Objective To investigate the early influences of laser photocoagulation on retinal function in diabetic retinopathy(DR). Methods The multifocal electroretinograms (MERG) of 30 eyes with DR (phase Ⅲ～Ⅳ) were tested with visual evoked response image system IV before,and the 3 rd day and the 7 th day after laser photocoagulation. Results Three days after photocoagulation, the latency of N1 prolonged in the central macula 5? area and superionasal quadrant.The response densities of N1,P1 and N2 markedly reduced, and most significant changes occurred in the central macula 5? area and then in the central 10?area. There were also differences in the changes of the amplitude of N1 and P1 in different quadrants .The changes of visual acuity were positively related to the decrease of amplitudes of N1,P1 and N2 in the macula. Conclusion The reduction of response densities in MERG reveals functional damage in diabetic retina occurring early after photocoagulation.The functional damage in macula induced indirectly by photocoagulation may explain the reduction of visual acuity after panretinal photocoagulation in some degree.

Objective To investigate the early effects of intervention with tanakan on retinal function in diabetic retinopathy(DR) after laser photocoagulation. Methods Prospective random controlled study was performed on 60 Patients (60 eyes) from 23 to 69 years old with DR(phase Ⅲ～Ⅳ). The multifocal electroretinograms (MERG) were tested with VERIS Ⅳ before , the 3rd day and the 7th day after photocoagulation. Results No significant differences were found in the latencies and response densities of N1,P1 and N2 between the two groups before photocoagulation. Compared with that before photocoagulation, three days after photocoagulation the latencies in tanakan group had no significant change. The response densities of N1,P1 and N2 reduced and the changes were much smaller than that in control. Three days after photocoagulation ,the response densities of P1 and N2 in the central macula 5? area were much higher and the latencies of P1 and N2 were significantly shorter than that in control group. There were no significant differences in the response densities in the 7th day and the differences in the latencies between two groups still existed. Conclusion Tanakan may be effective in preventing the retina from damage of retinal photocoagulation in some degree in DR.

This study presents a fitting method for the intensity-response curve of electroretinogram. The data of b-wave amplitudes from 10 eyes with idiopathic macular hole and their contra-lateral contrast eye (normal) were analyzed. It was observed that the Rmax de creased significantly (P=0.013) in the eyes with idiopathic macular hole.

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.

OBJECTIVETo study the effect of radiotherapy of nasopharyngeal carcinoma on visual evoked potential (VEP).

METHODSVEP of 63 patients with nasopharyngeal carcinoma were tested before, at the end of, half a year, one year, 2 years and 3 years after their radiotherapy.

RESULTSWithin the male group, one year after radiotherapy, the latency of VEP was significantly delayed than that before and at the end of radiotherapy, while the amplitude was decreased significantly. Two years after radiotherapy, the latency of VEP was significantly delayed more than that before radiotherapy. However there was no significant difference among VEP at the end of, half a year and 3 years after radiotherapy. Within the female group, 2 years after radiotherapy, the latency of VEP was significantly delayed than that before radiotherapy. Three years after radiotherapy, the latency of VEP was significantly delayed than that before, at the end of, half a year and one year after radiotherapy. There was no significant difference in VEP amplitudes before and after radiotherapy.

CONCLUSIONWithin the male group, the abnormal delay of VEP latency mostly happens one or two years after radiotherapy. Within the female group, the significant delay of VEP latency happens at the end of radiotherapy and lasts for 3 years, while the VEP amplitude does not change significantly during the 3 years after radiotherapy. The result indicates that the sustained radiation damage within the female visual nerve system starts at the end of radiotherapy, but to a lesser degree. It was shown that radiotherapy of nasopharyngeal carcinoma certainly damages the visual nerve system, though there is sex difference in the impairment.

Adult ; Evoked Potentials, Visual ; radiation effects ; Female ; Humans ; Male ; Middle Aged ; Nasopharyngeal Neoplasms ; radiotherapy ; Sex Factors ; Time Factors

OBJECTIVETo investigate the characteristics of multifocal electroretinograms (mf-ERG) of different phases in diabetic retinopathy (DR) and its clinical significance.

METHODSMultifocal electroretinograms in patients with DR (I - II stage) were tested with VERIS IV system.

RESULTSIn I - II stage, the absolute values of N1, P1 and N2 response densities, and the N1-P1 and P1-N2 response densities were attenuated is a field of about 45 degrees in diameter.

CONCLUSIONAs a new objective and quantitative examination for spatial visual function, multifocal electroretinograms may be valuable in the diagnosis of diabetic retinopathy.

Aged ; Diabetic Retinopathy ; pathology ; physiopathology ; Electroretinography ; methods ; Female ; Humans ; Male ; Middle Aged ; Retina ; pathology ; physiopathology ; Time Factors