Light is an important factor for regulation of circadian, endocrine and metabolic processes in the human body. Through this light has a positive effect on cognition, on the stabilization of circadian rhythms and for general wellbeing. These effects are described as non-visual effects of light. Many dynamic lighting systems are already in use in workplaces and living spaces, aiming to address visual and also non-visual effects. In Europe and US the term “Human Centric Lighting” or abbreviated "HCL” was introduced, as a scientifically agreed concept on how to plan non-visual effects of artificial light in synergy with natural light. Older people, especially with neurological and psychological diseases can especially benefit from this lighting concept. However, in order to achieve the desired non-visual effects, certain conditions should be fulfilled. In Germany the DIN SPEC 67600 is a guideline for the design of biologically effective illumination, with examples for senior- and nursing homes. A goal of this evaluation was to check whether the recommendations of the specification DIN SPEC 67600 in three nursing homes were met and another goal was if effectiveness of the lighting on residents and nursing staff can be determined. Photometric measurements were taken and subjective perceived non-visual effects of light were surveyed using a questionnaire. Results: Although none of the three facilities met all the criteria of the DIN SPEC 67600 guidelines, non-visual lighting effects on residents and nursing staff could be detected. The results also indicate that careful attention should be paid on maintenance of HCL systems. The correct use of HCL solutions in homes for the elderly has opportunities to improve health status if the system is properly designed and maintained. Therefore next to the existing (non-visual) metrics and HCL design guidelines, guidelines for maintaining and regular inspections should be established.

Hyperspectral imaging to monitor perfusion parameters during the Allen test was performed in 20 volunteers. Clear differences in tissue oxygenation and hemoglobin index during rest, occlusion and reperfusion were visually and computationally evident.

Objectives To evaluate the capability of hyperspectral imaging (HSI), a contact‐less and noninvasive technology, to monitor perfusion changes of the hand during a modified Allen test (MAT) and cuff occlusion test. Furthermore, the study aimed at obtaining objective perfusion parameters of the hand. Methods HSI of the hand was performed on 20 healthy volunteers with a commercially available HSI system during a MAT and a cuff occlusion test. Besides gathering red‐green‐blue (RGB) images, the perfusion parameters tissue hemoglobin index (THI), (superficial tissue) hemoglobin oxygenation (StO2), near‐infrared perfusion (NIR), and tissue water index (TWI) were calculated for four different regions of interest on the hand. For the MAT, occlusion (OI; the ratio between the condition during occlusion and before occlusion) and reperfusion (RI; the ratio between the non‐occlusion state and the prior occlusion state) indices were calculated for each perfusion parameter. All data were correlated to the clinical findings. Results False‐color images showed visible differences between the various perfusion conditions during the MAT and cuff occlusion test. THI, StO2, and NIR behaved as expected from physiology, while TWI did not in the context of this study. During rest, mean THI, StO2, and NIR of the hand were 34 ± 2, 72 ± 9, and 61 ± 6, respectively. The RI for THI showed a roundabout threefold increase after reperfusion of both radial and ulnar artery and was thus, distinctly pronounced when compared with StO2 and NIR (~1.25). The OI was lowest for THI when compared with StO2 and NIR. Conclusions HSI with its parameters THI, StO2, and NIR proved to be suitable to evaluate perfusion of the hand. By this, it could complement visual inspection during the MAT for evaluating the functionality of the superficial palmary arch before radial or ulnar artery harvest. The presented RI might deliver useful comparative values to detect pathological perfusion disorders at an early stage. As microcirculation monitoring is crucial for many medical issues, HSI shows potential to be used, besides further applications, in the monitoring of (free) flaps and transplants and microcirculation monitoring of critically ill patients.

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