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Biomedical subjects

D Z Wu

Publications and source records attributed to D Z Wu.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Clinical observation and analysis in age-related macular degeneration with one eye of wet form and the other of dry form].

Twenty two cases (44 eyes) of age-related macular degeneration with one eye of wet form and the other of dry form were included in this study. The range of the lesion was determined on magnified negative film of fluorescein angiography. In the dry group 72.7% eyes had normal FAZ and in the wet group 59.1% eyes revealed the lesion involving whole FAZ. The area of the lesion was measured by polar coordinates computational method, the mean area was 5.048mm2 in the wet form and 1.034mm2 in the dry form, there was statistically significant difference between the mean areas of the two groups (P < 0.01). The mean amplitude of photopic ERG b-wave was 101.74 mu v in the wet form and 126.35 mu v in the dry form. The morphological characteristics, the abnormalities of the visual function and possible changes in the two groups of this disease were discussed.

Age Factors↗
PubMed1991

[Quantitative evaluation of flicker ERG wave forms in low vision patients].

Flicker ERGs of 30 Hz were recorded for 46 eyes (23 cases) of low vision, including 38 eyes with retinal diseases and 8 eyes with optic neuropathy, and also for 39 normal eyes. The abnormality ratios were compared with regard to (1) the directly measured peak to peak amplitude and pseudo-phase, and (2) the amplitude and phase of fundamental response component (30 Hz) by discrete Fourier transform (DFT). All eyes with optic neuropathy showed normal flicker ERG, while the abnormality ratios of the directly measured pseudophase and the phase by DFT were 60.9% in 28 eyes and 82.6% in 38 eyes with retinal diseases respectively, the difference being statistically significant (P less than 0.05). These findings suggest that DFT for flicker ERG is more useful in quantitative evaluation of the retinal function.

Adolescent↗
PubMed1990

Model parameters of the smooth pursuit eye movement system with electrooculogram.

The visual pursuit test is a method that collects and analyzes the characteristics of pursuit eye movements and examines the function of the eye movement system. This paper analyzes the model parameters of the smooth pursuit eye movement system in order to explore a method for improving the analysis. The input-output relationship of the smooth pursuit system can be expressed by a quasilinear model. We compute the model parameters (gain, phase, spectral purity, cross covariance) by digital signal processing. Eye movement is recorded by electrooculogram. Both eyes are tested individually. The visual target moves at frequencies of 0.2, 0.4, 0.8, 1.2, and 1.6 Hz. Ranges are gain, 1.01 to 0.70; phase, -0.1 degree to -66 degrees; spectral purity, 0.97 to 0.70; and cross covariance, 0.99 to 0.26. We tested 40 normal subjects as well as patients with ataxia (8), vertigo (18), and ophthalmoplegia (9). The oculomotor system of normal subjects functions as a linear system in the performance of this test at 0.2 to 0.8 Hz. The spectral purity dropped to about 0.70 at 1.6 Hz. The variability of all measures increases greatly at 1.6 Hz, which indicates that this target motion exceeds the tracking ability of many normal subjects and that the oculomotor system of normal subjects functions as a nonlinear system in this condition. Statistical tests show no significant differences between sex, age, and the two eyes. The model parameters tentatively proved effective in clinical application.

Adolescent↗
PubMed1990

Objective measurement of contrast sensitivity using the steady-state visual evoked potential.

Contrast sensitivity functions (CSFs) were determined electrophysiologically with the steady-state visual evoked potential (VEP). Psychophysical CSFs obtained by the method of increasing contrasts were also measured concurrently with the VEP trials. The VEP contrast thresholds were obtained using a rapid recording technique in which the contrast of a counterphase sinewave modulated at a temporal frequency of 7.5 Hz was swept from 0.5% to 40% over a period of 22 s in 39 equal logarithmic steps. For this pattern reversal stimulus, the amplitude and phase of the second harmonic response as a function of contrast were measured using a discrete Fourier transform (DFT). Contrast sensitivities at five spatial frequencies ranging from 0.5 to 14.9 cpd were measured. The VEP contrast thresholds were determined by a linear extrapolation to zero amplitude. The contrast threshold obtained by the two methods correlated at 0.816 for 14 subjects. For all five spatial frequencies there were no significant differences between the contrast sensitivities derived from the two methods.

Adult↗
PubMed1990

[Effects of perilymphatic perfusion with cisplatin on the cochlear potential in guinea pigs].

The effects of three concentrations of cisplatin, administered by acute perilymphatic perfusion on the endocochlear potential (EP) and the cochlear microphonic potential (CM) of the guinea pig cochleae, at 1 kHz are reported. No change in EP magnitude was discovered and a concentration-dependent reduction in CM amplitude occurred during 60 minutes' perfusion period. The results suggest that cisplatin-induced hearing loss is not necessarily progressive degradation of EP.

Animals↗
PubMed1990

[Visual pigment genes for color vision defects].

