International Society For Clinical Electrophysiology Of Vision Research Articles

Localized retinal electrophysiological and fundus autofluorescence imaging abnormalities in maternal inherited diabetes and deafness.

To investigate retinal function in patients with maternally inherited diabetes and deafness (MIDD) and to correlate the findings with fundus autofluorescence (FAF) imaging. FAF was imaged in five patients (age range, 49-60 years) confirmed to have the mitochondrial DNA nucleotide A3243G point mutation. Retinal function was measured by full-field (Ganzfeld) electroretinography (ERG) and pattern ERG, incorporating the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. Multifocal ERG (mfERG) was also performed. For analysis of the mfERG data, five regional ring groups of equal eccentricity were formed. For each ring, the peak amplitude (defined as the difference between P1 and N1) and the implicit time of P1 were determined and compared with normative values. Visual acuity in the patients was between 20/20 and 20/40 (Early Treatment Diabetic Retinopathy Study [ETDRS] chart). Irregular increased FAF signals were observed adjacent to and between areas of atrophy of the retinal pigment epithelium (RPE). Ganzfeld ERGs were within normal limits in three patients. Pattern ERG was abnormal in five eyes of three patients. mfERG peak amplitude abnormalities were particularly present in rings 2 and 3 and were consistent with the distribution of FAF abnormalities. In all but one eye, no implicit times changes were present. Significant mfERG abnormalities with normal Ganzfeld ERG are consistent with nonuniform damage to the central retina in MIDD, in keeping with the FAF findings. Reduced peak amplitudes with normal implicit times in the mfERG suggest localized loss of function and may indicate damage to the cone photoreceptor outer segments or cone photoreceptor loss in MIDD.

Supernormal Electro-Oculograms in Patients with Neurofibromatosis Type 1

PurposeTo asses the retinal pigment epithelium (RPE) function measured by EOG testing in patients with neurofibromatosis type 1 (NF-1). Our preliminary EOG results suggested dysfunction of the RPE in individuals with NF-1. In order to confirm our initial results we performed EOG examination on a larger group of NF-1 patients.PatientsStudies were performed on 36 patients with clinically diagnosed NF-1 and compared to normal healthy controls.MethodsStandard EOG recordings were performed in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standards.ResultsIn NF-1 patients the Arden indexes of the EOG test were significantly higher primarily due to the lower values of dark troughs. Supernormal EOGs (exceeding the value of the mean + 2 SD from the control group) were present in 58% of NF-1 patients.ConclusionsDysfunction of the RPE is a characteristic feature of individuals with NF-1.

Standard full-field electroretinography in healthy preterm infants.

The purpose of this study was to determine electroretinographic parameters according to the standard protocol from the International Society for Clinical Electrophysiology of Vision (ISCEV) in healthy preterm infants with normal fundus. Seventeen healthy preterm infants with normal fundus were recruited and divided in two age groups: 3-week group, nine infants with mean adjusted age at test = 2.67 +/- 0.92 weeks and 8-week group, eight infants with mean adjusted age at test = 7.92 +/- 1.72 weeks. Full-field ERGs were obtained with a Burian-Allen bipolar contact lens electrode from the anesthetized cornea in one eye, through a fully dilated pupil after 30 min of dark adaptation. The standard ISCEV protocol was used and the following responses were recorded: rod, maximal, oscillatory potentials, cone and 30 Hz flicker. Median values and 1st, 5th, 95th and 99th percentiles for amplitude and implicit time are described for both age groups. There was statistically larger amplitude for 30 Hz flicker (t = 2.191; p = 0.046) and for cone response (t = 2.307; p = 0.044) in the 8-week-old group. Statistically shorter implicit times were found in 8-week group for rod response (t = 3.219; p = 0.015), cone response (t = 2.839; p = 0.016) and flicker response (t = 3.326; p = 0.005). Shortening of implicit time was evident in the older group of preterms and this finding is consistent with other maturational studies confirming the anatomical and functional development of the photoreceptors. Medians and ranges between the 1st and 99th and the 5th and 95th percentiles can be used as a baseline for future comparisons with infants with ROP.

Pattern ERG correlates of abnormal fundus autofluorescence in patients with retinitis pigmentosa and normal visual acuity.

