Distinction and processing of common artifact in clinical visual electrophysiology / 中华实验眼科杂志

Objective:To explore the common causes and solutions for artifacts in clinical visual electrophysiological examination.Methods:A cross-sectional study was performed.The clinical visual electrophysiological examination results of 25 001 cases were collected from 2012 to 2020 at the Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University). Artifacts were identified and analyzed according to the standard waveform provided by the International Society for Clinical Electrophysiology of Vision.The characteristics and causes of the artifact were analyzed.The solutions to reduce and eliminate the artifact were proposed.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of the Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University) (No.KY2020053).Results:There were 60 typical artifacts identified among the 25 001 cases.Common causes of the artifacts were classified as three categories, the factors related to subjects, environment, or instruments.Among the 60 cases, 42(70.0%) were caused by tension in head and facial muscles of patients, 9(15.0%) due to blinking of patients, 4(6.7%) resulted from 50 Hz power frequency artifact, 2(3.3%) arisen from abnormal amplifier, and 3(5.0%) for other reasons.The strategies to avoid artifact were as follows.First, examiners could inform patients of the examination process in advance to help patients to relax and avoid the influencing factors, such as muscle tension in head and face, blinking, inattention and so on; second, high-quality 50 Hz hardware wave trap was recommended to reduce 50 Hz artifact, with good ground connection and removing of the high-power electrical appliances near the visual electrophysiological instrument; third, clean the skin sufficiently to reduce the reference electrode impedance to less than 1 kΩ.Conclusions:There is a variety of artifact waveforms and causes.The technicians should make correct judgments and handle the artifact in time to provide more accurate examination results.The doctors should know about artifact, which is helpful for better interpretation of visual electrophysiological examination reports.

Objective Assessment of Visual Field Defects Caused by Optic Chiasm and Its Posterior Visual Pathway Injury / 法医学杂志

OBJECTIVES@#To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.@*METHODS@#Typical cases of visual field defects caused by injuries to the optic chiasm, optic tracts, optic radiations, and visual cortex were selected. Visual field examinations, visual evoked potential (VEP) and multifocal visual evolved potential (mfVEP) measurements, craniocerebral CT/MRI, and retinal optical coherence tomography (OCT) were performed, respectively, and the aforementioned visual electrophysiological and neuroimaging indicators were analyzed comprehensively.@*RESULTS@#The electrophysiological manifestations of visual field defects caused by optic chiasm injuries were bitemporal hemianopsia mfVEP abnormalities. The visual field defects caused by optic tract, optic radiation, and visual cortex injuries were all manifested homonymous hemianopsia mfVEP abnormalities contralateral to the lesion. Mild relative afferent pupil disorder (RAPD) and characteristic optic nerve atrophy were observed in hemianopsia patients with optic tract injuries, but not in patients with optic radiation or visual cortex injuries. Neuroimaging could provide morphological evidence of damages to the optic chiasm and its posterior visual pathway.@*CONCLUSIONS@#Visual field defects caused by optic chiasm, optic tract, optic radiation, and visual cortex injuries have their respective characteristics. The combined application of mfVEP and static visual field measurements, in combination with neuroimaging, can maximize the assessment of the location and degree of visual pathway damage, providing an effective scheme for the identification of such injuries.

Progress of Researches on Brain Mechanism Underlying Regulatory Effect of Acupuncture Intervention on Visual Plasticity of Amblyopia / 针刺研究

Acupuncture therapy has a positive effect in the treatment of amblyopia. This article summarizes findings of the research on brain mechanisms underlying the regulatory effect of acupuncture on visual plasticity of amblyopia. In a multi-system and multi-level viewpoints, we elaborated brain mechanism underlying the regulatory effect of acupuncture on visual plasticity in amblyopia from the perspective of ultrastructure, plasticity, electrical activities, neural coding and visual microcirculation of the neurons of the visual cortex, and the targeting points from the visual center to the effector organ.

Early visual changes in diabetic patients with no retinopathy measured by color discrimination and electroretinography

Early visual changes caused by diabetes include color vision losses and an abnormal full-field electroretinogram. The purpose of this study was to evaluate color vision in type 2 diabetic patients with no clinically detectable retinopathy using an objective psychophysical color vision test, evaluate retinal function assessed by full-field electroretinography (ffERG), and verify the agreement among the changes detected by each of these tests. Color vision was tested and ffERG was performed in 34 diabetic patients (20 males; ages 56 ± 9 years). Results were compared with those obtained from age-matched control groups. Color discrimination losses occurred in all three color-confusion axes with a higher incidence on the protan axis. The full-field electroretinographic data indicated that inner retinal components (i.e., ffERG oscillatory potentials) were more affected than outer retinal components, indicating impairment of second- and third-order retinal neurons early in the disease. Previous studies reported tritan losses as a classic color vision defect in diabetes, but our results showed that all three color-confusion axes (i.e., protan, deutan, and tritan) are compromised, at least during the very early stages of the disease, reflecting a diffuse pattern of color vision loss. The full-field electroretinographic results that showed abnormalities of the inner retina support the color vision findings...

Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation

This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m² mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols.

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.

Separation of rod- and cone-driven oscillatory potential from retinal cone degeneration rat and congenital stationary night blindness rat / 中华实验眼科杂志

BackgroundOscillatory potentials (OPs) has been used extensively in experimental research and clinical diagnosis,but it is well known that OPs are the summating potentials originated from retinal rod and cone.To separate the rod and cone OPs is helpful for us to diagnose some retinal diseases.ObjectiveThis study was to analyze the characteristics of cone-and rod-driven OPs. Methods The retinal cone degeneration ( RCD ) and congenital stationary night blindness(CSNB) rats were used in this study and SD rats served as control,and 6 rats for each kinds of animals.Scotopic and photopic OPs were recorded in each rat under the dark adaptation for 12 hours and light adaptation for 10 minutes at the stimulate light intensities of -35,-25,-15,-5,0,5 db respectively with RETIscan Visual Electrophysical System.The scotopic and photopic OPs were extracted from flash electroretinogram (FERG) with Maflab7.0 Butterworth filtering waves,and the frequency spectrum of the OPs was analyzed by fast Fourier transform.The characteristics of OPs from RCD rats and CSNB rats were assessed and compared.Results The a wave and b wave of ERG were showed under the dark adaptation condition in both SD and RCD rats,but the b wave was absent in CSNB rat.Under the light adaptation condition,b wave was seen in both SD and CSNB rats,but a wave and b wave of RCD rat were absent.Two peaks were exhibited in both SD and RCD rats under the darkadaptation condition and high intensity of stimulate light at the lower frequency( domain frequency) of 75-110 Hz,90-120 Hz and high frequency ( minor frequency) 90- 120 Hz,110- 135 Hz respectively.In various intensities of stimulate light,CSNB rats appeared a peak at 70-100 Hz.But in light-adaptation and various intensities of stimulate light,the frequency peaks were seen at 75-95 Hz and 70-85 Hz from both SD and CSNB rats respectively.However,under the light adaptation condition,only one peak was seen in SD and CSNB rats at the 75-95 Hz and 70-85 Hz respectively.Compared with SD rats,the mean implied time of b wave was delayed and the amplitude was lowed under the light adaptation (P＜0.05 ),however,no significant differences were found in the implied time and amplitude of b wave of scotopic ERG between SD rats and RCD rats( P＞0.05 ).The scotopic OPs showed the prolong implied time and depressed amplitudes in RCD rats and CSNB rats compared with SD rats( P＜0.05 ),and the photopic OPs presented the prolong implied time and lowed amplitude in CSNB rat in comparison with SD rats (P ＜ O.05 ).ConclusionsCone- and rod-driven OPs appear very different characteristics.The results of this study imply that rod pathway gives more contribution to OPs than cone pathway.Analysis of these results will be helpful for the exploration of the origin of OPs and the diagnosis of the related disease.

Recording method of mouse pattern electroretinogram / 中华实验眼科杂志

BackgroundMouse has been used in laboratory studies as the model of ocular diseases.Electroretinogram (ERG)is a non-invasive method for primary examination to evaluate retinal function.Though flash ERG has been widely applied in the mouse ocular disease model for the functional assessment of the retinal outer layer,pattern ERG(PERG) is seldom used for inner retinal evaluation.ObjeetiveThe present experimental study was to investigate the recording parameters and method,wave characteristics of PERG and influencing factors in mouse,and to build the foundation for further research.Methods Thirty C57BL/6 mice aged 6 weeks old were included in this research.RETLport ( Roland Consult,Germany) was adopted for the recording of PERG.The positive needle electrode was placed in the cornea,and the reference and earth electrodes were placed under the derma in the cheek and tail.The PERG under different temporal frequencies (0.5,1.0,2.0 and 4.0 Hz),and special frequencies (0.05,0.10,0.20 cpd) were recorded in a photopic environment,and different contrast ratio (95％ and 99％ ) of stimulator or different transmission bands ( 1-100 Hz,5-30 Hz) in the same temporal frequency and spatial frequency were regulated to analyze the influence on mouse PERG.The use of animals was in compliance to the Regulations for the Administration of Affairs Concerning Experimental Animals by the State Science and Technology Commission.ResultsThe latency of N1 PERG showed a negative N1wave at around 37 ms and positive P wave at about 86 ms in adult mice.The amplitude of N1-P was 2-6 μV.Different spatial frequency,temporal frequency and contrast can affect the final results,and the different temporal frequencies were statistically significant.The wave was stable and the amplitude was unaffected at 5-30 Hz transmission bands with pronounced interference (mean amplitude of N1-P waves were(3.40±0.71),(5.08±0.88),(3.21±1.54),(3.85±1.96)μV in 0.5,1.0,2.0,4.0 Hz,F=7.43,P=0.00).ConclusionsPERG wave from adult mouse is similar to that from human.It is a useful method in evaluating the inner retinal function.Appropriate stimulating parameters are critical for recording.

