Combined effects of cocaine and nicotine on cardiovascular performance in a canine model.

BACKGROUND: With the proliferation of cocaine abuse, increased incidence of catastrophic cardiovascular events such as angina pectoris, myocardial infarction, ventricular arrhythmias, or sudden death are reported. Many of these patients also smoke cigarettes before and after cocaine use, leading to a high frequency of simultaneous exposure to both drugs. Cocaine's and nicotine's independent effects on cardiodynamics are well documented, but combined effects of both on complete cardiovascular hemodynamics remain unknown. HYPOTHESIS: The study aimed to determine whether these effects are additive, synergistic, or antagonistic and was therefore designed to investigate the cardiovascular changes produced as a result of combined administration of cocaine and nicotine in a canine model. METHODS: Initially, in phase 1, 30 experiments were performed to study the dose-response curve of both drugs. In phase II and III, 12 dogs were subjected to 30 experiments. In phase II, cocaine was given intravenously (IV) followed by nicotine. In phase III, sequence of drug administration was reversed to study the effects on hemodynamics and coronary artery blood flow reserve. RESULTS: Hemodynamic parameters observed were Phase I: Dose-response curve established the IV bolus dose of cocaine 2 mg/kg and nicotine 50 microg/kg. Phase II: Cocaine increased heart rate, blood pressure, and dP/dt, but nicotine administration after cocaine produced marked significant synergistic excitatory effects: dP/dt increased from 1,810 +/- 210 to 6,300 +/- 460 (p < 0.003). Phase III: Nicotine significantly increased heart rate, mean arterial pressures, left ventricular end-diastolic pressure, pulmonary artery, pulmonary capillary wedge, and right atrial pressures. Nicotine increased dP/dt (1,810 +/- 192 to 5,000 +/- 160 mmHg/s; p < 0.004). These excitatory effects of nicotine were attenuated by cocaine when administered as a second drug (dP/dt decreased to 1,925 +/- 144 from 5,000 +/- 160 mmHg/s;p < 0.004). CONCLUSIONS: Cocaine, when administered alone, caused increase in heart rate, blood pressure, and dP/dt, but nicotine showed a significant increase in all the hemodynamic parameters. Both drugs reduced coronary blood flow reserve. In combination, cocaine plus nicotine administration had synergistic excitatory effects in dogs. A reversed drug combination, that is, nicotine plus cocaine, attenuated the excitatory effects of nicotine.

Usefulness of left atrial abnormality for predicting left ventricular hypertrophy in the presence of left bundle branch block.

The objective of this study was to identify left atrial (LA) abnormality on the electrocardiogram and other related variables as predictors of left ventricular (LV) hypertrophy in the presence of left bundle branch block (LBBB). In the presence of complete LBBB, the diagnosis of electrocardiographic abnormalities is problematic and that of LV hypertrophy remains difficult. The usual electrocardiographic criteria applied for the diagnosis of LV hypertrophy may not be reliable in the presence of LBBB. Therefore, noninvasive criteria will help physicians diagnose LV hypertrophy with electrocardiography. LA abnormality on the electrocardiogram was assessed by 2 independent observers as predictor of LV hypertrophy in the presence of LBBB in 120 patients, and data were compared with those of 100 patients without LA abnormality. LV mass was calculated from echocardiographic data. Besides LA abnormality, the other variables studied for prediction of LV hypertrophy were gender, age, body surface area, body mass index, frontal axis, and QrS duration. Of the 6 criteria analyzed, the P terminal force was found to be the most common and consistent criterion to detect LA abnormality. LV hypertrophy was confirmed by echocardiographic determination of LV mass in both groups. Observers reliably differentiated between the hypertrophied and normal-sized left ventricle in the presence of LBBB by correlating LA abnormality with LV mass determined by echocardiography. Observer 1 detected LA abnormality in 89% and observer 2 in 84% of patients. False-positive results were present in 11% and 16%. The observer's recognition of LA abnormality in the present study was 91%. The 2 observers showed a sensitivity of 81% and 79% and a specificity of 91% and 88%, respectively, when diagnosis of LV hypertrophy was determined. LV mass increased significantly and was diagnostic of LV hypertrophy in 92% of patients with LA abnormality. In the remaining 11 patients (8%), the LA abnormality was of marginal abnormal magnitude. Each 0.01-mV/s increase in LA abnormality gave an increase of 30 g of LV mass. LV mass was increased in 86% of patients when corrected by body surface area. LV hypertrophy in the presence of LBBB on electrocardiography was found in only 13 patients (10%) when the 6 frequently used conventional criteria for diagnosis of LV hypertrophy by electrocardiography were used. Regression analysis revealed LA abnormality to be a strong independent predictor of increased LV mass. Multivariate analysis also revealed age, body mass index, body surface area, frontal axis, and QrS duration to be significant predictors of LV mass. This noninvasive study correlates LA abnormality by electrocardiogram and LV hypertrophy with echocardiography to conclude that LA abnormality was significantly diagnostic of LV hypertrophy in the presence of LBBB. Age, body mass index, body surface area, frontal axis, and QrS duration were also significant predictors of LV mass.

