The electroretinogram c-wave is known as a good electrophysiologic test of retinal pigment epithelial function, but its large inter and intra individual variation prevented clinical and experimental application. We recorded a stable c-wave in pigmented rabbits and the following result was obtained. Under dark adaptation state the c-wave amplitude reached equilibrium after 60 minutes, but its interindividal variation was large. The similar c-wave amplitude of right and left eye indicates that contralateral eye can be used as a control during local administration of drugs. The interindividual variation of c-wave amplitude under dim light is much smaller than under dark adaptation. This may be a good indicator in pharmacologic experiment of systemically administered drugs.
Dark Adaptation ; Rabbits* ; Retinaldehyde

We studied changes of b-wave and oscillatory potential in ERG test during dark adaptation in white rats for the purpose of using it in experimental disease-group and studying difference in man. For this we performed ERG test on normal 14 S-D (Sprague-Dawley) rats (28 eyes) during dark adaptation. The implicit time of a-wave and b-wave was shortend during dark adaptation. The b-wave and oscillatory potential rapidly increased by 20 and 30 minutes during dark adaptation: in b-wave, these values were 425.89 +/- 141.15 micro v, 473.65 +/- 130.35 micro v respectively, and in oscillatory potential, 110.56 +/- 54.82 micro v, 126.27 +/- 48.24 micro v respectively. After then, these were slightly increased. This results reveal that dark adaptatin in ERG test using rats needs sufficient time from 20 minutes to 30 minutes in similar to man. The oscillatory potential in white rat had three components with 1] light stimulus and the increase of amplitude of oscillatory potential was similar to that of b-wave during dark adaptation. But we should consider that the decreased cone function of white rat was different from that of man, that amplitude of b-wave was continously increased without the break point of early 6 minutes, and that the implicit time of b-wave was continously decreased after 10 minute during dark adaptation, when we use rat.
Animals ; Dark Adaptation* ; Rats*

Authors studied changes of ERG b-wave and oscillatory potentials(OPs) in white rats according to dark adaptation and stimulus light intensity for experimental setting. For this purpose we performed ERG tests on 10 normal white rats(20 eyes) during progressive dark adaptation. ERG b-wave and OPs values increased significantly during the first 30 minutes and then made plateau pattern. Based on this result we concluded that 30 minutes dark adaptation was sufficient for getting stable rat ERGs. After 30 minutes of dark adaptation, ERG b-wave and OPs were measured in response to 0.3J(2.25 cd.s/m2), 0.6J(6.5 cd.s/m2) , 2J(27.5 cd.s/m2) light intensity. In ERG b-wave there was no significant differene between 0.3J and 2J. In OPs between 0.3J and 0.6J, the sum of amplitude was significantly increased(p<0.01), and between 0.6J and 2J this value was insignificantly increased(p>0.05). We concluded that 0.3J(2.25 cd.s/m2) was sufficient in ERG testing. And in OPs at least 0.6J(6.5 cd.s/m2) was needed for proper stimulation.
Animals ; Dark Adaptation* ; Rats*

The dark adaptation processes of the eight normal persons were investigated after ingestion of 700mg of Korean Ginseng extract. The decrease of the thresholds was found particulary during the early phase of dark adaptation in six cases, and in the remaining two cases, these effects were doubtful. The significance of these results in terms of the neural mechanism of the dark adaptation is discussed.
Dark Adaptation* ; Eating ; Humans ; Panax*

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

PURPOSE: To analyze the effect of the daily use of brimonidine tartrate 0.15% on the dark-adapted pupil diameter in dark brown irides. METHODS: Twenty-five healthy volunteers administered brimonidine tartrate 0.15% to their right eyes once daily for 3 weeks. Infrared digital photographs of the pupil were taken before administration and 1 hour and 4 hours after administration after dark adaptation (at <0.1 lux ambient illumination for 5 minutes). The diameters of both pupils were measured on the first day, on administration days 7 and 21, and on washout day 7. RESULTS: Four hours after the first administration, pupils showed a decrease of 0.95+/-0.74 mm, 1.03+/-0.94 mm, 0.61+/-0.85 mm on the first day, administration day 7, and administration day 21, respectively (p<0.01), compared with baseline data. The anti-mydriatic effect of brimonidine was sustained for 3 weeks, but the proportions of the eyes showing a reduction in pupil diameter by 0.5 mm or more were 84%, 76%, 68%, and 52% at 4 hours on the first day, administration days 7 and 21, and washout day 7, respectively. CONCLUSIONS: The anti-mydriatic effect of the daily use of brimonidine 0.15% on dark brown irides in a scotopic condition is maintained during the instillation period but has a tendency to fade over time. This point should be considered when using this compound as a miotic agent.
Dark Adaptation ; Eye ; Lighting ; Pupil ; Quinoxalines ; Brimonidine Tartrate

