Multifocal ERG findings in carriers of X-linked retinoschisis

Purpose To determine whether retinal dysfunction in obligate carriers of X-linked retinoschisis (XLRS) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG). Methods Nine obligate carriers of XLRS (mean age, 46.2 years) were examined for the study. Examination of each carrier included an ocular examination and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40° in diameter. The amplitudes and implicit times in each location for the mfERG were compared with the corresponding values determined for a group of 34 normally-sighted, age-similar control subjects. Results Mapping of 103 local electroretinographic response amplitudes and implicit times within a central 40° area with the mfERG showed regions of reduced mfERG amplitudes and delayed implicit times in two of nine carriers. Conclusions The mfERG demonstrated areas of retinal dysfunction in two carriers of XLRS. When present, retinal dysfunction was evident in the presence of a normal-appearing fundus. Multifocal ERG testing can be useful for identifying some carriers of XLRS.     

Detection using the multifocal electroretinogram of mosaic retinal dysfunction in carriers of X-linked retinitis pigmentosa

PURPOSE: To examine whether a mosaic pattern of retinal dysfunction in obligate carriers of X-linked retinitis pigmentosa (XLRP) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG). DESIGN: Prospective observational case series. PARTICIPANTS: Five obligate carriers of XLRP (mean age, 53.2 years) were recruited into the study. METHODS: Examination of each subject included a complete ocular examination, Humphrey visual field, standard full-field electroretinogram (ERG), and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 in diameter. The amplitudes and implicit times in each location for the mfERG was compared with the corresponding value determined for a group of normally sighted, age-corrected control subjects. MAIN OUTCOME MEASURES: Mapping of 103 local electroretinographic response amplitudes and implicit times within the central 40 with the multifocal electroretinogram. RESULTS: Localized regions of reduced mfERG amplitudes and/or delayed implicit times were found in four of five carriers. In one of these four carriers, a mosaic pattern of mfERG dysfunction was present even in the absence of any clinically apparent retinal changes, retinal sensitivity losses on Humphrey field testing, or abnormal full-field cone ERG responses. However, one carrier with a typical tapetal-like reflex demonstrated no deficit on any functional tests. CONCLUSIONS: The mfERG demonstrated patchy areas of retinal dysfunction in some carriers of XLRP. This mosaic pattern of dysfunction may be observed in some patients with a normal-appearing fundus, normal psychophysical thresholds, and normal amplitude and implicit time full-field ERG cone responses.     

Localized retinal dysfunction in central serous chorioretinopathy as measured using the multifocal electroretinogram

PURPOSE: To determine the extent of electrophysiologic dysfunction in patients with central serous chorioretinopathy (CSC). DESIGN: Prospective observational case series. PARTICIPANTS: Six patients with unilateral CSC (mean age, 40 years) were recruited into the study. METHODS: Six patients with CSC underwent multifocal electroretinogram (mfERG) testing on both their clinically affected and opposite uninvolved eyes using the VERIS System, with a stimulus array of 103 scaled hexagons. The first positive peak responses were analyzed within six concentric ring annuli centered on the fovea. Amplitudes and implicit times were compared with those of an age-similar control group. MAIN OUTCOME MEASURES: Local electroretinographic response amplitudes and implicit times within the central 40 degrees with the mfERG. RESULTS: All the clinically uninvolved eyes showed mfERG amplitudes and implicit times within the normal range throughout the central 40 degrees of the retina. All six eyes with CSC showed reduced amplitudes and/or delayed implicit times that were limited to the regions of the macula in which clinical changes associated with CSC were apparent. CONCLUSIONS: We observed electroretinographic changes only in the clinically affected eyes, and these were limited to regions with ophthalmoscopically apparent fundus changes. Our findings do not support the conclusion that functional impairment, as measured by the mfERG, in eyes with CSC extends beyond clinically observed fundus changes. We did not observe abnormal mfERG responses in the clinically normal eyes of such patients.     

