Retinal microcirculation characteristics in obstructive sleep apnea/hypopnea syndrome evaluated by OCT-angiography: a literature review.

PURPOSE: The retina may provide a window to estimate systemic vascular status; therefore, there has been interest in identifying microcirculation characteristics that possibly reflect hypoxic alterations in obstructive sleep apnea/hypopnea syndrome (OSAS). Emerging evidence has suggested that retinal microvasculature investigation holds the potential to characterize the pathophysiology involved in ocular manifestations of OSAS. The advent of optical coherence tomography angiography (OCT-A) has attracted significant attention as this technique offers detailed analysis of the retinal capillary plexus. METHODS: A detailed literature search was performed in PubMed database until December 2021. We identified and reviewed all papers referring to the alterations of the retinal capillary plexus in OSAS using OCT-A. RESULTS: A comprehensive update indicates that microcirculation alterations of the retinal capillary plexus utilizing OCT-A may differ with severity of OSAS and imply the potential underlying pathophysiology of ocular manifestations. The reviewed series have revealed variability concerning microvasculature characteristics at the macular and the peripapillary area. Further studies are warranted to establish the OCT-A parameters as biomarkers regarding the evaluation of OSAS in clinical practice. CONCLUSION: Retinal capillary plexus characteristics as seen on OCT-A reflect microvasculature alterations, potentially leading to concomitant ocular comorbidity in the context of OSAS. The reviewed literature may confirm the diagnostic and prognostic value of OCT-A in the assessment of the pathophysiology of ocular manifestations in OSAS and highlight unmet needs to be addressed by future research.

Ocular microcirculation changes, measured with laser speckle flowgraphy and optical coherence tomography angiography, in branch retinal vein occlusion with macular edema treated by ranibizumab.

PURPOSE: This study searched for early predictive vascular biomarkers for visual outcomes in eyes with macular edema caused by branch retinal vein occlusion (BRVOME). METHODS: Twenty-four eyes of 24 subjects with BRVOME were treated with the intravitreal injection of ranibizumab (IVR) for at least 6 months. We measured mean blur rate (MBR) in the optic nerve head (ONH) and vessel density (VD) in the macula with laser speckle flowgraphy and optical coherence tomography angiography, respectively. RESULTS: Six-month post-IVR best-corrected visual acuity (BCVA) was correlated positively with age, pre-IVR BCVA, 1-month post-IVR BCVA, 3-month post-IVR BCVA and pre-IVR systolic blood pressure (P < 0.001, P < 0.001, P < 0.001, P < 0.001 and P = 0.02, respectively) and negatively with pre-IVR overall MBR, 1-month post-IVR overall MBR, 6-month post-IVR overall MBR, 3-month post-IVR deep retinal capillary plexus (DCP) VD and 6-month post-IVR DCP VD (P = 0.03, P = 0.03, P = 0.02, P = 0.01 and P = 0.005, respectively). Furthermore, a multiple regression analysis showed that pre-IVR overall MBR (ß = - 0.67, P = 0.009) was among independent prognostic factors predicting 6-month post-IVR BCVA. Six-month post-IVR DCP VD was also correlated with overall MBR at all time points. CONCLUSION: ONH blood flow may be a pre-IVR biomarker of both visual outcomes and post-IVR deep macular microcirculation in eyes with BRVOME.

Association of retinal vessel density with retinal sensitivity in surgery for idiopathic epiretinal membrane.

PURPOSE: The success of surgical treatment for idiopathic epiretinal membrane (ERM) is measured by postoperative best-corrected visual acuity (BCVA), metamorphopsia, and foveal retinal sensitivity (RS).This study searched for predictive biomarkers of surgical success by determining the association between foveal RS and various aspects of vessel density (VD) in the fovea of patients with ERM. METHODS: The study examined 25 eyes of 25 patients with ERM who underwent 27-gauge microincision vitrectomy surgery (MIVS). RS was measured with microperimetry (MP-3; NIDEK) at four central points in the fovea with an interpoint distance of 2°. VD was measured with SD-OCT (RS 3000; NIDEK) within the 1-mm2 square defined by the 4 RS points at various depths, including the superficial and deep retinal capillary plexus (SCP and DCP, respectively). RESULTS: Though VD did not change throughout the follow-up period, BCVA and RS significantly improved 1 and 3 months after surgery, respectively (both P < 0.0017). Postoperative RS at 6 months was positively correlated with postoperative DCP VD at 1, 3, and 6 months (r = 0.62, P = 0.001; r = 0.40, P = 0.049; r = 0.53, P = 0.007, respectively), but not with SCP VD at any time point. Multiple regression analysis confirmed that postoperative RS at 6 months was associated with postoperative DCP VD at 1 month (P = 0.03). CONCLUSION: Higher postoperative DCP VD at 1 month contributed to better postoperative foveal RS at 6 months. Early postoperative VD in the fovea might be a useful predictive biomarker of late postoperative RS in the fovea in ERM patients.

