Development of receptoral responses in pigmented and albino guinea-pigs (Cavia porcellus)

We describe the postnatal development of the electroretinogram (ERG) receptoral response in the guinea pig. In addition, the time course and nature of maturation was compared between albino and pigmented strains to consider the role that melanogenesis might have in this process. Electroretinograms were collected on groups of albino and pigmented animals from postnatal day (PD) PD1 to PD60. A-wave amplitudes and implicit times were extracted from filtered data (0–75 Hz). Receptoral components were modelled using the delayed gaussian model of Hood and Birch [1] fitted as an ensemble to the raw data. Guinea pigs show saturated amplitudes (Rm_P3) that are 50% of adult values at birth, these mature by PD12. Receptoral delay (t_d) also undergoes some postnatal maturation, while phototransduction gain (log S) is adult-like at birth. Albino animals had significantly (p<0.05) larger Rm_P3 and log S across all ages. Guinea pigs have significant postnatal development in their receptoral response. Maturation of Rm_P3 implies a postnatal increase in rod outer segment length. Whereas the adult values of log S implies a mature phototransduction process at birth. We argue that the likely cause for the larger log S of albino eyes is compatible with theories of increased levels of internal light. Whereas the larger Rm_P3, even after allowing for increased light effectiveness, may reflect a lower ocular resistance in albino eyes due to their lower levels of melanin. Furthermore, decreased Rm_P3 and log S with age is observed in the pigmented group only and is consistent with increased ocular resistance due to melanin development in this strain. This revised version was published online in July 2006 with corrections to the Cover Date.     

Frequent scanning using flash glucose monitoring contributes to better glycemic control in children and adolescents with type 1 diabetes

Aims/IntroductionWe examined the impact of scanning frequency with flash glucose monitoring on glycemic control in children and adolescents with type 1 diabetes.Materials and MethodsThe study included 85 patients, aged 14.0 ± 0.5 years, with type 1 diabetes. The median time in the target glucose range (TIR) and glycosylated hemoglobin (HbA1c) values were 50.0 ± 1.4% and 7.5 ± 0.1%, respectively.ResultsThe median scanning frequency using flash glucose monitoring was 12.0 ± 0.4 times/day. Scanning frequency showed a significant positive correlation with TIR and an inverse correlation with HbA1c. Scanning frequency was identified to be the determinant of TIR and HbA1c by using multivariate analysis. The participants whose scanning frequency was <12 times/day were categorized as the low‐frequency group (n = 40), and those who carried out the scanning >12 times/day were categorized as the high‐frequency group (n = 45). Patients in the high‐frequency group were more likely to be treated with insulin pumps compared with those in the low‐frequency group; however, this difference was not significant (21.3 vs 5.3%, P = 0.073). The high‐frequency group showed significantly greater TIR than the low‐frequency group (57 ± 1.6 vs 42 ± 1.7%, P = 0.002). Furthermore, the high‐frequency group showed significantly lower HbA1c levels than the low‐frequency group (6.8 ± 0.1 vs 8.0 ± 0.1%, P < 0.001).ConclusionsThese findings showed that patients with a higher scanning frequency had better glycemic control, with greater TIRs and lower HbA1c levels, compared with those with a lower scanning frequency. Scanning frequency of >12 times/day might contribute to better glycemic outcomes in real‐world practice in children with type 1 diabetes.     

The effects of age on steady-state pattern electroretinograms and visual evoked potentials

Steady-state pattern-reversal electroretinograms and visual evoked potentials were simultaneously recorded in two groups of young and elderly normal volunteers. The young group consisted of 23 subjects (13 women and 10 men) aged 18 to 28 years, and the elderly group consisted of 24 subjects (11 women and 13 men) aged 58 to 77 years. Stimuli were square-wave gratings ranging in spatial frequency from 0.5 to 6 c/deg and phase reversed at a frequency of 4 Hz. Pattern-reversal electroretinograms and visual evoked potentials consisted of a prominent second and a smaller fourth harmonic response. Spatial frequency-amplitude functions of the pattern-reversal electroretinogram second and fourth harmonics were similar for the young and elderly groups. The mean fourth harmonic phase was significantly shifted in elderly subjects compared with young subjects for all spatial frequencies tested. Spatial frequency tuning was observed for amplitude and phase functions of the visual evoked potential second and fourth harmonic responses for both age groups. Age had a significant effect on phase for spatial frequencies above 1.5 c/deg. Amplitude of the fourth harmonic was significantly lower for the elderly group at 1.5–4 c/deg. Phase was significantly different between groups for spatial frequencies below 3 c/deg. Our results suggest that aging influences both retinal and central visual pathways. Aging differentially affected the visual evoked potential second and fourth harmonic responses, suggesting different neuronal origins for these components.     