Multifocal electroretinography as a function of age: the importance of normative values for older adults

PURPOSE: To determine the influence of age on local electroretinographic responses in humans. METHODS: Multifocal electroretinograms (mfERGs) were obtained from 62 normally sighted subjects ranging in age from 21 to 81 years. A stimulus array of 103 scaled hexagons was used to measure electrical signals within a retinal area approximately 46 degrees in diameter. Commonly reported mfERG methods were used to quantify the responses: peak-to-peak amplitudes and implicit times, scalar product amplitude, and amplitude and time scales derived from the algorithm of Hood and Li, published in 1997. RESULTS: Regression analysis showed significant linear relationships of amplitude and timing measures with age. The rates of losses were 10.5% per decade for peak-to-peak amplitude, 11.7% per decade for scalar product amplitude, and 9.5% per decade for a-scale. The rate of amplitude reduction was highest in the central 3 degrees. Age had less influence on implicit time measures. The rates of timing losses were 1.4% per decade for the N1 component and 1.0% per decade for both the P1 component and the t-scale measure. Using predicted interval ranges, the age was calculated at which 50% of the expected values would fall below the lower 95% prediction interval band of younger subjects. CONCLUSIONS: The age-associated mfERG alterations are presented to emphasize the importance of appropriate normative data in interpretation of mfERGs.     

The clinical applications of multifocal electroretinography: a systematic review

Multifocal electroretinography (mfERG) is an investigation that can simultaneously measure multiple electroretinographic responses at different retinal locations by cross-correlation techniques. mfERG therefore allows topographic mapping of retinal function in the central 40-50 degrees of the retina. The strength of mfERG lies in its ability to provide objective assessment of the central retinal function at different retinal areas within a short duration of time. Since the introduction of mfERG in 1992, mfERG has been applied in a large variety of clinical settings. This article reviews the clinical applications of mfERG based on the currently available evidence. mfERG has been found to be useful in the assessment of localized retinal dysfunction caused by various acquired or hereditary retinal disorders. The use of mfERG also enabled clinicians to objectively monitor the treatment outcomes as the changes in visual functions might not be reflected by subjective methods of assessment. By changing the stimulus, recording, and analysis parameters, investigation of specific retinal electrophysiological components can be performed topographically. Further developments and consolidations of these parameters will likely broaden the use of mfERG in the clinical setting.     

Assessing Responses of the Macula in Patients with Macular Holes using a New System Measuring Localized Visual Acuity and the mfERG

Purpose: To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. Methods: We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We measured local visual acuity thresholds at 27 discrete locations within 21° diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function of visual field location, and local ERG responses within 45° diameter using the mfERG. Results: In the affected eyes, the mean FFIS visual acuity thresholds were significantly elevated within the central 21° diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8° in affected eyes. In the central 2°, 4 out of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. Conclusions: Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range).     

Monitoring retinal function in neovascular maculopathy using multifocal electroretinography – early and long-term correlation with clinical findings

PURPOSE: To objectively investigate and longitudinally monitor retinal function in patients with choroidal neovascularization (CNV) due to exudative age-related macular degeneration (AMD) and myopia using multifocal electroretinography (mfERG). METHODS: Patients with classic and occult subfoveal CNV secondary either to AMD or to myopia were enrolled in the study. The mfERGs were performed at the beginning of the study and every 3 months subsequently during a follow-up period of 15 months. In addition, standardized visual acuity testing, ophthalmologic examinations, color fundus photographs and fluorescein angiography were performed. The mfERG records were derived with the VERIS-System (Electro-Diagnostic Imaging, San Mateo, Calif., USA); 103 locations within the central 50 degrees in diameter were stimulated concurrently by means of the m-sequence technique. Fixation stability was monitored throughout the recording session with an infrared eye monitoring system (VERIS Refractor/Camera unit). The first-order response component was extracted for each stimulated retinal location. The response densities of the first-order kernel were evaluated as a function of eccentricity from the center (ring 1) to the periphery of the stimulated area (ring 6). The results were compared to those derived from age-matched normal control groups. For each patient mfERG responses measured on follow-up visits were compared to each other to evaluate and monitor changes in retinal function. These changes were tested for correlation with those observed in other clinical and electroretinographic findings. Statistical analysis was performed using the Pearson coefficient. RESULTS: Subfoveal neovascular maculopathy was associated with a reduction in response density most prominent within the central 5 degrees over the area affected by CNV detected either at the beginning of the study or at the follow-up recordings. During the follow-up period patients 1 and 4 showed stabilization or a slight increase in response densities over the neovascular lesion-complex and a corresponding stabilization or slight increase in visual acuity accompanied by a decrease in the activity of the neovascular lesion as determined by fluorescein angiography. Patient 2 revealed an increase in response density correlating with an increase in visual acuity and decrease in lesion size. In the contralateral eye of this patient the response density dropped in the area of new subfoveal CNV. In patient 3 continuous progression of the disease was documented by fluorescein angiography and visual acuity. It correlated well with a continuous decrease in retinal response densities during the follow-up. CONCLUSIONS: Objective monitoring of retinal function and correlation with morphological and psychophysical findings was at least in part possible in patients suffering from AMD and myopia. In all of four patients whose subfoveal CNV was documented by fluorescein angiography. Response densities were reduced particularly in the central 5 degrees and in visual acuity. The mfERG data showed a moderate to high statistical correlation with visual function as measured by visual acuity. On the other hand, the greatest linear dimension of the lesion size showed only a weak to moderate statistical correlation with both the response densities of the mfERG and the visual acuity. We conclude that the size of the CNV complex does not represent an accurate measure of retinal function in neovascular maculopathy. The good correlation of the mfERG data with visual acuity suggests that it may serve for objective assessment of retinal function, of the areas overlying the CNV. It shows potential as a valuable tool for longitudinal monitoring of AMD patients.     

