Authors studied characteristics of ERG b-wave and oscillatory potential, which can be applied to ERG protocol for clinical purposes. Following conclusions were obtained from the ERG test performed on 20 normal men(40 eyes) during dark adaptation and light adaptation time, under the conditions where other factors were equal. 1. In the scotopic ERG test, 88%(364/414uv) of maximum b-wave amplitude in 30 minutes were obtained in first 1 minute of dark adaptation. By using this shortening scotopic protocol for the acquired retinal disease, sufficient result can be expected without the over 20 minutes dark adaptation. 2. In the photopic ERG test, if over 30 minutes dark adaptation time were given, it would take at least 15 minutes to reach the regular initial photopic value. Therefore, it is recommended that photopic ERG test be done before the scotopic ERG test. 3. In the oscillatory potential test, light adaptation time has little effect on summed photopic oscillatory potential amplitudes and implicit time. Summed scoto pic oscillatory potential amplitude reaches the highest 1 minute after the dark adaptation. Therefore, it is recommended that to obtain higher amplitude and more sensitive test result, oscillatory potential test be done 1 minute after the dark adaptation.
Adaptation, Ocular* ; Dark Adaptation* ; Retinal Diseases

The influence of sodium iodate and sodium iodoacetate on the standing potential of rabbits' eyes were investigated with the use of electro-oculography. The electro-oculogram was recorded 1, 3, 5, 24 hours and 5 days after the administrations of the drugs. In order to measure the potential changes induced by illumination, animals were maintained in the dark for 30 minutes and thereafter in the light(illumination 500 lux) for another 30 minutes, during which records were taken every two minutes. In normal eyes, the potential decreased during dark adaptation, and its maximum decrease(about 35%) was attained about 24 minutes. When the eye was exposed to illumination, potential increased, the maximum increase (30%) occurred at 18 minutes. Light peak-dark trough ratio was over 1.4 in all eyes and 1.6 on the average. When the dark-adapted retina was illuminated, EOG amplitude showed a rapid, transient rise followed by a slight fall, with the subsequent light rise. After administration of sodium iodate(20mg./kg.) fall of potential during dark adaptation and rise during light adaptation decreased in its magnitude, accompanied by shortening of dark trough time and light peak time. The light peak-dark trough ratio showed moderate diminution (between 1.2 and 1.3). At the beginning of light adaptation, potential fell transiently followed by continuous slow rise. In eyes treated by sodium iodoacetate (20mg./kg.) potential alterations due to illumination diminished as in eyes treated with sodium iodate. The base-value remained almost unchanged. From these observation, it became clear that the standing potential originated mainly from pigment epithelium, and that the presence of intact visual cells was responsible for alterations induced by level of illumination.
Adaptation, Ocular ; Animals ; Dark Adaptation ; Electrooculography ; Epithelium ; Iodoacetic Acid ; Lighting ; Rabbits* ; Retina ; Sodium

PURPOSE: To report a case of unilateral mydriasis after accidental exposure to an Angel's trumpet leaf. CASE SUMMARY: A 53-year-old woman visited the Eye Department complaining of blurred vision and difficulty in light adaptation in the left eye of 1-week duration. The best corrected visual acuity was 20/20 in both eyes and other ophthalmological findings were considered normal except for dilation of the left pupil and a decrease in light reflex. The patient was initially unaware of any cause of her eye problems, but when asked specifically, the patient remembered an Angel's trumpet leaf brushing against her left eye when she carried the plants. There were no other previous medical or drug histories, thus the Angel's trumpet was considered as the cause for the unilateral mydriasis. The patient's progress was followed for a week, her symptoms improved and the pupil size and reflex returned to normal. CONCLUSIONS: The cultivation of Angel's trumpet has become increasingly popular in Korea in recent years. The present case emphasizes the importance of an accurate and detailed history regarding specific contact history with plants like Angel's trumpet in otherwise healthy patients affected by unilateral mydriasis.
Adaptation, Ocular ; Eye ; Female ; Humans ; Korea ; Light ; Middle Aged ; Mydriasis ; Pupil ; Reflex ; Vision, Ocular ; Visual Acuity

OBJECTIVETo characterize dark-adapted and light-adapted oscillatory potentials (OPs) in human electroretinogram (EGR) elicited by flashing light stimulation of the same intensity.

METHODSDark- and light-adapted ERGs of normal eyes were studied. The frequency spectra of the extracted dark-adapted OPs and light-adapted OPs were analyzed by a fast Fourier transform. The peak frequency, latency and total power of the OPs were determined.

RESULTSThe averaged peak frequency, latency, and power of the dark-adapted OPs was 125.3∓9.93 Hz, 41.7∓3.56 ms, and 9.25∓5.55 (V·s)(2), as compared with 79.5∓6.79 Hz, 50.8∓5.36 ms, and 3.56∓2.18 (V·s)(2) for light-adapted Ops, respectively, showing significant differences in the parameters between dark- and light-adapted Ops (P<0.001).

CONCLUSIONSCompared with dark-adapted OPs, light-adapted Ops is characterized by a lower peak frequency and a lower power with a prolonged latency.