Combined effects of caffeine and alcohol on hemodynamics and coronary artery blood flow in dogs.

Alcohol intake is often followed by coffee drinking because of the universal acceptance of its sobering effect. Such effects were found inconsistent on motor functions. However, it is common belief that caffeine will antagonize the intoxicating effects of alcohol. The independent actions of caffeine and alcohol are well documented, but combined effects of short-term administration are unknown. This experimental work was designed to study the effects due to short-term administration of caffeine and alcohol on the cardiovascular system. In phase I, 30 experiments were performed in our laboratories to study the dose-response curves of both the drugs. In phases II and III, 15 dogs were subjected to 30 experiments. In phase II, caffeine, 5 mg/kg, was given i.v., followed by ethanol, 400 mg/kg i.v., and in phase III, sequence of drug administration was reversed to study the effects on hemodynamics and coronary artery blood flow. Caffeine did not show significant changes in all the cardiovascular parameters, and ethanol administration caused nonsignificant increase in heart rate, mean arterial pressure, left ventricular systolic pressure, and left ventricular (LV) mechanical work and decrease in the maximal rate of first derivative of LV pressure, stroke volume, and systemic vascular resistance. Left ventricular end-diastolic, pulmonary artery mean and right atrial pressures, pulmonary vascular resistance, myocardial oxygen consumption, and as coronary flow reserve increased as compared with controls. Combined caffeine and alcohol had synergistic effects, but when the order of drug administration was reversed (i.e., alcohol was followed by caffeine), the effect was antagonistic.

Combined effects of alcohol and nicotine on cardiovascular performance in a canine model.

Alcohol and tobacco consumption are correlated. Smokers consume more alcohol than do nonsmokers, and alcohol consumers smoke more than do teetotalers. The independent effects of alcohol and nicotine on the cardiovascular system are well documented, but combined effects of short-term administration are unknown. This experimental work was designed to study the effects due to short-term administration of alcohol and nicotine on cardiovascular system. In phase I, 30 experiments were performed to study the dose-response curve of both the drugs. In phases II and III, 15 dogs were subjected to 30 experiments. In phase II, ethanol, 400 mg/kg, was given i.v., followed by nicotine 50 microg/kg, i.v., and in phase III, sequence of drug administration was reversed to study the effects on hemodynamics and coronary artery blood flow. The dose-response curve established the i.v. dose of ethanol, 400 mg/kg, and nicotine, 50 microg/kg. Ethanol administration caused a nonsignificant increase in heart rate (HR), mean arterial pressure (MAP), left ventricular systolic pressure (LVS), and left ventricular mechanical work (LVMW), and a decrease in maximal rate of increase of LV pressure per second (dP/dt), stroke volume (SV), and systemic vascular resistance (SVR). Left ventricular end-diastolic pressure (LVEDP), pulmonary artery mean pressure (PAM), right atrial pressure (RAP), pulmonary vascular resistance (PVR), myocardial oxygen consumption (MVO2), and average peak velocity of coronary blood flow (APV) had mild significant increases as compared with controls. Nicotine significantly increased heart rate, mean arterial pressures, LVEDP, and pulmonary artery, pulmonary capillary wedge, and right atrial pressures. Nicotine increased dP/dt (2,062-3,188; p < 0.006) and decreased APV (9 to 8; p < 0.03). Combined ethanol followed by nicotine had synergistic increase in HR, SD, MAP, LVS, LVEDP, pulmonary pressures, CO, SV, dP/dt (2,184 > 5,206; p < 0.005), MVO2, and LVMW. However, the excitatory effects of nicotine were attenuated when ethanol was administered after nicotine (dP/dt, reduced from 2,058 to 1,653; p < 0.04, and APV increased from 10 to 12; p < 0.02). We conclude that ethanol increased APV but had nonsignificant effects on the hemodynamics, whereas nicotine reduced the APV and had significant excitatory responses. In combination (i.v.), ethanol + nicotine produced significant synergistic excitatory effects. On the other hand, the nicotine + ethanol combination increased APV and caused attenuation of the excitatory effects of nicotine in dogs.

