Night vision

About: Night vision is a research topic. Over the lifetime, 6004 publications have been published within this topic receiving 67372 citations.

Vehicle mounted night vision imaging system and method

Abstract: A vehicle mounted imaging system and method, enabling selective imaging of objects in a low-visibility environment. The system includes a light source (30) providing non-visible light pulses and a camera (40) having an image intensifier enabled to gate selected received images. The light source may be a laser generator, which may be enabled to generate a pulse width related to the depth of a field to be imaged. The gated image intensifier may determine gating time spans according to the depth of a field to be imaged.

Bovine and porcine transscleral solute transport: influence of lipophilicity and the Choroid-Bruch's layer.

Abstract: Advances in cellular and molecular biology have shown that an elevation in vascular endothelial growth factor (VEGF) is a key contributor to vision-threatening diseases such as diabetic retinopathy and age-related macular degeneration.1 To inhibit the expression and/or activity of VEGF, several pharmacological agents2 including corticosteroids,3 nonsteroidal anti-inflammatory drugs,4 anti-VEGF antibodies, VEGF soluble receptors, and VEGF aptamers5 are being developed. It is noteworthy that a monoclonal VEGF antibody (Avastin; Genentech, South San Francisco, CA) and a VEGF aptamer (Macugen; Eye Tech, New York, NY) have been recently approved to inhibit angiogenesis associated with colorectal cancer and for the treatment of age-related macular degeneration, respectively. However, the bottleneck in the treatment of retinal angiogenic disorders as well as other diseases of the posterior segment is the delivery of adequate levels of drugs to the retina for prolonged periods. The topical ocular route is inefficient in delivering adequate drug levels to the retina, and systemic modes of administration require high doses for delivering therapeutic concentrations, leading to systemic toxicity.6 Although intravitreal administration delivers adequate drug levels to the retina, repeated intravitreal injections as well as the surgical placement of intravitreal implants are associated with complications such as retinal detachment, endophthalmitis, and cataracts.7 Thus, there is a need for the development of alternative approaches for effective retinal drug delivery. Transscleral routes are now emerging as viable alternatives for retinal drug delivery. Studies over the past four decades have shown that the sclera is more permeable than the cornea8 and that various approaches, including particulate systems,3,5 episcleral implants,9 fibrin sealants,10 and collagen matrices,11 can be used for delivering effective drug levels transsclerally in a sustained manner to the retina. Despite this promise, relatively little is known about the drug permeability properties of the sclera and the underlying layers. In the transscleral route of drug entry, drug placed next to the sclera is expected to reach the retina primarily via transport across the sclera and underlying tissues including the choroid–Bruch’s layer and RPE. In all the earlier reports on transscleral drug transport, the solute permeability across the sclera has been reported. Also, the permeability-limiting nature of the RPE is well known.12–14 It is likely that the choroid layer containing Bruch’s membrane, located between the sclera and the RPE,15 can also affect the permeability of the drugs. There are no earlier reports on the influence of this layer on transscleral drug diffusion, although it is known that Bruch’s membrane thickens and the choroidal layer thins out with aging in the human eye.16 Our previous results demonstrate that celecoxib (a selective Cox-2 inhibitor) and budesonide (a corticosteroid) can inhibit VEGF expression in cell cultures.3,4,17 We have also demonstrated that transscleral sustained retinal delivery of celecoxib inhibits VEGF expression and vascular leakage in a diabetic rat model.17 Because of the promise of budesonide and celecoxib as therapeutic agents for inhibiting VEGF expression and other inflammatory mediators in disorders of the posterior segment, we chose these lipophilic, neutral molecules for use the present study. Further, we assessed commonly used marker solutes, including mannitol (hydrophilic, neutral), sodium fluorescein (hydrophilic, anionic), and rhodamine 6G (R6G; lipophilic, cationic). For investigating the effects of the choroid–Bruch’s layer on transscleral transport, we used bovine and porcine eyes in side-by-side diffusion chambers. The bovine eyes were used because freshly excised bovine eyes are readily available, and transport studies with the bovine eyes have been reported.18 The porcine eye, although limited in supply, resembles the human eye better in anatomic characteristics.19 The bovine eye, unlike the porcine eye, has a modified choroid called the choroid-tapetum, which enables night vision. The choroid layer in this report refers to the choroid–Bruch’s membrane combination with (bovine) or without (porcine) the tapetum.

Helmet mounted display system

Abstract: An apparatus for combining a display image with the field of view of a viewer. Light from either a night vision system (14) of a CRT (12) is directed into an eyepiece assembly (18). The eyepiece magnifies and focuses the image into a combiner (30). The combiner (30) consists of an elongated optical element with two parallel sides (36) and (38) and two concave reflective surfaces (32) and (34) at each end. Light entering the combiner (30) is reflected off the first reflective surface (32) and then is reflected back and forth between the sides of the combiner (36) and (38) and then onto the second reflective surface (32). Light reflected off the second reflective surface (32) is combined with light entering from the field of view of the viewer through a prism element (44). The result is that the display image is superimposed in the field of view of the viewer. The system is light in weight, does not protrude significantly from the user's head, introduces minimal distortion and offers a wide field view.

A reanalysis of California driver vision data: general findings

Abstract: Data on over 14000 drivers from the 1967 California driver vision study have been reanalysed with a view to establishing their implications for driver vision standards. For the main analysis the sample was divided into four age groupings: under 25, 25-39, 40-54, and over 54. The most consistent result throughout the study has been the failure to find a direct relationship between poor visual performance and high accident rates for young and middle-aged drivers. For the over 54 age group, dynamic and static visual acuity showed the most consistent relationships with accident rates but for an individual driver their accident prediction value remained very low. A more detailed age analysis failed to define more precisely the age at which these relationships develop. No evidence was found to support the use of total visual field as a driver screening test. The results for two tests of night vision were regarded as inconclusive for the over 54 age group. For the same nominal standard of binocular static visual acuity, the ortho-rater screener was found to fail markedly fewer drivers than the Snellen Wall Chart. The implications of varying the cut-off scores for each test were investigated, and the suggestion is made that perceptual rather than sensory tests with greater accident predictive power would be needed before acceptable alternative screening methods could be specified for driver licensing purposes. /Author/

Nanodomain Control of Exocytosis Is Responsible for the Signaling Capability of a Retinal Ribbon Synapse

Abstract: Primary sensory circuits encode both weak and intense stimuli reliably, requiring that their synapses signal over a wide dynamic range. In the retinal circuitry subserving night vision, processes intrinsic to the rod bipolar (RB) cell presynaptic active zone (AZ) permit the RB synapse to encode signals generated by the absorption of single photons as well as by more intense stimuli. In a study using an in vitro slice preparation of the mouse retina, we provide evidence that the location of Ca channels with low open probability within nanometers of the release sites is a critical determinant of the physiological behavior of the RB synapse. This gives rise to apparent one-to-one coupling between Ca channel opening and vesicle release, allowing presynaptic potential to be encoded linearly over a wide dynamic range. Further, it permits a transition from univesicular to multivesicular release (MVR) when two Ca channels/AZ open at potentials above the threshold for exocytosis. MVR permits small presynaptic voltage changes to elicit postsynaptic responses larger than quantal synaptic noise.