PubMed · 439740
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M Miś. 1979. [Plate photometer].. https://pubmed.ncbi.nlm.nih.gov/439740/
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Thresholds for seeing light from a stimulus are determined by a mechanism that pairs subliminal excitations from both halves of a twin unit. Such excitations stem from a package of k > or = 1 receptor responses. A half-unit contains one red or one green cone and P rods. The receptor's "Weber machine" controls the receptor's gain. Each half of a twin unit contains a "de Vries machine," which controls the half's k number. In the dark the receptor's dark noise events reset its Weber machine and the receptor's relation to its de Vries machine. A pairing product for light perception also represents a direction event. The local time signs of the two subliminal excitations are crucial for the polarity, size, and pace of the direction event. In relation to the time when and the area in which the stimulus is presented, these signs have average latency periods that depend on intensity and average locations that depend on movement. Polarity depends on which of the two subliminal excitations happens to arrive first at the twin's pairing facility. The intra- and inter-twin pairings in a persepton for the perceptions of light, edge and movement and the probability summation of the pairing products of the mutually independent three sets of twins of the retrinet improve intensity discrimination. Cross-pairings of intra-receptor pairings in red and green cones of a trion for yellow improve visual discrimination further. Discrimination of stimuli that exploit the model's entire summation mechanisms and pairing facilities represents "what the perfect human eye sees best." For the model this threshold of modulation in quantum absorption is the ideal limit that is prescribed by statistical physics. The lateral and meta interaction in a twin unit enhance the contrast of an edge and of a temporal transient. The precision of the local time sign of a half's stimulation determines the spatiotemporal hyperfunctions for location and speed. The model's design for the perfect retinal mosaic consists of red twins situated along clockwise and counterclockwise spirals and green twins along circles that are concentric with the fovea. The model's descriptions of discrimination, adaptation, and hyperfunctions agree with experimental data.
The existence of a negative ERG component following the b-wave has been known for a long time. Recently, in unilateral macaque experimental glaucoma, a negative response in flash electroretinograms under scotopic as well as photopic conditions has been shown to be greatly reduced or absent compared to the healthy fellow eye. The aim of this pilot study was to test whether a late negative electroretinogram component is reduced also in human glaucoma patients under different stimulus conditions. Dark-adapted ganzfeld flash electroretinograms were recorded after 30 min of dark using two test conditions, obtained as optimal in pilot studies on controls. Under the scotopic condition I white Xenon-flashes of intensity 0.53 Log photopic Td s were presented on a low white background of 1.38 Log scotopic Td. Under the more photopic condition II orange flashes of intensity -0.37 Log photopic Td s were presented on a blue-adapting background of 2.5 Log scotopic Td. Nine controls and 18 patients with advanced glaucoma were analyzed. The amplitude of the negative response was not significantly reduced in glaucoma patients (condition I: -28.5+/-23.7 microV; condition II: -25.2+/-19.7 microV) compared to controls (condition I: -41.4+/-36.6 microV; condition II: -31.3+/-26.2 microV). The peak latency of the responses under condition I and II did not differ significantly between patients and controls. Thus, the late negative electroretinogram component in ganzfeld flash electroretinograms obtained under scotopic and more photopic conditions does not seem to distinguish as easy between human controls and glaucoma patients as animal experiments suggest.
BACKGROUND: Pupillary observation in the dark is always a problem in a general ophthalmological practice or an outpatient clinic without specialized equipment. We present two methods for observation of the pupils in darkness: 1) illumination of the pupils with the skiascope as a routine examination and 2) infrared observation of the pupils with a consumer digital video camera. METHODS: (1) Pupillary reactions are observed with the skiascope/retinoscope, the observation beam of the device focused to infinity and documented with a video camera. (2) Infrared observation of the pupils was performed with a digital consumer video camera, allowing observation of the pupillary reaction in darkness. After recording, video sequences of interest were transferred to a personal computer and the still images of interest extracted. RESULTS: In everyday clinical routine, observation of the pupillary reaction with the skiascope/retinoscope proves as a reliable tool with a large bandwidth of illumination and a high contrast between pupil and surrounding area. The infrared video camera allows an excellent visualization of the pupillary reflex in darkness. The transfer of the video sequences to a personal computer proved to be simple and single images can easily be chosen. CONCLUSION: Observation of the pupillary reflex with the skiascope proved a useful tool that is available in practically every ophthalmological office. Use of the infrared digital consumer video camera (available at low prices) is a highly sophisticated tool for observation and documentation of pupillary reflex in darkness.