Comparing Short-Duration Electro-Oculograms with and without Mydriasis in Healthy Subjects.

BACKGROUND: In order to obtain artifact-free electro-oculogram recordings the subject's cooperation is necessary. The aim of our study is to evaluate the recording characteristics of short-duration EOG and to compare the effect of mydriasis on electro-oculogram recordings in a cohort of controls. PATIENTS AND METHODS: Electro-oculogram recordings were performed on a light-emitting diode stimulus screen using a RETI-port gamma plus2 system (RETIscan™, Roland Consult). Fast oscillations were set at 1.5 sec (6 cycles; total duration 75 sec).The dark phase included: pre-adaptation (6 min), alternate fixation (4 min), fixation-rest (20 sec), 100 sweeps. The light phase included: light adaptation (4 min), alternate fixation (10 min), fixation-rest (20 sec), 250 sweeps. The amplifier band pass was filtered at 0.1÷50 Hz. The background illumination in mydriasis was 100 cd/m2 and in miosis--450 cd/m2. RESULTS: A total of 55 controls participated and were divided into three age groups [number; mean (years, y); ±SD]: group 1: 18-20 years (19; 19.49 years; ±0.89); group 2: 20-40 years (18; 27.91 years; ±5.39) and group 3: 40-60 years (18; 48.66 years; ±4.00). The Arden ratio, dark-trough and light-peak did not differ between recordings with or without mydriasis (p=0.914; p=0.880; p=0.680, linear mixed-effects model). The age did not influence the Arden ratio, dark-trough, light-peak (p=0.206; p=0.112; p=0.155). Arden ratio, dark-trough, light-peak were comparable between tested eyes (p=0.934; p=0.193; p=0.270). CONCLUSIONS: Short-duration electro-oculograms allow successful recording, furthermore, the application of mydriasis does not influence the quality of the recording.

Effects of amphetamine, diazepam and caffeine on polysomnography (EEG, EMG, EOG)-derived variables measured using telemetry in Cynomolgus monkeys.

INTRODUCTION: Medication-induced sleep disturbances are a major concern in drug development as a multitude of prescription drugs alter sleep patterns, often negatively. Polysomnography is used in clinical diagnostics but is also applicable to animal models. Rodent sleep architecture (nocturnal) differs from larger diurnal mammals, including humans, increasing the translational potential of non-rodent species to the clinic. This study aimed to characterize the response to pharmacological agents known to affect sleep structure and EEG activity in a non-human primate (Macaca fascicularis) using telemetry-based polysomnography. METHODS: Animals were instrumented with telemetry transmitters for continuous electroencephalogram (EEG), electro-oculogram (EOG) and electromyogram (EMG) monitoring combined with video. EEG, EMG and EOG were monitored for 12 to 24h to establish baseline values, followed by administration of pharmacological agents (saline, d-amphetamine, diazepam or caffeine). RESULTS: Amphetamine (0.3 and 1mg/kg, by oral administration (PO)) significantly reduced total sleep time, including the duration of both non-rapid eye movement [NREM] sleep and REM sleep. It also decreased EEG activity in low frequencies (i.e., 4-6Hz) during wakefulness. Diazepam (2mg/kg, PO) did not significantly alter sleep duration, but importantly reduced EEG activity in low frequencies (approximately 2-12Hz) during wakefulness, NREM and REM sleep. Finally, caffeine (10 and 30mg/kg, PO) decreased both NREM and REM sleep duration. In addition, spectral analysis revealed important decreases in low frequency activity (i.e., 1-8Hz) during wakefulness with a parallel increase in high frequency activity (i.e., 20-50Hz) during NREM sleep. DISCUSSION: As these observations are similar to previously reported pharmacological effects in humans, results support that EEG, EOG and EMG monitoring by telemetry in Cynomolgus monkeys represents a useful non-clinical model to investigate and quantify drug-induced sleep disturbances.

Nifedipine alters the light-rise of the electro-oculogram in man.

