A Comparison of the Fast Stimulation Multifocal-ERG in Patients with an IOL and Control Groups of Different Age

[Performance evaluation of multifocal electroretinography for monocular and binocular stimulation in anisochromoartiphakia]

Multifocal electroretinography (mfERG) helps evaluate the electrical potential of the retina in a set of points within 30 degrees. There is a significant number of factors affecting the value of mfERG data, which should be taken into account in research studies.

PURPOSE

To evaluate the difference and nature of changes in the amplitude (P1) and latency (P1, L1) parameters of mfERG in monocular (MS) and binocular stimulation (BS) in individuals with anisochromoartiphakia.

MATERIAL AND METHODS

The study included 24 patients aged 76.3±7.9 years with anisochromoartiphakia [one eye - IOL with yellow spectrum SN60AT (yIOL); the other is a transparent IOL - Rayacryl (trIOL)] comprising the main group, and 16 patients without artiphakia aged 51.6±4.6 years in the control group [one eye with the addition of a yellow light filter (YF) ZHS1 - a spectral analog of SN60AT, the other - without YF]. Recording of mfERG was done with MS and BS. Parameters under evaluation were DP1 (nV/deg²), amplitude P1 (mV) and latency LP1, LN1 (ms) in rings R1-R5.

RESULTS

In general, when switching from one ring to another under both types of stimulation and spectral correction, all indicators decrease. DP1 and P1 in MS and BS in the control group (49.2±17.7 and 53.6±17.5 nV/deg²) compared to the main group were higher (42.9±15.0 and 47.7±17.3 nV/deg²), LP1 and LN1 were shorter (41.2±5.0 and 44.8±4.3 ms in the control group, 44.0±4.1 and 50.7±21.1 ms in the main group). There was a significant difference between DP1R3 and DP1R4 in the control group (p≤0.003-0.050). In the control group without YF, P1R2 under MS was statistically significantly higher than under BS (p≤0.028). LP1 of R1, R3, R5 in the intergroup comparison was statistically significantly shorter in the control group without YF and MS (p≤0.033) and with YF in R1-R3, R5 (p≤0.003-0.023). LP1R2, LP1R4 were statistically significantly higher with trIOL in the main group under MS (p≤0.015; 0.047) and with yIOL in LP1R1, LP1R4, and LR5 (p≤0.053). The intergroup comparison showed that in the main group with yIOL, LP1R5 was statistically significantly lower under MS than BS (p≤0.032). When comparing LN1 between the groups, the statistically significant difference under MS without YF was observed in R5 (p≤0.002), while the difference under BS was insignificant. For YF, the increase in LN1 was statistically significant for MS in R2 and R3 (p≤0.010; 0.037) and for BS - in R1, R2 and R4 (p≤0.037; 0.003; 0.020). The intergroup comparison revealed that in the control group without YF, LN1R2 was statistically significantly lower under MS than BS (p≤0.028), and in the main group with trIOL, LN1R3 under MS was statistically significantly lower than under BS (p≤0.041).

CONCLUSION

In anisochromoartiphakia, spectral differences in the optical environment of the eye lead to changes in the parameters of mfERG in the form of a decrease in DP1 and elongation of LP1 and LN1 in comparison with healthy eye and non-spectral intraocular correction. MS or BS in mfERG does not have a significant impact on the character and value of these parameters. The use of a single-stage binocular recording of mfERG reduces the duration of the study, which is especially important when examining elderly patients.

Fundus motion during mfERG testing

PURPOSE

The purpose of this study was to assess eye movements during a multifocal ERG (mfERG) recording. This study evaluated the relationship between bivariate contour ellipse areas (BCEAs), mfERG amplitudes (Amps) and mfERG implicit times (ITs) with repeat testing and experienced subjects.

METHODS

Thirty subjects were selected (15 experienced to ocular procedures and 15 novices). All were confirmed to have healthy retinas and at least 20/25 vision. MfERGs with a stimulus near 100% contrast and 4-min m-sequence were recorded on two different days using our common clinical technique, which did not constrain the head. VERIS with fundus monitoring system was used for recording with a Burian-Allen electrode. An external camera captured the fundus during each mfERG recording. The optic nerve head position was tracked in each video using a custom algorithm in order to determine BCEAs. Each subject performed one mfERG on two different days. MfERGs were analyzed for Amps and ITs for the fovea and whole eye.

RESULTS

There was no correlation between the mfERG metrics and BCEAs with repeat testing. There were also no differences between the experienced and novice subjects for mfERG Amps, ITs or BCEAs. Eye movements between visits were highly correlated (multiple r = 0.67). BCEAs were larger during mfERGs (1.04 ± 0.8 deg²) than those observed in previous literature using brief viewing tasks (< 0.3 deg²). The proportion of time spent fixating within 1.0 and 2.0 degrees of the central hexagon was 68 and 93%, respectively.

