| Backgrounds and aims:Cataract is the most common cause of blindness worldwide,of which the incidence is increasing with aging.A variety of factors can accelerate the formation of cataract,among which the persistently elevated blood glucose concentration in diabetic mellitus(DM)patients will change the osmotic pressure of the lens and accelerate the formation of cataract.With the continuous innovation of cataract surgical techniques and emergence of new intraocular lenses,more perfect postoperative visual quality is urgently needed by cataract patients.Evaluating the visual quality of the operated eye after cataract surgery has become an urgent problem for doctors.Clinical visual electrophysiology is a classical objective examination of visual function.In recent years,visual electrophysiology has been more and more widely used in the predication of visual function before cataract surgery.However,due to the low intensity of the electrical response of the visual system recorded on the body surface,the equipment for collecting visual electrophysiological signals is very sensitive,and various artifacts are often mixed in clinical examinations.Therefore,the identification and elimination of the spurious signals is a necessary prerequisite for clinical visual electrophysiological examination to obtain accurate results.This study aims to analyze the identification and treatment of common artifacts in clinical visual electrophysiological recording results.To summarize the clinical significance of flash visual evoked potential(FVEP)and full-field electroretinogram(ffERG)in DM patients with cataract,so as to provide a basis for clinical use of visual electrophysiological technology to predict the visual function of cataract patients.This paper has three parts:Part Ⅰ: Identification and treatment of common artifacts in clinical visual electrophysiological recordingsMethods:A total of 25 001 patients who were performed visual electrophysiology examinations in the First Hospital Affiliated to Army Medical University from 2012 to 2020 were retrospectively enrolled.According to the standard waveforms provided by the International Society of Visual Electrophysiology(ISCEV)guidelines,the typical artifact waveforms were identified,of which characteristics and causes were analyzed,and the methods to reduce and eliminate the artifacts were proposed.Results:Sixty cases with artifact waveform were noticed.Common causes of artifact waveform were classified as three categories: the factors related to subjects,environment,or instruments.The details were: muscles tension of head or face of patients(42 subjects,70.0%),blinking of patients(9 subjects,15.0%),50 Hz power frequency artifact(4 subjects,6.7%),abnormal amplifier(2 subjects,3.3%),or others(3 subjects,5.0%).The strategies to avoid artifact were as followed:(1)In order to avoid the patient’s own influencing factors,such as muscles tension of head and face,blinking,inattention and so on,we could inform the patient of the examination process in advance and relax them;(2)To reduce 50 Hz artifact,it was recommended to use high-quality 50 Hz hardware wave trap to ensure good ground connection and remove the high-power electrical appliances near the visual electrophysiological instrument;(3)Cleaning the skin sufficiently to reduce the reference electrode impedance to less than 1 KΩ.Conclusions:There are various types and causes of artifacts in clinical visual electrophysiology examination.The technicians should make accurate judgments and handle the artifact in time,and the doctors should know about artifacts,which is helpful for their analyzing the results.Part Ⅱ: Application of FVEP in the preoperative prediction of visual function in DM patients with cataractMethods:A total of 161 DM patients with cataract were enrolled in this retrospective study.Best-corrected visual acuity(BCVA),slit-lamp ophthalmoscopy and ISCEV standard flash evoked visual potential(FVEP)were examined.The right eye was selected for analysis.FVEP detection included the peak time and amplitude of N1,P1,N2,P2,N3 and P3 waves.All patients underwent BCVA examination one month after surgery and were divided into three groups according to the severity of vision loss: mild [logarithm of the minimum angle of resolution(log MAR)≤ 0.1],moderate(0.1 < log MAR < 0.5),and severe(log MAR ≥0.5).Analysis of