Adaptation, Ocular ; physiology ; Adult ; Dark Adaptation ; physiology ; Electroretinography ; methods ; Female ; Humans ; Male ; Oscillometry ; Retina ; physiology ; Young Adult

Light adaptation enables the vertebrate visual system to operate over a wide range of ambient illumination. Regulation of phototransduction in photoreceptors is considered a major mechanism underlying light adaptation. However, various types of neurons and glial cells exist in the retina, and whether and how all retinal cells interact to adapt to light/dark conditions at the cellular and molecular levels requires systematic investigation. Therefore, we utilized single-cell RNA sequencing to dissect retinal cell-type-specific transcriptomes during light/dark adaptation in mice. The results demonstrated that, in addition to photoreceptors, other retinal cell types also showed dynamic molecular changes and specifically enriched signaling pathways under light/dark adaptation. Importantly, Müller glial cells (MGs) were identified as hub cells for intercellular interactions, displaying complex cell‒cell communication with other retinal cells. Furthermore, light increased the transcription of the deiodinase Dio2 in MGs, which converted thyroxine (T4) to active triiodothyronine (T3). Subsequently, light increased T3 levels and regulated mitochondrial respiration in retinal cells in response to light conditions. As cones specifically express the thyroid hormone receptor Thrb, they responded to the increase in T3 by adjusting light responsiveness. Loss of the expression of Dio2 specifically in MGs decreased the light responsive ability of cones. These results suggest that retinal cells display global transcriptional changes under light/dark adaptation and that MGs coordinate intercellular communication during light/dark adaptation via thyroid hormone signaling.
Animals ; Mice ; Dark Adaptation ; Light ; Retina ; Retinal Cone Photoreceptor Cells/metabolism* ; Adaptation, Ocular ; Neuroglia/physiology* ; Cell Communication ; Thyroid Hormones

The electrophysiological effects of N-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine(NMPTP), a chemical inducer of Parkinsonism in man and monkey, on the pigmented rabbit retina were determined under acute condition. The amplitude of the b-wave of the rabbit electroretinogram was affected, but both the implicit time and half-amplitude duration of it were not. The amplitude of the photopic b-wave was increased by 72.9 +/- 32.1% 5 hours after NMPTP administration(P[t]<0.05), Whereas the scotopic b-wave was decreased by 31.2 +/- 6.4% 4 hours after injection(P[t]<0.05). The above results suggest or support that: (1) the dopaminergic amacrine cells are related to the modulation of the b-wave of the rabbit electroretinogram. (2) during light adaptation, the dopaminergic amacrine cells uncouple the rod and cone systems in the inner plexiform layer and are involved in functions of the rod system. (3) the hypothesis that the function of tyrosine hydroxylase may be affected by NMPTP.
Adaptation, Ocular ; Amacrine Cells ; Haplorhini ; Parkinsonian Disorders ; Rabbits* ; Retina ; Tyrosine 3-Monooxygenase

PURPOSE: The purpose of this study was to clarify the effects of zinc treatment and hypothermia on visual adaptation and visual sensitivity in bullfrogs (Rana catesbeiana), which are poikilothermal animals capable of adjusting quickly to environmental temperature changes. METHODS: The effects of both zinc treatment and hypothermia on visual sensitivity were studied by using electroretinogram (ERG) recording and absorption spectra scanning before and after zinc and TSQ (N-[6-methoxy-8-quinolyl]-p-toluene sulfonamide) treatment, with or without temperature changes. RESULTS: In spite of malnutrition due to hibernation, the optimal zinc concentration effect was obtained at 10-4 M (10-2 M 200 microliter ZnCl2 in 20 microliter Ringer's solution) according to ERG recording. After zinc treatment and hypothermia induction, increments of all ERG components and thresholds were taken by ERG recording. These results showed that both zinc treatment and hypothermia may increase visual sensitivity during visual adaptation. In spectral scans, the absorbance increment due to zinc treatment and hypothermia was shown over the whole spectral range (400~750 nm), and it was especially prominent at alpha-peak (about 500 nm). In addition, there was a decrease in absorption differences between dark adaptation and light adaptation after zinc treatment. Furthermore, according to the visual sensitivity decrement using TSQ as a zinc specific chelator, this visual sensitivity increase was shown to be caused by zinc. CONCLUSIONS: As the results suggest, both zinc treatment and hypothermic effects may improve visual sensitivity by promoting rhodopsin regeneration and inhibiting rhodopsin bleaching induced by light illumination. Zinc may activate the enzyme activity of retinol dehydrogenase and phosphodiesterase, while hypothermic effects may improve precursor transport, which is required for rhodopsin regeneration, by tightening membrane adhesion between retinas and retinal pigment epithelia. In addition, we believe that zinc treatment and hypothermic effects may work synergistically to accelerate visual sensitivity during visual adaptation.
Absorption ; Adaptation, Ocular ; Animals ; Dark Adaptation* ; Hibernation ; Hypothermia ; Lighting ; Malnutrition ; Membranes ; Oxidoreductases ; Rana catesbeiana ; Regeneration ; Retina* ; Retinaldehyde ; Rhodopsin ; Vertebrates* ; Vitamin A ; Zinc*