Purpose To investigate the influence of ametropia on stereopsis and its mechanism by using the disparity evoked potential testing. Methods A new set of static random dot stereograms was utilized as a stimulation to elicit the disparity evoked potentials in 21 ametropes and 40 stereo normal subjects. Rezults The P250 wave,which was related to stereoscopic stimulation in ametropes,was recorded in both the ametropes and emetropic stereo normal persons in this series,and the characteristic changes of P250 wave with increasing visual disparity in ametropes were similar to those in normal subjects.The differences of mean amplitudes and latencies of P250 waves between myopes and hyperopes were not significant. Conclusion Ametropia in full correction dose not significanly affect the function of stereopsis. (Chin J Ocul Fundus Dis,1998,14:225-227)
Purpose To observe the color motion perception of patients with diabetic retinopathy (DR) in very early stage and find a good way to diagnose early DR in time． Methods The motion perceptions of patients with early DR and normal subjects were tested by using equiluminant moving chromatic grating and moving luminance grating generated on VGA monitor in a PC compatible computer and the results were compared with those of electroretinogram(ERG),oscillatory potentials(OPs) and color perception． Results When the two gratings were of equal spatial frequency and equal time frequency,the normal subjects judged that chromatic grating moved faster than luminance grating．Very signifincant differences were detected between blue/yellow grating and black/white grating while the luminance contrast of was 80% and the velocity was 20.2 mm/s or 14.3mm/s(Plt;0.01).The abnormal ratio of color motion perception(69.2%)was higher than that of color vision(43.6%) and ERG OPs(48.9%) when the luminance contrast of black/white grating was 80% and the velocity was 20.2mm/s. Conclusion The test of color motion perception provides new method for diagnosing early DR. (Chin J Ocul Fundus Dis,1998,14:135-138)
Objective To observe the characteristics of magnetic resonance diffusion tensor imaging（MR-DTI）for optic nerves and optic radiation in blind patients.Methods The optic nerves and optic radiation of 20 blind patients（blind group）and 20 controls（control group） were scanned by MR-DTI. Fractional anisotropy (FA) and directional encoded color (DEC) maps were acquired through postprocessing with the aid of volumeone 1.72 software. The signal intensity of optic nerves and optic radiation were then observed. The FA, mean diffusivity (MD), lambda;∥ and lambda;perp; value of bilateral optic nerves and optic radiation in two groups were measured in the DEC maps.Results While the high signal intensity was found in bilateral optic nerves in FA and DEC maps in control group，the signal decreased markedly in the blind group. The FA and lambda;∥ value of optic nerves in the blind group were declined obviously compared to that in the control group. The difference was statistically significant (t=16.294, 14.660;P=0.000). The MD and lambda;perp; value of optic nerves in the blind group were increased obviously compared to that in the control group, the difference was also statistically significant (t=8.096, 8.538; P=0.000). The high signal intensity was found in bilateral optic radiation in FA and DEC maps in both the blind and control groups. There were no statistic differences in FA and MD value in bilateral optic radiation between the blind and control groups (Left：t=1.456，1.811；P=0.152，0.076. Right：t=0.779，0.073；P=0.440，0.942). Conclusion A low signal intensity of bilateral optic nerves and a high signal intensity of bilateral optic radiation were found in blind patients.
Objective To observe the results of multifocal visual evoked potential (mfVEP) examination in patients with anterior ischemic optic neuropathy (AION) before and ater treatment, and to probe its clinical significance. Methods A total of 90 patients (90 eyes) with AION were examined by mfVEP; the secondorder reaction of mfVEP was analyzed.The reaction was divided into upper and lower hemi field of visual field, or 1/4 quadrant visual field (superior nasal, inferior nasal, superior temporal, and inferior temporal). The sum of waves of each response was analyzed and the results in various regions were compared.The features of wave configuration was compared between the AION eyes and the contralateral eye, and between the AION eyes before and after treatment.Results The amplitude and latency of P-wave of mfVEP was 0.198plusmn;0.033 and 100.197plusmn;7.354 respectively in AION eyes before treatment, and was 0.271plusmn;0.024 and 98.567plusmn;6.794 in the contralateral eyes; the difference was significant (t=16.556,18.330; Plt;0.01). The amplitude and latency of P-wave of mfVEP was 0.229plusmn;0.016 and 100.104plusmn;10.603 respectively in AION eyes after treatment, which differed much from that before the treatment (t=13.649, 8.858; Plt;0.01) and also from that of the contralateral eyes (t=13.649，8.858；P＜0.01). ConclusionsThe amplitude and latency of P-wave of mfVEP may accurately reflect the recovery of local optic nerve damage in AION eyes before and after treatment with good repeatability. AION can be used as a new method for AION diagnosis and detection of the prognosis.
Objective To measure the macular function of the fellow eye in patients with unilateral retinal vein occlusion (RVO). Methods A total of 24 cases of unilateral RVO were diagnosed by fundus fluorescein angiography (FFA), and multifocal ERG (mfERG) was recorded by RETI scan. The mfERG data of 24 fellow eyes of those RVO patients, and 18 normal control eyes were analyzed and compared. The parameters included the amplitude density, latency of the P1 and N1 wave in 6 concentric circles and 4 quadrants of the mfERG graphics. Results The amplitude densities of P1 and N1 wave in first and second concentric circles of RVO fellow eyes were significantly lower than normal eyes (t=4.520, 2.147; P＜0.05). There was no significant difference (P＞0.05) of P1/N1 latency in any concentric circles or quadrants between RVO fellow eyes and normal eyes. Conclusion The central fovea of the RVO fellow eyes was functionally impaired.
A new form of static random-dot stereograms free of monocular clues was designed as stimulus to elicit disparity evoked potentials in 40 normal subjects.A characteristic wide positive wave at about 250ms was consistently recorded in disparity stimulation,which may be regard as evdence of the presence of stereopsis.In constrast,recordings for monocular stimulus all demonstrated a relatively smaller and sharper positive wave with a markedly shortened latency. （Chin J Ocul Fundus Dis,1993,9:214-217）