Nataša Mihailovic

BACKGROUND: There is increasing evidence for the involvement of cerebrovascular factors in Alzheimer's disease (AD). OBJECTIVE: To evaluate retinal and optic nerve head perfusion in patients with AD using optical coherence tomography angiography (OCTA), and to analyze the correlations of quantitative OCTA metrics with AD pathology and vascular cerebral lesions in AD patients. METHODS: 36 eyes of 36 patients with AD (study group) and 38 eyes of 38 healthy subjects (control group) were prospectively included in this study. OCTA was performed using RTVue XR Avanti with AngioVue. In addition, patients underwent a detailed ophthalmological and neurological examination including Mini-Mental State Examination, cerebral magnetic resonance imaging, and amyloid-β (Aβ) and tau levels in the cerebrospinal fluid (CSF). RESULTS: The flow density in the superficial retinal OCT angiogram of the macula in the study group was significantly lower compared to the control group (p = 0.001). There was a significant correlation between the flow density in the superficial retinal OCT angiogram of the macula, as measured using OCTA, and the Fazekas scale (Spearman's correlation coefficient = -0.520; p = 0.003). There was no significant correlation between the Aβ or tau levels in the CSF and the flow density data. CONCLUSION: Patients with AD showed a reduced flow density in the radial peripapillary capillaries layer and in the superficial retinal OCT angiogram when compared with healthy controls. The reduced retinal flow density measured using OCTA is not specifically associated with AD pathology but is associated with the vascular cerebral lesions in AD.

The aim of the study presented here was to evaluate retinal and optic nerve head (ONH) perfusion in patients with severe asymptomatic carotid artery stenosis (CAS) compared with healthy controls and to analyze the impact of carotid endarterectomy using optical coherence tomography angiography (OCT-A). 25 eyes of 25 patients with CAS (study group) and 25 eyes of 25 healthy controls (control group) were prospectively included in this study. OCT-A was performed using RTVue XR Avanti (Optovue, Inc, Fremont, California, USA). The flow density data in the superficial and deep retinal OCT-angiogram of the macula and in the radial peripapillary capillary network (RPC) of the ONH were extracted and analyzed. The flow density in the superficial retinal OCT angiogram of the macula and in the ONH were significantly lower in the study group compared with the control group (macula: p = 0.003) (ONH: p = 0.013). The flow density in the ONH improved significantly after carotid endarterectomy (p = 0.004). A reduced flow density was observed in patients with CAS when compared with healthy controls. The flow density also improved after carotid endarterectomy. Quantitative changes in the microvascular density, as measured using OCT-A, could well be useful in the diagnosis of CAS and the evaluation of therapy success.

PURPOSE: To evaluate the repeatability, the reproducibility and the agreement of foveal avascular zone (FAZ) measurements using three different optical coherence tomography angiography (OCT-A) devices. PROCEDURES: This prospective study included 24 eyes of 24 healthy volunteers. OCT-A imaging was performed using RTVue XR Avanti, Canon OCT-HS100 and Spectralis OCT-A. Repeated measurements were performed under the same conditions on two separate days, and the area of the FAZ was determined and analyzed using the above devices. RESULTS: All three devices showed a high ICC and there was no significant difference between the ICCs (pairwise comparison) of the three devices (Optovue-Canon (p = 0.66); Canon-Heidelberg (p = 0.21); Heidelberg-Optovue (p = 0.37). Agreement analysis of the three devices revealed a significant elevation of FAZ area values with the Heidelberg device and a slight underestimation of the FAZ area with the Canon device. Nevertheless, overall we found a high level of agreement between all of the three devices (ICC ≥ 0.958 (0.905-0.982)). CONCLUSIONS: Good reproducibility and repeatability were observed for all three devices. However, the agreement analysis revealed slight, but significant differences, which might limit alternating use of these devices for clinical research and follow-up examinations.

PURPOSE: To evaluate the accuracy of intraocular pressure (IOP) measurements obtained with the newly available iCare HOME (RTHOME) rebound tonometer compared with the iCare ONE (RTONE) tonometer and Goldmann applanation tonometry (GAT), and possible correlation with central corneal thickness (CCT). MATERIALS AND METHODS: IOP measurements were obtained from 154 patients by an ophthalmologist (doc) using each of the above-mentioned tonometers. In addition, patients (pat) measured their own IOP with the RTHOME and RTONE. The means and SD of results obtained with the different tonometers were compared. Agreement between the tonometers was calculated using the Bland-Altman method. RESULTS: Mean IOPs for the right eyes only were 15.9±6.4 mm Hg (RTONEdoc), 15.8±6.4 mm Hg (RTONEpat), 15.0±5.9 mm Hg (RTHOMEdoc), 14.9±6.3 mm Hg (RTHOMEpat), and 15.8±4.4 mm Hg (GAT). Bland-Altman analysis revealed mean differences (bias) between RTONEdoc and RTHOMEdoc, between RTHOMEdoc and RTHOMEpat, and between RTHOMEdoc and GAT of 0.8, 0.1, and -0.8 mm Hg, respectively, with 95% limits of agreement of -3.5 to 5.2, -4.9 to 5.1, and -7.2 to 5.6 mm Hg, respectively. Linear regression of the comparisons revealed a proportional error over the range of pressures examined in the case of RTHOMEdoc versus GAT (slope=0.32, P<0.001). Considering the data from all eyes, the difference between RTHOMEdoc and GAT correlated significantly with the CCT (P=0.01). CONCLUSION: RTHOME readings correlate well with the GAT results although some limitations such as dependency of readings on CCT and increasing differences at lower and higher IOP levels need to be taken into account.

PURPOSE: To evaluate the retinal microvascular density using optical coherence tomography angiography (OCTA) in patients with systemic lupus erythematosus (SLE) treated with hydroxychloroquine (HCQ). METHODS: Nineteen eyes of 19 patients with SLE (study group) without HCQ retinopathy and 19 eyes of 19 healthy subjects (control group) were included in this study. The study group was divided into patients using HCQ for > 5 years (high-risk group) and < 5 years (low-risk group). The VD data of the 3 × 3 mm OCT angiogram of the superficial capillary plexus (SCP) and the choriocapillaris (VD-CC), the foveal avascular zone (FAZ) area and the central retinal thickness (CRT) were extracted and analyzed. RESULTS: VD in the en face SCP was significantly reduced in the high-risk group and the low-risk group compared with that in the control group (p < 0.001, p = 0.001) and in the high-risk group compared with the low-risk group (p = 0.007). Correlation analysis between the cumulative dose of HCQ and the VD of the study group revealed a negative correlation, but no statistical significance (p = 0.074). However, a significant positive correlation was observed for the low-risk group (p = 0.035). In patients with SLE, VD-CC was lower (p = 0.042) and the FAZ area larger (p = 0.019). CRT showed no difference between the groups (p = 0.183). CONCLUSION: In this study, SLE patients showed a reduced VD in both groups. In patients treated with HCQ < 5 years, HCQ might have a protective effect on retinal microvasculature. Analysis of retinal microvascular density using OCTA could be useful in the diagnosis and monitoring of vascular alteration in patients with SLE.