BACKGROUND: To determine if the L-type calcium channel participates in the generation of the light-rise of the electro-oculogram (EOG) in man. The aim was to use nifedipine, a specific, L-type calcium channel inhibitor and determine the effects on the light-rise of the EOG in healthy participants. METHODS: The EOG was recorded in 14 participants before and after a 10 mg oral dose of fast-acting nifedipine. The Arden index, time to peak of the EOGs and pulse were recorded before and after ingestion of nifedipine. The test-retest variability of the EOG's light-rise in the absence of nifedipine was performed on 11 of the participants. The mean ± SEM oral dose was 147 ± 9 µg/kg. Scotopic electroretinograms (ERGs) were recorded at four intensities (0.0067, 0.0849, 0.364 and 1.140 cd.s.m⁻²) in six participants before and after a 10 mg oral dose of nifedipine. RESULTS: The light-rise of the EOG was significantly reduced in five participants by -22.80 ± 5.6% (p = 0.021), whilst in four of the participants the light-rise increased by +15.7 ± 1.9% (p = 0.033). The results of the test-retest EOGs showed a range of -9.1 to +9.8% Arden index in the absence of nifedipine. Thus, the responses of five participants were not included in the analysis, as the change in the EOG with nifedipine was within this range. The differences in the time to peak of the light-rise were not significantly different in those that showed an increase (p = 0.33) or a decrease (p = 0.87) in the EOG after nifedipine. Pulse rate was not significantly different after nifedipine in the group that showed an increased light-rise (p = 0.77) or in those whose light-rise fell after nifedipine (p = 0.33). No significant effect was observed on the a- and b-wave amplitudes and implicit times for the scotopic components of the scotopic ERG. CONCLUSIONS: The L-type calcium channel contributes to the light-rise of the EOG in man.

Theophylline induces changes in the electro-olfactogram of the mouse.

Options for the treatment of hyposmia are limited;available therapies do not provide a long-lasting effect.A recent study suggests that an unspecific phosphodiesterase inhibitor (PDE-I) increases olfactory sensitivity due to interaction with the signal transduction in the olfactory epithelium. The aim of the present study was to investigate whether theophylline, an unspecific PDE-I, evokes changes in the electro-olfactogram (EOG) which would support the hypothesis of a drug-related impact on signal transduction.In addition, the uptake of topically administered theophylline in the olfactory epithelium should be investigated. EOG was obtained in 29 samples of supravital mouse olfactory epithelia. Olfactory stimulation (phenylethyl alcohol, PEA and hydrogen sulfide, H2S) was performed using an air dilution olfactometer. Theophylline concentration in the olfactory epithelium of five samples was measured by means of high pressure liquid chromatography. Administration of theophylline resulted in a tendency towards smaller EOG amplitudes (p = 0.055), being reduced by 13 and 25% in response to stimulation with PEA or H2S,respectively. In comparison to the application of Ringer's solution, theophylline resulted in a significant (p = 0.031)decrease of the EOG amplitude. Latency was not significantly(p = 0.10) influenced by drug administration. The theophylline concentration in the olfactory epithelium ranged from 0.21 to 1.53 microg/mg. Theophylline seems to be taken up into the olfactory epithelium of supravital mice and to interact with the olfactory signal transduction.

[Sleep spindles in post traumatic stress disorder: significant importance of selective serotonin reuptake inhibitors].

BACKGROUND: Sleep spindles (SS) are conducted by the thalamus during sleep and have an inhibitory effect on information rising through the thalamus to the cortex, probably representing the mechanism called Arousal Inhibitory Mechanism. They appear during sleep stage 2 but also in stages 3, 4 and REM (Rapid Eye Movements). Patients with post traumatic stress disorder (PTSD) complain of insomnia, although objective studies have revealed that their sleep is deeper and their awakening threshold is higher. The relationships between PTSD or selective serotonin reuptake inhibitors (SSRI) to SS density are not described in the literature. GOALS: This study aimed to examine the hypothesis that the higher awakening threshold reflects an active defense process which would be manifested in increased sleep spindles in patients with PTSD. METHODS: A total of 15 PTSD patients (36.3 +/- 11.4 years) comprised the research group and 15 healthy students (27.3 +/- 2.18 years) comprised the control group. Participants underwent a polysomnography study in the sleep laboratory at 'Rambam' Hospital, Haifa, Israel. RESULTS: There was no difference in the sleep spindles density per minute during stage 2 between the research group (2.54 +/- 1.14) and the control group (2.86 +/- 1.3). However, sleep spindles density was highly affected by selective serotonin reuptake inhibitors, such that PTSD patients treated with SSRI's had significantly higher spindles density than the remaining PTSD patients (3.25 +/- 1.1 vs 1.72 +/- 0.46, p=0.0044). Stage 2 was shorter in the research group (47% +/- 8.75%) compared to the control group (58% +/- 8.5%, p=0.0014), while stages 3, 4 were longer (32% +/- 8% vs 18% +/- 6.26%, p<0.001). CONCLUSIONS: Sleep spindle density was generally not increased in patients with PTSD, thus other mechanisms are probably responsible for their stabilization of sleep. SSRI's were found to have an important role in spindles density, which supports a serotonergic mechanism in the stabilization of sleep, although it requires further research.

