Spatial Resolving Power and Contrast Sensitivity Are Adapted for Ambient Light Conditions in Australian Myrmecia Ants

Gastropod mollusks are convenient model organisms for studying the functioning of the visual system. The purpose of this work is to estimate the value of the optical sensitivity to white light for the camera-like eyes of gastropod mollusks and humans and analyze its effect on the spatial resolving power in two regions of the retina: in the center—for single photoreceptors of the first/second type in a mollusk and single cones in humans—and in the periphery—for single photoreceptors of the first/second type in a mollusk, as well as for single rods/cones and their groups, subject to spatial summation in humans. The methods of histology, light and transmission electron microscopy, morphometry, calculations and methods of statistical analysis are used in the work. In a mollusk, with a fixed pupil area, the value of the optical sensitivity of the eye to white light in the center of the retina for single photoreceptors of the first/second type is 0.5/0.006 μm2·sr and in the periphery of the retina, 0.9/0.009 μm2·sr. In humans, at the minimum and maximum pupil area, respectively, the value of the optical sensitivity of the eye to white light in the center of the retina (foveola) for single cones varies from 0.00053 to 0.028 μm2·sr, and in the periphery of the retina (far periphery) for single rods from 0.011 to 0.575 μm2·sr, for single cones from 0.025 to 1.319 μm2·sr, for the groups of rods from 3859 to 204,094 μm2·sr and for the groups of cones from 2.5 to 131 μm2·sr. The value of the optical sensitivity of the eyes to white light for single photoreceptors of the first/second type in both regions of the retina in a mollusk, as well as for single cones in the center and groups of rods/cones in the periphery of the retina in humans, corresponds to the ambient light conditions during periods of activity and does not affect the spatial resolving power.

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Contrast sensitivity and visual acuity under low light conditions in macular telangiectasia type 2

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2017-311785 ◽

2018 ◽

Vol 103 (3) ◽

pp. 398-403 ◽

Cited By ~ 6

Author(s):

Simone Müller ◽

Tjebo F C Heeren ◽

Roberto Bonelli ◽

Marcus Fruttiger ◽

Peter Charbel Issa ◽

...

Keyword(s):

Visual Acuity ◽

Contrast Sensitivity ◽

Neutral Density Filter ◽

Light Conditions ◽

Low Light ◽

Cross Sectional ◽

Macular Telangiectasia ◽

Low Luminance ◽

Macular Telangiectasia Type 2

Background/AimMacular pigment optical density (MPOD) is centrally depleted early on in macular telangiectasia type 2 (MacTel). Contrast sensitivity (CS) might be related to MPOD, and thus impaired in early MacTel. The effect of low luminance was assessed on both CS and best corrected visual acuity (BCVA).MethodsThis is a cross-sectional study. Pelli-Robson charts were used for CS testing at 1 m in photopic (110 lux) and mesopic (1 lux) conditions. BCVA was tested with ETDRS charts and low luminance visual acuity (LLVA) with a 2.0 log unit neutral density filter. MPOD was obtained with dual-wavelength autofluorescence.ResultsOne hundred and three eyes of 52 patients with MacTel (mean±SD age 62.9±10.2, range 35–77) were compared with 34 healthy eyes of 17 controls (mean±SD age 65.2±7.4, range 53–78). CS was significantly lower in the eyes with MacTel. This impairment was higher in low light conditions (low light contrast sensitivity (LL-CS)). Eyes at the early stages of MacTel had significantly lower LL-CS than controls, but normal (photopic) CS. The results were similar but less pronounced for BCVA/LLVA. Decrease in CS was correlated with loss of MPOD.ConclusionsLow light conditions have a detrimental effect on visual performance in MacTel. Impaired CS might correlate with MPOD depletion as a pathognomonic finding in MacTel. Functional impairment might precede structural disintegration, indicating dysfunction at the cellular level. The applied tests might be useful as additional functional assessments in clinical routine and as outcome measures in future interventional clinical trials.

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A method for reduction of eye fatigue by optimizing the ambient light conditions in radiology reading rooms

10.1117/12.655688 ◽

2006 ◽

Cited By ~ 4

Author(s):

Amarpreet S. Chawla ◽

Ehsan Samei

Keyword(s):

Ambient Light ◽

Light Conditions ◽

Eye Fatigue

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The diel pattern in harbour porpoise clicking behaviour is not a response to prey activity

Scientific Reports ◽

10.1038/s41598-020-71957-0 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Anna N. Osiecka ◽

Owen Jones ◽

Magnus Wahlberg

Keyword(s):

Behaviour Pattern ◽

Ambient Light ◽

Light Conditions ◽

Phocoena Phocoena ◽

Diel Pattern ◽

Acoustic Activity ◽

Clear Peak ◽

Similar Temperature ◽

Free Ranging ◽

Diel Behaviour

Abstract Wild harbour porpoises (Phocoena phocoena) mainly forage during the night and, because they rely on echolocation to detect their prey, this is also when they are most acoustically active. It has been hypothesised that this activity pattern is a response to the diel behaviour of their major prey species. To test this hypothesis, we monitored the acoustic activity of two captive harbour porpoises held in a net pen continuously during a full year and fed by their human keepers during daylight hours, thus removing the influence of prey activity. The porpoises were exposed to similar temperature and ambient light conditions as free-ranging animals living in the same region. Throughout the year, there was a pronounced diel pattern in acoustic activity of the porpoises, with significantly greater activity at night, and a clear peak around sunrise and sunset throughout the year. Clicking activity was not dependent on lunar illumination or water level. Because the porpoises in the pen are fed and trained during daylight hours, the results indicate that factors other than fish behaviour are strongly influencing the diel clicking behaviour pattern of the species.

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