Sequential multifocal electroretinogram findings in a case of Purtscher-like retinopathy

PURPOSE: To report the multifocal electroretinographic findings of a patient with pancreatitis-associated Purtscher-like retinopathy. DESIGN: Observational case report. METHODS: A 20-year-old man with a history of alcohol abuse and acute pancreatitis underwent multifocal electroretinography (mfERG; 103-scaled hexagons, 8-minute recording time) at 1 week, 4 weeks, and 6 months after the onset of the retinopathy. RESULTS: At 1 week, the patient had extensive cotton- wool spots in the posterior pole bilaterally, and visual acuity was significantly reduced. Both the A-waves and B-waves of the mfERG were depressed in the corresponding areas. At 4 weeks, neither visual acuity nor mfERG showed improvement, although the cotton-wool spots had resolved. Interestingly, at 6 months, visual acuity had improved significantly in the left eye, consistent with increased ratios of mfERG responses for the central area. CONCLUSION: There was no selective reduction of b-waves of the mfERG as anticipated in isolated inner retinal pathology. In this case, both the A-waves and B-waves were reduced, suggesting damage to both outer and inner retinal layers.     

Assessment of central retinal function in patients with advanced retinitis pigmentosa

PURPOSE: To assess central retinal function in patients with advanced retinitis pigmentosa (RP) using the multifocal (mf)ERG and static perimetry. METHODS: Patients with RP; a nonrecordable, full-field (ff)ERG; and visual acuity (VA) of 相似文献   

Local diabetic retinopathy prediction by multifocal ERG delays over 3 years

PURPOSE: To derive and validate a model for use in predicting local retinal areas in which nonproliferative diabetic retinopathy (NPDR) lesions will develop over a 3-year period, by using primarily the implicit time (IT) of the multifocal electroretinogram (mfERG). METHODS: Eighteen diabetic patients were examined at baseline and at three annual follow-ups. Ophthalmic examinations, including fundus photographs and mfERG testing, were performed at each visit. Thirty-five retinal zones were constructed from the 103-element stimulus array, and each zone was assigned the maximum IT z-score within it based on 30 age-similar control subjects. Logistic regression was used to investigate the development of retinopathy in relation to baseline mfERG IT delays and additional diabetic health variables. Receiver operating characteristic (ROC) curves were used to evaluate the models. RESULTS: Retinopathy developed in 77 of the 1208 retinal zones, of which 25 had recurring retinopathy. Multivariate analyses yielded baseline mfERG IT, duration of diabetes, and blood glucose concentration as the most important predictors of recurring retinopathy. mfERG ITs were not predictive of transient retinopathy. ROC curves based on the multivariate model for the prediction of recurring retinopathy resulted in an area under the curve of 0.95, sensitivity of 88%, and specificity of 98%. Ten-fold cross-validation confirmed the high sensitivity and specificity of the model. CONCLUSIONS: The development of recurring retinopathy over a 3-year period can be well predicted by using a multivariate model based on mfERG implicit time. Multifocal ERG delays are promising candidate measures for trials of novel therapeutics directed at preventing or slowing the progression of NPDR.     