Clinical electrophysiology in quinine induced retinal toxicity.

A 43-year-old woman was evaluated 9 months after a deliberate overdose of quinine. The patient's visual acuity was 20/20, but she had lost all peripheral vision beyond approximately 30 degrees eccentricity. The multifocal electroretinography (mfERG) and optical coherence tomography are described for the first time in this condition. The mfERG shows electronegative waveforms beyond 6 degrees . The mfERG response density is reduced at all retinal locations. Optical coherence tomography shows thinning of the middle and inner retina by 25 to 35%, with preservation of the photoreceptor layer. Recent regulatory restrictions in off-label uses of quinine products should help to reduce the incidence of adverse toxic reactions.

Reduced attentional engagement contributes to deficits in prefrontal inhibitory control in schizophrenia.

BACKGROUND: Problems with the voluntary control of behavior, such as those leading to increased antisaccade errors, are accepted as evidence of prefrontal dysfunction in schizophrenia. We previously reported that speeded prosaccade responses, i.e., shorter response latencies for automatic shifts of attention to visual targets, were associated with higher antisaccade error rates in schizophrenia. This suggests that dysregulation of automatic attentional processes may contribute to disturbances in prefrontally mediated control of voluntary behavior. METHODS: Twenty-four antipsychotic-naïve schizophrenia patients and 30 healthy individuals completed three tasks: a no-gap prosaccade task in which subjects shifted gaze toward a peripheral target that appeared coincident with the disappearance of a central fixation target and separate prosaccade and antisaccade tasks in which a temporal gap or overlap of the central target offset and peripheral target onset occurred. Sixteen patients were retested after 6 weeks of antipsychotic treatment. RESULTS: Patients' prosaccade latencies in the no-gap task were speeded compared with healthy individuals. While patients were not atypical in the degree to which response latencies were speeded or slowed by the gap and overlap manipulations, those patients with diminished attentional engagement on the prosaccade task (i.e., reduced overlap effect) had significantly elevated antisaccade error rates. This effect persisted in patients evaluated after antipsychotic treatment. CONCLUSIONS: This study provides evidence that a reduced ability to engage attention may render patients more distracted by sensory inputs, thereby further compromising impaired executive control during antisaccade tasks. Thus, alterations in attentional and executive control functions can synergistically disrupt voluntary behavioral responses in schizophrenia.

Safety monitoring in bevacizumab (Avastin) treatment: retinal function assessed by psychophysical (visual fields, colour vision) and electrophysiological (ERG/EOG) tests in two subgroups of patients.

BACKGROUND: Bevacizumab (Avastin) has been used as off-label treatment for the specific inhibition of the vascular endothelial growth factor (VEGF). Although only intravenous administration of the drug is approved in combination therapy of colorectal carcinoma, promising short-term results have been reported about its intravitreal administration. However, VEGF is also known to exhibit neurotrophic capabilities. Therefore, blockage of all VEGF isoforms by bevacizumab could induce toxic effects. Missing randomized controlled studies and unclear long-term risks require further evaluation. METHODS: Intensified monitoring of bevacizumab treatment was performed in consecutive patients. In ten patients, the functional field score was calculated after obtaining Goldmann visual fields at baseline and 1 year after injection. The other subgroup was examined by means of EOG, ERG and colour testing at baseline and 4 months following treatment. Naka-Rushton plots were calculated to enable statements about retinal function. Lanthony desaturated D15 test was used for repeated colour testing. RESULTS: Baseline parameters already disclosed predominant cone dysfunction. Drug-related effects caused a significant improvement of visual acuity. There was no sign of clinically relevant retinal toxicity following the bevacizumab injection. No progression of visual field defects was seen within the follow-up of 1 year. Performance in EOG testing was affected by restricted fixation stability, but no parameter indicated deterioration within the 4-month-period. CONCLUSIONS: Short-term results underline that intraocular bevacizumab injection promises to be not only a cost-effective, but safe treatment option. Assessed functional parameters as error scores (e.g., Lanthony) corresponded to the impaired retinal function which was presumed to be disease-related. Further long-term results have to confirm the good tolerability in repeated treatment.

