Visual electrophy siological tests in obstructive sleep apnoea / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare the pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) between obstructive sleep apnoea (OSA) patients and controls.METHODS: This was a prospective cross-sectional study involving 40 OSA patients and 31 control subjects in Hospital Universiti Sains Malaysia.Patients with a confirmed diagnosis of OSA who had no ocular pathology were randomly selected to participate in the study.The apnoea-hypopnoea index (AHI) was obtained from their records and used for stratification of OSA severity.Electrophysiological tests (PVEP and PERG) were performed on each patient by a trained technician in the electrophysiology laboratory of the Department of Ophthalmology, USM.The results obtained were recorded as median values.Data analysis was done using IBM Statistics Version 21.0.RESULTS: Among OSA patients, we observed a significant reduction of the PERG amplitude P50 (P<0.001) and the PVEP amplitude P100 (P<0.001) compared to the control group.OSA patients also had a significant increase in PVEP time to peak P100 (P=0.003) and time to peak N75 (P=0.004).However, no significant differences were detected in PERG time to peak between OSA patients and controls.There were likewise no significant differences in PVEP or PERG between OSA patients with different disease severity.CONCLUSION: OSA patients have significant abnormalities in PVEP amplitude and time to peak, as well as PERG amplitude.This may reflect subclinical optic nerve dysfunction in OSA.Further research is needed to determine the association between the severity of OSA and the degree of optic nerve dysfunction.

Significance of visual electrophysiological techniques in the early diagnosis of glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

Glaucoma is a group of diseases which can threaten and damage the optic nerve and its visual pathway, leading to visual impairment as a result. Glaucomatous optic neuropathy is a chronic disease accompanied by apoptosis of retinal ganglion cells ( RGCs ) , visual field defect and cupping of optic nerve head. The gold standard in functional glaucoma evaluation is standard automated perimetry ( SAP) , but it is often limited to the subjective feelings of the patients. Still, visual electrophysiological techniques cannot replace the conventional inspection, but with its rapid development, it has provided a new strategy for the early diagnosis of glaucoma as a supplement because it can show changes in amplitude and latency before visual field defect. Here we review three special electroretinograms and multifocal focal visually evoked potentials in the early diagnosis of glaucoma.

Analysis and study of intraocular pressure, visual field and P-ERG on patients with big cup/disk / 国际眼科杂志(Guoji Yanke Zazhi)

?AlM: To analyze and study the changes of intraocular pressure ( lOP) , visual field and P-ERG on patients with big cup/disk (C/D) in 24h. ?METHODS: A total of 120 cases ( 240 eyes ) diagnosed with big C/D (C/D>0. 3) were divided into group A (C/D ?RESULTS:There was no significant statistical difference in the 24h average lOP (P>0. 05) among the three groups, while the amplitudes had significant statistical differences (P0. 05);Compared with group A, the MD and the PSD were significantly higher in group B, and the difference was of statistical significance (P0. 05), but there were significant statistical differences in amplitudes (P0. 05); Compared with group A, the P50’s amplitude of group B was significantly lower, and the difference was of statistical significance (P ?CONCLUSlON: When the patients’ C/D is no less than 0. 6, there are obvious changes of 24h lOP, static threshold visual field and P-ERG’s P50 wave. For patients with big C/D, a single lOP examination is far from sufficient, so an in-depth visual function examination should be performed. Meanwhile, it’s feasible to regard C/D 0. 6 as a screening criterion for suspected glaucoma.

Clinical significance of preoperative PVEP joint PERG examination for assessing postoperative visual function in senile cataract patients / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To discuss clinical significance of comprehensive preoperative pattern visual electrophysiological ( PVEP ) testing for assessing postoperative visual function in senile cataract patients. METHODS: During the period of January 2013 to January 2014, 102 cases of senile cataract patients ( 126 eyes) were treated in our hospital. The detection result of the preoperative PVEP, electroretinogram (PERG), PVEP combined with PERG and postoperative best corrected visual acuity ( BCVA) were compared. RESULTS:Consistent rate of PVEP combined with PERG detection was 91. 3%, that of PVEP was 63. 5%, the difference was statistically significant (χ2= 27. 773, P =0.0000. 05), and the detection results of PERG combined with PVEP and BCVA after operation were positively correlated (r=0. 773, P0. 05). The combined method of PVEP and PERG to evaluate the postoperative visual function had good stability. CONCLUSION:Preoperative PVEP joint PERG examination can effectively and objectively assess postoperative visual function recovery in senile cataract patients.

Variation in Measurement of Pattern Electroretinogram (pERG) / Jurnal Sains Kesihatan Malaysia

Pattern electroretinogram (pERG) is a recording of retinal response to a phase reversing pattern stimulus. It gives information on the integrity of the inner retina specifically the ganglion cells. The recording of pERG in a laboratory is easily influenced by many factors hence standardization in a laboratory is required to ensure that pERG recorded is repeatable and reproducible. The objective of this study was to determine the factors that could affect pERG recordings at the Electrophysiology Laboratory, Optometry Program, Faculty of Health Sciences (FSK), Universiti Kebangsaan Malaysia (UKM). This study involved forty-five subjects, aged between 20 and 25 years. They were divided into three groups. The factors being investigated were effects of 1) Alcaine 0.5%, 2) diurnal variation and 3) different size and shape of fixation target for pERG measurement (amplitude and implicit time). Paired t-test showed no significant differences between the recording before and after instillation of Alcaine 0.5% for amplitude (p = 0.116) and implicit time (p = 0.557). Measurements carried out in the morning and afternoon did not show significant differences for amplitude (p = 0.864) and implicit time (p = 0.174). For different fixation targets, results also showed no significant difference for amplitude (p = 0.125) and implicit time (p = 0.404). In conclusion, use of Alcaine 0.5%, different time of measurements and different type of fixation targets do not influence pERG results at the Electrophysiology Laboratory, FSK, UKM. Results of this study can be used for comparisons in research or in diagnosing diseases of the retina in the future

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.