The electroretinogram:a useful tool for evaluating age-related macular disease?

With an ageing population, the number of age-related macular disease (ARMD) cases will inevitably rise. This gives greater impetus for the need to identify the disease earlier and assess treatments to slow disease progression. Differing electroretinogram (ERG) modalities have been reviewed in relation to the objective assessment of retinal function in ARMD and for monitoring the effectiveness of clinical interventions. Conflicting results have been found with regard to the efficacy of ERG findings in the investigation of ARMD in previous years. The newer multifocal ERG paradigm provides spatial topographical information about retinal function in ARMD. It has shown promising results in monitoring effectiveness of clinical interventions and studies are continuing in this area. Better knowledge of retinal function in ARMD may lead to enhanced treatments at each phase of the disease

Global flash multifocal electroretinogram: early detection of local functional changes and its correlations with optical coherence tomography and visual field tests in diabetic eyes

Purpose: To investigate the correlations of the global flash multifocal electroretinogram (MOFO mfERG) with common clinical visual assessments – Humphrey perimetry and Stratus circumpapillary retinal nerve fiber layer (RNFL) thickness measurement in type II diabetic patients. Methods: Forty-two diabetic patients participated in the study: ten were free from diabetic retinopathy (DR) while the remainder suffered from mild to moderate non-proliferative diabetic retinopathy (NPDR). Fourteen age-matched controls were recruited for comparison. MOFO mfERG measurements were made under high and low contrast conditions. Humphrey central 30-2 perimetry and Stratus OCT circumpapillary RNFL thickness measurements were also performed. Correlations between local values of implicit time and amplitude of the mfERG components (direct component (DC) and induced component (IC)), and perimetric sensitivity and RNFL thickness were evaluated by mapping the localized responses for the three subject groups. Results: MOFO mfERG was superior to perimetry and RNFL assessments in showing differences between the diabetic groups (with and without DR) and the controls. All the MOFO mfERG amplitudes (except IC amplitude at high contrast) correlated better with perimetry findings (Pearson’s r ranged from 0.23 to 0.36, p<0.01) than did the mfERG implicit time at both high and low contrasts across all subject groups. No consistent correlation was found between the mfERG and RNFL assessments for any group or contrast conditions. The responses of the local MOFO mfERG correlated with local perimetric sensitivity but not with RNFL thickness. Conclusion: Early functional changes in the diabetic retina seem to occur before morphological changes in the RNFL

MfERG responses to long-duration white stimuli in glaucoma patients

The intent of our study was to evaluate whether the response to a long-duration white stimulus in the multifocal electroretinogram (mfERG) is sufficiently sensitive to detect early retinal dysfunction in glaucoma. On-off mfERGs were recorded from 15 NTG and 15 HTG patients and compared with 14 control subjects. Recording parameters were the following: LED stimulus screen (RETIscan?), 100-ms stimulus duration, 200-ms stimulus interval, 11-min total recording time, stimulus matrix of 61 elements, frame rate: 70 Hz, Lmax: 180 cd/m(2), Lmin: 0 cd/m(2), and filter setting: 1-200 Hz. The second negative response following stimulus onset (N2-on), as well as following stimulus offset (N2-off), was analyzed as an overall response and in quadrants, as well as in 4 small central and four adjoining peripheral areas per quadrant. The latency of the N2-on was significantly delayed in HTG in all response averages tested, while in NTG this was only seen in the overall response and in the small central response averages (P > 0.05). The most sensitive measure in HTG was the latency of the N2-on of the small peripheral response average of the superior temporal quadrant with an area under the ROC curve of 0.881. For NTG, the most representative measure was the latency of the N2-on of the small central response average of the inferior nasal quadrant with an area under the ROC curve of 0.793. Our results showed that in stimulation with long-duration flashes, the second negative response following the on response, representative of the early PhNR, is affected in glaucoma where N2-on showed a latency delay in POAG patients. The latency delay of the N2-on was more prominent for HTG than for NTG