Safety profile of a taurine containing irrigation solution (AcriProTect) in pars plana vitrectomy.

PURPOSE: To evaluate the clinical safety of a taurine containing irrigation solution (AcriProTect) before its routine application in pars plana vitrectomy (PPV). METHODS: Twenty-five patients who underwent PPV were included in this prospective interventional clinical study. Standard irrigation solution containing the addendum 3 mmol/L taurine was used during PPV. Postoperative follow-up visits included a standard eye examination, corneal thickness measurements, endothelial cell counts, determination of the foveal thickness by optical coherence tomography (OCT), and an electrophysiologic examination. For statistical analysis Wilcoxon test was used. RESULTS: Significant improvement of visual acuity (VA) was observed at the 3- and 6-month controls (P = 0.024; P = 0.002 for 3 and 6 months, respectively). Endothelial cell counts and corneal thickness at 3 and 6 months were not significantly different from preoperative values (P = 0.204; P = 0.126 for endothelial cell count and P = 0.475; P = 0.095 for corneal thickness at 3 and 6 months, respectively). Both scotopic and photopic Ganzfeld electroretinography and electro-oculography did not show significant changes during the follow-up. No increase in complication rate was detected. CONCLUSIONS: The investigation demonstrates a good biocompatibility of taurine-containing irrigation solution developed for vitrectomy in humans concomitant with habitually observed good functional outcome.

Is it possible to predict the long-term response to venlafaxine with the use of biological markers and psychophysiological methods?

INTRODUCTION: The present study investigated whether it is possible to predict the medium term response to venlafaxine using biological markers and psychophysiological methods. MATERIAL: Fourteen (14) patients aged 21-60 years suffering from Major Depression according to DSM-IV were included in the study. METHODS: The SCAN v 2.0 and the IPDE were used to assist clinical diagnosis. Patients were investigated with electrooculogram (EOG), Pattern-Reversal Visual Evoked Potentials (PR-VEPs), Dexamethasone Suppression Test (DST), D-fenfluramine Challenge Test, and brain Single Photon Emission Tomography (SPECT). Venlafaxine 150-225 mg per os daily was administered. The follow-up period was 2 years. STATISTICAL ANALYSIS: Chi-square test and ANOVA were used for the analysis of data. RESULTS: There was a lower left globus pallidus regional cerebral blood flow in patients with better response. On the contrary, chronic patients were closer to normality. DISCUSSION: The results of the current study provide preliminary evidence concerning our ability to predict response to venlafaxine and to understand its way of action.

Light and alcohol evoked electro-oculograms in cystic fibrosis.

Cystic fibrosis (CF) is caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) which is a chloride channel. CFTR is expressed in the retinal pigment epithelium (RPE) where it is believed to be important in generating the fast oscillations (FOs) and potentially contributing to the light-electro-oculogram (EOG). The role of CFTR in the alcohol-EOG is unknown. We recruited six individuals with CF (three homozygotes for Delta508 and three heterozygous for Delta508) and recorded the light- and alcohol-EOGs as well as the FOs and compared them to a control group. The results showed that in the CF group the amplitude of the alcohol- and light-EOGs were normal. However, the time to peak of the light- and alcohol-rises were significantly faster than in the control group. We conclude that CFTR is not primarily responsible for the alcohol- or light-rises but is involved in altering the timing of these responses. The FOs showed differences between the homozygotes, heterozygotes and the controls. The amplitudes were significantly higher and the time to the dark troughs were significantly slower in the heterozygote group compared to both controls and the homozygotes. In contrast, the homozygotes did not differ in either amplitude or the timing of the FOs compared to the controls.

A combined neurophysiological and behavioural study into the stimulating effects of fexofenadine on performance.