Comparison of intraocular light scatter in carriers of choroideremia and X-linked retinitis pigmentosa.

OBJECTIVE: To compare the extent of intraocular straylight in carriers of choroideremia (CHM) and X-linked recessive retinitis pigmentosa (XLRP) to clarify further the relationship between photoreceptor cell degeneration and intraocular light scatter in retinal diseases. DESIGN: Prospective case-control study. PARTICIPANTS: Six obligate carriers of CHM, 12 obligate carriers of XLRP, and 30 age-similar control subjects with normal vision. The controls had no posterior subcapsular (PSC) lens opacities, and the carriers had minimal or no PSC lens opacities, as assessed by slit-lamp biomicroscopy. MAIN OUTCOME MEASURES: Straylight levels were measured using a van den Berg Straylightmeter. Visual acuity and Goldmann visual field area using a II/4e target were assessed for both eyes of each carrier. Electroretinogram (ERG) data were available on four of six carriers of CHM and all carriers of XLRP. The extent of retinal pigment epithelial degenerative changes was evaluated by fundus examination. RESULTS: All six carriers of CHM had typical fundus abnormalities with normal visual fields. Five of the six carriers of CHM had age-normal levels of intraocular light scatter, and one showed minimally elevated intraocular light scatter. The 12 carriers of XLRP had a spectrum of fundus abnormalities and varying severity of functional impairment as derived from visual field areas and ERG amplitudes. Seven of the 12 carriers of XLRP showed an elevated level of intraocular light scatter in at least one eye. The degree of straylight elevation above the normal mean age value was correlated significantly with both visual field area and amplitude of the maximal-intensity, dark-adapted ERG b-wave. CONCLUSIONS: The carriers of XLRP who had evidence of photoreceptor cell dysfunction (as determined by visual field loss and reduced ERG amplitudes) had increased levels of intraocular straylight, whereas the carriers of CHM, who showed fundus abnormalities alone, in the absence of demonstrable photoreceptor cell dysfunction, had normal or minimally elevated levels. This finding supports the hypothesis that the increased levels of intraocular light scatter observed in some patients with hereditary retinal degenerations result from subclinical changes in the PSC region of the lens as a consequence of photoreceptor cell degeneration.     

Multifocal electroretinogram delays reveal local retinal dysfunction in early diabetic retinopathy.

PURPOSE: To identify local retinal abnormalities in diabetic patients with and without retinopathy, by using the multifocal electroretinogram (M-ERG). METHODS: Electroretinograms were recorded at 103 discrete retinal locations in each eye of eight persons with nonproliferative diabetic retinopathy (NPDR) and eight diabetic persons without retinopathy, using VERIS (EDI, San Mateo, CA). The amplitude and implicit time of each local (first-order) retinal response were derived and compared with normal values obtained from 16 age-matched, nondiabetic subjects. Maps of local response amplitude and implicit time were compared with fundus photographs taken at the time of testing. RESULTS: In eyes with NPDR, the implicit times of responses from retinal sites manifesting clinical pathologic fundus lesions (e.g., microaneurysms and focal edema), were markedly delayed (e.g., up to 7 msec from normal). Responses from adjacent retinal sites that were more normal in clinical appearance were also delayed, but to a lesser extent (e.g., 2-5 msec). Smaller, yet significant local response delays were also found in eyes without retinopathy. By contrast, local response amplitudes bore no consistent relationship to fundus abnormalities in eyes with retinopathy, and amplitudes were typically normal in eyes without retinopathy. CONCLUSIONS: The M-ERG reveals local retinal dysfunction in diabetic eyes even before retinopathy. The magnitude of delay of local ERG implicit time reflects the degree of local clinical abnormality in eyes with retinopathy. Local response delays found in some eyes without retinopathy suggest that the M-ERG detects subclinical local retinal dysfunction in diabetes. Analysis of M-ERG implicit time, independent of amplitude, improves the sensitivity of detection of local retinal dysfunction in diabetes.     