Macular microcirculation changes after macula-off rhegmatogenous retinal detachment repair with silicone oil tamponade evaluated by OCT-A: preliminary results.

Background: Rhegmatogenous retinal detachment (RRD) with macular involvement is a sight-threatening condition. Silicone oil (SO) is efficacious for retinal tamponade, especially in complex cases. Whether macular detachment per se or the potential tamponading agent may affect macular microcirculation after RRD repair is a matter of research. Objectives: To investigate macular microcirculation changes using optical coherence tomography angiography (OCT-A) after pars plana vitrectomy (PPV) with intravitreal SO for RRD repair in the early posttreatment period. Design: Prospective comparative cross-sectional study. Data sources and Methods: Fourteen eyes of 14 patients were included in the study. All eyes underwent a single successful PPV with SO tamponade for macula-off RRD. OCT-A was performed to analyze macular microcirculation and visual outcomes at 1 month postoperatively. The fellow unaffected eye was used as control. Results: Vessel density (VD) in the superficial capillary plexus (SCP) was significantly lower at each macular region (fovea, parafovea, and perifovea) of SO-treated eyes compared with the fellow eyes (all p = 0.001). Similarly, perfusion density (PD) in the SCP was significantly lower at each macular region than the fellow eyes (all p = 0.001). There was enlargement of foveal avascular zone (FAZ) area and decrease of circularity at RRD eyes compared with the fellow ones (all p = 0.001). Postoperative logMAR visual acuity (VA) was significantly lower in treated eyes than fellow eyes and correlated inversely with foveal, parafoveal, and perifoveal VD and PD SCP (all p < 0.001). Postoperative VA had no correlation with FAZ parameters. Conclusion: Enlargement of FAZ SCP and decrease in VD and PD SCP during the short-term follow-up were possibly attributable to ischemic changes in the macular area after RRD repair with SO tamponade. In this preliminary study, the flow density in macular capillary plexus may represent an indicator of visual outcomes.

Macular microcirculation characteristics in Parkinson's disease evaluated by OCT-Angiography: a literature review.

PURPOSE: Given the fact that retina may provide a window into the central nervous system, there has been interest in identifying retinal biomarkers as predicting factors of pathological processes in neurodegenerative disorders. Emerging evidence has suggested that macular microcirculation changes in Parkinson disease (PD) may indicate the alterations of cerebral microvasculature. The use of Optical Coherence Tomography Angiography (OCT-A) has attracted significant attention in recent years as this technique offers a detailed analysis of the existence of changes at the macular capillary plexus. METHODS: A detailed review of the literature was performed in PubMed until June 2021. We identified all papers referring to the alterations of the macular capillary plexus in PD using OCT-A. RESULTS: A comprehensive update indicates that microvasculature alterations of the macular capillary plexus utilizing OCT-A may comprise useful biomarkers regarding the cerebral vasculature in PD. Since the available evidence is limited, additional studies are warranted to establish the OCT-A parameters as predicting factors in clinical practice. CONCLUSIONS: A review of the existing literature sheds light on the microvasculature changes of the macular capillary plexus as seen on OCT-A in PD patients. The current article discusses notable aspects of key publications on the topic, highlights the importance of the potential long-term effectiveness of OCT-A biomarkers in PD and proposes the need for further future research.

Assessment of Anatomical and Functional Macular Changes with Optical Coherence Tomography Angiography After Macula-Off Rhegmatogenous Retinal Detachment Repair.

