Evaluation of retinal ganglion cell function after intraocular pressure reduction measured by pattern electroretinogram in patients with primary open-angle glaucoma

Background

To evaluate retinal ganglion cell (RGC) function after intraocular pressure (IOP) reduction measured by pattern electroretinogram (PERG) in patients with newly diagnosed, non-treated preperimetric and early stages of primary open-angle glaucoma (POAG).

Methods

Twenty-four eyes from 24 patients with POAG: 11 eyes with preperimetric glaucoma and 13 eyes with early glaucoma received Ganfort ^® (bimatoprost + timolol) once a day for a period of 1 month. Before and after the treatment, following measurements were analyzed: IOP, mean ocular perfusion pressure (MOPP), peak time of P50 and amplitude of P50 and N95 waves in PERG (ISCEV standard 2012). Correlations between PERG P50 and N95 waves, IOP and MOPP were calculated.

Results

After therapy, IOP significantly decreased in all eyes, on average 31%. Significant increase in MOPP in all eyes on average 14% was detected. PERG amplitude of P50 and N95 waves increased in 75 and 79% eyes, respectively, on average P50 by 28% and N95 by 38%. There were no significant interactions between the change of PERG parameters in time and stage of glaucoma.

Conclusions

Significant IOP-lowering therapy can improve RGC function measured by PERG, in patients with preperimetric and early stages of POAG.

     

Multifocal electroretinogram responses in Nepalese diabetic patients without retinopathy

Purpose

To determine neuroretinal function with multifocal electroretinogram (mfERG) in diabetic subjects without retinopathy.

Methods

Multifocal electroretinogram (mfERG) was performed in 18 eyes of 18 diabetic subjects without retinopathy and 17 eyes of 17 age and gender-matched healthy control participants. Among 18 diabetic subjects, two had type 1 and 16 had type 2 diabetes. MfERG responses were averaged by the retinal areas of six concentric rings and four quadrants, and 103 retinal locations; N1–P1 amplitude and P1-implicit time were analysed.

Results

Average mfERG N1–P1 amplitude (in nv/deg²) of 103 retinal locations was 56.3 ± 17.2 (mean ± SD) in type 1 diabetic subjects, 47.2 ± 9.3 in type 2 diabetic subjects and 71.5 ± 12.7 in controls. Average P1-implicit time (in ms) was 43.0 ± 1.3 in type 1 diabetic subjects, 43.9 ± 2.3 in type 2 diabetic subjects and 41.9 ± 2.1 in controls. There was significant reduction in average N1–P1 amplitude and delay in P1-implicit time in type 2 diabetic subjects in comparison to controls. mfERG amplitude did not show any significant correlation with diabetes duration and blood sugar level. However, implicit time showed a positive correlation with diabetes duration in type 2 diabetic subjects with diabetes duration ≥5 years.

Conclusions

This is the first study in a Nepalese population with diabetes using multifocal electroretinography. We present novel findings that mfERG N1–P1 amplitude is markedly reduced along with delay in P1-implicit time in type 2 diabetic subjects without retinopathy. These findings indicate that there might be significant dysfunction of inner retina before the development of diabetic retinopathy in the study population, which have higher prevalence of diabetes than the global estimate and uncontrolled blood sugar level.     

Evaluation of structural and functional changes in non-pathologic myopic fundus using multifocal electroretinogram and optical coherence tomography

Purpose

To evaluate structural and functional changes in non-pathologic myopic fundus using multifocal electroretinogram (mfERG) and spectral domain-optical coherence tomography (SD-OCT).

Methods

A total of 90 myopic subjects underwent mfERG and SD-OCT. The subjects were divided into four groups according to spherical equivalent refractive error: Group 1 (?0.50 to ?2.75 D), Group 2 (?3.00 to ?5.75 D), Group 3 (?6.00 to ?9.75 D), and Group 4 (?10.0 to ?15.0 D). Total retinal thickness, photoreceptor retinal thickness (PR), outer nuclear retinal thickness and mid-inner retinal thickness (MIR) were measured using SD-OCT in foveola and two perifoveal retinal regions 2.0 mm nasal and temporal from the foveola. The amplitude and implicit time of N1 and P1 mfERG responses were analyzed using six-concentric-ring grouping. Correlations between each retinal thickness, amplitude, and implicit time among the four myopic groups were analyzed.

