Association of electroretinogram and morphological findings in central retinal vein occlusion with macular edema

Oscillatory potential findings in patients with acute ischaemic central retinal vein occlusion

AIMS

To explore the sensitive components of full-field electroretinography (ERG) as indicators of retina function at the onset of acute ischaemic central retinal vein occlusion (CRVO).

METHODS

11 patients (11 eyes) with ischaemic CRVO and 32 patients (32 eyes) with non-ischaemic CRVO who presented with first-episode unilateral CRVO within 1 month of symptom onset and with no previous intervention were examined by the International Society for Clinical Electrophysiology of Vision standard ERG.

RESULTS

A significant amplitude decline and peak time delay in light-adapted (LA) 3 ERG and LA 30 Hz flicker ERG (p<0.05 for all) was found in the ischaemic CRVO eyes, compared with the non-ischaemic CRVO eyes. The b/a amplitude ratio of dark-adapted (DA) 3 ERG, DA 10 ERG and LA 3 ERG was significantly different between the ischaemic and non-ischaemic groups (p<0.05 for all). Regarding oscillatory potentials (OPs), the amplitudes of OP1, OP2 and OP3 as well as the sum of DA 3 OP1-4 amplitudes (∑OPs) showed significant changes (p<0.01 for all) between two groups. No peak time delay of OPs was found between the ischaemic and non-ischaemic CRVO eyes.

CONCLUSION

The amplitude of DA 0.01 ERG, components of LA 3 ERG and LA 30 Hz flicker ERG, and the b/a amplitude ratio could be among the most sensitive indicators in patients with acute ischaemic CRVO. The amplitudes of OP1, OP2, OP3 and ∑OPs in the CRVO eyes were reduced to 40% of the control values, showing that this quantitative method is reliable for detecting ischaemic retinal diseases, even in early stage.

Efficacy and Safety Evaluation of Mometasone Furoate in Treating Ocular Inflammation

Mometasone furoate (MF) is a medium-potency synthetic glucocorticosteroid with anti-inflammatory, antipruritic, and vasoconstrictive properties. However, its role in the treatment of ocular inflammation has not yet been explored. This work investigated the anti-inflammatory activity of MF in ocular tissues. First, the in vivo safety of the intravitreal (IVT) injection of MF (80, 160, and 240 µg) was evaluated via clinical examination (including the assessment of intraocular pressure), electroretinography (ERG), and histopathology. Second, MF was tested in an experimental model of bacillus Calmette-Guérin (BCG)-induced uveitis in Wistar rats. Intraocular inflammation was then evaluated via a slit-lamp and fundus examination, ERG, histopathology, and the quantification of pro-inflammatory markers. Intravitreal MF showed no toxicity in all the investigated doses, with 160 µg leading to attenuated disease progression and improvement in clinical, morphological, and functional parameters. There was a significant reduction in the levels of inflammatory markers (myeloperoxidase, interleukins 6 and 1β, CXCL-1, and tumor necrosis factor-alpha) when compared to the levels in untreated animals. Therefore, MF should be further investigated as a promising drug for the treatment of ocular inflammation.

Time-Frequency Analysis of Photopic Negative Response in CRVO Patients

PURPOSE

The PhNR is driven by retinal ganglion cells (RGCs). Therefore, the function of RGCs could be objectively evaluated by analyzing the PhNR. The aim of this article is to determine the effect of central retinal vein occlusion (CRVO) on PhNR and RGCs performances.

METHODS

Seventeen patients with CRVO were included. Full-field photopic ERGs, including PhNR, were recorded and compared with the fellow normal eyes. ERG signals were analyzed based on the standard time-domain analyses of the PhNR as well as a continuous wavelet transform (CWT) to extract time-frequency components that correspond to the PhNR using MATLAB. We obtained the main frequencies and their occurrence time from CWT.

RESULTS

All a-wave, b-wave, and PhNR amplitudes of CRVO eyes showed a significant reduction compared to those of the fellow eyes (P < .01, P < .001, and P < .001, respectively). The peak times of a-wave, b-wave, and PhNR were increased significantly in the CRVO eyes (P = .04, P = .04, and P = .003, respectively). The dominant f₃ frequency, which corresponds to the PhNR in CRVO patients, showed a more significant decrease (P < .001) compared to other dominant frequencies (f₀, f₁, and f₂). The occurrence time of f₃ (t₃) was significantly higher in the CRVO eyes (P < .001). Time-domain of the PhNR was also affected in CRVO patients (P < .001).

CONCLUSION

CWT allows quantifications of ERG responses, especially for PhNR. The PhNR was severely affected in CRVO eyes implicating loss of RGCs. CWT might demonstrate the severity of CRVO more precisely and identify diagnostically significant changes of ERG waveforms that are not resolved when the analysis is only limited to the time-domain measurements.

Electroretinogram abnormalities in nonanterior childhood uveitis

Purpose

A major point of concern in uveitis is the development of irreversible retinal changes after inflammation. In this study, we assess how nonanterior childhood uveitis affects retinal function using full‐field electroretinography (ERG).

Methods

Cross‐sectional study. ERGs of 63 uveitis eyes (33 children) were measured according to extended International Society for Clinical Electrophysiology of Vision (ISCEV) protocols. ERG abnormalities were investigated in relation to the following clinical parameters: demographics, uveitis characteristics, including severity of inflammation, treatment, best corrected visual acuity (BCVA), cystoid macular oedema (CME) on optical coherence tomography and fluorescein angiography score.

Results

The ERG showed abnormalities in 34 eyes (54%). The most frequent ERG abnormalities were prolonged implicit times of the cone b‐wave (37%; n = 23/63) and an abnormal 30‐Hz flicker response (implicit time and/or amplitude) (33%; n = 21/63). Factors associated with these ERG abnormalities were CME (p = 0.021) and 3+ vitreous cells (p = 0.021). BCVA in eyes with and without these ERG abnormalities did not statistically differ and was relatively good (median: 0.05 LogMAR, IQR: 0.00–0.15 LogMAR).

Conclusion

The ERG is frequently affected in childhood uveitis indicating a global retinal dysfunction. ERG abnormalities seem to be associated with a more severe posterior segment inflammation and a younger age. If an association between ERG abnormalities and long‐term visual outcome can be made in the future, these early ERG findings during the course of childhood uveitis have significance for treatment strategies.

The diagnostic usefulness of the negative electroretinogram

The definition of the negative response of the full field electroretinogram is the presence of a b-wave with less amplitude than the a-wave (b/a ratio<1) in the combined response of cones and rods. The presence of this pattern reflects an alteration in the bipolar cells, the Müller cells, or in the transmission of the stimulus from the photoreceptors to the bipolar cells, with preserved photoreceptor function. This finding can be seen bilaterally and symmetrically in different hereditary conditions, such as congenital stationary night blindness, juvenile X-linked retinoschisis, and Duchenne and Becker muscular dystrophies. On the other hand, it can also be found unilaterally (or asymmetrically) in acquired pathologies, such as some types of immuno-mediated retinitis (Birdshot retinochoroiditis), autoimmune retinopathies, cancer/melanoma associated retinopathy, or retinal toxicity. The objective of this review is to summarise the characteristics of the pathologies in which this finding can be observed, in order to highlight its usefulness in the differential diagnosis of retinal conditions.