Retinal Vein Occlusion A clinical study of electrophysiology, certain prognostic factors and treatment

Abstract: The influence of the factor V Leiden mutation on the development of neovascular complications in central retinal vein occlusion was studied. The presence of the mutation was found to enhance the risk of developing neovascular complications almost threefold compared to in patients without the mutation. Optic nerve head swelling, which recently has been presented as an indicator of good prognosis in central retinal vein occlusion, was not found to be of any certain prognostic value in our study, whereas the prognostic value of fluorescein angiography, full field ERG and initial visual acuity in central retinal vein occlusion was confirmed. Full field electroretinography (ERG) was evaluated as a prognostic instrument for neovascular complications in hemi retinal vein occlusion. The cone b-wave implicit time in the 30 Hz-flicker ERG was shown to be of prognostic value. Multifocal ERG (mfERG) is an objective method for assessing the function in the central retina, but has not been used much in patients with retinal vein occlusion. We performed a pilot case-control study where we found that the mfERG responses in eyes with branch retinal vein occlusion significantly differed from the responses in the control eyes. In a second study we investigated the mfERG responses in correlation to other clinical parameters to try to get a better understanding of the underlying pathophysiology of the mfERG responses. We found that macular ischemia as measured by fluorescein angiography correlated well with reduced amplitudes and prolonged implicit times on the first order kernel in the mfERG. The strongest correlation was between macular ischemia and prolonged implicit time. A trend towards reduced amplitudes in eyes with central retinal thickening was present, but this was not statistically significant. In a retrospective case series an initial positive effect of vitrectomy for non-ischemic macular oedema in central and hemi retinal vein occlusion was shown. The macular oedema was significantly reduced at 1 and 2 months after surgery, whereas the visual acuity was improved after 1 month but not thereafter. No beneficial effect was seen in the long term.