Results

PR thickness in the foveola and MIR thickness in the perifoveal retina were significantly reduced with increasing myopic refractive errors (p = 0.001, respectively). Significant correlations appeared between N1 amplitude, P1 amplitude, P1 implicit time, and refractive errors (p = 0.001, respectively). Significant correlations appeared between MIR thickness and N1, P1 amplitude (p = 0.001, respectively) as well as N1, P1 implicit time (p = 0.02 and 0.03, respectively) in the perifoveal retina corresponding to ring 4.

Conclusions

The correlation between structural and functional changes in myopia should be considered when interpreting retinal structure and function using SD-OCT and mfERG, especially in high myopia.     

Visual prognostic value of photopic negative response and optical coherence tomography in central retinal vein occlusion after anti-VEGF treatment

Objective

To investigate the potential of optical coherence tomography (OCT) and photopic negative response (PhNR) for predicting visual outcome after intravitreal bevacizumab in patients with macular edema secondary to central retinal vein occlusion (CRVO).

Methods

Thirty-two consecutive patients with macular edema secondary to unilateral CRVO who were treated with three times of 6 weeks interval intravitreal bevacizumab were enrolled. LogMAR visual acuity (Va), OCT and PhNR were done before and 4 weeks after first and third injection. Stepwise multiple regression analysis was conducted between pre-treatment Va, central retinal thickness, b wave amplitude, PhNR amplitude, PhNR relative amplitude (affected eye/unaffected fellow eye,  % presentation) and post-treatment Va at 4 weeks after the third injection. The predictive values of pre-treatment parameters for good visual outcome (0.2 ≤ LogMAR Va) were assessed using receiver-operating characteristics (ROC) analysis.

Results

In multiple regression analysis, pre-treatment Va (β = 0.615, P = 0.001) and PhNR relative amplitude (β = ?0.352, P = 0.032) were correlated significantly with post-treatment Va. In ROC analysis, pre-treatment Va showed a 80 % sensitivity and 80 % specificity for predicting good visual outcome, at a cutoff value of 0.52 LogMAR. Pre-treatment PhNR relative amplitude demonstrated a 88 % sensitivity and 75 % specificity for predicting good visual outcome, at a cutoff value of 40.00 %.

Conclusions

The PhNR relative amplitude can be a useful prognostic factor for visual outcome after intravitreal bevacizumab therapy in patient with macular edema secondary to CRVO. Patients with larger pre-treatment PhNR relative amplitude with better pre-treatment Va showed a better post-treatment visual outcome.     

Multifocal electroretinography in subjects with age-related macular degeneration

Purpose

To evaluate retinal function objectively in subjects with different stages of age-related macular degeneration (AMD) using multifocal electroretinography (mfERG) and compare it with age-matched control group.

Methods

A total of 42 subjects with AMD and 37 age-matched healthy control group aged over 55 years were included in this prospective study. mfERG test was performed to all subjects. Average values in concentric ring analysis in four rings (ring 1, from 0° to 5° of eccentricity relative to fixation; ring 2, from 5° to 10°; ring 3, from 10° to 15°; ring 4, over 15°) and in quadrant analysis (superior nasal quadrant, superior temporal quadrant, inferior nasal quadrant and inferior temporal quadrant) were recorded. Test results were evaluated by one-way ANOVA test and independent samples t test.

Results

In mfERG concentric ring analysis, N1 amplitude, P1 amplitude and N2 amplitude were found to be lower and N1 implicit time, P1 implicit time and N2 implicit time were found to be delayed in subjects with AMD compared to control group. In quadrant analysis, N1, P1 and N2 amplitude was lower in all quadrants, whereas N1 implicit time was normal and P1 and N2 implicit times were prolonged in subjects with AMD.

Conclusion

mfERG is a useful test in evaluating retinal function in subjects with AMD. AMD affects both photoreceptors and inner retinal function at late stages.     

Optical coherence tomography shows early loss of the inferior temporal quadrant retinal nerve fiber layer in autosomal dominant optic atrophy

Purpose

The aim of the study was to evaluate the relationship between visual function and retinal nerve fiber layer thickness (RNFLT) determined using Stratus optical coherence tomography (OCT) in patients with autosomal dominant optic atrophy (ADOA).

Methods

The study was a retrospective, institutional, and comparative case series. Thirty-six consecutive patients with ADOA and 72 age-matched normal controls were compared with regard to RNFLT, best-corrected visual acuity (BCVA), and visual field.