Antihistamines are known for their sedative effects. However, some studies suggested mild stimulant effects in the case of fexofenadine. The goals of this study are to examine whether fexofenadine possesses stimulating properties and to determine whether such stimulating effects are related to workload. Sixteen healthy volunteers received a single dose of 180 and 360 mg fexofenadine and placebo on separate test days. Drug effects were assessed using a divided attention task (DAT), continuous performance task (CPT) and motor choice reaction time test (MCRT). Sensitivity of the tasks was increased by manipulating the workload during task performance. Event Related brain Potentials (ERPs) were measured in the DAT and CPT to study the underlying neurophysiological processes. An interaction effect of Treatment and Workload was found on tracking performance in the DAT and on movement time in the MCRT. Performance on the DAT was less affected by increments in workload after fexofenadine as compared to placebo. P1 and P3 latency were affected by Treatment x Workload and Treatment respectively and indicated faster attentional and information processing latencies following fexofenadine treatment. Treatment did not influence performance in the CPT task or in the ERPs measured during this task. The MCRT demonstrated faster movement times following fexofenadine treatment. These results suggest that although the neurophysiological data indicate central nervous system (CNS) activation after fexofenadine treatment, the magnitude of the centrally activating effects is too small to produce relevant performance improvement at the behavioural level.

Alcohol- and light-induced electro-oculographic responses: variability and clinical utility.

The alcohol-induced electro-oculographic (EOG) response has been proposed by Arden as an indicator of retinal pigment epithelial (RPE) integrity. We have evaluated the consistency of the alcohol-EOG with respect to clinical applicability and compared this response to the ISCEV-standard EOG. We recorded, in a group of normal subjects (n=29, 14 men with mean age 42+/-11 years and 15 women with mean age 36+/-13 years), the alcohol response to a single oral dose of ethanol at 160 mg/kg (as 40 proof vodka, drunk in 15 s after 12 h of fasting), followed by an ISCEV-standard EOG 90 min after alcohol administration. Blood alcohol levels were monitored at regular intervals with a breath analyzer. We found a wide range of amplitudes in both light and alcohol responses among participants, from minimal to large values. Subjects had a wide range of blood alcohol concentrations from 0.02 to 0.10%; near the time of the response peak, but there was no relationship between alcohol levels and peak/baseline ratios. In addition, there was no relationship between alcohol peak/baseline ratio and the Arden ratio. Neither the alcohol nor the light response parameters showed any relationship with age or gender. Some of the inter-individual variability in the EOG response to alcohol may reflect variable absorption of oral alcohol. The alcohol-induced EOG has too broad a range of responses to be useful clinically for the one-time evaluation of individual patients. We have similar concerns regarding clinical applications of the standard light-induced EOG.

Alcohol- and light-induced electro-oculographic responses in age-related macular degeneration & central serous chorioretinopathy. alcohol- and light-induced EOG responses in ARMD & CSC.

The non-photic electro-oculographic (EOG) response induced by alcohol has been proposed as an indicator of retinal pigment epithelial (RPE) integrity, and reported to be abnormal in age-related macular degeneration (ARMD). To evaluate this proposal, we have measured the alcohol-EOG as well as the ISCEV-standard EOG in patients with ARMD (n=11 patients, 4 eyes with drusen, 8 eyes with 'dry' and 7 eyes with 'wet' lesions) and central serous chorioretinopathy (CSC, n=11 patients, 7 eyes with active and 6 eyes with inactive lesions), compared with 29 normal controls. We recorded the alcohol-induced EOG response after a single oral administration of ethanol at 160 mg/kg, followed by an ISCEV-standard EOG. Blood alcohol levels were monitored with a breath analyzer. We found that neither the alcohol-EOG nor the light-induced EOG response showed any difference between either ARMD or CSC patients and normal controls. Nor was there difference among eyes of different ARMD or CSC subgroups. In addition, blood alcohol concentrations near the time of the alcohol-EOG peak showed no obvious relationship with peak/baseline ratios. These data suggest that neither the alcohol- nor the light-induced EOG is a sensitive indicator of these diseases.

Retinal electrophysiological results in patients receiving lamotrigine monotherapy.