PURPOSE: To investigate the incidence, associated factors, and the prognostic significance of relative afferent papillary defect (RAPD) in the eyes with less severe cataract and determine which mechanism of 'scattering' or 'dark adaptation' is more applicable, we evaluated 40 patients with asymmetric cataract (AC). METHODS: Forty patients of AC with the differences of three lines or more of visual acuity by Han's visual acuity chart underwent ophthalmic examinations including the 'swinging flashlight test' and electroretinogram before and after cataract surgery. RESULTS: There were nineteen patients who showed definite RAPD in the eyes with less severe cataract. The differences of log MAR between the two eyes were more than 1.55 or less than 0.73 in 17 patients (89.5%) with RAPD. Degree of posterior subcapsular opacity was marginally associated with RAPD in the eyes with less than 1.06 of log MAR differences. There was no association between the presence of RAPD and postoperative visual acuities. In the eyes with RAPD, b wave amplitudes tended to be smaller in the eyes with more severe cataract than those with less severe cataract before dark adaptation. However, after dark adaptation, b wave amplitudes tended to be larger in eyes with more severe cataract than those in the eyes with less severe cataract, and preoperatively than postoperatively. CONCLUSIONS: The incidence of RAPD of less severe cataract eye was significant (48%) but RAPD was not associated with visual acuity prognosis. The results of electroretinogram more favored 'scattering ' than 'dark adaptation' as the mechanism of RAPD phenomenon.
Cataract* ; Dark Adaptation ; Humans ; Incidence ; Prognosis ; Pupil Disorders* ; Visual Acuity

The author observed a case of retinitis punctata albescens who showed typical fundus findings with numerous, diffusely scattered whitish dots in the whole fundus, sparing the macular area. Under ordinary illumination, the peripheral visual field contracted concentrically from 20 to 50 degrees. There were also slight degree of reduction of central visual acuity, raised thresholds in dark adaptation and red-green color deficiencies.
Dark Adaptation ; Lighting ; Retinitis* ; Visual Acuity ; Visual Fields

Two cases of Retinitis Punctata Albescens are presented. One case occurred in two successive generations without a history of consanguity and is suspected strongly a dominant form of heredity which has been reported for tbe first time in Korea, and is probably a progressive type for its clinical signs and symptoms. The other case is stationary type of albipunctate dystrophy and is inherited in usual recessive form of heredity. In both cases, there were fundus changes characterized by a powdering with white discrete dots beneath the retinal vessels, raised threshold in dark adaptation and other typical signs.
Dark Adaptation ; Family Characteristics ; Heredity ; Korea ; Retinal Vessels ; Retinitis*

The Naka-Rushton equation of the form, R = R(max) I(n)/(I(n)+K(n)), has been used to describe the b-wave luminance-response function of the scotopic electroretinogram. Rmax is the asymptotic value of the b-wave amplitude as a function of stimulus luminance I, K is the luminance that produces a b-wave amplitude that is one-half R(max), and n is a dimensionless constant that controls the slope of the function. These three parameters are often used in research laboratories, since it can show selective changes in each parameter. The present study describes these parameters (R(max) = 354 +/- 28 uV, n = 0.80 +/- 0.06, log K = -2.26 +/- 0.15 log cd. sec/m2) and the values obtained from the derivative analysis of Naka-Rushton equation (Anastasi et al) in 20 normal pigmented rabbit eyes. However, Naka-Rushton equation accurately describes the function only at low to moderate flash luminances. At high flash luminances, a second amplitude increase appears in the function.
Animals ; *Dark Adaptation ; Electroretinography ; Light ; Rabbits ; Retina/*physiology