Results

The relative reduction of RNFLT of ADOA patients was most evident in the temporal quadrant (56.8 %), followed by the inferior (35.5 %), superior (27.2 %), and nasal quadrants (26.4 %). In ADOA patients, BCVA decreased with RNFL thinning (p?<?0.001), and was not related to age (p?=?0.210). Papillomacular bundle RNFLT decreased with age throughout the study period of 3.7?±?2.3 years (?3.83?±?9.96 μm, p?=?0.017). The presence of a superotemporal central scotoma (61.1 %) was related to decreased inferotemporal RNFLT (7 and 8 o’clock, p?=?0.016 and p?=?0.036, respectively).

Conclusions

The papillomacular bundle RNFL of ADOA is most vulnerable and progressively damaged with age, despite early temporal RNFL loss. Early loss of inferior temporal RNFL in ADOA is related to superotemporal central scotoma.

     

Pattern electroretinogram in neuromyelitis optica and multiple sclerosis with or without optic neuritis and its correlation with FD-OCT and perimetry

Purpose

To evaluate the ability of transient pattern electroretinogram (PERG) parameters to differentiate between eyes of patients with neuromyelitis optica (NMO), longitudinally extensive transverse myelitis (LETM), multiple sclerosis with optic neuritis (MS + ON), multiple sclerosis without optic neuritis (MS ? ON), and controls, to compare PERG and OCT with regard to discrimination ability, and to assess the correlation between PERG, FD-OCT, and visual field measurements (VFs).

Methods

Visual field measurements and full-field stimulation PERGs based on both 48- and 14-min checks were obtained from patients with MS (n = 28), NMO (n = 20), LETM (n = 18), and controls (n = 26). In addition, FD-OCT peripapillary retinal nerve fiber layer (RNFL) and segmented macular layer measurements were obtained and their correlation coefficients were determined.

Results

Compared to controls, PERG amplitude measurements were significantly reduced in eyes with NMO and MS + ON, but not in eyes with LETM and MS ? ON. PERG amplitudes were significantly smaller in NMO and MS + ON eyes than in MS ? ON eyes. PERG and OCT performance was similar except in NMO eyes where macular thickness parameters were more efficient at detecting abnormalities. A significant correlation was found between N95 amplitude values and OCT-measured macular ganglion cell layer thickness, total retinal thickness, and temporal peripapillary RNFL thickness. PERG amplitude was also significantly associated with VF sensitivity loss. No statistically significant difference was observed with regard to the best-performing parameters of the two methods.

Conclusions

Pattern electroretinogram measurements were able to detect RNFL loss in MS + ON and NMO eyes, with a performance comparable to OCT. PERG amplitude measurements were reasonably well correlated with OCT-measured parameters.     

Topography and correlation of radial peripapillary capillary density network with retinal nerve fibre layer thickness

Purpose

To analyse the expansion of radial peripapillary capillary (RPC) network with optical coherence tomography angiography (OCT-A) in normal human eyes and correlate RPC density with retinal nerve fibre layer thickness (RNFLT) at various distances from the optic nerve head (ONH) edge.

Methods

Fifty eyes of 50 healthy subjects underwent imaging with RTVue XR-100 Avanti OCT. OCT-A scans of Angio disc (6 × 6 mm) and Angio retina (8 × 8 mm) were combined to create a wide-field montage image of the RPC network. RPC density and RNFLT was calculated at different circle diameter around the ONH, and their correlation was measured.

Results

In the arcuate region, RPC was detected as far as 8.5 mm from the ONH edge, but not around the perifoveal area within 0.025 ± 0.01 mm². The mean RPC density (0.1556 ± 0.015) and RNFLT (245.96 ± 5.79) were highest at 1.5 mm from ONH margin, and there was a trend in its decline, in a distance-dependent manner, with the least density at 8.5 mm (all P < 0.0001). Highest RPC density was noted in the arcuate fibre region at all the distances. Overall mean RPC density correlated significantly (P < 0.0001) with the overall mean RNFLT.

Conclusions

Wide-field montage OCT-A angiograms can visualize expansion of the RPC network, which is useful in obtaining information about various retinal disorders. The results obtained support the hypothesis that the RPC network could be responsible for RNFL nourishment.

     

The association of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> with choroidal and retinal nerve fiber layer thickness

Purpose

To investigate the effect of Helicobacter pylori (H. pylori) infection on choroidal thickness (CT) and retinal nerve fiber layer thickness (RNFLT).