PURPOSE: To evaluate the effects on vision in patients receiving lamotrigine (LTG) monotherapy. METHODS: Twenty-four consecutive patients taking LTG for partial seizures were referred for a routine ophthalmologic examination including visual acuity testing, tonometry, slit lamp, and fundus examination. Automated kinetic perimetry, electrooculogram (EOG), and electroretinogram were performed after informed consent was obtained. RESULTS: In 18 patients finally included, the clinical ophthalmologic examination showed no abnormality. Four patients complained of blurring; among them, one patient had a visual field constriction in both eyes, which, however, was of unclear clinical significance (poor compliance) and a reduced light/dark ratio of the electrooculogram. One other patient with blurred vision had a reduced EOG, but the visual field was normal. Two patients had a reduced EOG but no visual symptoms. Considering the whole group of patients receiving LTG therapy, the light/dark ratio of the EOG was reduced in a dose-dependent fashion (p < 0.0001). The electroretinogram was normal in all patients. CONCLUSIONS: No irreversible visual field impairment in patients treated with LTG was encountered, although a dose-dependent retinal toxicity may have been present. The exact cellular mechanism of the electrophysiologic changes in patients taking LTG remain to be explained.

Electrophysiological characterisation and monitoring in the management of birdshot chorioretinopathy.

AIMS: To characterise patients with birdshot chorioretinopathy (BCR) clinically and electrophysiologically in order to monitor changes in retinal function before and after treatment with corticosteroids and/or immunosuppression. METHODS: 18 patients with BCR were characterised clinically and electrophysiologically. Serial studies were performed on 14 patients in order to monitor changes in retinal function before and after treatment with corticosteroids and/or immunosuppression. RESULTS: Most patients presented with characteristic subretinal pale spots, were HLA-A29 positive, and had diverse signs of ocular inflammation. Various electrophysiological abnormalities were present. Moderately severe bilateral pattern electroretinogram (PERG) abnormalities at presentation were common, reflecting macular dysfunction. Cone mediated 30 Hz flicker electroretinograms (ERGs) were consistently delayed before treatment, and were the most sensitive parameter of retinal dysfunction. Scotopic maximal ERG responses were abnormal in 13 patients; 10 had an electronegative maximal ERG or a reduced b:a ratio in one or both eyes. Single flash photopic ERGs were less often and less severely affected. Photopic ON and OFF ERG responses often revealed predominant ON response b-wave abnormalities with relative OFF response preservation. ERGs improved in treated cases, sometimes preceding clinical signs of recovery. Pattern ERG improvements occurred, possibly reflecting the resolution of macular oedema. CONCLUSIONS: The ERG data confirm that BCR frequently affects inner retinal function of cone and rod systems. Clinical features were not reliable indicators of functional deterioration or recovery. Objective electrophysiological assessment of retinal function demonstrated improvement following treatment and provides a reliable method of monitoring treatment efficacy, enabling management decisions to be taken with greater confidence and allowing early initiation or modification of treatment.

Early evening low alcohol intake also worsens sleepiness-related driving impairment.

Following night-time sleep restriction, afternoon driving performance during the bi-circadian surge in afternoon sleepiness is markedly worsened by blood alcohol concentrations (BACs) well under most national driving limits. This study assessed how driving with this same sleep restriction and BACs (av 40 mg and 28 mg alcohol/100 ml blood at the beginning and end of drive, respectively) respond during the evening circadian rise in alertness. In a 2 x 2 (alcohol versus control drink [double blind] x normal night sleep versus sleep restricted), repeated-measures design, eight healthy young men drove for 2 h from 18:00 h, in a real-car simulator, on a monotonous, simulated highway. Driving impairment (lane drifting), subjective sleepiness and EEG measures of sleepiness were recorded. While sleep restriction alone produced significant impairments to evening driving and subjective sleepiness, alcohol alone did not. However, alcohol combined with sleep restriction significantly worsened all indices, although, this was less than that found for afternoon driving with identical interventions. Whereas low BACs may not affect driving in normally alert drivers in the early evening, the addition of moderate sleep restriction still produces a dangerous combination. Probably, there is no 'safe' level of alcohol intake for otherwise sleepy drivers, at any time of the day.

Two components of the human alcohol electro-oculogram.

