Night vision

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

Effect of the Synthetic Retinoid Fenretinide on Dark Adaptation and the Ocular Surface

Abstract: BACKGROUND: Fenretinide, a synthetic derivative of retinoic acid, is under study in clinical trials for the prevention of breast, skin basal cell, bladder, and oral cancer in patients at risk. Although fenretinide is well tolerated even after prolonged use, it does lower plasma retinol levels and thus may affect night vision. PURPOSE: The purpose of this study was to measure changes in dark adaptation resulting from fenretinide administration, to compare the measured results with the patient's subjective perception, to define the association with plasma retinol levels, to assess the reversibility of alterations in night vision, and to assess the effects of fenretinide on the surface of the eye. METHODS: The study involved 65 women who had been operated on for stage I breast cancer. Of the study group, 34 received 200 mg daily of fenretinide for a median of 32 months, while 31 control subjects did not. Dark adaptation was studied with the Goldmann-Weekers adaptometer and with a subjective questionnaire. Plasma retinol levels were measured at each test of dark adaptation. Effects of fenretinide on the ocular surface were evaluated through conjunctival impression cytology. RESULTS: Of the patients on fenretinide, eight (23.5%) showed mild and nine (26.5%) showed moderate alterations of measured dark adaptability, compared with just two controls (6.5%) with mild alterations (cumulative odds ratio = 15.4; P = .0008). A significant inverse correlation exists between the final sensitivity threshold of dark-adaptometry and plasma retinol levels, with mild alterations arising below 16 micrograms/dL and moderate alterations below 10 micrograms/dL. Abnormal rod function improved significantly after 7 days and normalized 1 month after use of fenretinide was stopped or vitamin A supplementation was begun, while the conventional 3-day drug suspension, or drug half dose, did not allow sufficient recovery. Alterations of conjunctival cytology were slightly higher in patients receiving fenretinide, but no clinical disorders of the ocular surface were observed. CONCLUSIONS: The women treated with 200 mg fenretinide daily showed a relatively high incidence of mild-to-moderate alterations of dark-adaptometry as measured with the Goldmann-Weekers adaptometer. However, the real-life implication of the measurements is an open question, for the questionnaire shows that 50% of the patients with altered dark adaptometry were asymptomatic.

Disturbances in night vision after excimer laser photorefractive keratectomy

Abstract: Eighty-four patients with up to -6.00 dioptres of myopia underwent photorefractive keratectomy (PRK), using 5.00 mm ablation zones. Three months post-operatively 38 (45%) complained of disturbances in night vision, compared with 21 (25%) pre-operatively. In the majority, these disturbances were regarded as negligible. However, 9 (11%) reported significant problems, defined as an inability to drive safely at night with the treated eye. At 12 months, 32 patients (38%) complained of impaired night vision, 4 (5%) of whom had significant problems. A series of measurements were performed to investigate the origins of these disturbances, especially in patients reporting significant problems. Visual impairment from forward scattered light was investigated using a computerised technique. Back scattered light was measured with a charge coupled device-camera system and a computer program was used to assess the degree of halation around a bright light source on a high-resolution monitor. Pupillary diameters were measured by infrared television pupillometry. At 6 months, those reporting a starburst effect around lights at night had small hyperopic shifts, minimal halos and high forward and back light scatter measurements. Patients who reported halo phenomena had large hyperopic shifts, little light scatter and large pupillary diameters. Of the 4 patients who reported significant disturbances at 12 months, all had persistent halo problems. Those with starburst effects in the early post-operative period noticed an improvement with time as their corneal haze gradually improved. Perturbations of night vision after PRK manifest as starbursts and halos around lights.(ABSTRACT TRUNCATED AT 250 WORDS)

Conditions and significance of night feeding in shorebirds and other water birds in a tropical lagoon

Abstract: -On a small bay of the Chacopata lagoon complex in northeastern Venezuela, we analyzed the temporal feeding activity patterns of shorebirds and other water birds, and we determined the factors or conditions related to these patterns. During daytime and nighttime observations, we measured the abundance of each species as well as environmental factors (time, wind velocity, cloudiness, tide level, presence of moonlight and bioluminescence). A night vision module (light intensifier) was used during nighttime observations. Samples x species matrices were summarized by reciprocal averaging (RA) analysis, and the information was related to environmental factors. Feeding activity patterns were related most significantly to time of day, i.e. daytime and nighttime. Some species like "egrets," the Whimbrel (Numenius phaeopus), and the Black-bellied Plover (Pluvialis squatarola) fed principally during daylight, but most other species (including a majority of shorebird species) fed more regularly and in higher numbers at night. Lesser and Greater yellowlegs (Tringa flavipes and T. melanoleuca, respectively) and Willets (Catoptrophorus semipalmatus) foraged with comparable frequency during the day and the night. Daytime and nighttime data were analyzed separately, and tide level best explained both the variations of nocturnal and diurnal abundance of foraging birds. Nocturnal feeding may be a natural habit in response to regularly limited feeding space and time mainly induced by tide. Received 4 January 1988, accepted 24

Homography normalization for robust gaze estimation in uncalibrated setups

Abstract: Homography normalization is presented as a novel gaze estimation method for uncalibrated setups. The method applies when head movements are present but without any requirements to camera calibration or geometric calibration. The method is geometrically and empirically demonstrated to be robust to head pose changes and despite being less constrained than cross-ratio methods, it consistently performs favorably by several degrees on both simulated data and data from physical setups. The physical setups include the use of off-the-shelf web cameras with infrared light (night vision) and standard cameras with and without infrared light. The benefits of homography normalization and uncalibrated setups in general are also demonstrated through obtaining gaze estimates (in the visible spectrum) using only the screen reflections on the cornea.