Left atrial abnormality by electrocardiogram predicts left ventricular hypertrophy by echocardiography in the presence of right bundle-branch block.

BACKGROUND: Left ventricular hypertrophy (LVH) on the electrocardiogram (ECG) may be masked in the presence of complete right bundle-branch block (RBBB). Left bundle-branch block on the ECG is associated with LVH at autopsy in 93% of hearts studied. However, RBBB does not predict LVH and the usual ECG criteria applied for LVH may not be reliable in the presence of RBBB. HYPOTHESIS: The study was undertaken to evaluate left atrial (LA) abnormality as a criterion for the diagnosis of LVH in the presence of RBBB. METHODS: Left atrial abnormality in the ECG was assessed by two independent observers as a criterion of LVH in the presence of RBBB in 100 patients, and data were compared with those of 50 patients without LA abnormality. RESULTS: Left ventricular hypertrophy was confirmed by echocardiographic determination of left ventricular (LV) mass in both groups. Observers reliably differentiated between hypertrophied and normal-sized LV in the presence of RBBB by using LA abnormality as an ECG criterion when correlated with LV mass determined by echocardiography. Observer 1 correctly detected LVH in 88% and Observer 2 in 82% of patients. False positive diagnosis was made in 12 and 18% of patients by Observers 1 and 2, respectively. Observers' performance of recognition of LA abnormality in the present study was 94%. Results showed sensitivity of 76 and 70% and specificity of 84 and 92% for Observers 1 and 2, respectively. Left ventricular mass increased significantly and was diagnostic of LVH in 92% of patients with LA abnormality. Left ventricular mass was high in 84% of patients when corrected by body surface area. LVH in the presence of RBBB by the ECG was found in only seven patients (5%) when six commonly used conventional criteria of diagnosis of LVH by ECG were employed. Regression analysis found LA abnormality to be a strong independent predictor of increased LV mass. Multiple regression analysis revealed that age, body mass index, body surface area, and frontal axis are also significant predictors of LV mass. CONCLUSION: The results obtained by the correlation of LA abnormality by ECG and LVH by echocardiography conclude that LA abnormality by ECG was significantly diagnostic of LV hypertrophy in the presence of RBBB.

Combined effects of caffeine and nicotine on cardiovascular hemodynamics in canine model.

The independent effects of caffeine and nicotine on cardiodynamics are well documented, but combined effects of both are not reported. Initially, in phase I, 18 experiments were performed to study the dose-response curve of both the drugs. In phases II and III, 13 mongrel dogs were subjected to 30 experiments. In phase II, caffeine, 5 mg/kg, was given i.v. followed by nicotine, 50 micrograms/kg, and in phase III, the sequence of drug administration was reversed to study the effects on hemodynamics. In phase II, caffeine did not show significant changes in all the cardiovascular parameters, but nicotine administration after caffeine produced marked significant synergistic excitatory effects: the rate of increase of the first derivative of left ventricular pressure (dP/dt) increased from 1,101 +/- 111 to 3,194 +/- 872 (p < 0.003). In phase III, nicotine significantly increased heart rate, mean arterial pressures; left ventricular end-diastolic pressure (LVEDP); and pulmonary artery, pulmonary capillary wedge, and right atrial pressures. Nicotine increased dP/dt (964 +/- 182 to 1,639 +/- 60 mm Hg/s; p < 0.004). The excitatory effects of nicotine were attenuated by administration of caffeine (dP/dt, 918 +/- 140 reduced to 715 +/- 144 mm Hg/s; p < 0.04). Caffeine and nicotine, alone, caused nonsignificant and significant increases in hemodynamics, respectively. In combination, caffeine + nicotine administration produced significant synergistic excitatory effects in dogs. On the other hand, the nicotine + caffeine combination caused attenuation by caffeine of the excitatory effects produced by nicotine.

