Retinal function in diabetic macular edema after focal laser photocoagulation

PURPOSE: To assess the effects of focal photocoagulation on retinal function in the macular and perimacular areas in patients with diabetes who have clinically significant macular edema. METHODS: Eleven patients were assessed after focal laser treatment. Multifocal electroretinogram (ERG) and full-field ERG techniques were used to evaluate the effects of treatment on macular, paramacular, and peripheral retinal function. A modified visual field technique was used to obtain local threshold fields. The posttreatment results were compared with pretreatment results. Changes in local ERG response amplitudes and implicit times were calculated for each patient and presented as difference fields. The changes in local ERG responses were compared with the changes in local field sensitivity. RESULTS: After treatment, the results of the psychophysical tests suggested little or no change in visual function, but changes in retinal function were observed with the multifocal ERG technique. Local ERG responses showed increases in implicit time and decreases in amplitude, compared with pretreatment values. Timing was affected more than amplitude. CONCLUSIONS: The results suggest that focal treatment produces changes in retinal function, and these changes are not restricted to the treated macular area.     

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.     

Multifocal electroretinogram in occult macular dystrophy

PURPOSE: Occult macular dystrophy (OMD) is an unusual macular dystrophy presenting with an essentially normal fundus and fluorescein angiography but with progressive central visual loss. The authors studied the function of local retinal areas in the posterior pole of patients with OMD using multifocal electroretinograms (ERGs). METHODS: Multifocal ERGs were recorded using the Visual Evoked Response Imaging System with 61 hexagonal elements within a visual field of 30 degrees radius from 8 OMD patients and 20 age-matched, normal subjects. The amplitudes and implicit times of the patients and normal control subjects were compared at the various retinal eccentricities. RESULTs. The amplitudes of the multifocal ERGs in the OMD patients were markedly reduced in the central 7 degrees of the fovea. The difference of the ERG amplitudes between OMD and normal subjects became smaller toward the peripheral retina. Most OMD patients had slight but significantly delayed implicit times across the whole testing field, and the differences between the OMD and the normal subjects did not change with retinal eccentricity. CONCLUSIONS. Our results for multifocal ERG amplitudes support the idea that OMD patients have localized retinal dysfunction distal to the ganglion cells in the central retina. The delayed implicit times across the whole test field suggest that the retinal dysfunction has a broader boundary than expected by ERG amplitudes and psychophysical perimetric results.     

Solitary albinotic spot of the retinal pigment epithelium: a functional and imaging study

PURPOSE: The presence or absence of functional changes associated with solitary, congenital, hypopigmented lesions of the retinal pigment epithelium (RPE) have been a matter of controversy. This case report describes retinal and functional findings in a young patient with such a lesion. METHODS: A 10-year-old Hispanic female with a solitary congential hypopigmented spot of the RPE was examined using fundus photography, fluorescein angiography, autofluorescence imaging (AF) and optical coherence tomography (OCT). Functional analyses were performed using the Humphrey 24 - 2 visual field, Goldmann perimetry and the multifocal ERG (mfERG). RESULTS: A small visual field defect was demonstrated on both Goldmann perimetry (I/ 2e test object) and on Humphrey 24 - 2 visual field testing (significant at the 0.5 % level for pattern deviation). The multifocal ERG response amplitudes were decreased in the corresponding area and increased in implicit time. Autofluorescence imaging showed an absence of fluorescence corresponding to the area of the lesion. OCT findings were indicative of a small amount of subretinal fluid or schisis-like changes overlying the RPE anomaly. CONCLUSION: The results indicate that solitary, albinotic spots of the RPE can be associated with visual field defects and outer retinal deficits; these may be related to impaired RPE function and/or chronic exudative changes.     