Multifocal electroretinogram delays predict sites of subsequent diabetic retinopathy

PURPOSE: To examine the potential of abnormal mfERGs to predict the development of diabetic retinopathy at corresponding retinal locations 1 year later. METHODS: One eye of 11 diabetic patients with nonproliferative diabetic retinopathy (NPDR) and 11 diabetic patients without retinopathy were retested 12 months after initial testing. At each time, mfERGs were recorded from 103 retinal locations, and fundus photographs were taken within 1 month of each recording. Local mfERG implicit times were measured and their z-scores were calculated based on results obtained from 20 age-matched control subjects. mfERG abnormalities were defined as z-scores of 2 or more for implicit time and z-scores of -2 or less for amplitude (P < or = 0.023). mfERG z-scores were mapped onto fundus photographs, and the relationship between baseline abnormal z-scores and new retinopathy at follow-up was examined. RESULTS: New retinopathy developed in 7 of the eyes with NPDR after 1 year. In these eyes, 70% of the mfERGs in areas of new retinopathy had abnormal implicit times at baseline. In contrast, only 24% of the responses in regions that remained retinopathy free were abnormal at baseline. Relative risk of development of new retinopathy over 1 year in the areas with abnormal baseline mfERG implicit times was approximately 21 times greater than that in the areas with normal baseline mfERGs (odds ratio = 31.4; P < 0.001). Eyes without initial retinopathy did not develop new retinopathy within the study period, although 4 of these 11 eyes had abnormal implicit times at baseline. mfERG implicit times tended to be more delayed at follow-up than at baseline in NPDR eyes, but not in eyes without retinopathy and control eyes. mfERG amplitudes had no predictive power. CONCLUSIONS: Localized functional abnormalities of the retina reflected by mfERG delays often precede the onset of new structural signs of diabetic retinopathy. Those functional abnormalities predict the local sites of new retinopathy observed 1 year later.     

Assessment of retinal function in patients with HIV without infectious retinitis by multifocal electroretinogram and automated perimetry

PURPOSE: To determine if multifocal electroretinogram (mfERG) testing shows abnormalities that correspond to perimetric defects in HIV positive patients without infectious retinitis. METHODS: We studied three groups of patients: HIV negative controls, HIV high CD4 nadir patients (lowest CD4 T cell count is over 100) and low CD4 nadir patients (below 100 for over 6 months). Twenty-six HIV positive eyes and 16 HIV negative control eyes were studied by mfERG. A subset of 10 eyes also underwent computerized perimetry for comparison. We analyzed mfERG by hexagons as well as by quadrants and rings. RESULTS: Of 103 hexagon locations there was no significant difference in the amplitudes P1 and N1 (nV/degree) between the three studied groups (p>0.05), similarly, the latencies were not different (p>0.05). All eyes with significant visual field defects at the 0.01 and 0.005 level (Humphrey pattern deviation; 24-2) were compared to mfERG amplitudes and latencies at those locations-there were no corresponding defects in mfERG data (p>0.2). CONCLUSION: In the era of HAART there are still demonstrable visual field defects and other evidence of damage to the retinal nerve fiber layer in HIV patients. Our mfERG studies show that the damage appears to affect the inner retina, the outer retina is spared. Further studies of inner retinal structure and function are indicated to elucidate this process.     

The effects of retinal abnormalities on the multifocal visual evoked potential

PURPOSE: To examine the effects on the amplitude and latency of the multifocal visual evoked potential (mfVEP) in retinal diseases associated with depressed multifocal electroretinograms (mfERG). METHODS: Static automated perimetry (SAP), mfERGs, and mfVEPs were obtained from 15 individuals seen by neuro-ophthalmologists and diagnosed with retinal disease based on funduscopic examination, visual field, and mfERG. Optic neuropathy was ruled out in all cases. Diagnoses included autoimmune retinopathy (n = 3), branch retinal arterial occlusion (n = 3), branch retinal vein occlusion (n = 1), vitamin A deficiency (n = 1), digoxin/age-related macular degeneration (n = 1), multiple evanescent white dot syndrome (n = 1), and nonspecific retinal disease (n = 5). Patients were selected from a larger group based on abnormal mfERG amplitudes covering a diameter of 20 degrees or greater. RESULTS: Fourteen (93%) of 15 patients showed significant mfVEP delays, as determined by either mean latency or the probability of a cluster of delayed local responses. Thirteen of 15 patients had normal mfVEP amplitudes in regions corresponding to markedly reduced or nonrecordable mfERG responses. These findings can be mimicked in normal individuals by viewing the display through a neutral-density filter. CONCLUSIONS: Retinal diseases can result in mfVEPs of relatively normal amplitudes, often with delays, in regions showing decreased mfERG responses and visual field sensitivity loss. Consequently, a retinal problem can be missed, or dismissed as functional, if a diagnosis is based on an mfVEP of normal or near-normal amplitude. Further, in patients with marked mfVEP delays, a retinal problem could be confused with optic neuritis, especially in a patient with a normal appearing fundus.     