Applying recombinant DNA techniques, the structures of red pigment gene (RPG) and green pigment gene (GPG) were analyzed for 43 patients with protan or deutan (including 3 females), 4 normal relatives and 3 carriers out of 3 families, as well as 11 normal controls. Abnormality of RPG was detected in all 19 protan and that of GPG was found in 14 out of 24 deutan. In about 80% (32/40) of protan and deutan the changing of exon 5 for RPG or GPG was discovered. In protan the normal RPG was replaced by a 5' red -3' green hybrid gene. Some of the deutan had no GPG, some had 5' green -3' red hybrid gene with or without GPG. Furthermore, the exon 5 of RPG and GPG was amplified by polymerase chain reaction (PCR) and further analyzed by Rsa I digestion. The results for PCR are identical to that of Southern blot hybridization.

Color Perception↗
PubMed1990

[The visual-vestibular interaction in normal subjects].

Full-field optokinetic nystagmus (OKN) at constant speed of 40 degrees/s and 60 degrees/s, vestibular ocular reflex (VOR) (sinusoidal 0.2Hz, 60 degrees/s peak velocity) with different background (light and dark) and VOR-fix were observed in 72 normal subjects (144 normal eyes). The gain, FCV and DP of OKN, VVOR, VOR were also analysed. The gain of OKN is reduced accompanied with stimulation increasing, while the FCV is increased. The gain of VVOR is 1.08 +/- 0.09(mean +/- SD), while the gain of VOR is 0.64 +/- 0.09. The FCV of VOR is much reduced than that of VVOR. The FCV in the groups under 30 years of age are much faster than the groups above 30 years of age. The VOR-fix gain is 0.05 +/- 0.04. The DP of OKN, VVOR, and VOR are 0.05 +/- 0.04. The results showed an co-operation between visual and vestibular systems and the results also suggested that the series methods of visual-vestibular interaction (OKN, VVOR, VOR, VOR-fix) might be useful in eye movement examination.

Adolescent↗
PubMed1989

The electroretinogram in Marfan's syndrome.

Marfan's syndrome (MS) is an inherited disease of connective tissue. The most characteristic ocular change is dislocation of lens, but myopia and retinal detachment also can occur. We examined 11 MS patients using electroretinography (ERG). 6 cases showed normal ERG. 5 cases had abnormal ERG. One had retinal detachment. 3 had myopia and 1 case suffered from secondary glaucoma. The defects of visual function were shown by electrophysiological test in those MS patients.

Adolescent↗
PubMed1989

Clinical study of low vision. Part I: Refraction and the aided distance vision.

Eighty three cases of low vision patients (144 eyes) were examined with distant visual aids. The average visual acuity of the 144 eyes before refraction was approximately 0.07, while the counterpart afterwards was about 0.1 (p less than 0.01). With the 4x monocular focusable aid, acuity improved in 142 eyes out of the 144 eyes. The combined use of clip-on distance aid and the spectacle reading aid was observed to be especially suitable for partially sighted students. The mean MEF of 142 eyes was 0.9435 +/- 0.2068. The paired T-test between the difference of actual magnification and theoretical magnification was not significant at the 5% level. The factors contributing to the variance of MEF were discussed.

Adolescent↗
PubMed1989

Visual field versus visual evoked potentials in maculopathies and optic neuropathies.

Both kinetic and static visual fields and visual evoked potential (VEP) were tested in 52 patients with maculopathies and in 29 patients with axial optic neuropathies. The results of central static quantitative perimetry and pattern reversal VEP were compared. The amplitude and latency of P100 were correlated with the total loss of central visual threshold in maculopathies. While the P100 latency was not correlated with the total loss of the central visual threshold in neuropathies, their latency delay was more obvious than that in maculopathies. We arrived at the conclusion that both VEP and visual field are necessary for assessing function loss and reflecting different pathological mechanisms in macular and optic nerve diseases.

Adolescent↗
PubMed1989

[ERG characteristics of congenital stationary night blindness].

The ERG of 9 cases (18 eyes) of congenital stationary night blindness with normal fundi or myopia were tested. All eyes showed absence of rod ERG and cone ERG with normal a-wave. Scotopic mixed ERG were of the negative type in 7 eyes and the subnormal type in 11 eyes. The b/a ratio was reduced in all eyes. The ERG characteristics are useful for the classification, estimation of the probable location of the lesion, and differential diagnosis of the disease.

Adolescent↗
PubMed1989

[Preoperative electroretinogram for predicting postoperative visual function of vitrectomy].

Vitrectomy was performed on 17 patients [19 eyes] who had dense vitreal opacity and precluding inspection of the ocular fundus. The preoperative visual acuity was light perception to 0.1, the postoperative visual acuity was 0.03 to 0.9. The preoperative electroretinogram [ERG] was tested on all patients. The correlation of the amplitudes of the ERG b-wave to the postoperative visual acuities were statistically analysed. The results showed that there was positive correlation of the amplitude of the preoperative scotopic bright ERG b-wave to postoperative visual acuity [r = 0.7709, p less than 0.01], and positive correlation of the amplitude of the preoperative photopic ERG b-wave to the visual acuity [r = 0.8086, p less than 0.01]. It suggests that the bigger amplitude of the preoperative ERG b-wave was, the better postoperative visual acuity was improved. Thus, the preoperative ERG could predict the outcome of vitrectomy in various ocular diseases with vitreal opacities and very low visual acuity.

Adolescent↗