Recent advances in the dark adaptation investigations

Dark adaptation is a highly sensitive neural function and may be the first symptom of many status including the physiologic and pathologic entity, suggesting that it could be instrumental for diagnose. However, shortcomings such as the lack of standardized parameters, the long duration of examination, and subjective randomness would substantially impede the use of dark adaptation in clinical work. In this review we summarize the recent research about the dark adaptation, including two visual cycles-canonical and cone-specific visual cycle, affecting factors and the methods for measuring dark adaptation. In the opinions of authors, intensive investigations are needed to be done for the widely use of this significant visual function in clinic.

A Research on Darkness Adaptation of Drivers

This paper presents the results of darkness adaptationtest for drivers. It is shown that there is a significant difference ( p <0.05)in their darkness adaptation ability between the drivers in accident group and non-accident group. It is further revealed that the accident rate of the drivers with darkness adaptation time ≤10 s is 2.6%, while that with darkness adaptation time >10 s is 7.3%, implying that the high accident rate of the drivers in accident group might be caused by their longer darkness adaptation time.

Single-cell profiling reveals Müller glia coordinate retinal intercellular communication during light/dark adaptation via thyroid hormone signaling

Light adaptation enables the vertebrate visual system to operate over a wide range of ambient illumination.Regulation of phototransduction in photoreceptors is considered a major mechanism underlying light adaptation.However,various types of neurons and glial cells exist in the retina,and whether and how all retinal cells interact to adapt to light/dark conditions at the cellular and molecular levels requires systematic investigation.Therefore,we utilized single-cell RNA sequencing to dissect retinal cell-type-specific transcriptomes during light/dark adaptation in mice.The results demonstrated that,in addition to photoreceptors,other retinal cell types also showed dynamic molecular changes and specifically enriched signaling pathways under light/dark adaptation.Importantly,Müller glial cells(MGs)were identified as hub cells for intercellular interactions,displaying complex cell‒cell communication with other retinal cells.Furthermore,light increased the transcription of the deiodinase Dio2 in MGs,which converted thyroxine(T4)to active triiodothyronine(T3).Subsequently,light increased T3 levels and regulated mitochondrial respiration in retinal cells in response to light conditions.As cones specifically express the thyroid hormone receptor Thrb,they responded to the increase in T3 by adjusting light responsiveness.Loss of the expression of Dio2 specifically in MGs decreased the light responsive ability of cones.These results suggest that retinal cells display global transcriptional changes under light/dark adaptation and that MGs coordinate intercellular communication during light/dark adaptation via thyroid hormone signaling.

TSC1 enables plastid development under dark conditions, contributing to rice adaptation to transplantation shock

Since its domestication from wild rice thousands of years ago, rice has been cultivated largely through transplantation. During transplantation from the nursery to the paddy field, rice seedlings experience transplantation shock which affects their physiology and production.However, the mechanisms underlying transplantation shock and rice adaptation to this shock are largely unknown. Here,we isolated a transplant-sensitive chloroplast-deficient（tsc_1）rice mutant that produces albino leaves after transplantation.Blocking light from reaching the juvenile leaves and leaf primordia caused chloroplast deficiencies in transplanted tsc_1 seedlings. TSC_1 encodes a noncanonical adenosine triphosphate-binding cassette（ABC） transporter homologous to At NAP_（14） and is of cyanobacterial origin. We demonstrate that TSC_1 controls plastid development in rice under dark conditions, and functions independently of light signaling.However, light rescued the tsc_1 mutant phenotype in a spectrum-independent manner. TSC_1 was upregulated following transplantation, and modulated the iron and copper levels, thereby regulating prolamellar body formation during the early P_4 stage of leaf development. Therefore, TSC_1 is indispensable for plastid development in the absence of light,and contributes to adaptation to transplantation shock.Our study provides insight into the regulation of plastid development and establishes a framework for improving recovery from transplantation shock in rice.

Rapid retinal functional testing

The most prominent causes of loss of vision in individuals over 50 years include age-related macular degeneration(AMD),glaucoma,and diabetic retinopathy(DR).While it is important to screen for these diseases effectively,current eye care is not properly doing so for much of the population,resulting in unfortunate visual disability and high costs for patients.Innovative functional testing can be unified with other screening methods for a more robust and safer screening and prediction of disease.The goal in the creation of functional testing modalities is to develop highly sensitive screening tests that are easy to use,accessible to all users,and inexpensive.The tests herein are deployed on an iPad with easily understood and intuitive instructions for rapid,streamlined,and automatic administration.These testing modalities could become highly sensitive screenings for early detection of potentially blinding diseases.The applications from our collaborators at AMA Optics include a cone photostress recovery test for detection of AMD and diabetic macular edema(DME),brightness balance perception for optic nerve dysfunction and especially glaucoma,color vision testing which is a broad screening tool,and visual acuity test.Machine learning with the combined structural and functional data will optimize identification of disease and prediction of outcomes.Here,we review and assess various tests of visual function that are easily administered on a tablet for screening in primary care.These user-friendly and simple screening tests allow patients to be identified in the early stages of disease for referral to specialists,proper assessment and treatment.

A preliminary observation on rod cell photobiomodulation in treating diabetic macular edema

Purpose:To evaluate the safety and effectiveness of photobiomodulation(PBM)in the treatment of diabetic macular edema(DME).Methods:It was a single-center,self-controlled prospective study.The clinical records of 12 diabetic retinopathy patients(5 males and 7 females,20 eyes in total)who were treated with PBM for DME at the Second Affiliated Hospital,Zhejiang University School of Medicine,were analyzed.The mean age was 56(26–68)years.All the participants received PBM treatment during darkness at night in no less than 5 days per week and no less than 8 h per day.In the baseline check and follow-up checks(1,2,6,10,and 12 months after the start of treatment),the best-corrected visual acuity,the thickness of the retina in the macula,and the changes of the fundus lesions were observed.Wilcoxon signed rank test was used to compare the results before and after treatment.P<0.05 was considered statistically significant.Results:No fundus complication was observed during follow-up checks.In baseline and 12-month follow-up checks,the best-corrected visual acuity was 71.75
12.47 and 79.50
10.85,maximal retinal thickness in macular area was 390.95
77.12μm and 354.13
55.03μm,average retinal thickness in macular area was 334.25
36.45μm and 314.31
33.28μm,foveal thickness was 287.00
46.79μm and 265.63
67.14μm.The best-corrected visual acuity,average retinal thickness in macular area in consecutive follow-up results except that in the 1st month showed significant difference compared with baseline results.There were significant difference between every follow-up result and baseline result of maximal retinal thickness in macular area(P<0.05).All follow-up results of foveal thickness were not significantly different(P>0.05)from the baseline result,except that in the 6th month(P?0.049).Obvious improvement could be observed in retinal fundus fluorescein angiography images.Conclusions:PBM is a safe and effective treatment of DME,which deserves further investigation.