Methods

The study included 25 patients with H. pylori infection and 25 healthy individuals as the control group. Helicobacter pylori patients were classified as the pre-treatment (Group 1; n: 25) and the post-treatment (Group 2; n: 25). RNFLT and CT were measured before and after treatment of H. pylori infection, using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering, Heidelberg, Germany). The axial length and intraocular pressure were also measured.

Results

The mean subfoveal CT was 320.96 ± 29.15 μm in Group 1 and 287.48 ± 49.17 in the control group (p = 0.007), while the mean subfoveal CT did not show any difference between Group 2 and the control group (p > 0.05). No statistically significant difference was determined between the H. pylori patients and the control group in respect of RNFLT values (p > 0.05).

Conclusions

CT increases during H. pylori infection and returns to the normal range within 6 weeks of treatment. RNFLT does not show any change during H. pylori infection. The data related to the subfoveal CT may be useful in understanding the pathogenesis of central serous chorioretinopathy developing in H. pylori patients.

     

Pattern ERG and RNFL thickness in hypertensive eyes with normal blue-yellow visual field

Purpose

To evaluate the transient pattern electroretinogram (t-PERG) and the retinal nerve fiber layer (RNFL) thickness in eyes with ocular hypertension (OH) and normal short-wavelength automated perimetry (SWAP).

Methods

In 26 patients with bilateral OH with normal SWAP, and in 26 age and sex matched healthy controls, t-PERG recording and RNFL thickness measurement were performed. Mean deviation (MD) and pattern standard deviation (PSD) of a reliable full threshold 24-2 SWAP were considered. RNFL thickness was determined by OCT3. Monocular PERG were recorded by using a black and white checkerboard pattern (check size 0.9°, contrast 100 %, mean luminance 80 cd/m2) generated on a monitor and reversed in contrast (four reversals per second, 2 Hz) at a distance of 70 cm. Patients had optimal correction at viewing distance; no mydriatic or miotic eye drops were used. Silver/silver chloride skin electrodes were placed over the lower eyelids in the stimulated eye (active electrode) and in the patched eye (reference electrode); ground electrode was in the Fpz scalp. Peak-to peak amplitude of P50 (N35-P50) and N95 (P50-N95) waves, and implicit time of P50, were considered.

Results

Compared to controls, in OH eyes, a reduction of N35-P50 amplitude (2.86?±?1.49 vs. 3.77?±?1.08 microvolts, ?24.1 %, t-test p?=?0.015), of average RNFL thickness (88?±?11 vs. 96?±?10 μm, ?9.5 %, t-test p?=?0.002), and of RNFL thickness in superior (p?=?0.015) and inferior quadrant (p?<?0.001), were found. Multivariate analysis showed that in OH eyes, N35-P50 amplitude was inversely related to intraocular pressure (IOP) (p?=?0.001); no correlation was found between N35-P50 amplitude and MD, PSD, CCT or RNFL thickness.

Conclusions

In OH eyes, both PERG and RNFL thickness changes occur in hypertensive eyes with undamaged SWAP; the correlation of PERG amplitude with IOP, but not with RNFL thickness, suggests that such PERG changes are an effect of the IOP on retinal ganglion cells, rather than a sign of their loss.     

Morphological and electrophysiological outcome in prospective intravitreal bevacizumab treatment of macular edema secondary to central retinal vein occlusion

Purpose

To evaluate intravitreal bevacizumab (IVB) treatment in patients with central retinal vein occlusion (CRVO) by spectral domain optical coherence tomography (OCT) and electroretinography (ERG).

Methods

Twenty-two CRVO patients were treated with IVB injections and followed for 1 year. Morphological effect of treatment was observed with fluorescent angiography and OCT. Functional effect was followed with best corrected visual acuity (BCVA) and ERG: combined rod-cone response of the standard full-field ERG (dark adapted 3.0 ERG), photopic negative response (PhNR), and pattern ERG (PERG).

