Visual evoked cortical potential can be used to differentiate between uncorrected refractive error and macular disorders

Vision before and after scharioth macular lens implantation in patients with AMD: an electrophysiological study

Background

For patients with age-related macular degeneration (AMD), a special intraocular lens implantation partially compensates for the loss in the central part of the visual field. For six months, we evaluated changes in neurophysiological parameters in patients implanted with a “Scharioth macula lens” (SML; a center near high add + 10 D and peripheral plano carrier bifocal lens designed to be located between the iris and an artificial lens).

Methods

Fourteen patients (5 M, 9 F, 63–87 years) with dry AMD were examined prior to and at 3 days after, as well as 1, 2, and 6 months after, implantation using pattern-reversal, motion-onset, and cognitive evoked potentials, psychophysical tests evaluating distant and near visual acuity, and contrast sensitivity.

Results

Near visual acuity without an external aid was significantly better six months after implantation than before implantation (Jaeger table median (lower; upper quartile): 4 (1; 6) vs. 15 (13; 17)). Distant visual acuity was significantly altered between the pre- (0.7 (0.5; 0.8) logMAR) and last postimplantation visits (0.8 (0.7; 0.8) logMAR), which matched prolongation of the P100 peak time (147 (135; 151) ms vs. 161 (141; 166) ms) of 15 arc min pattern-reversal VEPs and N2 peak time (191.5 (186.5; 214.5) ms vs. 205 (187; 218) ms) of peripheral motion-onset VEPs.

Conclusion

SML implantation significantly improved near vision. We also observed a slight but significant decrease in distant and peripheral vision. The most efficient electrophysiological approach to test patients with SML was the peripheral motion-onset stimulation, which evoked repeatable and readable VEPs.

Supplementary Information

The online version containssupplementary material available at (10.1007/s10633-020-09814-8).

The Role of mf-ERG in the Diagnosis and Treatment of Age-Related Macular Degeneration: Electrophysiological Features of AMD

INTRODUCTION

Age-related macular cegeneration (AMD) is the leading cause of visual dysfunction worldwide, affecting 9-25% of individuals between 65 and 75 years old.

METHODS

We have reviewed the published articles investigating the role of multifocal electroretinogram (mf-ERG) in the diagnosis and treatment of AMD.

RESULTS

Visual evoked potentials have revealed decreased amplitudes and higher latencies in patients with AMD, while the degeneration of photoreceptors and abnormalities of retinal pigment epithelium can be identified by electro-oculogram recordings. Moreover, ERG can detect the functional abnormalities observed in AMD and evaluate each therapeutic approach. The record of local electrophysiological responses coming from different retinal areas can be accurately performed by mfERG.

CONCLUSION

The accuracy of mfERG in detecting the degeneration of photoreceptors, as well the disturbances of macular function, could be useful both in the early diagnosis of AMD and the assessment of treatment efficacy.

The Parameters of Pattern Visual Evoked Potential in the Severe Visual Loss Patients in Korean

Purpose

To compare the characteristics of the pattern visual evoked potential (PVEP) in patients with severe visual loss and normal controls, and to demonstrate the range of PVEP parameters in normal Koreans.

Methods

The patients were divided into three groups according to visual acuity: group 1, ranging from no light perception to less than 0.02; group 2, ranging from 0.02 to 0.1; and group 3, ranging from 0.125 to 0.25. Group 4 was established as a healthy control group. The 95% confidence intervals (CIs) of the PVEP parameters were calculated for group 4. The PVEP parameters were compared among these four groups, and the amplitudes were evaluated with respect to the 95% CIs. We used the area under the curve to integrate the sensitivity and the specificity of the PVEP parameter quantitative values (7.01 to 9.57 µV and 6.75 to 10.11 µV).

Results

A total of 101 eyes were investigated. The 95% CIs of the P100 and N135 amplitudes of group 4 were 7.01 to 9.57 µV and 6.75 to 10.11 µV, respectively. The amplitudes of P100 and N135 were significantly higher in group 4 (p < 0.001). The P100 and N135 amplitude were below the 95% CI in all group 1 patients. The area under the curve of the P100 amplitude was the highest (0.789).

Conclusions

No legally blind patient in the present study exhibited a value within the 95% CI of the controls. The P100 amplitude may be the best parameter for defining blindness in patients.

