Carl Arndt

Visual impairment at large eccentricity in participants treated by vigabatrin: Visual, attentional or recognition deficit?

A relationship between peripheral visual field loss and vigabatrin (VGB) has been reported in several studies but with inconsistent results. We investigated the level of visual processing at which the impairment occurs: attentional or cognitive (recognition) deficit. A simple reaction time task was used as a baseline condition. A spatial attention task measured the benefit and cost for the detection of a target appearing at a cued or at an uncued location. A rapid categorization task assessed object recognition. Performance was tested at eccentricities varying from 30 degrees to 60 degrees on a panoramic screen covering 180 degrees. Participants were patients with epilepsy treated with VGB, patients treated with other drugs and healthy controls. In the VGB group 9 patients exhibited a mild visual field constriction. We observed a general slowing down of response times in participants treated by VGB, especially at 60 degrees eccentricity but their performance remained above chance at large eccentricity in the most complex categorization task. The slowing down of visual processing at large eccentricity for flashed stimuli suggests that VGB treated patients might be impaired at detecting moving objects in the periphery and this may have consequences in behavioural tasks like driving.

Comparison between multifocal ERG and C-Scan SD-OCT (“en face” OCT) in patients with a suspicion of antimalarial retinal toxicity: preliminary results

PurposePericentral visual field changes and disruption of the ellipsoid layer on spectral domain optical coherence tomography (SD-OCT) are the main features of antimalarial retinal toxicity. C-Scan OCT or “en face” enables a topographic frontal view of the changes observed within the different retinal layers in particular the ellipsoid layer. The aim of this prospective study was to compare multifocal ERG (mfERG) responses with the results of C-Scan OCT (“en face” OCT) in patients with abnormal visual field and to analyze relationships between the structural and functional abnormalities.MethodsIn 354 consecutive patients screened for antimalarial toxicity between January 1, 2014 and December 31, 2016, central visual field, mfERG recording, C-Scan OCT and short-wavelength fundus autofluorescent imaging were performed.ResultsAmong the 17/354 patients with abnormal central visual field results, all presented with abnormalities on the mfERG at least in one eye. In 16/33 eyes, there was a good concordance between focal loss of the mfERG response and the disruption of the ellipsoid layer on C-Scan OCT. In one eye with characteristic changes in the ellipsoid layer on the C-Scan OCT, the mfERG was normal, whereas in three eyes the mfERG was abnormal in eyes with a normal C-Scan OCT.ConclusionsThe contribution of the C-Scan OCT changes remains difficult to establish as there is no strict concordance with the local ERG responses. Although C-Scan OCT technology provides a new approach in analyzing focal abnormalities in the photoreceptor–retinal pigment epithelium interface, the sensitivity of this method compared with mfERG and other tests (central visual field, B-Scan OCT) needs to be evaluated. This study is still ongoing on a larger cohort.

Cytologic analysis in vitreo-retinal surgery

Purpose Proliferative vitreoretinopathy (PVR) is the leading cause of failure in retinal detachment (RD)surgery. The migration of retinal pigment epithelial cells and the proliferation of the extracellular matrix has been associated with PVR. The purpose of this prospective study was to compare the cellular contents of the vitreous of patients undergoing RD surgery with patients scheduled for epiretinal membrane surgery (ERM). Methods The vitreous samples of patients with ERM and RD were obtained at the initial phase of surgery. A immunocytochemical labeling was performed in all cases with AE1/AE3, CD68, Vimentin and GFAP antibodies. The cytological identification was performed by a trained pathologist unaware of immunocytochemical labeling. The concentration of vitreous cells were analyzed semi-quantitatively. Results 14 vitreous samples were analysed, 9 patients with RD and 5 undergoing ERM. In the RD group, the cytological findings correlated with the results of immunolabeling. Hyalocytes (labeled with vimentin only)were present in all cases, more abundant in RD cases. Macrophages (labeled with vimentin and CD68) were found in 10/14 cases. Macrophages were more abundant in RD cases (p<0,05). Only in one case of RD, GFAP positive cells were found, in which PVR was particularly severe. In 6/14 samples, glial cells were identified with AE1/AE3 without difference between RD and epiretinal membrane cases. Conclusion Vitreous changes observed in patients with retinal detachment appear to involve particularly hyalocytes and macrophages, which could be identified with immunolabeling. Interestingly glial cells (GFAP positive)were only present in severe PVR. A link between this cell population in the vitreous and the clinical outcome remains to evaluated in a prospective study.

Peripheral capillary network enlargement in diabetic maculopathy

Purpose Diabetic macular edema has been associated with increased intravitreal levels of VEGF. Therefore, ischemia is probably part of the physiopathology. The purpose of this study is to evaluate the rarefaction of peripheral capillaries.

Transferrin and prealbumin: indicators of PVR and risk of recurrence in retinal detachment

Purpose Proliferative vitreoretinopathy (PVR) is the leading cause of failure in retinal detachment surgery. Increased levels of transferrine have been found in proliferative vitreoretinopathy. A relationship between the level of prealbumin and the functional outcome has been previously reported. The purpose of this prospective study was to look for a link between the vitreous levels and preoperative PVR or post‐operative outcome.