Results

Best corrected visual acuity (BCVA) improved by 18.2 letters after 6 months (p ≤ 0.001) and additional 4.7 letters by the 12th month (p ≤ 0.001). The central retinal thickness of 829.8 ± 256.7 μm decreased to 398.8 ± 230 μm (p ≤ 0.001) after 6 months and to 303.7 ± 128.9 μm during the following 6 months (p ≤ 0.001). The total macular volume (14.4 ± 4.2 mm³) decreased to 9.6 ± 3.2 mm³ and 8.5 ± 2.0 mm³ after 6 months and 1 year of treatment, respectively (p ≤ 0.001). Electrophysiological measures improved significantly after 6 months and 1 year of treatment: the a-wave implicit time of dark adapted 3.0 ERG from 25.6 ± 2.3 to 24.1 ± 2.1 and 24.1 ± 2.0 ms (p ≤ 0.01); the PhNR from ?5.9 ± 6.6 to ?9.4 ± 6.1 and ?10.4 ± 4.6 µV (p ≤ 0.05); the PERG P50 amplitude from 0.2 ± 0.3 to 0.9 ± 0.6 and 1.1 ± 0.6 µV (p ≤ 0.001); and N95 amplitude from 0.4 ± 0.6 to 1.2 ± 0.9 and 1.6 ± 0.9 µV (p ≤ 0.001).

Conclusions

Intravitreal bevacizumab (IVB) treatment of macular edema due to CRVO improved standard morphological measures and the electrophysiological function of outer and inner retinal layers, which was most evident in central retina.     

Predictive value of N95 waveforms of pattern electroretinograms (PERGs) in children with optic nerve hypoplasia (ONH)

Purpose

As part of a long-term, prospective study of prenatal and clinical risk factors for optic nerve hypoplasia (ONH) at Children’s Hospital Los Angeles, pattern ERGs (PERGs) were evaluated for prognostic value using an automated objective and robust analytical method.

Methods

Participants were 33 children with ophthalmoscopically diagnosed ONH [disc diameter-to-disc macula ratio (DD/DM) less than 0.35 in one or both eyes on fundus photographs]. Using cycloplegia and chloral hydrate sedation in one session before 26 months of age, we recorded PERGs to checkerboard reversal using five check sizes. Participants were followed with clinical and psychometric testing until 5 years of age. PERGs were analysed using automated robust statistics based on magnitude-squared coherence and bootstrapping optimized to objectively quantify PERG recovery in the challenging recordings encountered in young patients. PERG measures in the fixating or better-seeing eyes were compared with visual outcome data.

Results

PERG recording was complete to at least three check sizes in all eyes and to all five sizes in 79%. Probability of recording a PERG that is significantly different from noise varied with check size from 73% for the largest checks to 30% for the smallest checks (p = 0.002); smaller waveforms were associated with earlier implicit times. The presence of significant PERGs in infancy is associated with better visual outcomes; the strongest association with visual outcome was for the threshold check size with a significant N95 component (ρ = 0.398, p = 0.02).

Conclusions

Automated statistically robust signal-processing techniques reliably and objectively detect PERGs in young children with ONH and show that congenital deficits of retinal ganglion cells are associated with diminished or non-detectable PERGs. The later negativity, N95, was the best indicator of visual prognosis and was most useful to identify those with good visual outcomes (≤0.4 LogMAR). Although PERGs reflect function of the inner layers of the central retina, they lack the specificity required to determine prognosis reliably in individual cases.

     

Extrafoveal changes following intravitreal bevacizumab injections for macular edema secondary to branch retinal vein occlusion: an mfERG and OCT study

Purpose

To evaluate the functional and structural changes of extrafoveal macula after intravitreal bevacizumab (IVB) injection in patients with macular edema due to branch retinal vein occlusion (BRVO) using multifocal electroretinogram (mfERG) and optical coherence tomography (OCT).

Methods

A total of 19 eyes of 19 patients with macular edema due to BRVO received three consecutive IVB injections with a 6-week interval. Spectral domain optical coherence tomography (SD-OCT), mfERG, and fluorescein angiography (FA) were performed at baseline. The macular area was divided into four quadrants (Q1–Q4) based on FA. The mean retinal thickness (MRT) and mfERG parameters in each of the four quadrants were measured at baseline and 4 weeks after the third injection.

Results

The MRT in the four quadrants improved significantly after IVB injections (p < 0.01 for Q1 and Q2, p < 0.05 for Q3 and Q4) compared to baseline. The significant improvements in mfERG responses were seen in Q1 and Q2. In Q1, there were 68 and 56 % improvement in N1 and P1 amplitude, respectively (p < 0.01). N1 and P1 amplitude in Q2 increased significantly by 43 and 46 %, respectively, compared to baseline (p < 0.05). The MRT and P1 amplitude were significantly correlated at baseline in Q1 and Q2, but no significant correlations were found after three IVB injections.