Acute macular neuroretinopathy--case report

PURPOSE: The aim of this study is to present rare retinal disease of unknown origin. MATERIAL AND METHODS: 27-years-old man was diagnosed because of poor vision in the left eye, which lasted 4-5 weeks. Following examinations were performed: Visual acuity, contrast sensitivity, color perception, visual field, fluorescein angiography (AF), visual evoked potentials (VEP), full-field flash electroretinography (flash ERG), focal-foveal electroretinography (focal ERG), multifocal electroretinography (multifocal ERG). Follow-up 1.5 year. RESULTS: Visual acuity of right eye was 1.25 (-0.1 log MAR) and left eye 1.0 (0.0 log MAR). In left eye between optic disc and macula irregular lesion with dots of retinal pigment epithelium atrophy and little edema was seen. AF revealed small "window" defects. In visual field of the left eye paracentral relative scotoma occurred and in stereokampimetry central relative scotoma was found about 5 degrees from the fixation point. In VEP latency of P100 was delayed and amplitude was reduced in both eyes. In flash as well as focal ERG small reduction of cone function and delayed implicit time of b-wave were found in left eye. In general examination no focal inflammation and no abnormalities in laboratory tests were found. The patient was treated with steroids for 3 weeks. After ten days of general steroid treatment visual acuity improved to 1.25 and subjective improvement of vision occurred. Control examination after 1.5 year revealed no patient's complains, visual acuity 1.25, no change in visual field, VEP improvement. In left eye flat irregular area with pigment epithelium atrophy was seen. CONCLUSIONS: Acute macular neuroretinopathy may be diagnosed after detail examination. Prognosis is generally good, recovery is slow, but despite of local retinal atrophy subjective complains disappear completely.     

Multifocal ERG and VEP responses and visual fields: comparing disease-related changes

Static visual perimetry and the multifocal technique both measure the local effects of diseases of the retina and optic tract. The purpose here is to relate the measures obtained from each technique and to describe this relationship in some diseases. It is important to measure both the implicit time and amplitude of the multifocal ERG (mERG) or multifocal VEP (mVEP) responses. Some diseases affect one measure of the responses but not the other. The comparison of either measure to local sensitivity changes measured with static perimetry (e.g. the Humphrey 24-2 and 30-2) presents a problem. Different stimulus displays are employed. Further, the multifocal responses are displayed with arbitrary spacing between the responses. One approach is to measure the amplitude and implicit time of the multifocal responses and display these values on the same coordinates as in the visual field plots. This allows a qualitative comparison of fields and multifocal responses on the same scale. A second approach involves modifying the Humphrey perimeter software so that the test spots are placed in the centers of the multifocal stimuli (e.g. the center of each hexagon of the mERG display). A third approach involves estimating the thresholds for the regions of the multifocal display by interpolating from values at the standard Humphrey locations. The second and third approaches produce a one-to-one mapping of the multifocal and field measures and allow a quantitative comparison between the two. The relationship between visual fields and multifocal responses, determined through one or more of these approaches, is different depending upon whether the disease primarily affects the outer retina (retinitis pigmentosa), ganglion cell (glaucoma), or optic nerve (ischemic optic neuropathy and optic neuritis). This revised version was published online in July 2006 with corrections to the Cover Date.     

Perifoveal function in patients with North Carolina macular dystrophy: the importance of accounting for fixation locus

PURPOSE: To quantify the extent of visual function losses in patients with North Carolina Macular Dystrophy (NCMD) and to demonstrate the importance of accounting for eccentric fixation when making comparisons with normal data. METHODS: Five patients with NCMD who were from a single family were examined. Multifocal electroretinograms (mfERGs) and psychophysical assessments of acuity and luminance visual field sensitivities were measured throughout the central retina. Comparisons of responses from equivalent retinal areas were accomplished by shifting normal templates to be centered at the locus of fixation for each patient. RESULTS: Losses of psychophysically measured visual function in patients with NCMD extend to areas adjacent to the locations of visible lesions. The multifocal ERG amplitude was reduced only within the area of visible lesion. Multifocal ERG implicit times were delayed throughout the entire central retinal area assessed. CONCLUSIONS: ERG timing is a sensitive assay of retinal function, and our results indicate that NCMD has a widespread effect at the level of the mid and outer retina. The findings also demonstrated that it is necessary to account for fixation locus and to ensure that equivalent retinal areas are compared when testing patients with macular disease who have eccentric fixation.     

