Changes of Oscillatory Potentials of Electroretinogram after Methanol Intoxication in Rats / 法医学杂志

Objective To study the characters of oscillatory potentials (OPs) of electroretinogram (ERG) after methanol intoxication in rats. Method The SD rat models of methanol intoxication were established and divided into control group, 3-day intoxication group, 7-day intoxication group. The changes of OPs of ERG were recorded in a dark room. Results The total amplitudes of 3-day and 7-day intoxication groups decreased approximately 50% compared with that of the control group, while the schedule de-layed approximately 16% and 61%, respectively. Conclusion The characters of methanol intoxication in rats included delay in schedule and decline in the total amplitude of OPs.

Frequency spectrum analysis of dark-adapted oscillatory potentials in normal rats / 中华实验眼科杂志

Background Oscillatory potentials (OPs) of scotopic electroretinogram (ERG) plays an important role in the evaluation of visual function in multiple retinal diseases.However,the origin of OPs is uncompletely clear.It is essential to analyze the time domain and frequency domain components for the further study of OPs.Objective The present study was to investigate the change characteristics of frequency spectrum of scotopic OPs with age and stimulating intensity.Methods RCS-rdy+-p+rats with the ages of 21,25,32,35,37,46,60,90 days were selected iu this study and 3 rats for each.Scotopic flash ERG were recorded from all the rats with RETI-scan system.Gold-foil ring cornea recording electrode was used as the recording electrode and the steel needle electrode was used as the reference and earth electrode during the record.The intensity of stimulating light was set at-20,-10,-5,0 and 5 dB respectively.Data were output into the computer and processed by the software Matlab7.0.Results The principle frequency corresponding to maximum amplitude component was 80-120 Hz in the various ages of rats under the different stimulating conditions above.With the increase of the intensity of stimulating light,high frequency component (200-250 Hz) began to appear and the amplitudes showed a gradually raise upon the intensity of light.The major component was subdivided into two peaks at 0 dB stimulation.Further,the age affected the major frequency peak with the maximum value at 60-day-old rats and the minimum value at 25-day-old rats.Also,the pass-band width of main amplitude appeared to be maximal at 60-day-old rats and minimal at 25-day-old rats.Conclusions OPs in Rcsrdy+-p+ rats are influenced by stimulating intensity and agc.Stimulating intensity affects the amplitude and age lead to the change of distribution of primary frequency of OPs.It is possible to know the influences of the degeneration of rods and be helpful to diagnosis this kind of disease.

The Role of Electroretinography in Assessing the Progression of Diabetic Retinopathy

PURPOSE: To investigate the clinical significance of electroretinographic (ERG) responses, including the photopic negative response parameter, in assessing the progression of diabetic retinopathy. METHODS: Standard flash ERG was tested on 28 normal controls and 143 patients who were diagnosed with diabetes mellitus. Of those, 97 patients had diabetic retinopathy in different stages. Electroretinography was performed according to the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. Amplitudes and implicit times of ERG responses, including the photopic negative response (PhNR), were compared at different stages of diabetic retinopathy. RESULTS: Amplitudes of oscillatory potentials were significantly reduced in mild NPDR. Cone b-wave amplitude, 30--Hz flicker response, and PhNR were significantly reduced in moderate NPDR. CONCLUSIONS: These results suggest that oscillatory potentials are good indicators of retinal function change in the early stage of diabetic retinopathy, and the appropriate results of the cone b-wave, 30-Hz flicker response and PhNR tests are good indicators of moderate NPDR.

Clinical Analysis of Electroretinogram in Hypertensive Retinopathy

PURPOSE: Among electroretinogram variables, changes in OPs have frequently been reported as an early index of microcirculatory changes in diabetes mellitus patients without clinical signs of diabetic retinopathy. But studies on the relationship of hypertensive retinopathy and ERG have rarely been reported. This study was performed to investigate the relationship between retinal functional damage of hypertension and related changes in ERG. METHODS: Sixty-six essential hypertensive patients who visited our health screening center from January to July in 2001 were incruited as subjects. Among 122 eyes of 61 patients, 56 eyes with normal appearing retina were classified as group A while another 66 eyes with evidence of hypertensive retinopathy were as group B and 30 eyes of 15 persons of similar ages with normal blood pressure were normal control group as group C. Amplitude and implicit time were measured according to the standard electroretinogram procedure recommended by the ISCEV. RESULTS: In rod response, the amplitude of b wave of group A and B were smaller than that of group C(p<0.01), and the SOP of group A and B were also smaller than that of group C(p<0.01). The SOP of group B was smaller than that of group A(P<0.01). Regardless of degree of hypertension, the SOP value of group B was smaller than that of group A(P<0.01). Among patients with less than 5 years of duration, the SOP value of group B was smaller than that of group A(P<0.01). Among Group A with more than 5 years of duration, regardless of hypertensive retinopathy, the SOP was decreased. Among Group B with less than 5 years of duration, the SOP was also decreased regardless of retinopathy. CONCLUSIONS: Regardless of hypertensive retinopahy, scotopic b-amplitude and SOP were reduced in hypertension patients. Those patient with longer duration, decreased SOP was related to microcirculation alteration in hypertension despite normal appearing retina.