Light onset or drinking alcohol causes the standing potential of the eye to rise and then fall to a trough (the EOG). After allowing for the time for the alcohol to be absorbed into the blood stream, the changes of current with time are identical for the two agents but each acts through a separate pathway, on the same effector mechanism. We have shown that +ve and -ve processes of the alcohol-EOG may be differentially affected in disease. We have now determined the separate dose-response relationship of the two voltage changes. Alcohol diluted with water was given by mouth to fasting dark-adapted subjects. Recordings continued until both the positive peak and the later negative trough were well-characterised. Doses of alcohol ranged from 3.54 to 450 mg Kg(-1) of body weight. Experiments were carried out on three normal subjects, 4-8th decade. The results are consistent with the hypothesis that each voltage change is determined by the relation: [EtOH] x [R] <--> [EtOH.R], where <--> represents a reversible reaction. For the +ve peak, semi-saturation occurs at approximately 35 mg Kg(-l). For the -ve trough it is smaller, 11 mg Kg(-l). Therefore the result is consistent with there being 2 distinct processes, and the human EOG cannot be a single 'damped oscillation'. During the short period when change of blood alcohol concentration is effective in causing the EOG sequence (using doses which provoke large voltage changes), the computed blood concentration varies from 0.01 to 0.1 mM, i.e. is > 2 orders of magnitude less than the levels required for intoxication.

Pattern electroretinogram for monitoring the efficacy of intravitreal triamcinolone injection in diabetic macular edema.

PURPOSE: To investigate the efficacy of intravitreal triamcinolone (IVT) by evaluation of pattern electroretinogram (PERG) in diabetic patients with clinically significant macular edema (CSME). METHODS: Forty eyes of 40 diabetic patients were treated with 8 mg of IVT injection as primary therapy for CSME. The main outcome measures included best-corrected visual acuity, fundus fluorescein angiography, P50 amplitudes of pattern electroretinogram (PERG) and intraocular pressures before and after injection. RESULTS: The mean follow-up time was 6.1 months. Mean visual acuity improved significantly from a mean LogMAR value of 1.14 +/- 0.16 at baseline to a maximum of 0.73 +/- 0.30. The mean baseline P50 amplitude of PERG before intravitreal injection was 1.5 +/- 0.9 microV. After the treatment, it was 2.1 +/- 1.1 microV at 1-month, 2.4 +/- 1.0 microV at 3-month and 2.1 +/- 0.9 microV at last visit and the differences were significant when compared with baseline values (for each, p < 0.001). Temporary increases in intraocular pressures were controlled with topical antiglaucomatous medications, if required. CONCLUSION: IVT injection provides rapid improvement in visual acuity of diabetic patients with CSME that has been supported by P50 amplitudes of PERG. P50 amplitudes of PERG may he used as novel predictive value in the evaluation of the effectiveness of IVT injection.

Differential effects of light and alcohol on the electro-oculographic responses of patients with age-related macular disease.

PURPOSE: Alcohol (EtOH) affects the electro-oculogram (EOG) in ways very similar to light, although the two agents act on the RPE through different routes. Are the EOGs to light and to alcohol affected similarly in age-related macular degeneration (AMD) and age-related maculopathy (ARM)? METHODS: Standard eye movements and recording of EOGs were used. After 26 minutes of baseline recording in darkness, subjects were either exposed to 30 cd/m(2) light or drank 226 mg/kg alcohol (7.1% vol/vol) in water. RESULTS: In 17 patients with ARM and AMD (aged 67-86 years; mean, 77), the light-EOG was slowed in comparison to normal, and the voltage changes were somewhat reduced. The mean reduction in the alcohol-EOG (EtOH-EOG) was much greater. The reduction was equal in the two eyes, regardless of uniocular foveal impairment. Some EtOH-EOG loss occurred in patients with minor fundus changes and no loss of acuity, but the loss was greater in patients with "wet" or "dry" ARM and AMD. Grading of RPE changes correlated with the decrease in EtOH-EOG responsiveness, but not with light-EOG responsiveness. CONCLUSIONS: EtOH- and light-EOGs are affected differentially. In ARM, even with minor fundus changes, patients appear to have a general abnormality in the RPE. The alcohol response abnormality is correlated to the fundus appearance, but not with age. These results provide further evidence that EtOH acts by a pathway different from that governing the action of light. These results support histologic and other evidence that in ARM there is a functional barrier between the choroid and the RPE-retina.