Multifocal electroretinography in patients with exudative amd and intravitreal treatment with pegaptanib sodium

BACKGROUND: To objectively investigate central retinal function in patients with choroidal neovascularization (CNV) due to age-related macular degeneration (AMD) before and after treatment with pegaptanib sodium (PS). METHODS: Patients with CNV due to exudative AMD received intravitreal injections of 0.3 mg PS every sixth week if angiographic activity was evident. Longitudinal observation included recordings with multifocal electroretinography (mfERG) before the first treatment and before each injection at follow-up intervals. RESULTS: During the observation period of 30.5 +/- 8 weeks (mean +/- SD) a mean number of 5.3 +/- 1.3 injections were applied. Final mean log(MAR) visual acuity decreased, statistically nonsignificant, from 0.67 +/- 0.3 at baseline to 0.74 +/- 0.16. mfERG recordings in 12 patients after 25 +/- 9 weeks evinced a decrease in response density which was statistically significant in the central 5 degrees . Mean P1-amplitudes of ring 1, 2, and 3 were reduced by 66%, 39% and 30%, respectively. During follow-up, implicit times of the P1 components remained stable within 4% of baseline. In three of four patients with vision loss of 2 lines or more, P1-response amplitudes decreased substantially at least 6 weeks prior vision loss. CONCLUSION: Treatment with PS resulted in a decrease of central retinal function more obvious in mfERG than in VA longitudinal testing. Good correlations were seen between changes in mean vision and changes in mfERG response density components. As a decline in P1-response amplitudes anteceded vision loss in this study, our results indicate a possible role of mfERG to predict vision loss during intravitreal pharmacotherapy.     

A longitudinal study of visual function in carriers of X-linked recessive retinitis pigmentosa

OBJECTIVE: This study was carried out to evaluate the progression of visual function impairment in carriers of X-linked recessive retinitis pigmentosa. We also assessed the relationship between the retinal findings at presentation and the extent of deterioration. DESIGN: Observational, retrospective, case series. PARTICIPANTS: Twenty-seven carriers of X-linked recessive retinitis pigmentosa. METHODS: Each carrier was clinically categorized into one of four grades (grades 0 through 3) depending on the presence or absence of a tapetal-like retinal reflex and the extent of peripheral pigmentary degeneration. A complete ophthalmologic examination was performed and data for visual acuity, visual field area, and electroretinographic measurements were collected on the most recent visit in both eyes. These were then compared with similar data obtained on their initial visits. MAIN OUTCOME MEASURES: A comparison of visual function was carried out between the initial visit and the most recent visit on each carrier. The visual acuity was measured with Snellen's acuity charts. The visual fields to targets V-4-e and II-4-e were planimeterized and used for the analysis. The electroretinographic (ERG) measures used were light-adapted single-flash b-wave amplitudes and 30-Hz red flicker for cone function, dark-adapted maximal b-wave amplitudes, and response to a low intensity blue-flash for rod function. RESULTS: None of the 11 carriers with a tapetal-like reflex only (grade 1) showed any significant change in visual acuity or fields as compared with 3 of 7 (43%) carriers with diffuse peripheral pigmentary findings (grade 3) who showed significant deterioration in visual acuity in at least one eye, and 6 of 7 (86%) who showed a significant decrease in visual field area with at least one target size in at least one eye. By comparison, only 1 of 10 carriers with a grade 1 fundus finding demonstrated a significant decrease in maximal dark-adapted ERG function as compared with 5 of 6 (83%) carriers with grade 3 in response to a single-flash stimulus and with 4 of 5 (80%) carriers in response to a single-flash blue stimulus. For the single-flash photopic response, none of the 10 carriers with grade 1 showed any significant deterioration, whereas 2 of 4 (50%) with grade 3 did show such deterioration. The ERG responses for carriers with grade 2 were in between the extent of decrease in ERG amplitudes of those in carriers with grades 1 and 3. CONCLUSIONS: In our cohort of X-linked retinitis pigmentosa carriers, those with only a tapetal-like retinal reflex at presentation had a better prognosis to retain visual function than those with peripheral retinal pigmentation. These data are useful in counseling such carriers as to their visual prognosis.     