Electroretinographic studies in rhegmatogenous retinal detachment before and after reattachment surgery

Changes in the scotopic electroretinogram (ERG) and oscillatory potentials (Ops) were examined in patients who had rhegmatogenous retinal detachment within 3 days before and also at regular intervals after a successful reattachment operation. Electroretinograms were recorded in 38 patients (age 10 to 62 years) for the recent 5 year period. The amplitudes of the scotopic a-wave and b-wave in the detached eye were significantly decreased compared to the fellow normal eye preoperatively. Statistically significant differences were found between the preoperative and the postoperative recordings of the diseased eye. However, postoperative interocular differences in the amplitude of the a-wave between the reattached and normal fellow eye were not statistically significant. The amplitudes of the a-wave and b-wave were inversely related to the extent of the retinal detachment area, the duration of the detachment, and the extent of the buckles that were applied. Significant interocular differences in the b/a wave amplitude ratio and the Ops amplitude were observed. These results strongly suggest that the retinal function, even after successful reattachment surgery, might be compromised mainly by an inner retinal malfunction rather than from a photoreceptor dysfunction.

Digital signal processing of oscillatory potentials and its clinical application / 眼科新进展

Objective　To study the analyzing method of oscillatory potentials (OPs) and its clinical application.Methods　OPs from 40 normal control eyes, 33 eyes (33 cases) with early (0～Ⅱ stage) diabetic retinopathy (DR), 9 eyes (9 cases) with central retinal vein occlusion (CRVO) and 9 eyes (9 cases) with branch retinal vein occlusion (BRVO) were tested. In each OPs waveform, the frequency spectra from 10 to 290 Hz were derived by Fast Fourier Transform (FFT). The sum of power and the maximum power were calculated. The OPs in time domain was re-constructed by counter FFT with the components from 110 to 250 Hz in the frequency spectrum. The latencies, the amplitudes and the sum of amplitudes of wavelets in the re-constructed OPs were measured by the computer.Results　Comparing with normal control eyes, in the OPs of early DR, the mean frequency spectra from 140 to 210 Hz were reduced; the sum of power and the maximum power were reduced; the latencies of the four wavelets were prolonged; the amplitudes of the four wavelets and the sum of the amplitudes were attenuated. In the OPs of CRVO, the mean frequency spectra from 150 to 180 Hz were reduced; the sum of power and the maximum power were reduced; the latencies from the first to the third wavelets were prolonged; the amplitudes from the first to the third wavelets and the sum of amplitudes were attenuated. In the OPs of BRVO, the sum of power and the maximum power were reduced; the latencies from the second to the third wavelets were prolonged; the amplitudes from the first to the third wavelets and the sum of amplitudes were attenuated.Conclusion　The analysis of OPs in the present study can provide effective and objective indices for diagnosis of DR, CRVO and BRVO.

Us efulness of Standard Electro retinogram in the Early Diagnosis of Diabetic Retinopathy: Analysis using Receiver Operating Characteristic(ROC) Curve

Authors recorded standard electroretinogram in two groups of diabetic patients. Group A, consisted of 60 eyes with no visible diabetic retinopathy and Group B, 30 eyes with mild nonproliferative diabetic retinopathy. The electroretinogram was recorded according to the standard electroretinogram procedure recommanded by the ISCEV. In rod and cone response, the amplitude of b wave were 329.0+/-46.9 microvoltin Group A and 308.8+/-37.8 microvoltin Group B. The implicit time of b wave were 40.5+/-3. 0microvoltin Group A and 45.8+/-5.4microvolti n Group B. The summed amplitude of oscillatory potentials were 125.7+/-38.7microvolt in Group A and 112.0+/-17.7microvoltin Group B. Above results indicate that for the disgnostic criteria for diabetic retinopathy, the amplitude and implict time of b wave, and the summed amplitude of oscillatory potentials in maximal combined response were useful. On receiver operating characteristic(ROC) curves in maximal combined response, cut off value for the amplitude and implicit time of b wave were 315 microvoltand 42ms espectively. Cut off value for the summed amplitude of oscillatory potentia-als was 118 microvolt. In results, on ROC curve, the implicit time of b wave in maximal combined response was most accurate, and the summed amplitude of oscillary potentials was the next, followed by the amplitude of b wave in the maximal combined response.

The Effects of Calcium Dobesilate(Doxium) on the Electroretinogram in Patients with Diabetic Retinopathy

The purpose of the study is to evaluate the effects of calcium dobesilate (Doxium) on the electroretinographic changes in 60 non-insulin dependent diabetic patients with mild to moderate diabetic retinopathy, randomly assigned to receive either oral calcium dobesilate l000mg twice 8 day for 6 months or without medication. And also the effects of blood HbAlc and retinal photocoaglulation on the electroretinographic changes were evaluated. All patients were tested electroretinography with UTAS-2000 (LKC co., USA) before treatment and six months later respectively. The time interval changes of the electroretinogram were analyzed with student t-test program. As a result, no interval changes of the electroretinographic b-wave amplitudes and b/a ratio were noted in both groups, but the oscillatory potentials were significantly decreased after 6 months in the non-treated group (p:0.002). As compared to calcium dobesilate treated group, the non-treated group with blood HbAlc over 6.5mg% (p:0.008) or treated with retinal photocoagulation (p:0.001) showed a significant decrease of the oscillatory potentials. In conclusion, the administration of calcium dobesilate in the patients with diabetic retinopathy prevents an oscillatory potentials reduction, especially in patients with blood level of HbAlc below 6. 5mg% or treated with retinal photocoagulation.