Testing central retinal function with multifocal electroretinography before and after photodynamic therapy

BACKGROUND: Photodynamic therapy (PDT) is applied for certain forms of choroidal neovascular membrane (CNV). The aim of this study was to investigate the effect of PDT on central retinal function as assessed by multifocal electroretinography (ERG). METHODS: 24 patients (25 eyes) with CNV (>50% classic 12 eyes) or occult (9 eyes) in age related macular degeneration (AMD) and CNV with pathological myopia (4 eyes) were treated by PDT using Verteporfin((R)). Before and a median of 6 weeks after therapy, central retinal function was examined using multifocal ERG (RetiScan, 61 hexagons, first-order response). RESULTS: In the area of treatment,we found a tendency of the amplitude of the first positive deflection (P1) to decrease and of the implicit time to increase, but both effects were not statistically significant. These alterations were more pronounced in eyes with occult CNV and in myopia-related CNV. Amplitude reduction and implicit time prolongation could also be found in the areas represented by the multifocal ERG but not treated. There was no significant correlation between change in visual acuity after PDT and amplitude of the multifocal ERG. CONCLUSION: The effects of PDT on retinal function seem to be moderate as assessed by multifocal ERG. An inherent problem of this investigation was the recruitment of nontreated patients as controls. Future goals are investigations of patients with repeated PDT and of long-term alterations in multifocal ERG after PDT.     

Multifocal Electroretinogram Changes and Normal Ganzfeld-ERG in Patients with AZOOR

Abnormal electroretinogram (ERG) findings are essential to the diagnosis of acute zonal occult outer retinopathy (AZOOR), however, the standard Ganzfeld-ERG can record only the mass retinal response. The multifocal electroretinogram (mfERG) can simultaneously evaluate the local function of numerous small retinal areas. A neuro-ophthalmologic examination including visual field, ERG, and mfERG was performed in two patients with presumed AZOOR. Two patients showed a normal response to the standard ERG and an abnormal response to mfERG. In conclusion, the mfERG may be essential in the diagnosis of AZOOR.     

Multifocal electroretinogram in diabetic subjects

PurposeTo identify local retinal abnormalities and evaluate the nature and extent of retinal dysfunction in diabetics using full field electroretinogram (ERG) and multifocal ERG (MF-ERG) and to determine the correlation between features of optical coherence tomography (OCT) and MF-ERG.MethodsTwenty-eight normal subjects (Control Group; 56 eyes) and 37 patients (72 eyes) with diabetes mellitus (DM Group) were evaluated. In the DM Group, 17 eyes had no retinopathy (grade 1), 18 eyes had early non proliferative diabetic retinopathy (NPDR) (grade 3), 16 eyes had late NPDR (grade 4), 21 eyes had proliferative diabetic retinopathy (PDR) (grade 5). Full field ERG and MF-ERG, were used to assess the effects of diabetic retinopathy on retinal function. OCT and fluorescein angiography were used to assess and compare morphological changes with functional changes in diabetes mellitus.ResultsIn diabetic patients without retinopathy (17 eyes), the amplitudes of the second order component of MF-ERG were reduced and implicit times were delayed, while only implicit times of first order component of MF-ERG were delayed but the amplitudes of first order component were normal. In diabetic patients with retinopathy (55 eyes), the overall amplitudes were reduced and peak implicit time increased in the first order component and second order component.OCT of the DM Group showed the fovea of eyes with edema were thicker than the Normal Group. The fovea of eyes with cystoid macular edema (CME) were significantly thicker than the fovea of eyes with diffuse swelling. The implicit times of MF-ERG were directly correlated with foveal thickness.ConclusionMF-ERG reveals local retinal dysfunction in diabetic patients. MF-ERG offers the advantage of topographic mapping of retinal dysfunction. The magnitude of delay of MF-ERG implicit time reflects the degree of local clinical abnormalities in eyes with retinopathy. Local response delays found in eyes without retinopathy detects subclinical local retinal dysfunction in diabetics. The combination of OCT and MF-ERG may provide objective criteria for evaluation and assessment of diabetic retinopathy.     