Conclusions

The injection of IVB improved functional and structural outcomes in the primarily affected half of the extrafoveal macula effectively. The measurements of structural and functional changes using mfERG and OCT may be appropriate for monitoring the effects of IVB injection in BRVO patients.     

The importance of the electrophysiological tests in the early diagnosis of ganglion cells and/or optic nerve dysfunction coexisting with pituitary adenoma: an overview

Background and methods

Based on the available literature, it is suggested, in the clinical evaluation of the chiasmal tumors, that the following electrophysiological tests: visual evoked potentials to pattern-reversal stimulation, multifocal visual evoked potentials (mfVEPs), and pattern electroretinogram (PERG) play an important role in the diagnosis of the optic nerve and retinal dysfunction in the course of pituitary tumors.

Results

Macroadenomas and also microadenomas may cause dysfunction of retinal ganglion cells (RGCs) and their axons, even in the absence of changes in the routine ophthalmological examination, retinal sensitivity in standard automated perimetry, and retinal nerve fiber layer thickness in optical coherent tomography. The most frequently observed changes in electrophysiological tests were as follows: in PVEPs—the crossed/uncrossed asymmetry distribution, altered waveform, increase in P100-wave peak time, and/or reduction in amplitude; in mfVEPs—the peak time prolongation and/or amplitude reduction in C1-wave; in PERG—the reduction in N95-wave amplitude and decreased N95:P50 amplitude ratio. Hemifield PVEPs were more often abnormal than full-field PVEPs. Multi-channel recording is recommended for the assessment of the anterior visual pathway. The use of mfVEP offers the possibility to register localized disturbances of the optic nerve and ganglion cells. Additionally, an amplitude of N95-wave reduction in PERG correlated with a lack of postoperative visual acuity recovery. The postoperative improvement in the visual field was found to be associated with a normal N95:P50 amplitude ratio. The RGCs dysfunction manifested by decrease in PhNR/b-wave amplitude ratio was associated with the worse visual fields outcome. A review of the literature summarizing the electrophysiological testing in the pituitary adenoma is discussed.

Conclusion

In patients with pituitary tumor, detection of the early dysfunction of the visual pathway may lead to modification of the medical treatment regimen and reduce the incidence of irreversible optic nerve damage.

     

Electroretinography in idiopathic intracranial hypertension: comparison of the pattern ERG and the photopic negative response

Purpose

To evaluate the relationship between electrophysiological measures of retinal ganglion cell (RGC) function in patients who have idiopathic intracranial hypertension (IIH).

Methods

The pattern electroretinogram (pERG) and photopic negative response (PhNR) were recorded from 11 IIH patients and 11 age-similar controls. The pERG was elicited by a contrast-reversing checkerboard. The PhNR, a slow negative component following the flash ERG b-wave, was recorded in response to a long-wavelength flash presented against a short-wavelength adapting field. The PhNR was elicited using full-field (ffPhNR) and focal macular (fPhNR) stimuli. Additionally, Humphrey visual field mean deviation (HVF MD) was measured and ganglion cell complex volume (GCCV) was obtained by optical coherence tomography.

Results

The ffPhNR, fPhNR, and pERG amplitudes were outside of the normal range in 45, 9, and 45% of IIH patients, respectively. However, only mean ffPhNR amplitude was reduced significantly in the patients compared to controls (p < 0.01). The pERG amplitude correlated significantly with HVF MD and GCCV (both r > 0.65, p < 0.05). There were associations between ffPhNR amplitude and HVF MD (r = 0.58, p = 0.06) and with GCCV (r = 0.52, p = 0.10), but these did not reach statistical significance. fPhNR amplitude was not correlated significantly with HVF MD or GCCV (both r < 0.40, p > 0.20).

Conclusions

Although the fPhNR is generally normal in IIH, other electrophysiological measures of RGC function, the ffPhNR and pERG, are abnormal in some patients. These measures provide complementary information regarding RGC dysfunction in these individuals.

     

Evaluation of light- and dark-adapted ERGs using a mydriasis-free,portable system: clinical classifications and normative data

Purpose

The full-field electroretinogram (ff-ERG) is a widely used clinical tool to evaluate generalized retinal function by recording electrical potentials generated by the cells in the retina in response to flash stimuli and requires mydriasis. The purpose of this study was to determine the intra-visit reliability and diagnostic capability of a handheld, mydriasis-free ERG, RETeval (LKC Technologies, Gaithersburg, MD, USA), in comparison with the standard clinical ff-ERG by measuring responses recommended by the International Society for Clinical Electrophysiology of Vision (ISCEV).