Relationship of chromatic visual-evoked potentials and the changes of foveal photoreceptor layer in central serous chorioretinopathy patients

PURPOSE

To investigate the relative involvement of chromatic and achromatic visual subsystems in central serous chorioretinopathy, and to correlate the function changes with the changes of the foveal photoreceptor layer using Fourier domain optical coherence tomography (FD-OCT).

METHODS

Central serous chorioretinopathy patients and control subjects were tested and compared. Equiluminant Chromatic sinusoidal gratings were presented in a pattern onset-offset mode. We measured the distance between the internal limiting membrane (ILM) and the external limiting membrane (ELM) on FD-OCT images.

RESULTS

Visual evoked potential mean latency was delayed significantly in central serous chorioretinopathy patients compared to controls. The visual evoked potential delay was greater for chromatic than for achromatic stimuli. Retinal thickness from ILM to ELM was associated significantly and selectively with short-wavelength-sensitive (S) cone visual evoked potential latency (r = -0.40, p = 0.032).

CONCLUSIONS

These results are consistent with data that indicate the loss of photoreceptors in central serous chorioretinopathy resulting in a reduced thickness of the outer nuclear layer. Additionally, they are consistent with data which indicate that the photoreceptor loss is relatively greater in cones. The S-cone pathway was affected the most.

Hypotrichosis with Juvenile Macular Dystrophy

PURPOSE

To evaluate retinal function in subjects suffering from hypotrichosis with juvenile macular dystrophy (HJMD).

DESIGN

Retrospective case-control study.

PARTICIPANTS

Sixteen HJMD patients belonging to 2 genetic groups and 20 control subjects.

METHODS

The HJMD patients underwent clinical ophthalmological examination and electrophysiological testing for a period of as many as 14 years. The electroretinogram (ERG), electro-oculogram (EOG), and visual evoked potential (VEP) were recorded serially to assess visual function and to follow possible progression of the disease.

MAIN OUTCOME MEASURES

Amplitudes and implicit times of ERG and VEP, and Arden ratio of EOG.

RESULTS

Fundus examination revealed pigmentary abnormalities with atrophic changes at the posterior pole extending to regions beyond the macular area. A slow and time-dependent decline in visual acuity was noted. The ERG responses were subnormal in amplitude. The ERG deficit was similar for light- and dark-adapted responses. There was a gradual but consistent decrease in the ERGs with time. The EOG measurements were within the normal range. Pattern reversal VEPs were very subnormal, even in patients with mild deterioration of visual acuity. The flash VEPs were of slightly subnormal amplitudes and implicit times in the upper limit of the normal range.

CONCLUSIONS

The fundus pictures and electrophysiological tests were consistent with retinal involvement extending beyond the macular region. Follow-up of visual acuity and ERG testing indicated a slowly progressing retinal disorder affecting cone-mediated vision as well as rod-mediated vision. Therefore, we suggest that a more appropriate name for this syndrome is hypotrichosis with cone-rod dystrophy.

Effect of defocusing and of distracted attention upon recordings of the visual evoked potential

Pattern reversal visual stimuli are used to evoke potentials (VEPs) for assessment of visual acuity and for localizing defects along the visual pathways. Our goal was to assess the importance of attention and defocusing to the recordings of pattern VEP. Forty-one volunteers with normal (6/6) corrected visual acuity participated in this study. Twenty-one were asked to defocus intentionally the visual stimulus (located 200 cm away) by fixating at a target 25 or 50 cm from the eye. Twenty other subjects performed auditory tasks to distract their attention from the visual stimulus. Pattern VEPs were elicited by different check sizes. The amplitude and time-to-peak of the P100 wave were measured. Intentional defocusing caused amplitude reduction and prolongation of the time-to-peak in young subjects (20-34 years old). With the smallest checks used (7.5') we could not record a reliable response from 43% of the young subjects (6 out of 14). In older patients (35-61 years old), intentional defocusing induced negligible effects on pattern VEPs regardless of check size. There were no effects of auditory distraction upon the pattern VEPs. Our data suggest that intentional defocusing can produce false positive results (reduced VEP with prolonged time-to-peak) only when small checks are used in young subjects. Divided attention has negligible effect on the recordings of pattern VEPs. With proper controls, the pattern VEP test can be used for objective assessment of visual function.