Left atrial abnormality in acute myocardial infarction.

This study assessed left atrial abnormality by electrocardiogram as a predictor of left ventricular dysfunction during acute myocardial infarction. Hemodynamic, angiocardiographic, echocardiographic, and serial creatine kinase-MB studies revealed the electrocardiogram to be a significant predictor of location of acute myocardial infarction, prevalence of occlusive disease in coronary vessels, myocardial contractility, low ejection fraction, increased left ventricular end-diastolic pressure, and serial creatine kinase-MB.

Caffeine and cardiac arrhythmias. An experimental study in dogs with review of literature.

In spite of widespread belief among clinicians that caffeinated drinks are linked with palpitations, tachycardia and dysrhythmia there is paucity of documentary evidence. We investigated the arrhythmogenic activity of caffeine in canine model. The alkaloid was given i.v. to perform 51 experiments in 13 anesthetized dogs in three different doses. The Low dose generated significant Sinus (S) bradycardia (70%; p < 0.006, S. arrhythmia (70%; p < 0.02), S. arrest (50%; p < 0.04), Atrial (A) ectopics (40%; p < 0.016), Wandering of pacemaker (WPM) (50%; p < 0.04), and Ventricular premature contractions (VPC--unifocal 40%; p < 0.05) as compared with control ECGs. Medium dose induced significant S. arrhythmia (62%; p < 0.001), A. ectopics (25%; p < 0.01), A. tachycardia (25%; p < 0.01), WPM (25%; p < 0.01), VPCs--unifocal (50%; p < 0.002), multifocal (25%; p < 0.01), couplets (25%; p < 0.01) and interpolated (25%; p < 0.01). High dose of caffeine revealed significant S. arrhythmia (56%; p < 0.002), A. ectopics (44%; p < 0.005), A. tachycardia (32%; p < 0.01), WPM (32%; p < 0.01) and VPCs--unifocal (64%; p < 0.001), multifocal (32%, p < 0.01), couplets (32%, p < 0.01), interpolated (32%; p < 0.01) and Ventricular tachycardia (VT) (20%; p < 0.01). A. flutter and fibrillation each were observed in two experiments only. In conclusion, these data indicate a dose dependent arrhythmogenecity of caffeine. Small dose, mostly, generated, benign arrhythmias due to vagal stimulation. More severe arrhythmias like VT, multifocal VPC. A. flutter and A. fibrillation were generated with higher dose of caffeine. Mechanism remains uncertain as caffeine has multiple actions. Further studies in human beings with normal and compromised myocardium may elucidate arrhythmogenic effects of caffeine.

Spatial tuning loss of pattern reversal visual evoked response in optic nerve disease.

We compared the pattern reversal visual evoked response (PVER) amplitude-check size functions from 25 eyes (25 normal subjects; visual acuities > or = 20/20) with those from 32 eyes (22 patients; visual acuities 20/15 to 20/50; mean, 20/25.5) with mild optic nerve disease to determine if spatial tuning loss of the PVER occurs in the presence of optic nerve dysfunction. The steady-state PVER was recorded with five check sizes (range, 160 to 10 minutes of arc). To analyze the PVER amplitude-check size function, we calculated the difference between the maximum and minimum PVER amplitudes and then calculated the area of spatial tuning (the area under the function). Values were significantly smaller in patients than in normal subjects (1.81 +/- 1.27 microV versus 5.73 +/- 3.27 microV; F = 41.24, p = 0.0001; 3.87 +/- 2.70 area units versus 12.57 +/- 7.60 area units; F = 38.62, p = 0.0001). There was no shift in the distribution of peak check sizes. Results suggest that a spatial tuning loss occurs in optic nerve disease. The shape of the function, including the area of spatial tuning, appears to be a sensitive indicator of early or mild optic nerve dysfunction.

