Diopsys® ffERG shows treatment end-point when functional improvements stabilize after multiple Avastin® (bevacizumab) injections.
An 88-year-old male patient presented with a chief complaint of blurred central vision OD for 1-2 weeks. He had a past medical history of coronary artery disease. Past ocular history consisted of S/P cataract extraction OU, laser posterior capsulotomy OS, chronic open-angle glaucoma OU, dry age-related macular degeneration OU, and chronic visual acuity loss following possible previous ischemic choroidal event. Patient was taking Timolol 0.5 OU qam and Latanoprost 0.005 OU qhs.
|Pupils:||No APD||No APD|
|OCT:||V.M. adhesion||V.M. adhesion|
|Fundus Exam:||Hard drusen, disc edema,
dilated venous tree
|Diagnosis:||Central retinal vein occlusion OD|
|Figures 1-3 Fundus Exam. Extensive hemorrhages OD, with diffusion of dye on angiography.|
Why Full Field Electroretinography (ffERG)?
ffERG, specifically flicker ERG (ffERG flashing at ≥ 30Hz), is clinically effective in helping to evaluate the level of retinal dysfunction in CRVO patients, and track efficacy of therapy for potential changes to treatment.1-2 Flicker ERG has also shown to help predict which eyes with CRVO will develop retinal ischemia and potentially neovascularization.3-5
|Figures 4-5 Initial OCT and ffERG. OCT shows minor macular involvement possibly due to CRVO, but no significant structural abnormalities. Diopsys® ffERG/Fixed Luminance Flicker results show dysfunction with an out of range Phase parameter OD. Note the angle of phase responses is 258.3⁰, with most responses falling in the lower, left quadrant of the Mag/Phase Plot. It is typical for a healthy eye to have similar responses to each flash stimulus where the responses are tightly packed together close to or within the lower, right quadrant.|
Post 1st Bevacizumab Injection
|Figures 6-7 OCT and ffERG 1 Month Post 1st Injection. OCT shows no significant structural change. Diopsys® ffERG results show functional improvement, with an in range Phase response of 279.4⁰ (now within the lower, right quadrant).|
Post 2nd Bevacizumab Injection
|Figures 8-9 OCT and ffERG 1 Month Post 2nd Injection (2 Months Post 1st). OCT shows no significant structural change. Diopsys® ffERG results show additional functional improvement, with an in range Phase response of 301.11⁰.|
Post 3rd Bevacizumab Injection
|Figures 10-11 OCT and ffERG 1 Month Post 3rd Injection (3 Months Post 1st). OCT shows no significant structural change. Diopsys® ffERG results show functional stability, with an in range Phase response of 293.99⁰.|
Impact on Care
By combining structural and functional information from the OCT and Diopsys® ffERG/Fixed Luminance Flicker results, the doctor was able to track the efficacy of the bevacizumab injections. Once in range retinal function was restored, and functional test results were stable, the doctor had the evidence needed to confidently stop treatment, as further injections would provide no additional benefit to the patient.
1. Kjeka O, et al. Early panretinal photocoagulation for ERG-verified ischaemic central retinal vein occlusion. Acta Ophthalmol. 2011;91(1):37–41.
2. Larsson J, et al. The 30-Hz flicker cone ERG for monitoring the early course of central retinal vein occlusion. Acta Ophthalmol Scand. 2000;78(2):187–90.
3. Larsson J, Andréasson S. Photopic 30 Hz flicker ERG as a predictor for rubeosis in central retinal vein occlusion. Br J Ophthalmol . 2001;85(6):683–5.
4. Yasuda S, et al. Electroretinograms and level of aqueous vascular endothelial growth factor in eyes with hemicentral retinal vein occlusion or branch retinal vein occlusion. Jpn J Ophthalmol. 2014;58(3):232–6.
5. Morrell A, et al. Electroretinography as a prognostic indicator or neovascularisation in CRVO. Eye (Lond). 1991;5(Pt 3):362–8.