Photopic 30 Hz flicker electroretinography predicts ocular neovascularization in central retinal vein occlusion

Abstract

ABSTRACT.Purpose: To confirm the predictive value of photopic cone b-wave implicit time in 30 Hz flicker electroretinography (ERG) for ocular neovascularization (NV) in central retinal vein occlusion (CRVO), and to compare the ERG results to the presumed healthy fellow eye. Methods: A retrospective analysis of 71 consecutive patients with CRVO. After ERG examination, all patients were followed for at least 12 months, or until NV was found. Three patients died during the study period; none of the other patients were lost to follow-up. Results: Twenty-four patients (33.8%) developed NV during follow-up. The mean cone b-wave implicit time of all patients was 32.6 ms [standard deviation (SD) 5.21]. All 18 patients with an implicit time of 35.0 ms or higher (> 0.5 SD from mean) developed NV. In patients who developed NV, the average implicit time was 38.5 ms (range 29.7-43.9 ms); in patients without NV (n ¼ 47), the average implicit time was 29.6 ms (range 24.7-34.9 ms) (P < 0.0001). The average implicit time in the presumed healthy fellow eye was 28.7 ms (range 24.4-33.9 ms) in patients with NV, and 26.5 ms (range 23.7-33.2 ms) in patients without NV (P ¼ 0.002). The mean interocular difference in implicit time was 9.9 ms (range 4.1-15.7 ms) in patients with NV and 2.9 ms (range )1.0 to 10.0 ms) in patients without NV (P < 0.0001). Conclusion: Patients with CRVO should be examined routinely with photopic 30 Hz flicker ERG, which is a simple and objective clinical test that can identify patients at risk of ocular NV. On the assumption that the presented ERG settings are used, implicit times of 35.0 ms or higher (> 0.5 SD from mean) are clearly associated with the development of ocular NV. To compare the ERG result of the affected eye to the presumed healthy fellow eye is probably of less value.

Peripheral retinal function assessed with 30-Hz flicker seems to improve after treatment with Lucentis in patients with diabetic macular oedema

“…5). Changes in 30-Hz flicker have been described in other retinal diseases [15][16][17]. These studies may indicate that an increased 30-Hz flicker implicit time indicates damaged cone function of the entire retina, either in the form of ischaemia or in the form of a detached retina.…”

Central Retinal Vein Occlusion in Younger Swedish Adults: Case Reports and Review of the Literature

“…Retinal ischemia was studied in 18 of the patients in this study using the cone b-wave implicit time in the 30 Hz flicker ERG. There is evidence that the cone implicit times in the 30 Hz flicker ERG are the most predictive ERG parameter for the development of neovascularization in the eyes with CRVO [44-47]. …”

“…The risk of neovascular complications in patients with CRVO is related to the extent of capillary nonperfusion or the degree of retinal ischemia, and can be evaluated with fluorescein angiography (FA) [41-43], but several recent studies have demonstrated that full-field electroretinography (ERG) could be a more suitable method of identifying ocular ischaemia, especially the cone b-wave implicit time, in both photopic and scotopic 30 Hz flicker ERG [44-47]. The cone b-wave implicit times in the 30 Hz flicker ERG have been found to be the most predictive ERG parameter for the development of ocular neovascularization [45], and were found to be significantly correlated with the concentration of vascular endothelial growth factor (VEGF) in the aqueous in CRVO patients [48].…”

The flicker electroretinogram interocular amplitude ratio is a strong prognostic indicator of neovascularization in patients with central retinal vein occlusion

“…Morrell et al found that the interocular difference in the flicker ERG latency was the significant distinguishing factor [17]. Kjeka et al found that the latency was the significant factor, but interocular difference was of less value [11]. Larsson et al found that the implicit time, but not the amplitude of 30-Hz flicker ERG was a good predictor of rubeosis in CRVO patients [15].…”

“…In recent years, most papers have focused on the investigation of brief protocol for busy clinical practices [11,14,15,26]. Flicker ERG has the benefits of simplicity, not subjected to photomyoclonic reflex and as reliable as standard ERG.…”