Purpose: To evaluate macular capillary plexus changes with OCT-angiography with regard to macular detachment duration in macula-off rhegmatogenous retinal detachment (RRD).Methods: 23 eyes of 23 patients were included in this retrospective case-control study and were divided into 2 groups. Group-A had a macular detachment duration of 0 to 10 days and group-B of 11 to 30 days. All eyes underwent a single successful pars plana vitrectomy (PPV) and gas tamponade. We analysed the OCT-A characteristics and visual outcomes at 12 weeks postoperatively in the 2 groups. The fellow eye was used as control.Results: Vessel density (VD) and flow density (FD) in the superficial capillary plexus (SCP) were significantly lower in group-B (p < .01) than in group-A and control. FAZ SCP in both groups was significantly larger than the control (p < .01), although it did not differ significantly between the two groups (p = 1.000). BCVA was significantly lower in group-B compared to group-A (p < .01). BCVA was positively correlated with VD SCP in group B (p = .015), but not in group-A. Postoperative BCVA had no correlation with FAZ SCP in both groups.Conclusions: The macular detachment duration could be a predicting factor of flow density in macular capillary plexus which in turn might be an indicator of visual outcomes in chronic cases.

A New Approach for the Segmentation of Three Distinct Retinal Capillary Plexuses Using Optical Coherence Tomography Angiography.

PURPOSE: To segment three distinct retinal capillary plexuses by using optical coherence tomography angiography (OCTA). METHODS: This prospective study included 30 eyes of 15 healthy subjects. En face OCTA images generated by the AngioPlex platform were manually segmented by the "progressive matching" method to the superficial, middle, and deep capillary plexuses (SCP, MCP, and DCP, respectively). The estimated position of each plexus relative to the reference line was calculated. Vascular density (VD) and skeleton density (SD) analyses, as well as the interclass correlation coefficient and relative standard deviation, were performed on each capillary plexus. We also measured central retinal thickness (CRT) and ganglion cell layer thickness (GCT). RESULTS: Thirty eyes of 15 healthy subjects (9 females; average age of 28.33 ± 3.07 years) were included in the analysis. We defined the relative estimated positions of the outer boundary MCP to the RPEfit as MCP = 14.491 - 0.307 CRT - 1.443 GCT, while the outer boundary of DCP was 37.63 ± 7.04 µm below the IPL. The VDs of SCP, MCP, and DCP were 32.97% ± 3.90%, 45.05% ± 5.34%, and 37.34% ± 4.96%, respectively, while the SDs of SCP, MCP, and DCP were 14.45 ± 1.51 mm-1, 19.80 ± 1.92 mm-1, and 17.38 ± 1.97 mm-1, respectively. CONCLUSIONS: With the progressive matching method, we segmented three capillary plexuses and defined the relative estimated positions of each capillary plexus to the reference line and calculated the VD and SD of three capillary plexuses in healthy subjects, providing controls for future studies. TRANSLATIONAL RELEVANCE: Our study provides a visual method for OCTA image vascular segmentation and provides reference and control for future studies on retinal three capillary plexuses.

Macular blood flow changes assessed by optical coherence tomography angiography after pars plana vitrectomy with gas or silicone oil tamponade for the patients with rhegmatogenous retinal detachment / 上海交通大学学报（医学版）

Objective • To investigate the effect of different vitreous fillers on the macular blood flow of patients with rhegmatogenous retinal detachment (RRD), and the correlation between the macular blood flow and the best corrected visual acuity (BCVA). Methods • In this retrospective study, 74 eyes in 74 patients with RRD for first time underwent pars plana vitrectomy in Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine from Dec. 2017 to Jun. 2018 were included. According to different vitreous fillers, the patients were divided into two group, i.e. pars plana vitrectomy with gas tamponade group (gas group) and pars plana vitrectomy with silicone oil tamponade group (silicone oil group). The blood flow in 3 mm×3 mm macular area was detected by optical coherence tomography angiography (OCTA). The blood flow densities of superficial capillary plexus (SCP) and deep capillary plexus (DCP) at foveal and parafoveal area, and the areas and perimeters of foveal avascular zone (FAZ) were calculated. The correlations between the macular blood flow parameters and BCVA were analyzed by partial correlation. Results • Compared with the silicone oil group, the blood flow densities of SCP and DCP in the whole 3 mm×3 mm regions in the gas group were higher at 6 months after surgery (both P=0.000). The partial correlation showed that the improvement of visual acuity was negatively correlated with the change of FAZ area (r=-0.216, P=0.015). Conclusion • Gas is an advantageous tamponade for the patients with RRD in improvement of blood flow density in the macular area. Meanwhile, assessing the macular blood flow density of the patients with retinal detachment by using OCTA after vitrectomy is significant to monitor the changes of structure and function of retina.