CONCLUSIONS

This study is the first to evaluate the stability of the retina while recording a mfERG in healthy subjects and indicates that the center of fixation during a mfERG stays within the central hexagon. Eye stability during an initial recording is the best indicator of stability on the second recording. The amount of movement during these recordings did not seem to affect the mfERG Amps or ITs. These data suggest clinical confidence with mfERGs when recording novice patients.

[Functional results of spectral correction of vision]

PURPOSE

To study the data of monocular and binocular multifocal electroretinogram (mfERG), flash visual evoked potential (f-VEP), spatial contrast sensitivity (SCS) with and without yellow filters in healthy elderly people.

MATERIAL AND METHODS

The study included 16 people (8 male and 8 female) with average age of 51.63±4.7 years. Their visual acuity was 0.5±0.35 without correction and 1.0 with correction. For spectral correction, we used Y1 color filters (CF) (analogue of SN60AT) from the «Lornet-M vision spectral correction kit» set with 80% light transmission and wave cut-off of 460 nm. Patients had mfERG recordings performed monocularly and binocularly, f-VEP monocularly, and their spatial contrast sensitivity (SCS) was measured (Astroinform SPE, Russia). The data acquired before and after applying CF was compared.

RESULTS

The data of SCS with light filter was slightly higher at medium and high spatial frequencies (SF): for the right eye on medium SF of 43.8 and 41.8 dB (p≤0.735), 41.5 and 39.8 dB (p≤0.061) for the left eye. The increase of mfERG P1 latency monocularly after application of CF in the R1 ring area was 3.0 ms (40.8-43.8ms) for the right eye (p≤0.05) and 0.9 ms for the left eye (43.7-44.5ms) (p≤0.326). The trend remained for simultaneous mfERG.

CONCLUSION

The influence of yellow filters on spectral vision correction can be manifested in inconsistency of SCS, f-VEP, monocular and binocular mfERG readings. Statistically significant differences in healthy individuals of 5th-6th age decades manifest as elongation of the latency of mfERG peaks.

[Morphological and functional condition of the macula after different types of phaco cataract surgeries]

One of the directions of advancing phaco technology is related to adoption of hybrid phacoemulsification for clinical practice. Potential postsurgical changes in the macular area, when other factors are equal, can be seen as a conditional criterion for the injury rate of phaco surgeries.

PURPOSE

To evaluate morphological and functional condition of the macular area after different types of phaco cataract surgeries.

MATERIAL AND METHODS

Two groups were formed for comparative study in accordance with criteria for standardization and maximum mitigation of the impact of other factors on the condition of the retina - with standard ultrasound and hybrid (femtolaser-assisted) phacoemulsification (30 operations in each group). Examinations were performed initially, then 7-10 days, and 2-3 month after the surgery. Optical coherence tomography (OCT) and multifocal electroretinography (mfERG) were performed for evaluation of the morphological and functional condition of the macular area.

RESULTS

There was no statistically significant dependence of linear and volumetric measures in the macular area on phaco surgery method, and the few variations were most likely related to increasing the time of ultrasound action in standard phacoemulsification. Revealed changes turned out to be significantly less marked than what is considered critical for development of macular edema. Improvement of baseline multifocal electroretinography measurements (increase of the density of retinal biopotential and decrease of latent time) just after the surgery results from the effect the lens opacification has on basic parameters, regardless of phacoemulsification technique. There were no significant differences in postsurgical measurements of multifocal electroretinography obtained in similar periods of postsurgical assessment after standard ultrasound and hybrid phacoemulsification.

CONCLUSION

The results prove the safety of phaco surgery methods and the absence of negative impact of femtolaser component of hybrid phacoemulsification on structural and functional condition of central retina.

Test-retest repeatability of the pattern electroretinogram and flicker electroretinogram

PURPOSE

To evaluate the repeatability of the steady-state pattern electroretinogram (PERG) and full-field flicker electroretinogram (Flicker ERG) protocols, delivered by the office-based Neuro Optic Vision Assessment (NOVA)™ testing platform, in healthy subjects.

METHODS

Healthy individuals underwent PERG (16° and 24°) and Flicker ERG [fixed luminance (FL) and multi-luminance (ML)] testing protocols. Test-retest repeatability of protocols was calculated using intra-class correlation coefficients (ICC). Reference values of the parameters of the aforementioned tests were also calculated.

