Untersuchung einer cyan-farbigen Signalleuchte zur Kommunikation mit anderen Verkehrsteilnehmern

Die Thematik der lichtbasierten Kommunikation im Straßenverkehr wird derzeit im Rahmen verschiedener Forschungsvorhaben untersucht. [1],[2] Ziel ist es, die bisher mit der fahrzeugführenden Person stattfindende Kommunikation mit Hilfe einer lichttechnische Einrichtung am Fahrzeug zu ersetzen. Ansätze verwenden beispielsweise Scheinwerferprojektion oder Displays am Fahrzeug zur Darstellung höher aufgelöster Inhalte wie Symbole oder Schrift. [3],[4],[5] Diese Technologien bieten in der Gestaltung der Nachrichten, beispielsweise in Form von Symbolen viele Freiheitsgrade. Die Verwendung unterschiedlicher Farben und die Darstellung feiner, auch diagonal oder rund verlaufender Linien ist möglich. Ebenso kann die Darstellung über der Zeitachse verändert werden, so dass auch bewegte Zeichen und Animation für die Kommunikation nutzbar sind. Im Rahmen einer Konzeptstudie wurde bewusst auf diese Möglichkeiten verzichtet und eine niedrig aufgelöste Kommunikationseinrichtung am Fahrzeug implementiert und untersucht. Diese soll als Grundlage für die Durchführung einer Probandenstudie dienen

Two-Photon Vision in Age-Related Macular Degeneration: A Translational Study

The recently introduced term “two-photon vision” relates to the visual perception resulting from a simultaneous absorption of two photons by photoreceptors. In this study, we determined two-photon retinal sensitivity in age-related macular degeneration (AMD) and compared it that in normal aging. Microperimetry was performed with visible (white) light and infrared (IR) light, which was perceived as green in the two-photon stimulation. In total, 45 subjects were included with one (better) eye studied. Furthermore, best-corrected visual acuity (VA) and ocular straylight were assessed. AMD resulted in decreased median (interquartile range) logMAR VA, i.e., 0.15 (0.05; 0.24), which in normal eyes was −0.02 (−0.06; 0.02). The two groups showed comparable straylight levels. Sensitivity to IR light was significantly lower in the AMD group (p < 0.001): 8.3 (7.4, 9.3) dB than in controls 10.7 (9.7, 11.2) dB. AMD also significantly affected visible light sensitivity (p < 0.001): 14.0 (11.0; 15.5) dB vs. 18.0 (16.3; 18.9) dB. Notably, the two-photon approach yielded a lower data spread. In conclusion, AMD considerably impairs retinal sensitivity measured in the single- and two-photon realm. However, two-photon-vision microperimetry may improve the testing accuracy and offer an additional diagnostic parameter (beyond VA measurements) for retinal function assessment

The human eye: From Gullstrand’s eye model to ray tracing today

In order to understand how the vision process works, than to develop and design precise optical systems and instruments, the optical modelling of the human eye and the accurate prediction of the optical performance is a crucial topic for the light engineering as well as vision science. In the past, various optical eye models with different features were developed, among them the Gullstrand’s schematic eye model won the Nobel prize in 1911 [1]. He illustrated relevant optical surfaces (the cornea and the crystalline lens) of an eye and described their geometry quantitatively. After 100 years, today, the development of optical simulation software and ray tracing methods enable us to reproduce the optical system of the human eye quantitatively with more accuracy. For instance, to construct a statistical eye model, at first the biometrical data of the human eye was assessed using clinical devices, than new simulated data were generated and finally validated with biometric data [2]. However, previous eye models focused particularly only in some features like only corneal data, only accommodation or aging, used personalised or average population data and either mono- and polychromatic light. To the best of our knowledge, there is no eye model of the complete optical system. Therefore, developing a complete eye model may prove advantageous to understand the vision process and its application in the ophthalmology, the medical technology and the light engineering. This paper presents a review of optical eye models and provide insight into which facts will play an important role to develop a complete eye model by using contemporary technology

The loss of infrared-light sensitivity of photoreceptor cells measured with two-photon excitation as an indicator of diabetic retinopathy: A pilot study