Early repolarization on scalar electrocardiogram.

Sixty thousand electrocardiograms were analyzed for 5 years. Six hundred (1%) revealed early repolarization (ER). Features of ER were compared with race-, age-, and sex-matched controls (93.5% were Caucasians, 77% were males, 78.3% were younger than 50 years, and only 3.5% were older than 70). Those with ER had elevated, concave, ST segments in all electrocardiograms (1-5 mv), which were located most commonly in precordial leads (73%), with reciprocal ST depression (50%) in a VR, and notch and slur on R wave (56%). Other results included sinus bradycardia in 22%, shorter and depressed PR interval in 38%, slightly asymmetrical T waves in 96.7%, and U waves in 50%. Sixty patients exercised normalized ST segment and shortened QT interval (83%). In another 60 patients, serial studies for 10 years showed disappearance of ER in 18%, and was seen intermittently in the rest of the patients. The authors conclude that in these patients with ER: 1) male preponderance was found; 2) incidence in Caucasians was as common as in blacks; 3) patients often were younger than 50 years; 4) sinus bradycardia was the most common arrhythmia; 5) the PR interval was short and depressed; 6) the T wave was slightly asymmetrical; 7) exercise normalized ST segment; 8) incidence and degree of ST elevation reduced as age advanced; 9) possible mechanisms of ER are vagotonia, sympathetic stimulation, early repolarization of sub-epicardium, and difference in monophasic action potential observed on the endocardium and epicardium.

Pattern-reversal visual-evoked response in bull's eye maculopathy associated with Stargardt's disease.

Using steady-state pattern-reversal visual-evoked response (PVER), we studied the macular function in patients with bull's eye maculopathy. The results were correlated with fluorescein angiography. Study patients with an established (25 eyes of 14 patients) and a suspected (8 eyes of 4 patients) diagnosis of Stargardt's disease with bull's eye maculopathy were divided into group G (good vision group: 15 eyes with visual acuity of 20/40 or better) and group P (poor vision group: 18 eyes with visual acuity of 20/50 or worse). The diameters of the atrophic area and the normal or less affected central area of the bull's eye were measured form the fluorescein angiograms. The mean diameter of the central area in group G (2.0 degrees) was significantly larger than that in group P (0.6 degrees; d.f. = 17, p = 0.0227). The PVER amplitudes were reduced in the patient groups with all check sizes and the amplitude-check size functions were flat. Amplitude differences were observed between the patient groups with the 20' checks (d.f. = 17, p = 0.0638), probably due to the difference in the mean central diameters (2.0 degrees vs. 0.6 degrees). Patients with a perifoveal abnormality can have an abnormal PVER despite relatively good visual acuity. We also recorded the PVER in 7 normal controls tested with simulated ring-shaped scotomas, the sizes of which matched the mean diameters of the scotomas in the patient groups (7.0 degrees x 0.6 degrees and 7.0 degrees x 2.0 degrees). The controls also showed markedly reduced responses with all check sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of electroretinographic and fluorescein angiographic findings in unilateral central retinal vein obstruction.

BACKGROUND: In central retinal vein obstruction (CRVO), electroretinogram (ERG) abnormalities and extensive retinal capillary dropout (CD) in the fluorescein angiogram (FA) are good indicators of retinal ischemia. We retrospectively studied patients with unilateral CRVO and compared the ERG and FA results. METHODS: Single white flash ERG, photopic ERG, scotopic ERG and flicker ERG were recorded in 30 cases of unilateral CRVO. We analyzed the correlation between the ERG results and the presence/absence of extensive CD. RESULTS: The ERG b/a-wave amplitude ratios, photopic and scotopic b-wave amplitudes, and flicker amplitudes were significantly smaller (P < 0.05) in eyes with extensive CD (n = 12, 40%), than in eyes without (n = 18, 60%). When the photopic or scotopic b-wave amplitudes were normal or supernormal, extensive CD on FA was absent in all eyes. When the b/a-wave ratios were > or = 1.0 or when the b-wave amplitudes with white flash or flicker amplitudes were normal or supernormal, extensive CD was present in less than 32% of eyes. CONCLUSION: These results suggest that the ERG results, especially the b/a-wave amplitude ratio, are significantly correlated with the presence/absence of CD on FA in CRVO.

