Retrospective Analysis of Prognostic Value of Optical Coherence Tomography Angiography for the Development of Glaucomatous Damage - One Year Follow-Up Retrospective Observational Cohort Analysis.

PURPOSE: Detecting glaucoma damage progression is an essential component of follow-ups in glaucoma patients. It is still unclear which of the currently available and routinely used parameters of glaucoma damage heralds the loss of retinal ganglion cells first. We analysed local hospital data on primary open-angle glaucoma (POAG) patients and looked for correlations between the optical coherence tomography (OCT) structural, OCT angiography (OCTA), and visual field (VF) parameters. PATIENTS AND METHODS: Results of eye examinations of POAG patients at baseline, 6 months, and 12 months were analysed. Inclusion criteria were, apart from the diagnosis of POAG, availability and quality of all modalities of examination data and no surgical intervention on the eyes during the observation period. Data on VF mean defect (MD), OCT peripapillary nerve fibre layer (RNFL), OCT macular ganglion cell layer, and OCTA, peripapillary and in the macula, were parameters of interest. Correlations of structural (OCT and OCTA) on one, and functional parameters (VF MD) on the other side, at baseline and as changing over time (first 6 months vs. second 6 months) were performed. RESULTS: All together, data from 78 eyes of 78 POAG patients were included in the analysis. Correlations at baseline were all highly significant (Spearman's r-coefficients between 0.31 and 0.8, all p < 0.05). None of the correlations of parameter changes over time were significant (all p > 0.05). CONCLUSION: Whereas a robust correlation was observed at baseline between the structural (OCT and OCTA) and functional (VF MD) parameters, none of the examination modality could predict a change in the other modalities during the 1-year period. Results confirm the necessity of regularly performing both the structural and functional examinations in our glaucoma patients.

Analysis of Retinal Vessel Pulsations with Electrocardiographic Gating.

PURPOSE: The origin of retinal venous pulsations has been a matter of debate for some time. One classical explanation to the origin of these pulsations has been that the cardiac cycle induces systolic peaks in the intraocular pressure (IOP) which leads to decreases in retinal vein diameters. Recently, theoretical concepts have been published which postulate that IOP changes during the pulse cycle is not the primary driving force for venous pulsation, and hence, predict that the retinal vein diameter is indeed reduced during IOP diastole. The aim of the study was to test this hypothesis in a clinical trial. SUBJECTS AND METHODS: Continuous IOP and retinal vessel analyser (RVA) measurements were taken from 21 subjects, ages 20 to 30 years, with no known ophthalmologic diseases, while connected to a standard electrocardiograph (ECG). With this methodology, average and synchronised curves for the pulse cycle of IOP and retinal vessel pulsations were calculated for each subject. Each pulse cycle was standardised to 50 timepoints, which enabled direct phase shift comparisons. RESULTS: All subjects showed comparable results. Close to the optic disc (within 0 to 1.5 optic disc diameters away from the disc), retinal arteries led with the first peak at the 16/50 pulse cycle position, followed by IOP peak at the 23/50 cycle position, and then by veins at the 26/50 cycle position. CONCLUSION: The present method indeed shows that retinal veins do not collapse when the IOP is highest, on the contrary, IOP and retinal vein diameters seem to be in phase, which lends support to the hypothesis that IOP is not the major driving force of the retinal vein pulsations.

Analysis of Retinal Vessel Pulsation with Electrographic Gating - Pulsation Amplitude and the Influence of Hyperoxia.

PURPOSE: To analyse the amplitude of vessel pulsation in the retina and to determine whether constriction of the vessels by oxygen would decrease their pulsation amplitude and could thus be used to quantify the rigidity of the retinal vessels. PATIENTS AND METHODS: The study included 20 healthy young subjects. With the RVA (retinal vessel analyser), we aimed to quantify vessel pulsations under normal and hyperoxic conditions. Electrocardiographic (ECG)-gated RVA was used for this purpose, with change in vessel pulsation as the primary endpoint and shift in vessel pulsation during the heart cycle as the secondary endpoint. Furthermore, we assessed the correlation between the amplitude of retinal vessel wall pulsation and blood pressure. Descriptive statistics, paired t-tests, and correlation analysis were applied. RESULTS: Retinal veins in proximity to the optic disc demonstrated the highest pulsation amplitude under all conditions. All retinal vessels significantly constricted under hyperoxic conditions. There was no significant change in the amplitude of vessel pulsation nor a significant shift in the pulsation cycle under hyperoxic conditions in the examined cohort. No correlation was found between systemic blood pressure parameters and amplitude of retinal vessel wall pulsation or any change in this. CONCLUSION: ECG-gated RVA recording is not able to detect any relevant change in vessel pulsation behaviour under oxygen, despite clearly observed vasoconstriction in retinal vessels. New approaches are necessary to reliably quantify the rigidity of the retinal vessels.