scholarly journals Aging, light sensitivity and circadian health

Aging ◽  
2021 ◽  
Author(s):  
Sarah L. Chellappa
Keyword(s):  
Light Sensitivity

Biomedical Materials to Repair Retinal Detachments

1985 ◽  
Vol 55 ◽  
Author(s):  
Miguel F. Refojo
Keyword(s):  
Retinal Detachment ◽  
Silicone Rubber ◽  
Methyl Acrylate ◽  
Silicone Oil ◽  
Vitreous Body ◽  
Light Sensitivity ◽  
Scleral Buckling ◽  
Intraocular Injection ◽  
Other Substances

ABSTRACTImplants are essential for the repair of retinal detachments. The implant buckles the wall of the eye and apposes the detached retina with the choroid, thus restoring light sensitivity to the retina. The scleral buckling also relieves traction on the retina from a shrinking vitreous body. The implant materials most commonly used are solid silicone rubber and silicone sponges, but both types have some disadvantages. A poly(hydroxyethyl acrylate-co-methyl acrylate) hydrogel implant with improved properties of softness and antibiotic absorption is also available for retinal detachment surgery. Proliferative vitreoretinopathy involves various conditions of retinal detachment complicated by vitreous fibrosis, which, after vitrectomy, may be treated with intraocular injection of fluids that support the retina against the choroid. For conditions requiring a long-term implant, silicone oil although controversial is the material of choice. Many other substances have been investigated but none better has yet been found.

Results of Applying the Method of Visual Fatigue Prevention Using Low-Intensity Laser Radiation

2020 ◽  
pp. 56-59
Author(s):  
NYu Mal’kova ◽  
MD Petrova
Keyword(s):  
Laser Radiation ◽  
Work Experience ◽  
Study Groups ◽  
Light Sensitivity ◽  
Control Group ◽  
Sensitivity Threshold ◽  
Visual Fatigue ◽  
Strain Relief ◽  
Visual Stress ◽  
Stress At Work

Summary. Introduction: Visual fatigue is caused by changes in the muscular apparatus and retina of the eye and is characterized by deterioration in their functional activity. Along with an increase in work experience and age, workplace visual stress promotes the loss of performance. Known methods of visual fatigue prevention and eye strain relief are ineffective. In this regard, a technique of relieving visual fatigue using scattered low-level red laser radiation was developed and patented. The purpose of our study was a retrospective evaluation of effectiveness of the visual fatigue reduction technique. Materials and methods: We examined two groups of women (PC operators and jewellers) aged 43–57 years experiencing visual stress at work and practicing the method under study over the previous 20 years. The state of daylight vision was assessed by adaptation time. Results: A five-day testing of the method of visual fatigue relief showed stabilization of the light sensitivity threshold throughout the work shift. Over the 20-year period, the female workers had had no complaints of eye strain, burning or lacrimation. Objective studies of the functional state of the organ of sight showed that the light sensitivity threshold during the working day in two study groups was significantly lower than that in the control group with no preventive measures taken. Conclusions: We established that using the technique of eye strain relief based on a two-minute binocular exposure to red laser radiation with the power density of 2×10–7 W/cm2, a 5-day course every six months over the period of 20 years, helped retain retinal activity in terms of light sensitivity, thus preventing visual fatigue.

scholarly journals An engineered membrane-bound guanylyl cyclase with light-switchable activity

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yuehui Tian ◽  
Georg Nagel ◽  
Shiqiang Gao
Keyword(s):  
Guanylyl Cyclase ◽  
Green Light ◽  
Chemical Properties ◽  
Light Sensitivity ◽  
Cgmp Level ◽  
Volvox Carteri ◽  
Non Invasive ◽  
Cgmp Signaling ◽  
Membrane Bound ◽  
Light Flashes

Abstract Background Microbial rhodopsins vary in their chemical properties, from light sensitive ion transport to different enzymatic activities. Recently, a novel family of two-component Cyclase (rhod)opsins (2c-Cyclop) from the green algae Chlamydomonas reinhardtii and Volvox carteri was characterized, revealing a light-inhibited guanylyl cyclase (GC) activity. More genes similar to 2c-Cyclop exist in algal genomes, but their molecular and physiological functions remained uncharacterized. Results Chlamyopsin-5 (Cop5) from C. reinhardtii is related to Cr2c-Cyclop1 (Cop6) and can be expressed in Xenopus laevis oocytes, but shows no GC activity. Here, we exchanged parts of Cop5 with the corresponding ones of Cr2c-Cyclop1. When exchanging the opsin part of Cr2c-Cyclop1 with that of Cop5, we obtained a bi-stable guanylyl cyclase (switch-Cyclop1) whose activity can be switched by short light flashes. The GC activity of switch-Cyclop1 is increased for hours by a short 380 nm illumination and switched off (20-fold decreased) by blue or green light. switch-Cyclop1 is very light-sensitive and can half-maximally be activated by ~ 150 photons/nm2 of 380 nm (~ 73 J/m2) or inhibited by ~ 40 photons/nm2 of 473 nm (~ 18 J/m2). Conclusions This engineered guanylyl cyclase is the first light-switchable enzyme for cGMP level regulation. Light-regulated cGMP production with high light-sensitivity is a promising technique for the non-invasive investigation of the effects of cGMP signaling in many different tissues.