To examine the functional significance of central abnormalities present in fundus autofluorescence (AF) images in patients with rod-cone dystrophy and good visual acuity. Thirty patients were selected according to three criteria: a clinical diagnosis of retinitis pigmentosa (RP) confirmed with International Society for Clinical Electrophysiology of Vision (ISCEV) standard ERGs, a parafoveal ring of increased high density on fundus AF imaging, and a visual acuity of 20/30 or better. Macular function was assessed with pattern electroretinography (PERG) to checkerboard stimuli of different field sizes. Fundus AF imaging was performed with a confocal scanning laser ophthalmoscope. The radius of the parafoveal ring of high density varied between 1.5 degrees and 9 degrees. The PERG P50 amplitude correlated highly with the radius of the ring of increased autofluorescence (r = 0.80, P < 0.0005, n = 30). PERGs to smaller circular field sizes were present, but increasing field size to beyond that of the high-density autofluorescence ring did not produce further increases in P50 amplitude. There was a high correlation between the minimum stimulus size required to elicit a maximum-amplitude PERG and the radius of the ring (r = 0.87). The high correlation between AF imaging and PERG, an established technique in the assessment of central retinal function, demonstrates the likelihood that autofluorescence abnormalities have functional significance and may therefore be a valuable additional parameter in the monitoring of these patients.

Influence of axial length of normal eyes on PERG.

The influence of the axial length (AL) of the eye on flash electroretinogram (ERG) responses has been well established in the literature, suggesting an association between ERG abnormalities with myopia (AL > 25 mm). The aim of our present study was to determine whether the AL of normal eyes can also influence the pattern electroretinogram (PERG) on normal subjects. Thirty-nine normal volunteers were subjected to PERG measurements following the standard set by the International Society for Clinical Electrophysiology of Vision (ISCEV). The AL of the eyeball was measured using a TOMEY ultrasonic A scanner. Each volunteer had a complete ophthalmic examination including visual acuity, refraction, intraocular pressure, visual field, colour vision, orthoptic assessment and retinal photographs and had a best corrected visual acuity of 6/9 or better. Only one eye from each of the 39 normal volunteers was included in the statistical analysis of the results. The normal volunteer group had a mean P50 amplitude of 3.8 +/- 1.1 SD microV. The range of AL was between 21.8 and 25.7 mm (mean = 23.8 +/- 1.0 SD mm). Overall findings obtained from this investigation indicate a significant correlation between the AL of normal eyes and the PERG P50 amplitude (Spearman rank correlation coefficient r = -0.413, p < 0.01). The correlation accounts for 17% of the variance observed in the 39 amplitude values. This confirms the current hypothesis that the PERG amplitude is inversely related to axial length and means that AL should be considered when interpreting PERG amplitudes.

Retinal function in the von Hippel-Lindau disease.

To assess the retinal function in patients with von Hippel-Lindau disease (VHL). Studies were undertaken in 12 patients (17 eyes) with detected VHL gene mutation and 12 normal healthy controls (17 eyes). Pattern ERG (PERG), standard flash electroretinogram (ERG) recordings were performed in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. In VHL patients, electrophysiological statistically significant changes were found. In PERG examination, increased latency of P50 was found in the total VHL group (p < 0.02) and in the VHL subgroup with retinal angiomas (p < 0.04). In ERG examination, photopic b-wave latency was increased in the total VHL group (p < 0.03) and also in the VHL subgroup without retinal angiomas (p < 0.05). In OPs, latency increase of OP2, OP3 waves and reduced amplitude of OP3 wave in the total VHL group (OP2 latency, p < 0.05; OP3 latency, p < 0.01; OP3 amplitude, p < 0.03) and in the VHL subgroup with retinal angiomas (OP2 latency, p < 0.02; OP3 latency, p < .008; OP3 amplitude, p < 0.02) were obtained. It can be hypothesized that dysfunction of the inner retinal layer is present in individuals with VHL disease even in patients without retinal angiomas.

Electroretinographic changes in the inner retinal layers of the retained eyes of patients with sporadic unilateral retinoblastoma

Purpose: Examination of retinal function as measured by flash electroretinogram (ERG) including oscillatory potentials (OPs) and pattern electroretinogram (PERG) in a series of patients with unilateral sporadic retinoblastoma. Patients: Studies were undertaken in the retained eye (without clinical evidence of retinoblastoma) of 13 patients with sporadic unilateral retinoblastoma and in 13 healthy controls. Methods: Standard flash ERG including scotopic OPs and PERG recordings were performed in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. Results: Statistically significant differences between the studied and the control groups were observed with flash ERG (OP1 amplitude increase, p < 0.003; photopic flicker amplitude increase, p < 0.05) and PERG (P50 latency increase, p < 0.008). Conclusions: Inner retinal layer dysfunction may be a characteristic feature of individuals with unilateral sporadic retinoblastoma.