Pattern reversal visual evoked response and Snellen visual acuity.

Because the pattern-reversal visual evoked response (PVER) reflects the central retinal function, PVER results generally agree with those of psychophysical tests. The visual acuities (VAs) calculated from PVER recordings and Snellen acuity (SA) measurements were compared in 500 eyes (261 patients; ages 8 to 88 years; mean, 44.5 years). The best-corrected VA was measured using the ETDRS chart, and the PVER acuity was determined by the smallest check size that produced a definite PVER (critical check size). In 288 eyes with a critical check size of 10 min of arc, the SAs ranged from 20/15 to 20/800 (mean 20/38). In 68 eyes with a critical check size of 20 min, the SAs ranged from 20/15 to 20/800 (mean 20/97). In 70 eyes with a critical check size of 40 min, the SAs ranged from 20/20 to 20/1600 (mean 20/156). In 29 eyes with a critical check size of 80 min and 14 eyes with a critical check size of 160 min, the SAs ranged from 20/50 to 20/1600 (mean 20/312 and 20/398, respectively). In 31 eyes in which the PVER was non-recordable, the SAs ranged from 20/70 to 20/3200 (mean 20/1177). The PVER acuity using the smallest check size seemed to agree with the SA, but large deviations were observed in certain subjects.

Stargardt's disease/fundus flavimaculatus: psychophysical and electrophysiologic results.

Retinal functions were analyzed psychophysically and electrophysiologically in 73 patients (146 eyes) with Stargardt's disease/fundus flavimaculatus. Patients were classified into types 1, 2, 3, and 4; patients with type 3 were subdivided into 3E and 3L (early and late onset of initial symptoms). Most had visual acuity (VA) of 20/200 or greater at initial testing. VA declined 0.25 octave/year during follow-up (mean, 6.1 years). Four of 16 patients (25%) older than 40 years had VA of 20/200 or less in the stronger eye. Psychophysical tests (flicker profile, central scotoma, dark adaptation) showed variable degrees of abnormalities. Electrophysiological tests showed significant photopic b-wave amplitude decreases, particularly in type 3E (42.2% of normal). The electro-oculogram light peak/dark trough ratio was abnormal in 60 of 132 eyes (45.5%), especially in type 3E (25 of 34 eyes, 73.5%). Visual prognosis and overall visual function varied depending upon disease type, location of retinal lesions, and age of onset. In Type 3E, overall retinal function was poorest and accompanied by the most severe decline of central vision and function in the surrounding macula.

Retinal detachments in incontinentia pigmenti.

We report on retinal detachments in six eyes of four patients with incontinentia pigmenti. These nonrhegmatogenous traction retinal detachments are characterized by extensive preretinal and vitreous fibrous organization that pull the retina anteriorly behind the lens. The clinical course and fundus appearance of the retinal detachments, beginning with the avascular peripheral retina and leading to traction retinal detachment, are similar to those of cicatricial retinopathy of prematurity. Vitreous surgery was performed on three eyes (two patients), with partial reattachment of a total retinal detachment in one eye and complete reattachment of a partial retinal detachment in a second eye. These cases represent the first successful surgical interventions reported for retinal detachment in incontinentia pigmenti.

Vision in stage 5 retinopathy of prematurity after retinal reattachment by open-sky vitrectomy.

Performing vitrectomy in stage 5 retinopathy of prematurity is controversial, partially due to limited anatomical and poor reported visual results. Fifty-five eyes of 50 patients whose retinas were reattached by open-sky vitrectomy in stage 5 retinopathy of prematurity and who were followed up for more than 12 months were analyzed retrospectively to ascertain clinical factors that may influence visual outcome. Vision was evaluated by preferential looking. Visual ability to discriminate stationary objects was obtained in 32 (58.2%) eyes, 18 (32.7%) had motion perception, and five (9.1%) had light stimulus perception. Although visual acuities were relatively low, they were useful to these patients. Age at the time of vitrectomy and the shape of the retinal detachment were found to be important factors in predicting visual prognosis.