RESULTS

The ICCs for the PERG parameters ranged from 0.793 to 0.911 (p < 0.001). The ICCs for the Flicker ERG parameters ranged from 0.968 to 0.994 (p < 0.001). A linear regression analysis was applied to assess the impact of age on ERG responses. Age had a significant impact on all PERG parameters (16° or 24°). The phase response of the FL Flicker ERG significantly decreased with age (β = - 0.837, p ≤ 0.001). The FL Flicker ERG Magnitude was also impacted with a significant quadratic effect of age (β = - 0.0047, p = 0.0004). Similarly, the Phase Area Under the Curve (Phase AUC) of the ML Flicker ERG significantly declined with age (β = - 0.007, p = 0.009), and the impact on the Magnitude AUC was significant as well, with a negative quadratic age effect.

CONCLUSIONS

The PERG and Flicker ERG protocols, delivered by an office-based testing platform, were shown to have good-to-excellent test-retest repeatability when tests were performed in the same order and in immediate succession.

Ganglion cell layer segmentation and the two-flash multifocal electroretinogram improve structure function analysis in early glaucoma

Purpose

To improve structure-function analysis in primary open-angle glaucoma (POAG) by including the two-global flash multifocal electroretinogram (2F–mfERG) and macular ganglion cell layer segmentation.

Methods

Twenty-five glaucoma patients (six pre-perimetric (PPG), 19 POAG) and 16 controls underwent 2F–mfERG, optical coherence tomography (OCT), and standard automated perimetry (SAP). For 2F–mfERG, the root mean square was calculated for the focal flash response at 15–45 ms (DC) and the global flash responses at 45–75 ms (IC1) and 75–105 ms (IC2). For OCT, macular total thickness (mT) and ganglion cell-inner plexiform layer (GCIPL) thickness were analysed. Values from the central 10° and 15° of 2F-mfERG were compared to the corresponding areas from OCT and visual field.

Results

Both PPG and POAG had significantly lower mfERG responses in the central 10° and 15° than the control group. Of the glaucoma patients, 30.7% (three PPG, five POAG) showed central mfERG and GCIPL reduction without a SAP defect in the central 15 degrees. Four patients had a central SAP defect associated with a reduced GCIPL without any detectable dysfunction on mfERG. MfERG DC and IC2 were larger with increased mT (p ≤ 0.02), but GCIPL only related positively to IC2 (p = 0.027). SAP sensitivity also increased with thicker mT but not with GCIPL (p < 0.03 and p = 0.35). DC, IC2, and GCIPL could best differentiate glaucoma from control (AUC values: 0.897, 0.903, and 0.905).

Conclusions

Structure function analysis in glaucoma can be improved when the GCIPL thickness as well as the 2F–mfERG is included as these measures complement information obtained by SAP.

The Effect of an Inverted Internal Limiting Membrane Flap on Retinal Function after Macular Hole Surgery

PURPOSE

To study the effect of an inverted internal limiting membrane (ILM) flap on the retina.

DESIGN

Prospective case series.

PARTICIPANTS

Twenty-nine patients with large (>400 μm) unilateral macular holes underwent surgery using a modified inverted ILM flap technique.

METHODS

The macular ILM was peeled, and a large (2-3 disc diameter) ILM flap was made on the superior side of the hole, and then the flap was inverted on the inferior side.

MAIN OUTCOME MEASURES

In all patients, multifocal electroretinograms (mfERGs) were recorded from operated eyes and normal fellow eyes. The peak time and amplitude of N1, P1, and N2 in the focal ERG from the upper retina without the ILM flap and those from the lower retina with the ILM flap were evaluated. In 14 patients, microperimetry was also performed in both eyes, and the averaged sensitivity was measured from the upper and lower areas.

RESULTS

The peak times of P1 and N2 from the upper and lower retina were significantly longer in operated eyes than in the fellow eyes (P1 upper and lower: P < 0.04, N2 upper: P < 0.01, and N2 lower: P < 0.04), although we could not identify a significant difference in peak time and amplitude of N1, P1, and N2 between the upper retina and lower retina in both eyes (fellow eye-N1 amplitude: P > 0.2, N1 peak time: P > 0.5, P1 amplitude: P > 0.9, P1 peak time: P > 0.4, N2 amplitude: P > 0.9, N2 peak time: P > 0.9; operated eye-N1 amplitude: P > 0.8, N1 peak time: P > 0.4, P1 amplitude: P > 0.6, P1 peak time: P > 0.4, N2 amplitude: P > 0.9, N2 peak time: P > 0.9). We could not observe a significant difference in sensitivity between the upper and lower retinas in both eyes (fellow eye: P = 0.28, operated eye: P = 0.66).

CONCLUSIONS

The results of this study revealed no significant difference between the upper retina without the ILM flap and the lower retina with the ILM flap, suggesting that an inverted ILM flap has little effect on retinal function.