Ethambutol neuroretinopathy

OBJECTIVE: To describe the clinical features of ethambutol neuroretinopathy. DESIGN: Case report and meta-analysis of the literature. PARTICIPANTS: A patient with clinical and electrophysiological findings suggestive of ethambutol neuroretinopathy. TESTING: Electroretinogram, electro-oculogram and visual fields. MAIN OUTCOME MEASURE: Clinical and electrophysiological findings. RESULTS: 101 cases were reviewed, retinal findings include retinal pigment epithelial changes, macular edema, flame-shaped hemorrhages. Electroretinogram findings include decreased amplitude and abnormal wave pattern in full field ERG, multifocal or pattern ERG and electro-oculogram findings include abnormal Arden ratio. CONCLUSIONS: Clinical, electrophysiological and in vitro studies support the toxic effect of ethambutol on the retina. Therefore ethambutol ocular toxicity may be a neuroretinopathy.     

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.     

屈光参差性弱视同步记录多焦视觉诱发电位和多焦视网膜电图的对比研究

目的探讨弱视发病的可能机制。方法采用VERIS Science^TM4．2多焦电生理系统对24例屈光参差性弱视患者双眼分别进行多焦图形视觉诱发电位(VEP)、视网膜电图(ERG)同步记录和多焦闪光VEP、ERG同步记录,并与30例正常对照的结果进行比较。结果在不同视网膜区域弱视眼多焦图形VEP、ERG反应和多焦闪光VEP、ERG二阶反应振幅均降低,VEP特征峰潜时延长,ERG潜时无改变。弱视眼多焦闪光一阶反应VEP、ERG的反应振幅密度均降低,潜时无明显改变。多焦图形VEP波形异常程度中心区大于周边区,且与弱视眼的视力异常程度有相关性。弱视眼多焦图形和闪光二阶反应的视网膜．皮层传导时间(RCT)显著延长,闪光一阶反应RCT三组无明显差异。结论弱视眼的mVEP和mERG具有明显的特征性改变,表明弱视眼的视网膜、视觉传导通路和视皮层都存在明显损害,且中心区损害重于周边区,中枢损害重于视网膜。(中华眼科杂志,2005,41：41-46)     

老年黄斑变性的多焦ERG检测

目的：运用多焦视网膜电图（electroretinography,ERG）评价老年黄斑变性（age-related macular degeneration,AMD）患者的局部视网膜功能。方法：采用103个六边形刺激图形，记录12例（24只眼）AMD患者在4分钟记录时间内的多焦ERG波形图及三维功能图。结果：AMD患者总体ERG的a波、b波振幅在正常范围内，而1环及2环a波、b波振幅下降。三维图显示中央局部视网膜功能降低。结论：多焦ERG是一种评价局部视网膜功能的新技术，可用于眼底病的早期诊断。     

The nature and extent of retinal dysfunction associated with diabetic macular edema

PURPOSE: To evaluate the nature and extent of retinal dysfunction in the macular and surrounding areas that occurs in patients with diabetes with clinically significant macular edema (CSME). METHODS: Eleven patients were evaluated before focal laser treatment. Multifocal electroretinogram (ERG) and full-field ERG techniques were used to assess the effects of diabetic retinopathy and CSME on macular, paramacular, and peripheral retinal function. A modified visual field technique was used to obtain local threshold fields. The relationship between local sensitivity changes and local ERG changes was determined. RESULTS: Local ERG responses were significantly delayed and decreased in amplitude, and timing changes were observed in a larger area of the retina than amplitude changes. Visual field deficits were similarly widespread with marked sensitivity losses occurring in retinal areas with normal ERG amplitudes and in areas that appeared to be free of fundus abnormalities. Despite this similarity and the finding that retinal areas with elevated thresholds have timing delays, timing delays were not good predictors of the degree of threshold elevation. CONCLUSIONS: The results demonstrate the widespread nature of timing deficits and visual field deficits that are associated with CSME.     

Differenzierte Untersuchung der Netzhautfunktion bei regionaler Retinitis pigmentosa mit Hilfe des multifokalen Elektroretinogramms

Purpose. Generalized retinal degenerations such as retinitis pigmentosa may manifest with focal retinal dysfunctions. These may be detected objectively by new electrophysiological techniques, such as multifocal electroretinography (ERG). Case report. A mother and daughter, aged 81 and 46 years, showed bilateral caudal bone spiculae formations with corresponding cranial visual field defects in the static perimetry of the central visual field (Octopus) and in the kinetic perimetry (Goldmann). Results. Pattern VEP, pattern ERG, EOG, and cone ERG were within the normal range. The scotopic ERG was in the lower normal range. The multifocal cone ERG of the central 50° showed reduced amplitudes and prolonged latencies in the first-order response component. These findings corresponded to the area of the bone spiculae and the scotomata. Conclusion. Multifocal ERG enables the detection of focal retinal cone dysfunction in segmental retinitis pigmentosa. It is an additional tool that may aid in the diagnosis and classification of this disease.     