Measuring vision with temporally modulated stripes in infants and children with ROP.

PURPOSE: To determine differences in preferential looking (PL) acuities using stationary and temporally modulated stripe patterns in patients with various stages of retinopathy of prematurity (ROP). METHODS: We measured the PL acuities of 134 patients (ages 4 mo to 13 yr) with various stages of ROP. Patients were divided into six subgroups according to PL vision measured with stationary stripes: (1) equal to or better than 20/200 (n = 24); (2) worse than 20/200 to 20/400 (n = 10); (3) worse than 20/400 to 20/800 (n = 15); (4) worse than 20/800 to 20/1600 (n = 13); (5) worse than 20/1600 to 20/6400 (n = 26); and (6) worse than 20/6400 (n = 46; no stationary vision). RESULTS: In the group with PL acuity equal to or better than 20/200, no difference in vision was apparent between the two methods. In patients with acuities worse than 20/200 to 20/400, the temporally modulated PL acuities were 0.23 octave better than the PL acuities measured with the stationary stripes. The difference increased to 0.86 and 1.12 octaves in the groups with visual acuities worse than 20/400 to 20/800 and worse than 20/800 to 20/1600, respectively. The difference in the group with PL acuities worse than 20/1600 to 20/6400 was 1.69 octaves. The 46 patients with no stationary vision detected only the temporally modulated stripes. CONCLUSIONS: The results suggest that the PL acuity difference between the temporally modulated and stationary stripes increases with visual impairment. Measuring PL acuity with temporally modulated stripes is an important addition to the evaluation of severely visually impaired subjects.

Correlating visual acuity and electrooculogram recordings in Best's disease.

The visual function in 54 eyes of 27 patients with Best's disease was analyzed by retrospectively examining the Snellen visual acuities and the electrooculogram (EOG). Visual acuities, generally well maintained in most patients, were 20/40 (0.5) or better in 41 of 54 (75.9%) eyes, and showed no correlation with age. Those in the cicatricial stage had worse visual acuities than those in the previtelliform stage. The EOG was abnormal in 47 eyes (87.0%) with a subnormal light peak/dark trough (Lp/Dt) ratio less than 1.85. Seven eyes (13.0%) with an Lp/Dt ratio 1.85 or higher had significantly smaller Dt values compared with those with a low Lp/Dt ratio. The Lp/Dt ratio did not correlate with patient age or disease stage. No correlation existed between visual acuities and Lp/Dt ratios. The Lp/Dt ratio did not reflect the severity of the macular lesions. The results indicate that not only a low Lp/Dt ratio but also a low dark trough value in cases with a normal Lp/Dt ratio are helpful in diagnosing Best's disease.

Effect of hemifield stimulation on simultaneous steady-state pattern reversal electroretinogram and visual evoked response.

Steady-state pattern reversal electroretinograms (PERG) and pattern reversal visual evoked responses (PVER) were recorded simultaneously in 4 normal subjects using hemifield stimulation of the upper/lower and nasal/temporal conditions with 95 and 60% stimulus contrasts. A square-wave checker-board pattern (check size 40 min of arc) was used. The temporal frequency (reversal rate) was 6 Hz (12 reversals/s). With nasal/temporal hemifield stimulation, neither the PERG nor the PVER amplitudes differed significantly with either stimulus contrast. With the upper/lower hemifield stimulation, PERG amplitudes were not significantly different; PVER showed a significantly larger amplitude for lower than for upper hemifield stimulation with both contrasts (ANOVA test: p = 0.0064, 95% contrast; p = 0.0018, 60% contrast). PVER amplitudes recorded with lower hemifield stimulation were 2.05 and 2.63 times larger than those elicited with upper hemifield stimulation, for the 95 and 60% contrasts, respectively. The difference in response to the upper/lower hemifield stimulation, observed only in PVER, suggests that the lower stimulus field dominancy may be processed in a visual pathway proximal to the retinal level.