Methods

This prospective, cross-sectional study included 35 patients recruited at the Hospital for Sick Children (median age?=?17, range 11 months–69 years) who had undergone a clinical ff-ERG according to ISCEV standards. For RETeval (n?=?35), pupils were undilated in most (n?=?29) and sensor strip electrodes were placed under the inferior orbital rim. Stimulus settings on RETeval were equivalent to those used in the clinical ERG. Fifty-seven control participants (median age?=?22, range 8–65 years) underwent undilated RETeval ERG to establish standard values for comparison. Patient waveform components with amplitudes?<?5th percentile, or implicit times?>?95th percentile of normal relative to control data were classified as abnormal for the RETeval system.

Results

The RETeval system demonstrated a high degree of within-visit reliability for amplitudes (ICC?=?0.82) and moderate reliability for implicit times (ICC?=?0.53). Cohen’s Kappa analysis revealed a substantial level of agreement between the diagnostic capability of RETeval in comparison with clinical ff-ERG (k?=?0.82), with a sensitivity and specificity of 1.00 and 0.82, respectively. Pearson’s correlations for clinical ERG versus RETeval demonstrated a positive correlation for amplitudes across the rod (r?=?0.65) and cone (r?=?0.74) ERG waveforms. Bland–Altman plots showed no bias between the mean differences across all amplitude and implicit time parameters of the two systems.

Conclusions

The present study demonstrated that RETeval is a reliable tool with reasonable accuracy in comparison with the clinical ERG. The portable nature of RETeval system enables its incorporation at resource-limited centers where the ff-ERG is not readily available. The avoidance of sedation and pupillary dilation are added advantages of RETeval ERG.

     

Relationship Between the s-wave Amplitude of the Multifocal Electroretinogram and the Retinal Nerve Fiber Layer Thickness in Glaucomatous Eyes

Purpose

To determine whether a significant correlation exists between the amplitude of the s wave of the multifocal electroretinogram (mfERG) and the retinal nerve fiber layer thickness (RNFLT) in glaucomatous eyes.

Methods

Twenty-three eyes of 23 patients with glaucoma were studied. In all eyes, the severity of the defects in the upper visual field differed significantly from the severity of those in the lower half. Patients having visual field halves with mean deviation (MD) values lower than ?5?dB were placed in group A, and patients having visual field halves with MD values greater than ?5?dB were placed in group B. The mfERGs were elicited by 37 stimulus elements alternating from white to black in a pseudorandom binary m-sequence at a frequency of 9.4?Hz. The mfERGs in the upper and lower visual field halves were summed to yield upper and lower averaged waves. The GDx variable corneal compensator and optical coherence tomography were used to measure the RNFLT.

Results

The retinal nerve fiber layer was significantly thinner in group A than in group B. There was a significant correlation between the RNFLT and the MD values of visual field defects. The s-wave amplitude was significantly smaller in group A than in group B. The s-wave amplitude also correlated significantly with the MD and the RNFLT.

Conclusion

The significant correlations between the s-wave amplitude and the MD, and between the S-wave amplitude and the RNFLT, indicate that the s-wave receives significant contributions from the retinal ganglion cells and their axons. Jpn J Ophthalmol 2005;49:481–490 © Japanese Ophthalmological Society 2005     

The factors influencing peripapillary choroidal thickness in primary open-angle glaucoma

Purpose

To investigate whether there is a difference between primary open-angle glaucoma (POAG) patients and control group with regard to choroidal thickness (CT) and the factors influencing CT.

Methods

Ninety eyes of 90 patients who were being followed up with POAG and 72 eyes of 72 healthy subjects matched for age and gender were included. Peripapillary retinal nerve fiber layer thickness (RNFLT), peripapillary CT, lamina cribrosa thickness (LCT), and prelaminar tissue thickness (PTT) were measured with spectral-domain optical coherence tomography (SD-OCT) enhanced depth imaging (EDI) in all patients.