视网膜分支静脉阻塞多焦视网膜电图特征及其与视野改变相关性分析

目的 观察视网膜分支静脉阻塞多焦视网膜电图特征,分析其与视野改变的相关性.方法 回顾性临床病例自身对照研究.对2006～2009年在承德医学院附属医院眼科就诊的32例(32只眼)视网膜颞上支分支静脉阻塞患者进行多焦视网膜电图检查,分析其一阶反应,N1、P1波振幅密度值及潜伏期;并行视野平均光敏感度检查.结果 视网膜静脉阻塞区域多焦视网膜电图N1、P1波振幅密度下降,潜伏期延长;P1波振幅密度与视野平均光敏感度差异行统计学意义(r=0.545,P<0.01 ).结论 视网膜分支静脉阻塞多焦视网膜电图能够准确反映发生在视网膜局部病变的位置与程度,并与视野改变具有相关性.

Abstract：

Objective To observe the characteristics of multifocal electroretinogram in branch retinal vein occlusion and analyze its correlativity with perimetry.Methods Implemented multifocal electroretinogram to 32 cases (32 eyes) of temporal branch retinal vein occlusion and analyzed the first-order kernel responses: amplitude density and latency of N1-wave, P1-wave; Implemented perimetric sensitivity test and analyzed mean light sensitivity.Results Compared with collateral eyes,N1-wave, P1-wave amplitude densities of thrombotic retina attenuated, latencies were delayed.Statistically positive correlation was founded between mean light sensitivity and P1-wave amplitude density (r=0.545, P <0.01).Conclusions Responses from multifocal electroretinogram accurately demonstrate the location and degree of retinal dysfunction in branch retinal vein occlusion and correlate well with perimetry.     

葛根素对兔视网膜缺血/再灌注损伤的保护作用

目的:动态观察葛根素对新西兰大白兔视网膜缺血-再灌注损伤的保护作用.方法:新西兰大白兔30只随机分为缺血再灌注对照组和葛根素治疗实验组每组15只,各组右眼应用前房灌注加压法使前房内压力升高至120 mmHg(1 mmHg=0.133 kPa)维持60 min后再灌注,再灌注后第12、24、72 h分别记录其视网膜电图,与缺血前视网膜电图相比,观察a、b波的变化.葛根素治疗组在造成缺血前2 h予葛根素溶液玻璃体腔内注射,对照组予以玻璃体腔内注射等体积生理盐水.结果:两组右眼在结束造模后立即进行视网膜电图记录所得图形均呈直线;对照组与实验组再灌注各时段视网膜电图a波振幅差异无统计学意义(P》0.05);实验组各时段b波振幅明显高于对照组(P《0.001).结论:葛根素能促进缺血-再灌注损伤的视网膜功能恢复,对视网膜神经组织有保护作用.     

NPDR患者黄斑区视网膜厚度、视网膜神经纤维层厚度与全视野闪光ERG的变化

目的探讨非增生性糖尿病视网膜病变(non-proliferative diabetic retinopathy,NPDR)患者黄斑区视网膜厚度(retinal thickness,RT)、视网膜神经纤维层(retinal nerve fiber layer,RNFL)厚度与全视野闪光视网膜电图(electroretinogram,ERG)的变化及相互关系。方法选择2010年2月至12月于我院就诊的2型糖尿病患者91例(168眼),依据糖尿病视网膜病变(diabetic retinopathy,DR)国际分期标准分为3组:无糖尿病视网膜病变(NDR)组39例(78眼),轻度NPDR组28例(52眼),中重度NPDR组24例(38眼)。另选择同龄正常人30例(60眼)作为正常对照组。通过光学相干断层扫描检测黄斑区中心RT及RN-FL厚度,全视野闪光ERG检测视网膜功能。结果 NDR组、轻度NPDR组、中重度NPDR组患者黄斑区RT分别为(198.01±22.51)μm、(218.00±28.15)μm、(239.90±65.04)μm,均较正常对照组(184.45±18.50)μm增厚,差异均有统计学意义(t=2.312、5.235、7.947,均为P<0.05);随着DR加重,糖尿病各组间黄斑区RT比较,差异均有显著统计学意义(t=3.305、6.300、3.069,均为P<0.01)。正常对照组与NDR组黄斑区RNFL厚度比较,差异无统计学意义(P>0.05);轻度NDPR组及中重度NPDR组与正常对照组相比,黄斑区RNFL厚度变薄,差异均有统计学意义(均为P<0.05)。与正常对照组比较,中重度NPDR组全视野闪光ERG暗适应0.01反应及明适应3.0反应b波潜伏期明显延长(均为P<0.05),暗适应0.01反应b波振幅和暗适应3.0反应a波振幅均下降(均为P<0.05)。结论随着NPDR病情加重,2型糖尿病患者黄斑区中心RT增加,RNFL厚度减小,视网膜功能受损。     