A Korean family with an early-onset autosomal dominant macular dystrophy resembling North Carolina macular dystrophy

PURPOSE: To characterize and report the phenotype of a Korean family with an early-onset autosomal dominant macular dystrophy resembling North Carolina macular dystrophy (NCMD). METHODS: Five members of a Korean family were examined clinically and underwent fundus photography, fluorescein angiography, indocyanine green angiography, optical coherence tomography, full field electroretinogram (ERG), multifocal ERG, electro-oculography (EOG), a color vision test, and a visual field test. RESULTS: Visual acuity ranged from 20/200 to 20/20. Fundus findings demonstrated varying degrees of involvement ranging from drusen only to chorioretinal involvement. Central scotoma corresponded to retinal lesions in two patients. Full field ERG was normal but multifocal ERG showed decreased amplitude and delayed implicit time in the macular area. EOG was normal except in one patient. Color vision tests were also normal. CONCLUSIONS: The phenotype of this Korean family is consistent with NCMD. Linkage analysis is required to confirm the diagnosis.     

Pupil perimetry using M-sequence stimulation technique

PURPOSE: M-sequence stimulation technique allows mapping of the retinal function by multifocal electroretinographic (ERG) recordings. However, the information provided about visual field is limited to retinal function. Optic nerve diseases and diseases of the higher visual pathways usually show normal multifocal ERGs. Using pupillary responses instead of the electrical retinal responses might enhance the diagnostic possibilities of this system. The problems of local ERG recordings are very similar to those encountered in pupil perimetry: Local stimuli have to be dim to avoid or at least reduce stray-light responses. Dim stimuli, close to the absolute threshold, elicit only subtle pupillomotor responses. Therefore, techniques that are able to detect small focal responses are promising. METHODS: Pupillography was done by means of an infrared video camera and real time image processing (50 Hz) using a custom-designed videoboard in a personal computer (486). Recording conditions: The stimulus was presented on a monitor (75 Hz) in 26 cm distance from the patient's eyes. It contained 37 hexagons in a 25 degrees visual field. Each element changed between black (1.6 cd/m2) and white (160 cd/m2) after a binary M-sequence independently from other elements. Four thousand ninety six different stimulus pictures of 120-msec duration were shown during a single pupillogram recording. Thirty-seven local pupillograms were calculated in a cross-correlation of stimulus sequence and the pupil diameter. RESULTS: The pupillomotor fields in normals showed a shape and sensitivity distribution as known from conventional pupil perimetry techniques. Artificial paracentral scotomas (5 degrees) created by masking different locations could be demonstrated convincingly. Even in patients with optic nerve lesions it was possible to demonstrate visual field defects. CONCLUSIONS: Pupil perimetry using the M-sequence technique is a promising method of objective perimetry that may find its entrance into clinical application.     

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).     

Ethambutol Neuroretinopathy

Objective: To describe the clinical features of ethambutol neuroretinopathy. Design: Case report and meta-analysis of the literature. Participants: A patient with clinical and electrophysiological findings suggestive of ethambutol neuroretinopathy. Testing: Electroretinogram, electro-oculogram and visual fields. Main outcome measure: Clinical and electrophysiological findings. Results: 101 cases were reviewed, retinal findings include retinal pigment epithelial changes, macular edema, flame-shaped hemorrhages. Electroretinogram findings include decreased amplitude and abnormal wave pattern in full field ERG, multifocal or pattern ERG and electro-oculogram findings include abnormal Arden ratio. Conclusions: Clinical, electrophysiological and in vitro studies support the toxic effect of ethambutol on the retina. Therefore ethambutol ocular toxicity may be a neuroretinopathy.