Human photoreceptors are sensitive to infrared light (IR). This sensitivity can be used as a novel indicator of retinal function. Diabetic retinopathy patients were assessed using in vivo two-photon excitation and compared their scotopic IR threshold with that of healthy patients. METHODS: Sixty-two participants, 28 healthy and 34 with diabetic retinopathy, underwent a comprehensive eye examination, where visual acuity and contrast sensitivity were assessed. Infrared thresholds were measured in the fovea and parafovea following 30-minute dark adaptation. A two-photon excitation device was used with integrated pulsed laser light (1,045 nm) for sensitivity testing and scanning laser ophthalmoscopy for fundus imaging. RESULTS: The mean Snellen visual acuity of diabetic patients (6/7.7) was worse than that of the healthy patients (6/5.5), which was significantly different (P < 0.001). Disease patients had decreased contrast sensitivity, especially at 6 and 18 cycles/degree. The mean retinal sensitivity to IR light in eyes with diabetic retinopathy (11.6 ± 2.0 dB) was significantly (P < 0.001) lower than that in normal eyes (15.5 ± 1.3 dB). CONCLUSION: Compared with healthy control subjects, the IR light sensitivity of diabetic patients was significantly impaired. Two-photon measurements can be used in the assessment of retinal disease, but further studies are needed to validate IR light stimulation in various stages of diabetic retinopathy

Two-Photon Vision in Age-Related Macular Degeneration: A Translational Study

The recently introduced term &ldquo;two-photon vision&rdquo; relates to the visual perception resulting from a simultaneous absorption of two photons by photoreceptors. In this study, we determined two-photon retinal sensitivity in age-related macular degeneration (AMD) and compared it that in normal aging. Microperimetry was performed with visible (white) light and infrared (IR) light, which was perceived as green in the two-photon stimulation. In total, 45 subjects were included with one (better) eye studied. Furthermore, best-corrected visual acuity (VA) and ocular straylight were assessed. AMD resulted in decreased median (interquartile range) logMAR VA, i.e., 0.15 (0.05; 0.24), which in normal eyes was &minus;0.02 (&minus;0.06; 0.02). The two groups showed comparable straylight levels. Sensitivity to IR light was significantly lower in the AMD group (p &lt; 0.001): 8.3 (7.4, 9.3) dB than in controls 10.7 (9.7, 11.2) dB. AMD also significantly affected visible light sensitivity (p &lt; 0.001): 14.0 (11.0; 15.5) dB vs. 18.0 (16.3; 18.9) dB. Notably, the two-photon approach yielded a lower data spread. In conclusion, AMD considerably impairs retinal sensitivity measured in the single- and two-photon realm. However, two-photon-vision microperimetry may improve the testing accuracy and offer an additional diagnostic parameter (beyond VA measurements) for retinal function assessment

Clinical Application of Infrared-Light Microperimetry in the Assessment of Scotopic-Eye Sensitivity.

PURPOSE: The eye can see pulsed near-infrared (IR) radiation with the color corresponding to half of the wavelength used. Until recently, the technology required for measuring IR vision was confined to optical laboratories and was not studied clinically. The current investigation sought to determine the values for IR thresholds in a healthy population. METHODS: IR-light threshold was measured in 45 healthy participants, aged from 21 to 70 years. Ten patients with retinal pathology were included for comparison. Ocular media clarity was assessed with a straylight parameter. The sensitivity of dark-adapted eyes (expressed on a 0-26 dB scale) were tested using an IR microperimeter. The device consists of a femtosecond laser that emits 1045 nm light to project a stimulus at the retina. RESULTS: All participants were able to see the IR stimulus, which they perceived as green, and all performed the test. Measurements at seven locations revealed lower sensitivity at the fovea (15.5 dB) than in paracentral regions (18.2 dB). We noted a significant straylight increase with age. Although, in our study population, it was only a slight, -0.18 dB decline per decade of the average IR-sensitivity. The retinal-pathology group demonstrated impaired sensitivity to IR light. CONCLUSIONS: We showed that IR-light sensitivity does not significantly decrease with age despite a straylight increase. A reference level for the IR threshold was proposed. The application of IR-light microperimetry can be extended to the assessment of retinal pathology. TRANSLATIONAL RELEVANCE: IR-light microperimetry could be applied clinically to measure visual function