Prognosis of visual function of uveitis / 中华实验眼科杂志

Uveitis is one of the leading causes of visual impairment.The method of evaluate to visual function include visual acuity,visual field,contrast sensitivity,color vision and visual electrophysiology.Among these methods,the most direct and common one is visual acuity.The visual outcomes are various because of the differences of cause of disease,severity of inflammation,location of lesion and complications.Visual impairment is most common in panuveitis.The risk of serious visual impairment is increased with aging.Bilateral inflammation is more serious and difficult to cure.Of varied causes of disease,the visual outcomes in sarcoid-related uveitis,Behcet' s disease and juvenile arthritis-related uveitis are poor.The complications of uveitis can cause visual impairment directly as well.Cystoid macular edema is the most common complication of uveitis,and which to bring up to visual impairment.There are abnormalities left in contrast sensitivity,visual field and electroretinogram.This article mainly summarize the visual function outcomes of uveitis and factors affecting the visual function.

Influence of posterior intrascleral iron foreign body on rabbit retina and opticus / 中华实验眼科杂志

BackgroundIron-containing foreign body trapped in the eyeball wall without affecting the opticus occurs occasionally in clinic. Operation always is performed in an attempt to avoid the deposition of rust in different tissues of the eye-balls. However,a few animal experimental studies showed that a small foreign body does not affect the retina and opticus in the period of three months. The question of whether surgery needs to be carried out is worth discussion. ObjectiveThe aim of this study was to evaluate the influence of posterior intrascleral iron foreign body on the rabbit retina and opticus. MethodsTwelve healthy adult Japan flap-eared white rabbits were randomly divided into two groups. Medium carbon iron with rust or without rust( size of 2. 0 mm × 1. 0 mm×0. 2 mm) were implanted into the posterior sclera of the left eye to create the animal model with iron foreign body in the eyeball wall. The cornea, anterior chamber, crystalline lens, vitreous and fundus of the rabbits were observed under a slit lamp microscope 1weekbeforeoperationand 1week, 2weeks, 1monthand 3months after operation.Flash electroretinogram(F-ERG) and flash visual evoked potential (F-VEP) were recorded at the time points mentioned above. All the rabbits were sacrificed and the eye balls were extracted at the end of the experiment, and the position of the iron foreign body was determined. The histopathological examinations of the retina and opticus were performed under the light microscope. This experiment complied with the Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission. ResultsThere were no statistical differences for the a-wave amplitude of F-ERG among different time points( F =1. 885,P =0. 129 ) and different treatment groups ( F =1. 188, P =0. 340 ), as with the ERG b-wave amplitude ( time: F =2. 73, P =0. 064 ; group : F =1. 114, P =0. 367). The differences in the latencies of F-VEP N1-wave were insignificant among the different time points( F =1. 605, P =0. 263 ) as well as various groups ( F=1. 556, P =0.314 ), and those of F-VEP P1 -wave were not evidently changed ( time: F =2. 329, P =0. 092 ; group : F =2. 186, P =0. 103 ). No correlations were seen between the time factor and grouping factor ( P ＞ 0. 05 ). There was no apparent siderosis bulbi change during the follow-up duration. No morphological abnormality in the retina and optical nerve was found under the light microscope. At the end of the experiment,intrascleral iron foreign body was wrapped by surrounding tissue in a stable condition. Conclusions The small posterior intrascleral iron foreign body, whether it is oxidized or not, does not produce distinctive functional or pathological damage on retina and opticus in the short term.