Electroretinographic Findings in Patients with Branch Retinal Vein Occlusion

To evaluate the electroretinographic findings in cases of branch retinal vein occlusion(BRVO), Electroretinogram(ERG) were performed according to ISCEV(International Society for Clinical Electrophysiology of Vision) protocol in 17 unilateral BRVO patients. According to fluorescein angiographic acute stage group, hemorrhagic area of fundus was evaluated from retinal photo obtained by fundus camera. And correlation between hemorrhagic area and ERG was evaluated In acute stage group, the b-wave amplitude and b/a ratio of scotopic maximal combined response and oscillatory potential were significantly decreased at the affected eye compared unaffected eye. These findings were not found in chronic stage group. The relationship between hemorrhagic area and ERG finding was not detected in acute stage group. ERG findings in the acute stage of BRVO show that main pathologic lesion of BRVO is located in the inner retinal layer and inner retinal circulation. With further follow-up study, It is possible to use ERG data as a predictor of the course of BRVO.

Pressure-Induced Ischemia in the Cat

The effects of pressure induced ischemia on the retina were studied by means of Electroretinogram(ERG) and Electron microscopy. Acute ischemias were induced in the cat's eyes by raising the intraocular pressure over the systolic pressure for 90 minutes in group one and 3 hours in group two. ERGs and OPs(Oscillatory potentials) were recorded 1 hour. 1 day, 3 days, 7 days and 14 days after prsssure-induced ischemia, respectively. The eyes were enucleated 1 hour, 1 day, 3 days, 7 days and 14 days after ischemia for evaulation of structural damage of the retina. The amplitudes of a-, b-waves and the summed amplitudes of OPs(SOP) were decreased to 57.4%, 51.9% and 45.2% of control values at one day after ischemia and then recovered to 80%, 68.8% and 59% at 14 days after ischemia in group one. In group two, the amplitudes of a-, b-waves and the summed amplitudes of OPs appeared to flat at 1 hours after ischemia and then recovered to 50%, 50% and 30.7% of control values at 14 days after ischemia. In group one, electron microscopic study revealed generalized retinal damages including retinal edema and the pyknosis of the nucleus. And these changes seemed to be recovered gradually until two weeks after damages. In group two, the retina received more severe ischemic damages than group one, such as destruction of photoreceptors, necrosis of photoreceptor, bipolar cells and ganglion cells on one day after ischemia. After 2 weeks, the loss of photoreceptors and the pigment epithelial migration into the inner retinal layer were noted. In conclusion, the ERG study revealed that the OPs was the most vulnerable components to the ischemia and the histopathological study showed that the photore ceptors received more severe damage from the retinal ischemia than the other components.

Normal Oscillatory Potentials in Rabbits

Ten pigmented raqbits were dark adapted for 30 minutes previously and then exposed to room illumination of 200 lux for 10 seconds. In mesopic adaptation, the oscillatory potentials(OPs) were recorded. The coefficient of variation in the peak latency, time interval, summed amplitude, and amplitude of each individual OP wavelet were obtained. The peak latency showed the smallest coefficient of variation. The summed amplitude of the OPa and the time interval showed smaller coefficient of variation than amplitude of each individual OP component. Therefore the peak latency, summed amplitude, and time interval may be reliable factors to evaluate the OPs. The increase of the light stimulus did not affect the amplitude of O3. However, O1 and O2 tended to increase in amplitude and O4 to decrease as the intensity of light stimulus increased. These facts may suggest that each individual component of OP has different orign. As the intensity of light stimulus increased, the summed amplitude of OPs was increased and peak latency of O1, O2, O3, and O4 were decreased. Time intervals showed no significant changes.

Oscillatory potentials of local macular ERG in diabetic retinopathy

The oscillatory potentials (OPs) in electroretinogram (ERG) have clinical values in measuring retinal functions of the early stage of diabetic retinopathy.However, OPs have, until now, been evaluated as components of total ERG recorded with a full field stimulus over the entire retina. Therefore, little information could be obtained about the macular condition (diabetic retinopathy). Using focal stimuli, we successfully recorded OPs in the human macular region. We modified our previously reported system for recording local macular ERG under the fundus monitor with an infrared television fundus camera. We evaluated macular OPs with simultaneously recorded a-and b-waves in many patients with diabetic retinopathy. In some kinds of early diabetic maculopathy, the macular OPs were selectively reduced, leaving the a- and b-waves intact. The macular OPs can be a valuable indicator in assessing the macular function in diabetic maculopathy.