Electro-oculogram in patients with neurofibromatosis type 1.

The electro-oculogram (EOG) is a powerful test to evaluate the functional status of the retinal pigment epithelium (RPE). Clinically detectable changes of the RPE desribed in neurofibromatosis type 1 (NF-1) patients include combined hamartoma of the retina/RPE and congenital hypertrophy of the RPE. The goal of this study was to determine whether the function of RPE as measured by EOG is also changed in individuals with NF-1. Studies were undertaken in 20 patients with clinically diagnosed NF-1 and compared to 16 normal healthy controls. Standard EOG and flash ERG recordings were performed in accordance with International Society for Clinical Electrophysiology of Vision (ISCEV) standards. In NF-1 patients the Arden indexes of the EOG test were significantly higher primarily due to the lower values of dark troughs. Supernormal EOGs were present in 60% of NF-1 patients in comparison to the control group mean +2 SD. No one patient showed so high abnormalities during flash ERG examination. Dysfunction of the RPE may be characteristic feature of individuals with NF- 1.

Values of electroretinogram responses according to axial length.

Accurate interpretation of electroretinograms (ERGs) requires knowledge of effects of axial myopia on ERG responses. Our purpose was to derive expected changes of ERG responses according to axial length, to stimulus conditions that conform to the International Society for Clinical Electrophysiology of Vision (ISCEV) Standard for Electroretinography. ERGs from 60 subjects were recorded. The subjects were assigned to one of three groups according to the level of myopia. Thirty-three subjects had high myopia (-6.00 D to -14.50 D; mean age, 31 years), eight had mild myopia (-3.00 D to -5.00; mean age, 28 years), and 19 had a small refractive error (+0.75 D to -2.75 D; mean age, 27 years). No subjects had myopic retinopathy. Stimulus-response curves were fitted to dark-adapted b-wave amplitudes and maximum amplitude and semi-saturation constants derived. Axial lengths, measured with A scan ultrasound, ranged from 22.2 mm to 30.0 mm. Analysis of variance and post hoc t-tests revealed significant difference between subjects with high myopia and subjects with small refractive error for ERG amplitude data. There were no significant differences between the three groups for implicit times, the ratio of b- to a-wave and semi-saturation constant. There is linear reduction in the logarithmic transform of ERG amplitude with increasing axial length, related more to axial length than refractive error. We provide relative slope and intercept values, allowing labs to derive expected ERG amplitudes according to axial length. These derivations are valid for persons with no retinopathy.

Electrophysiologic studies according to ISCEV (International Society for Clinical Electrophysiology of Vision) standards in children under 10 years of age

To analyze the value of electrophysiologic testing according to standards of the International Society for Clinical Electrophysiology of Vision (ISCEV) in infants less than 10 years of age. In 64 infants less than 10 years, the results from of age electroretinograms (n = 47), visual evoked potentials (n = 30), or electro-oculograms (n = 1) were recorded. Twenty-nine infants were less than 6 years of age, and 17 infants were less than 3 years of age. Indications for examination were unexplained visual loss in 54 infants and familial hereditary retinal dystrophies in ten infants. Sedation with chloral hydrate was performed in seven children. In 40/64 infants (62%), the results of electrophysiologic examination were pathologic. In 29 infants visual loss was due to retinochoroidal dystrophies, and in 11 infants it was due to disturbances in the optic pathway. In 7/64, infants the suspected retinochoroidal dystrophy could be excluded. Therefore electrophysiologic testing was diagnostically accurate in 47/64 (73%) of cases. Electrophysiologic testing according to TSCEV standards can be reliably performed in infants less than 10 years of age. When the indication for electrophysiologic testing is made following meticulous ophthalmologic examination, diagnostic accuracy is given in at least 73% of cases.

Methodologic dependence of electroretinogram oscillatory potential amplitudes.