Current progress of visual physiology in retinopathy of prematurity / 中华实验眼科杂志

Retinopathy of prematurity( ROP),a leading cause of childhood visual impairment,is a vascular proliferative retinopathy in premature infants. Although the hallmark of ROP is abnormal retinal vasculature, a growing body of research in animals and observations in patients support a critical role for the neural retina in the ROP disease process. ROP can affect the foundation of the retina and optical nerve during the development duration in childhood, presenting with abnormalities in electroretinogram and multifocal electroretinogram. In addition,it was found that ROP has different degrees of influence on the development of the dioptric system ,which will result in refractive error as the child progress to adulthood. The relationship of the electrophysiology features or refractive abnormality and ROP was summarized in this article.

Investigação eletrofisiológica multifocal de sujeitos com toxoplasmose ocular / Multifocal eletctrophysiological investigation of subjects with ocular toxoplasmosis

Objetivo: avaliar as amplitudes das respostas eletrorretinográficas multifocais de pacientes com perda visual decorrentes de toxoplasmose ocular. Método: estudo longitudinal prospectivo comparativa no qual foi usado o sistema VERIS Science v6.0.5d para estimulação, registro e extração da resposta para cada hexágono que constitui o estímulo em 3 sujeitos com toxoplasmose ocular (grupo estudo) e 10 sujeitos saudáveis (grupo controle). Os dados dos registros foram exportados para análise no ambiente de programação MATLAB. Neste ambiente de programação foi realizada a análise dos componentes principais sobre as respostas multifocais para aumentar a razão sinal-ruído dos registros. A amplitude do registro dos pacientes foi comparada com os resultados do grupo controle. Foi realizada a avaliação psicofísica do campo visual em todos os indivíduos através da perimetria estática de Humphrey. Resultados: os registros de todos os sujeitos saudáveis exibiram três deflexões como descritos internacionalmente. Nos pacientes com toxoplasmose ocular os resultados da amplitude de resposta apresentaram semelhanças dos obtidos com a perimetria visual. Conclusão: a eletrorretinografia multifocal permite quantificar as perdas de sensibilidade retiniana em pacientes com toxoplasmose ocular de uma forma que pode ser diretamente comparável à avaliação psicofísica do campo visual.

Purpose: to perform a quantitative analysis of the visual losses of three patients suffering from ocular toxoplasmosis by using multifocal electroretinography. Methods: a VERIS Science v6.0.5d hardware and software was used to evoke retinal bioelectric activity, to record this activity, and to extract its first order kernel. Data were exported to MATLAB environment to perform a principal component analysis of the first order kernel. Multifocal eletroretinography obtained from patients were then compared with those obtained from healthy subjects. We performed psychophysical assessment of visual in all subjects through the static Humphrey perimetry Results: recordings from healthy subjects exhibited three components. Ocular toxoplasmosis patients had decreased response amplitude in many areas of the retina and the pattern of visual loss is similar to that found by threshold static automated perimetry. Conclusion: patients with ocular toxoplasmosis showed different degrees of visual impairment that were revealed by using multifocal electrorretinography. The electrophysiological losses matched those revealed by threshold static automated perimetry.

Retinal Function after Laser in Situ Keratomilensis / 中国康复理论与实践

@#ObjectiveTo observe the retinal function and nerve fiber layer (RNFL) thickness after laser in situ keratomileusis (LASIK). MethodsLASIK was performed in 15 cases (30 eyes) with myopia after strict preoperative examination. All examinations such as vision, correction vision, diopter, intraocular pressure, corneal thickness, ocular axis, topography scan and fundus of eye examination were performed before and 1 day, 1 week, 1 month,3 months and 6 months after operation, as well as electroretinography (ERG), visual evoked potential (VEP), optical coherece tomography at same time. ResultsThere was not significant difference in the intraocular pressure, ERG and VEP 1 day after LASIK. The thickness of RNFL decreased 1 week after LASIK (P<0.05) and recovered 1～6 months later. ConclusionLASIK does not disturb the retinal function and RNFL thickness irreversiblely.

Early changes of retinal function in diabetic patients detected by multifocal electroretinogram / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the early changes of retinal function in diabetic patients detected by multifocal electroretinogram (mfERG).METHODS: The first-order kernel responses of mfERG were recorded from eyes of 33 normal control subjects,63 diabetic patients without retinopathy and 43 diabetic patients with background retinopathy. The response densities and implicit times of N1 and P1 were compared among the control, diabetic patients without retinopathy and diabetic patients with retinopathy.RESULTS: The response densities of N1 and P1 in central 3 rings were reduced significantly in diabetic eyes with and without retinopathy. And the implicit times of N1 and P1 were delayed significantly only in diabetic eyes with retinopathy.CONCLUSION: mfERG can detect the early changes of retinal function quantitatively in diabetic patients. Analysis of response densities and implicit times of N1 and P1 can reflect the progress of local retinal dysfunction in diabetes.