Smartphone fundus photography: a narrative review

Background The idea to use smartphone for fundus photography was put forward in 2010. Over the last decade, there has been a dramatic development in this field. This narrative review focuses on the principle of smartphone fundus photography, how to master this technique, problems encountered by the beginners, camera applications/devices designed for this purpose and the safety profile of smartphone flashlights for retinal photoreceptors. Discussion Smartphone fundus photography using a condensing lens is based on the same principle as indirect ophthalmoscopy. Smartphone flashlight serves the purpose of light source or illuminating system. Real and inverted image of the retina is focused by the smartphone camera after adjustment of the filming distance. Beginners can face difficulties like adjustment of the filming distance, glare from condensing lens and reflection from the ceiling lights. Mobile camera applications and holding devices designed for this purpose can help the beginners to address these difficulties. There have been safety concerns about photo-biological risk for retinal photoreceptors by flashlight. Although the spectral irradiance on the retina, while using smartphone for fundus imaging is within the safety limits set by ISO 15004-2.2. The safety profile of latest model flashlights which deliver more power compared to older flashlights, need to be assessed. Conclusion Smartphone fundus photography is a cheap, cost effective, portable and a convenient method for retinal imaging. With practice and use of smartphone camera applications designed for this purpose, the beginners can master this technique. By training young ophthalmology residents and ophthalmic primary caretakers, this retinal imaging technique can be utilized for artificial intelligence, patient diagnostic and educational purposes.

The coevolutionary biology of brood parasitism: a call for integration

Obligate brood-parasitic cheats have fascinated natural historians since ancient times. Passing on the costs of parental care to others occurs widely in birds, insects and fish, and often exerts selection pressure on hosts that in turn evolve defences. Brood parasites have therefore provided an illuminating system for researching coevolution. Nevertheless, much remains unknown about how ecology and evolutionary history constrain or facilitate brood parasitism, or the mechanisms that shape or respond to selection. In this special issue, we bring together examples from across the animal kingdom to illustrate the diverse ways in which recent research is addressing these gaps. This special issue also considers how research on brood parasitism may benefit from, and in turn inform, related fields such as social evolution and immunity. Here, we argue that progress in our understanding of coevolution would benefit from the increased integration of ideas across taxonomic boundaries and across Tinbergen’s Four Questions: mechanism, ontogeny, function and phylogeny of brood parasitism. We also encourage renewed vigour in uncovering the natural history of the majority of the world's brood parasites that remain little-known. Indeed, it seems very likely that some of nature’s brood parasites remain entirely unknown, because otherwise we are left with a puzzle: if parental care is so costly, why is brood parasitism not more common?This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

Research on the Weighting Coefficients of the Lighting Evaluation for the Target Lane

The visual experience factors of influencing the target lane’s illuminating system are analyzed and the concrete index is determined with the design of illuminating for the totally enclosed target lane. The shooting scores and the visual experience are tested at the designed illuminating system and the comparison data of the optical aiming set to mechanical aiming set and pistol to rifle are counted. The weighting value of the light evaluation is computed with the fuzzy analytic hierarchy process and the rationality of the design is verified objectively based on the analysis of the data.