The International Society for Clinical Electrophysiology of Vision (ISCEV) protocol for eliciting oscillatory potentials uses a considerably lower flash intensity and a different preconditioning stimulus than the only oscillatory potential protocol used to predict progression of diabetic retinopathy. To determine if the ISCEV protocol will be useful in predicting progression of diabetic retinopathy, summed oscillatory potential amplitudes were measured by both protocols in a population of diabetics. Summed oscillatory potential amplitudes measured by the ISCEV protocol, although smaller, are highly correlated with the summed oscillatory potential amplitudes measured with the higher-intensity flash. Thus, summed oscillatory potential amplitudes measured with the ISCEV protocol should be useful in predicting outcome in diabetic retinopathy. Different signal processing filters used to extract oscillatory potentials from the electroretinogram waveform have a small, but significant, effect on summed oscillatory potential amplitude. Use of the caliper-square method or the summed peak-to-trough method for measuring oscillatory potential heights had an insignificant effect on measured oscillatory potential amplitude.

Standard for Clinical Electro-oculography

The electro-oculogram is a widely used electrophysiological test, but recording techniques vary among different laboratories. This standard, approved by the International Society for Clinical Electrophysiology of Vision (ISCEV), describes simple technical procedures that will allow reproducible and comparable electro-oculograms to be recorded under a few defined conditions. The document is intended to improve the comparability of electro-oculographic data obtained throughout the world by guiding both clinicians and manufacturers, and the ISCEV recommends that future published reports indicate whether the recording technique meets the international standard.

Standard for clinical electro-oculography. International Society for Clinical Electrophysiology of Vision.

The electro-oculogram is a widely used electrophysiologic test, but recording techniques vary among different laboratories. This Standard, approved by the International Society for Clinical Electrophysiology of Vision (ISCEV), describes simple technical procedures that will allow reproducible and comparable electro-oculograms to be recorded under a few defined conditions. The document is intended to improve the comparability of electro-oculogram data obtained throughout the world by guiding both clinicians and manufacturers, and ISCEV recommends that future published reports indicate whether the recording technique meets the international Standard.

Air medical communications centers

Major depressive disorder (MDD) is a major public health problem. The retina is a relevant site to indirectly study brain functioning. Alterations in retinal processing were demonstrated in MDD with the pattern electroretinogram (PERG). Here, the relevance of signal processing and machine learning tools applied on PERG was studied.PERG – whose stimulation is reversible checkerboards – was performed according to the International Society for Clinical Electrophysiology of Vision (ISCEV) standards in 24 MDD patients and 29 controls at the inclusion. PERG was recorded every 4 weeks for 3 months in patients. Amplitude and implicit time of P50 and N95 were evaluated. Then, time/frequency features were extracted from the PERG time series based on wavelet analysis. A statistical model has been learned in this feature space and a metric aiming at quantifying the state of the MDD patient has been derived, based on minimum covariance determinant (MCD) mahalanobis distance.MDD patients showed significant increase in P50 and N95 implicit time (p = 0,006 and p = 0,0004, respectively, Mann–Whitney U test) at the inclusion. The proposed metric extracted from the raw PERG provided discrimination between patients and controls at the inclusion (p = 0,0001). At the end of the follow-up at week 12, the difference between the metrics extracted on controls and patients was not significant (p = 0,07), reflecting the efficacy of the treatment.Signal processing and machine learning tools applied on PERG could help clinical decision in the diagnosis and the follow-up of MDD in measuring treatment response.

Electrodiagnosis: Toxic Agents and Vision: Proceedings of the 15th International Society for Clinical Electrophysiology of Vision Symposium

Documenta Ophthalmologica includes in their proceedings series the annual symposium of the International Society for Clinical Electrophysiology of Vision (ISCEV) (formerly the ISCERG), which was held in Ghent, Belgium, June 20 through 23, 1977. This arrangement provides the ophthalmic community with welcome enrichment from an area (clinical electrodiagnosis) that is otherwise sparsely covered. About 40% of the 54 articles are devoted to the main topic of the meeting, toxic manifestations on electroretinograms and electro-oculography. Considerable attention is given to metallosis. As usual, a part of the free contributions covers technical improvements on electrodiagnosis and attempts at standardization. The volume is well edited and handsomely printed, with particular attention to the reproduction of halftone illustrations. The president of ISCEV, Professor Henkes, and the organizers of the symposium have again provided a forum for presentation and discussion of clinical electrodiagnosis in ophthalmology. The proceedings are an invaluable repository of the state