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Multifocal ERG (multifocal + erg)
Selected AbstractsCASE REPORT: Clinical application of mfERG/VEP in assessing superior altitudinal hemifield lossCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 4 2005Dr Henry Ho-lung Chan PhD FAAO Multifocal ERG (mfERG) and multifocal VEP (mfVEP) have been used widely in the investigation of pathological changes or functional variations in the visual system. Altitudinal hemifield loss is a visual field defect that is usually found in patients with ischaemic optic neuropathy (ION). Anterior ischaemic optic neuropathy (AION) is a complex multi-factorial disease and it is difficult to diagnose according to clinical symptoms and signs alone. AION is believed to be caused by an infarction of the optic nerve due to the occlusion of the posterior ciliary arteries. The current report presents a patient diagnosed with non-arteritic AION. In this report, the mfERG findings did not match the results of the visual field test but those of the mfVEP did. After consideration of the visual electrophysiological and visual field results, the defect arises from neither the retina nor the visual pathway behind the optic chiasma. Hence, the optic nerve is the most likely location of the lesion, causing the superior altitudinal hemi-field loss. This report shows that the mfERG and mfVEP techniques can be used for objective visual field assessment to supplement the conventional visual field testing. [source] Comparison of chromatic macular ERG and multifocal ERG in diabetic macular edemaACTA OPHTHALMOLOGICA, Issue 2007MA ARAKELYAN Purpose: To evaluate the degree of macular function disturbances in patients with diabetes mellitus and high glycosylated haemoglobin (HbA1c). Methods: 11 patients with type II diabetes were included in our study. In 6 patients a clinically significant macular edema was detected; other 5 patients showed slight vascular changes and absence of macular pathology. All patients had much too high (8-10%) or extremely high (above 10%) levels of HbA1c and underwent a chromatic macular ERG test to red, green and blue stimuli (MBN, Russia). A RETIScan system for multifocal ERG was also used (Roland Consult, Germany). Results: Patients with macular edema and long duration of the disease had significant reduction of a- and b-wave amplitudes of macular ERG, whereas those with short duration of diabetes showed slight decrease of macular ERG amplitude. The density of photoreceptors in multifocal ERG and amplitudes of N1 and P1 components were analyzed in area of 15° of visual angle: the mean of 3 central rings' values was calculated. Correlation between mf-ERG data and macular ERG amplitudes were found. In patients without macular edema and duration of the disease from 7 to 10 years who had background diabetic retinopathy no significant changes of function testing of the macula were revealed. The amplitude values were close to lower normal data. Conclusions: Macular function in diabetic patients is mainly safe in spite of high levels of glycosylated haemoglobin. The complexity of pathogenetic mechanisms of diabetic retinopathy along with functional tests is still the subject of an investigation. [source] Detection of glaucomatous damage using multifocal ERGCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 6 2005Henry Ho-Lung Chan PhD FAAO The first-order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103-scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first-order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low-contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma. [source] Morphological study of acute zonal occult outer retinopathy (AZOOR) by multiplanar optical coherence tomographyACTA OPHTHALMOLOGICA, Issue 4 2009Yoshiko Takai Abstract. Purpose:, We set out to determine whether morphological retinal changes occur in patients with acute zonal occult outer retinopathy (AZOOR). Methods:, Five patients diagnosed with AZOOR were studied. They included two men and three women, with an age range of 23,51 years. Symptoms and findings were retrospectively and prospectively collected. The three-dimensional multiplanar optical coherence tomography (OCT) Ophthalmoscope® was used to examine the morphology of the retina in patients who were examined between April 2000 to December 2004. Standardized full-field electroretinograms (ERGs) and multifocal ERGs (mfERGs) were recorded. Results:, All the patients reported an acute onset of visual disturbances including a decrease of central vision and photopsia. The a- and b-waves of full-field ERGs were decreased, and the mfERGs in the central area were reduced. Ophthalmoscopic examination showed no obvious fundus abnormalities. OCT Ophthalmoscopic® images of a cross-sectional plane revealed hyporeflection at the level of the photoreceptor layer in the macular region in three of five patients, and presence of one or two layers in which the inner/outer segment junction of the photoreceptor layer was absent in the other two patients. En-face, constant depth C-scans, which present the image parallel to the retina, revealed an abnormal, patchy hyper-reflection in the affected eyes of two patients and in the non-affected eye in one of these two patients. Conclusions:, The changes in OCT Ophthalmoscope® B-scan images indicate morphological damage to the photoreceptors, which probably accounts for the functional alterations. The alterations in the C-scan image in the normal fellow eye of one patient suggest that morphological changes may precede symptomatic changes. [source] | ||||||||||