次声作用对小鼠视觉电生理学的影响

目的 探讨次声暴露对小鼠视觉电生理学的影响。方法 150只昆明种成年雄性小鼠按次声的不同参数随机分为5大组，每组30只，每大组小鼠按暴露时间随机分为6小组，每组5只，分别暴露于8Hz、90dB，8Hz、130dB，16Hz、90dB，16Hz、130dB的次声压力舱中，每天暴露2h，分另1在暴露0、1、4、7、14、21d后进行视网膜电图(KRG)、闪光视诱发电位(FVEP)、振荡电位(OPs)的检测。结果 8Hz、90dB，16Hz、90dB实验组视觉电生理指标改变较为相似，仅在一些时间点发生改变。8Hz、130dB实验组大部分视觉电生理指标在第7天实验后就明显改变，并随着暴露时间的增加而加重。16Hz、130dB实验组大部分视觉电生理指标在第1天即明显改变，此后增加暴露时间视觉电生理指标有所恢复。结论 次声对小鼠视觉电生理功能的影响与次声的强度和频率有关。不同参数次声对小鼠视觉功能影响程度不同，可能是由于不同频率的次声与视网膜自身频率接近或符合的程度不同，使视网膜不同种类细胞受损程度不一，产生不同的电位变化。     

斜视性弱视伴偏中心注视眼的多焦视网膜电图表现

目的：探究斜视性弱视伴偏中心注视眼的多焦视网膜电图(mfERG)特征性变化。

方法：收集2018-01/2020-12在我院就诊的斜视性弱视伴偏中心注视患者20例作为研究组(4例为外斜视,16例为内斜视),同时收集屈光不正性弱视患者20例作为对照组。散瞳状态下检查mfERG,记录P1波的振幅密度和潜伏期。

结果：斜视组弱视眼多焦视网膜电图P1波振幅密度与対侧眼相比第一环(P=0.001),第二环(P<0.001),第三环(P=0.001),第四环(P=0.009),第五环(P=0.026)明显降低; 与对照组相比第一环(P=0.033),第二环(P=0.002),第三环(P<0.001),第四环(P=0.014)明显降低; 斜视组弱视眼潜伏期与対侧眼相比第一环(P=0.017)、第二环(P=0.001)有明显缩短,与对照组相比第二环(P=0.007)明显缩短。

结论：斜视性弱视伴偏中心注视眼的多焦视网膜电图P1波振幅密度越靠近黄斑中心凹下降越多,且与屈光不正性弱视眼相比下降更多。     

Adaptive changes of inner retina function in response to sustained pattern stimulation

We have characterized adaptive changes of inner retina function in response to sustained pattern stimulation in 32 normal subjects with an age range 23-77 years by measuring changes of the pattern electroretinogram (PERG) as a function of time. Contrast-reversal stimuli had square-wave profile in space and time, with peak spatial and temporal frequency and high contrast to maximize response amplitude. The PERG signal was sampled over 5 min with a resolution of 15 s. PERG signals were non-stationary, resulting in either progressive amplitude decline or even enhancement to a plateau, with a time course that could be well described by an exponential function with a time constant of 1-2 min. Higher initial amplitudes were generally associated with amplitude decline, and lower initial amplitudes with enhancement. The delta amplitude (plateau minus initial) was a linear function of the initial amplitude. The magnitude of delta decreased with decreasing initial amplitude and inverted its sign for initial amplitudes about 1/3 lower than the maximum initial amplitude measured, but still about 3-4 times larger than the noise. Amplitude decline was generally associated with phase lag, whereas amplitude enhancement was associated with phase advance. Altogether, PERG generators appear to slowly adjust their gain in order to keep their sustained activity at an intermediate level that is rather independent of the level of activity at stimulus onset. This behavior is reminiscent of a buffering mechanism, where glial cells may play a primary role. An energy-budget model of neural-vascular-glial interaction is provided together with an equivalent electrical circuit that accounts for the results.     

Variability in clinically measured photopic oscillatory potentials

Oscillatory potentials found on the ascending phase of the electroretinogram b-wave probably originate in some element(s) of the inner plexiform layer. As oscillatory potentials are particularly sensitive to changes in retinal, and possibly choroidal, blood flow, they have been used extensively to provide clinical measures of the degree of retinal ischemia during the progression of diabetic retinopathy. Recent studies in our laboratories have disclosed previously unreported significant variability in the photopic oscillatory potentials on repeated measures even in tightly controlled conditions. The amplitude of five recordable light-adapted wavelets exhibited considerable intra- and inter-subject variability. Until further investigation can determine factors affecting standardization of testing, it appears that changes in oscillatory potential implicit times rather than in amplitudes are a better measurement in clinical neurophysiology.