The outer and inner retinal function in patients with multiple evanescent white dot syndrome

Background:  To investigate the outer and inner retinal function in patients with multiple evanescent white dot syndrome (MEWDS).
Methods:  The retinal function of three subjects with MEWDS was investigated using one or a combination of full-field electroretinography (ERG), multifocal electroretinography (mfERG) or recording of multifocal oscillatory potentials (mfOP).
Results:  In case 1, the scotopic, maximal, photopic and flicker ERG responses of the two eyes were similar but the amplitudes of the dark- and light-adapted OPs were markedly reduced in the affected eye. In cases 2 and 3, the ERG responses were grossly reduced in amplitude and as expected the OPs were also diminished. However, using the mfERG a residual area of 'normal' retinal function in the affected eye was identified. The local OP, assessed by the mfOP, within the residual 'normal' retinal area was reduced as compared with the corresponding retinal area of the fellow unaffected eye. Subsequently, the mfERG responses of the 'normal' retinal area were also reduced.
Conclusion:  The OPs were reduced throughout the retina in patients with MEWDS, even in the area with a normal mfERG. The electrophysiological findings suggest that functional abnormality in MEWDS may occur initially in the inner retina and subsequently involves the outer retina.     

Neuroretinal dysfunction in patients affected by neurofibromatosis type 1

AIM: To examine neuroretinal function by using the multifocal electroretinography (mfERG) test in patients with neurofibromatosis type 1 (NF1) without optic pathway gliomas (OPGs). METHODS: This study was conducted on 35 patients (35 eyes) with NF1 and 30 healthy subjects (30 eyes) for the control group. Each subject underwent a complete ophthalmological examination including spectral domain-optical coherence tomography (SD-OCT) and mfERG. The 1.5-Tesla magnetic resonance imaging (MRI) scan of the brain was performed in NF1 patients to assess the presence of OPGs. All participants were recruited having a best corrected visual acuity (BCVA) of no less than 20/20 in each eye. The amplitude and implicit time of the P1 wave (first-order Kernel component) were evaluated on mfERG. Data analysis was carried out in the two central degrees and in the four quadrants from two to 25 degrees of visual field. RESULTS: Statistically significant results were obtained for the P1 wave amplitudes in the 4 quadrants in NF1 patients compared to healthy controls, while the reduction was not significant in the 2 central degrees between the groups. A statistically significant difference was observed among the P1 wave amplitudes as recorded in the 4 quadrants within the NF1 group, with lower amplitudes detected in the nasal quadrants. No differences in the implicit times were recorded in the 2 central degrees and in the 4 quadrants as compared between NF1 patients and controls. CONCLUSION: Impaired neuroretinal function in NF1 patients is expressed in a decreased amplitude of the P1-wave between 2 and 25 central retinal degrees on mfERG. Altered intracellular signal transduction due to abnormal neurofibromin-mediated cyclic adenosine monophosphate (cAMP) generation, can be involved. The possible use of mfERG as subclinical retinal damage indicator has a potential utility in clinical practice for the follow-up of NF1 patients.     

ISCEV guidelines for clinical multifocal electroretinography (2007 edition)

The clinical multifocal electroretinogram (mfERG) is an electrophysiological test of local retinal function. With this technique, many local ERG responses, typically 61 or 103, are recorded from the cone-driven retina under light-adapted conditions. This document specifies guidelines for performance of the test. It also provides detailed guidance on technical and practical issues, as well as on reporting test results. The main objective of the guidelines is to promote consistent quality of mfERG testing and reporting within and among centers. These 2007 guidelines, from the International Society for Clinical Electrophysiology of Vision (ISCEV: http://www.iscev.org ), replace the ISCEV guidelines for the mfERG published in 2003.