Criteria of light sensitivity of media and optimization of hologram recording

1982 ◽  
Vol 12 (12) ◽  
pp. 1593-1597
Author(s):  
A O Ozols ◽  
K K Shvarts
Keyword(s):  
Light Sensitivity ◽  
Hologram Recording

Light-Sensitivity of Hazel Seeds with Respect to the Breaking of Dormancy

1983 ◽  
Vol 24 (5) ◽  
pp. 933-936 ◽  
Author(s):  
P.R.M. Shannon ◽  
R.A. Jeavons ◽  
B.C. Jarvis
Keyword(s):  
Light Sensitivity

Tetrahydrobiopterin-Derivat als lichtempfindliche Verbindung bei Amphibien und Insekten

1960 ◽  
Vol 15 (7) ◽  
pp. 460-465 ◽  
Author(s):  
Irmgard Ziegler
Keyword(s):  
Light Sensitivity

A tetrahydrobiopterin-compound (in addition to biopterin) has been found in the eyes and skins of Amphibians as well as in the eyes of insects. Evidence is given that this tetrahydrobiopterin-compound occurs as a N (8) -ribosid. The compound originally does not fluoresce. It is very light-sensitive; by irradiation hydrogen is split off, which can be transferred to TTC, and the fluorescing degradationproducts appear. The possibility of a tetrahydro-dihydro-equilibrium and the importance of this widely distributed compound for light-sensitivity is discussed.

Visual Field Damage and Progression in Glaucomatous Myopic Eyes

2007 ◽  
Vol 17 (4) ◽  
pp. 534-537 ◽  
Author(s):  
A. Perdicchi ◽  
M. Iester ◽  
G. Scuderi ◽  
S. Amodeo ◽  
E.M. Medori ◽  
...  
Keyword(s):  
Visual Field ◽  
Open Angle Glaucoma ◽  
Linear Regression Analysis ◽  
Visual Fields ◽  
Light Sensitivity ◽  
Progressive Increase ◽  
Central Visual Field ◽  
Trend Function ◽  
Visual Field Damage ◽  
Loss Variance

Purpose To make a visual field retrospective analysis on a group of patients with primary open angle glaucoma (POAG) and to evaluate whether different refractive errors could have different progression of the 30° central sensitivity. Methods A total of 110 patients with POAG (52 men and 58 women) were included in the study. All the patients were divided into four subgroups based on the refractive error. The visual field of all the included patients was assessed by an Octopus 30° central visual field every 6 months, for a total of 837 visual fields examined. The resulting data were analyzed by PERIDATA for Windows 1.7 TREND function. Mean defect (MD) and loss variance (LV) were considered for the analysis. Results At the first examination, 82% of eyes showed a global decrease of differential light sensitivity (MD >2 dB) and in 67% the distribution of the defect was nonhomogeneous (LV >6 dB). The analysis of variance for subgroups showed a more significant decrease of MD in highly myopic patients. A linear regression analysis highlighted a statistically significant change in time of MD in 36% and of LV in 34% of the eyes studied. Highly myopic patients had the highest (p<0.01) percentage of change of MD and LV (46% and 42%, respectively). Among the four subgroups, there was no difference in progression of MD decrease in time. Conclusions These results showed that after 5 years of glaucoma, the visual field was altered in most of the eyes examined (82%) and that in 67% of cases, its defect was nonhomogeneous and worsened with the increase of myopia. The regression linear analysis of visual field changes in time showed a progressive increase of MD and LV in approximately one third of all the eyes examined.

Comparison of the parameters of retinal sensitivity after vitrectomy due to rhegmatogenous retinal detachment

2021 ◽  
pp. 349-354
Author(s):  
R.R. Fayzrakhmanov ◽  
◽  
A.V. Sukhanova ◽  
O.A. Pavlovsky ◽  
E.D. Bosov ◽  
...  
Keyword(s):  
Retinal Detachment ◽  
Rhegmatogenous Retinal Detachment ◽  
Silicone Oil ◽  
Light Sensitivity ◽  
Control Group ◽  
Strong Positive Correlation ◽  
Gas Tamponade ◽  
Group I ◽  
Silicone Oil Tamponade ◽  
Group Ii

Purpose. To compare the parameters of a light sensitivity (LS) of the central zone of a retina after vitrectomy due to reghmatogenous retinal detachment (RRD) with a silicone oil tamponade (SOT) and gas tamponade (GT). Material and methods. The study included 20 eyes after pars plana vitrectomy due to macula-off rhegmatogenous retinal detachment (RRD) by 25G. All patients were divided in 2 groups depending on the choice of the tamponade. The group I (10 eyes) included cases with the silicone oil tamponade (SOT) (1300 cSt), in the group II (10 eyes) – the gas tamponade (GT) (C2F6). The control group included contralateral eyes without ophthalmic pathology. All patients underwent standard ophthalmological examination and fundus- microperimetry (FMP) on the 30th day after removal of the SOT for the group I, or on the 30th day after the C2F6 tamponade for the group II. Results. According to FMP data, the parameter of average light sensitivity (LS) in the group I was significantly reduced, both in comparison with the group II (p=0.007) and the control group (p=0.003). Differentiation by zones in the group I revealed a decrease in each analyzed parameter in comparison with the control group (p<0.05) and a decrease in the 2nd zone (p=0.031) and the 4th zone (p=0.038) in comparison with the group II. In the 1st zone of the group I the formation of a relative scotoma was revealed in 4 cases out of 10 (40%). The parameters of light sensitivity (LS) in comparison with the control in the group II were significantly reduced when analyzed in each zone (p<0.05). A strong positive correlation was found between the Best Corrected Visual Acuity (BCVA) and the average LS in the group II (r=0.87). Conclusion. There is a decrease in the functional parameters of the retina with SOT compared with GT in the form of a decrease in the LS parameter in the 10° zone according to FMP data. Key words: retinal detachment, photosensitivity, microperimetry, silicone tamponade.

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