bleaching in vivo is explained by waveguide condensing of light in propagation from rod inner segment (RIS) to rod outer segment (ROS). The similar photosensitivity of rhodopsin in the two strains reveals that little light backscattered from the sclera can enter the ROS. The bleaching-induced increases in reflectance at the IS/OS junctions and OS tips resemble results previously reported in human cones, but are ascribed to rods due to their 30/1 predominance over cones in mice and to the relatively minor amount of cone M-opsin in the regions scanned.

SUBMITTER: Zhang P

PROVIDER: S-EPMC4959838 | biostudies-other | 2016 Jul

REPOSITORIES: biostudies-other

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The Photosensitivity of Rhodopsin Bleaching and Light-Induced Increases of Fundus Reflectance in Mice Measured In Vivo With Scanning Laser Ophthalmoscopy.

Zhang Pengfei P Goswami Mayank M Zawadzki Robert J RJ Pugh Edward N EN

Investigative ophthalmology & visual science 20160701 8

<h4>Purpose</h4>To quantify bleaching-induced changes in fundus reflectance in the mouse retina.<h4>Methods</h4>Light reflected from the fundus of albino (Balb/c) and pigmented (C57Bl/6J) mice was measured with a multichannel scanning laser ophthalmoscopy optical coherence tomography (SLO-OCT) optical system. Serial scanning of small retinal regions was used for bleaching rhodopsin and measuring reflectance changes.<h4>Results</h4>Serial scanning generated a saturating reflectance increase cente ...[more]

PMID: 27403994

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Project description:IntroductionSilicone oil (SO) is a crucial agent used as an intraocular tamponade in the treatment of complex vitreoretinal diseases. Despite its effectiveness, SO is prone to emulsification, which can lead to significant and sometimes irreversible complications in both the anterior and posterior segments of the eye. The detection and monitoring of SO emulsification are therefore of paramount importance. Traditional imaging modalities have limitations in visualizing SO, leading to the exploration of more advanced imaging techniques. This study introduces the application of dynamic infrared confocal scanning laser ophthalmoscopy (IRcSLO) for this purpose and evaluates its effectiveness.Case presentationWe report on 2 patients who underwent pars plana vitrectomy with subsequent SO injection for the management of retinal detachment. Postsurgery, both patients were imaged using the Heidelberg Retina Tomography Spectralis IRcSLO. The focus was on the visualization of the SO status, including the presence and distribution of emulsified SO droplets. The IRcSLO imaging technique demonstrated its capability to effectively visualize emulsified SO droplets. Interestingly, this was also true for cases where the SO had been removed. The emulsified droplets were observed as micron-sized, spherical entities with a nonuniform distribution throughout the vitreous cavity.ConclusionDynamic IRcSLO has proven to be an effective imaging modality for visualizing the emulsification of SO, offering a novel perspective into the characterization of SO droplets. It facilitates the analysis of droplet count, motility, and precise localization within the vitreous cavity. The findings from the case presentations underscore the variability of SO emulsification patterns and the sensitivity of IRcSLO in detecting even minuscule emulsified droplets. This imaging technique has significant potential for future research, particularly in understanding the timing of emulsification, the factors contributing to it, and the development of possible preventive strategies. Additionally, it allows for a more in-depth analysis of the behavior of emulsified SO droplets across different SO viscosities, which could be instrumental in optimizing patient outcomes.

Dataset Information

The Photosensitivity of Rhodopsin Bleaching and Light-Induced Increases of Fundus Reflectance in Mice Measured In Vivo With Scanning Laser Ophthalmoscopy.

Publications

The Photosensitivity of Rhodopsin Bleaching and Light-Induced Increases of Fundus Reflectance in Mice Measured In Vivo With Scanning Laser Ophthalmoscopy.

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