Results

According to multi-variable linear regression analysis results, the factors influencing CT were found as axial length (AL) (B = ?22.78, p = 0.002), intraocular pressure (IOP) (B = ?7.95, p = 0.001), age (B  = ?1.77, p = 0.009), and radial pulse rate (B  = 1.42, p = 0.015). A statistically significant relationship was not detected between CT and central corneal thickness, mean deviation value of visual field, cup/disk ratio, RNFLT, LCT, PTT. CT was found significantly thinner in glaucoma group (147.5 ± 61.2 μm) compared to control group (167.1 ± 37.3 μm). However, IOP was found significantly higher (p < 0.001) and pulse rate was found significantly lower (p = 0.021) in POAG group. IOP and pulse rate were considered to have affected CT difference between the groups. In advanced and worser stage patients, there were significant positive correlations between CT and RNFLT in inferior and superior quadrants.

Conclusions

In addition to previous studies, IOP and pulse rate were detected to be effective on CT. Further studies are required for determining the whole factors effective on CT and better understanding CT and glaucoma relationship.

     

Structural and functional comparison of the persistent and resolved amblyopia

Purpose

To assess structural or functional differences of the retina among subjects with persistent and resolved amblyopia.

Methods

Fourteen eyes with persistent amblyopia that did not reach normal visual acuity (VA) levels (≤0.1 LogMAR) despite amblyopia treatment, 18 eyes with resolved amblyopia, and 16 eyes of 16 normal subjects were included. All subjects underwent optical coherence tomography (OCT), pattern visual evoked potential (PVEP), and pattern electroretinography (PERG) evaluation.

Results

There was no significant difference in foveal thickness, foveal volume, macular volume, ganglion cell layer thickness, and total and sectorial retinal nerve fiber layer measurements among three groups (p > 0.05). Foveolar thickness was significantly increased in both resolved and persistent amblyopia groups compared with the control group (p = 0.031). However, there was no difference between amblyopic groups (p = 0.98). Although, in the PVEP study, N75 implicit time was found significantly prolonged in both amblyopia groups (p = 0.046), there were no significant differences in P100 implicit time and amplitude among the groups (p > 0.05). PERG amplitude of the persistent group was significantly lower than that of the control group (p = 0.003). There were no significant differences in P50, N95 implicit times among groups (p > 0.05).

Conclusions

In our study, the only significant difference between persistent and resolved amblyopia groups was the initial VA. Neither OCT nor electrophysiological examinations were found to be useful in order to explain why some cases were resistant to the treatment for amblyopia.     

Foveal amplitudes of multifocal electroretinograms are larger following full-field electroretinograms

Purpose

The clinical standards for multifocal electroretinograms (mfERG) call for adaption to normal room lighting before the mfERG begins. They specify that any assessments where bright lights are used, should be done after the mfERG to prevent excess stimulation of retinal cells. However, full-field electroretinograms (FFERG) are performed prior to mfERGs in some clinical settings. It is unclear from the literature whether the FFERG has an impact on the mfERG. This study seeks to examine the effect of the FFERG on the mfERG when performed sequentially.

Methods

Thirty young healthy subjects (age 27.1?±?3.5 years) were included. Patients reported for two visits and were fully dilated at both visits. At visit one, a FFERG was recorded (VERIS 6.2) using our clinical protocol which includes an ISCEV standard flash sequence; each flash condition was repeated 4–6 times. Following the FFERG, an mfERG was recorded using a 4-min m-sequence at near 100% contrast. At visit two, only the mfERG was recorded. A Burian–Allen contact lens electrode filled with celluvisc was used for all recordings. The two mfERGs were compared for foveal, peripheral, and overall implicit time (IT) and amplitudes (amp). Paired t tests were used to evaluate the data. Coefficient of variation and Bland–Altman analysis was also reported for this patient group.

Results

There was a small but statistically significant difference in foveal amplitudes (amp) (p?=?0.004) wherein the amp was larger following the FFERG stimuli. The mean difference was 11.1 nV/deg² (100.9 nV vs 89.8 nV). There was no difference in foveal IT (p?=?0.66). There was no difference in overall IT or amp when averaging the entire eye (p?=?0.44 amp and p?=?0.54 IT) or just evaluating the periphery (p?=?0.87 amp and p?=?0.051 IT). Bland–Altman analysis found a coefficient of repeatability overall was 1.57 ms (IT) and 10.7 nV/deg² (amp).

Conclusions

The difference in foveal amplitude is likely the result of a small long-term cone adaptation, but further studies are needed. While it is statistically significant, the small difference is unlikely to be clinically important. These results should help increase clinical confidence in mfERG results when recorded following a FFERG.