Abstract
Abstract: :
Purpose: To determine the effects of central retinal vein occlusion (CRVO) on wide field multifocal electroretinography (mfERG), and to compare mfERG parameters in eyes with ischaemic and non-ischaemic CRVO. Methods: Sequential mfERG was performed on 22 patients with CRVO, using a custom-built widefield system. All patients were tested within the first 16 weeks of the acute event and re-examined every 6-12 weeks thereafter, depending on clinical findings. In addition, all patients underwent detailed ophthalmic assessment,including LogMar acuity, pupil assessment, tonometry, gonioscopy, Humphrey perimetry, fundoscopy, fluorescein angiography (FFA) and conventional electroretinography (ERG), in order to differentiate ischaemic from non-ischaemic CRVO in the acute stage. Eleven eyes had ischaemic CRVO and 11 had non-ischaemic CRVO. Local mfERG responses and conventional ERG responses were determined within each group and compared to normal age-matched controls (5-95% confidence limits). Results: The local mfERG P1 amplitude fell below the normal range in all of the eyes with ischaemic CRVO and in 3 of the 11 eyes with non-ischaemic CRVO. The local mfERG P1 implicit times fell beyond the normal range in eyes with ischaemic and non-ischaemic. The local P1 latencies were more significantly delayed in eyes with ischameic CRVO when compared to eyes with non-ischaemic CRVO (P<0.003). Local mfERG abnormalities were more widespread in areas of retinal non-perfusion determined with FFA. Standard ERG responses were within normal limits in patients with non-ischaemic CRVO and were abnormal in 7 of 11 patients with ischaemic CRVO. Conclusion: These results indicate that mfERG is a sensitive diagnostic tool for differentiating ischaemic from non-ischaemic CRVO in the acute phase of the disease. Importantly, mfERG has the ability to localise and potentially quantify the degree of retinal ischaemia, complementing FFA and facilitating early detection of eyes at high risk of developing neovascular complications.
Keywords: 615 vascular occlusion/vascular occlusive disease • 395 electroretinography: clinical • 566 retinal neovascularization