variance or non-parametric Kruskal-Wallis H test was used to compare the FVEP amplitudes and peak time among the three groups.Spearman rank correlation analysis was performed to analyze the correlation between parameters of significant differences among the three groups and postoperative Log MAR BCVA.Results:There were 23,57 and 81 patients divided into the mild group,moderate group and severe group,respectively.The preoperative N1 wave amplitudes of mild group,moderate group and severe group were-7.87 ± 5.12 m V,-5.28 ± 4.57 m V and-3.53 ± 3.36 m V,respectively.The P1 wave peak time was 57.24 ± 11.47 ms,67.52 ± 9.99 ms,and 67.80 ±10.68 ms,respectively;the P1 wave amplitudes were 3.72 ± 2.31 m V,9.81 ± 4.96 m V,and8.18 ± 5.00 m V,respectively;the N2 wave peak time was 67.70 ± 12.56 ms,86.84 ± 12.53 ms and 84.80 ± 15.05 ms,respectively;the P2 wave peak time was 94.41 ± 13.70 ms,107.17 ± 15.90 ms and 104.95 ± 15.15 ms,respectively;the P2 wave amplitudes were 12.35± 5.90 m V,9.80 ± 5.24 m V and 9.05 ± 5.58 m V,respectively;the N3 wave amplitudes were-15.93 ± 10.55 m V,-6.08 ± 5.60 m V and-4.83 ± 5.39 m V,respectively.Statistically significant differences were observed in the above parameters among the three groups(all P≤ 0.019).Correlation analysis showed that N1 wave amplitude,P1 wave peak time,N2 wave peak time,N3 wave amplitude were weakly correlated with postoperative Log MAR visual acuity(r =-0.287,P < 0.001;r = 0.232,P = 0.003;r =-0.209,P = 0.008;r = 0.311,P< 0.001).Conclusions:FVEP has limited predictive value for postoperative visual acuity in DM patients with cataract.In clinical practice,FVEP alone cannot be used to predict postoperative visual acuity in DM patients with cataract.Part Ⅲ: Application of ffERG in the preoperative prediction of visual function in DM patients with cataractMethods:The clinical data of 74 eyes of 41 DM patients and 21 eyes of 12 non-diabetic patients were retrospectively analyzed,including BCVA,slit-lamp ophthalmoscopy and ISCEV standard full-field electroretinogram(ffERG).Dark-adapted(DA)and light-adapted(LA)ERG and oscillatory potentials(Ops;OP1,OP2,OP3)of ffERG examination were analyzed.All DM patients underwent BCVA examination one month after surgery and were divided into different groups based on the severity of vision loss: mild(log MAR ≤ 0.1),moderate(0.1 < log MAR < 0.5),and severe(log MAR ≥ 0.5).Cataract patients without DM were included in the non-diabetic control group.Analysis of variance was used to compare the preoperative electrophysiological results of the four groups.Spearman rank correlation analysis was performed to analyze the correlation between the parameters of significant differences among the four groups and postoperative Log MAR BCVA.Results:According to the severity of vision loss postoperative,22 eyes,31 eyes and 21 eyes were divided into the mild group,moderate group and severe group,respectively.In the control group(21 eyes),the postoperative visual impairment was mild.The preoperative DA 10.0 ERG a-wave amplitudes were-277.16 ± 44.66 μV,-220.04 ± 45.92 μV,-107.73 ±66.73 μV,and-304.29 ± 47.10 μV in the mild group,moderate group,severe group,and control group,respectively;the DA 3.0 ERG OP2 wave amplitudes were 45.17 ± 14.18 μV,33.48 ± 14.97 μV,17.49 ± 7.05 μV,and 51.54 ± 4.71 μV,respectively;the amplitudes of LA3.0 a wave were 37.91 ± 8.33 μV,32.23 ± 6.76 μV,16.12 ± 4.59 μV,and-37.98 ± 5.27 μV,respectively;the amplitudes of LA 3.0 b wave were 129.03 ± 23.33 μV,102.45 ± 24.07μV,44.42 ± 22.62 μV,and 111.33 ± 19.39 μV,respectively.Statistically significant differences were observed in the above parameters among the four groups(all P ≤ 0.026).Correlation analysis showed that DA 10.0 ERG a wave amplitude,DA 3.0 ERG OP2 wave amplitude,and LA 3.0 ERG a and b wave amplitude were significantly correlated with postoperative Log MAR BCVA(r =-0.799,P < 0.001;r =-0.619,P < 0.001;r =-0.754,P <0.001;r =-0.783,P < 0.001).Conclusions:ffERG components including DA 10.0 ERG a wave,DA 3.0 ERG OP2 wave,and LA3.0 ERG a wave and b wave amplitude,have a good predictive value for postoperative visual acuity in DM patients with cataract.LA 3.0 ERG responses are easy to operate,based on which it can be used as a routine examination for predicting postoperative visual acuity in DM patients with cataract. |
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