Longitudinal assessment of type 3 macular neovascularization using 3D volume-rendering OCTA.

OBJECTIVE: To investigate the evolution of treatment-naive type 3 macular neovascularization (MNV) undergoing anti-vascular endothelial growth factor (VEGF) treatment through volume rendered three-dimensional (3D) optical coherence tomography angiography (OCTA). DESIGN: Retrospective observational study. PARTICIPANTS: Patients with type 3 MNV and age-related macular degeneration (AMD). METHODS: Included subjects had three loading injections of an anti-VEGF agent. The OCTA volume data at baseline and follow-up were processed with a previously published algorithm in order to obtain a volume-rendered representation of type 3 MNV. Progressive changes in type 3 lesions were analyzed via 3D OCTA volume rendering. RESULTS: A total of 14 treatment-naive eyes with type 3 MNV from 11 AMD patients (7 females) were included. At both baseline and follow-up visits, a type 3 MNV complex was identifiable. Each complex was composed of a mean number of 2.5 ± 0.7 vascular branches at baseline and 1.4 ± 0.6 at the follow-up visit (p < 0.0001). The mean changes in central macular thickness and visual acuity were significantly correlated with modifications in the number of type 3 MNV branches (ρ = -0.533, p = 0.049, and ρ = -0.581, and p = 0.040, respectively). CONCLUSIONS: This study demonstrated that type 3 lesions do not disappear completely after loading treatment, as indicated previously by histopathologic studies. Importantly, quantitative volume changes in type 3 lesions are directly associated with treatment response.

Volume rendered 3D OCTA assessment of macular ischemia in patients with type 1 diabetes and without diabetic retinopathy.

The aim of this study was to measure macular perfusion in patients with type 1 diabetes and no signs of diabetic retinopathy (DR) using volume rendered three-dimensional (3D) optical coherence tomography angiography (OCTA). We collected data from 35 patients with diabetes and no DR who had OCTA obtained. An additional control group of 35 eyes from 35 healthy subjects was included for comparison. OCTA volume data were processed with a previously presented algorithm in order to obtain the 3D vascular volume and 3D perfusion density. In order to weigh the contribution of different plexuses' impairment to volume rendered vascular perfusion, OCTA en face images were binarized in order to obtain two-dimensional (2D) perfusion density metrics. Mean ± SD age was 27.2 ± 10.2 years [range 19-64 years] in the diabetic group and 31.0 ± 11.4 years [range 19-61 years] in the control group (p = 0.145). The 3D vascular volume was 0.27 ± 0.05 mm3 in the diabetic group and 0.29 ± 0.04 mm3 in the control group (p = 0.020). The 3D perfusion density was 9.3 ± 1.6% and 10.3 ± 1.6% in diabetic patients and controls, respectively (p = 0.005). Using a 2D visualization, the perfusion density was lower in diabetic patients, but only at the deep vascular complex (DVC) level (38.9 ± 3.7% in diabetes and 41.0 ± 3.1% in controls, p = 0.001), while no differences were detected at the superficial capillary plexus (SCP) level (34.4 ± 3.1% and 34.3 ± 3.8% in the diabetic and healthy subjects, respectively, p = 0.899). In conclusion, eyes without signs of DR of patients with diabetes have a reduced volume rendered macular perfusion compared to control healthy eyes.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ASSESSMENT OF THE DIABETIC MACULA: A Comparison Study Among Different Algorithms.

PURPOSE: To assess the impact of histogram adjustments and binarization thresholding selection on quantitative measurements of diabetic macular ischemia using optical coherence tomography angiography (OCTA). METHODS: Patients with diabetic retinopathy (DR) who had swept-source OCTA imaging obtained were enrolled. An additional group of 15 healthy control subjects was included for comparison. Previously used brightness/contrast changes and binarization thresholds were applied to original OCTA images to obtain and compare different binarized images. Qualitative and quantitative comparisons were performed. RESULTS: Thirty patients with DR (30 eyes) were included in the analysis. Fifteen eyes displayed the presence of diabetic macular edema. Qualitative grading revealed that binarized images obtained using a global threshold had better quality compared with local or multistep thresholds. The "median" filter was most frequently graded as the histogram adjustment resulting in binarized images with best quality. In the quantitative analysis, local thresholds tended to generate higher values of measured metrics. Differences in OCTA metrics between global and local thresholds were associated with presence of diabetic macular edema and signal strength index value. In the comparison between healthy and DR eyes, differences in OCTA metrics were significantly affected by binarization threshold selection. CONCLUSION: Quantitative OCTA parameters may be significantly influenced by strategies to quantify macular perfusion. Image quality and presence of macular edema can significantly impact OCTA-derived quantitative vascular measurements and differences between global and local binarization thresholds. These findings highlight the importance of consistent strategies to reliably generate quantitative OCTA metrics in patients with DR.

Multimodal Imaging Assessment of Vascular and Neurodegenerative Retinal Alterations in Type 1 Diabetic Patients without Fundoscopic Signs of Diabetic Retinopathy.

The aim of this cross-sectional case-control study is to investigate the possible presence of vascular/neurodegenerative alterations in the retina of type 1 diabetes mellitus (T1DM) patients without diabetic retinopathy (DR). Thirty-four eyes of 34 consecutive T1DM without DR (mean age 21 ± 2 years) were included. Another cohort of 27 eyes (27 healthy control subjects matched with age and sex) was also recruited. All patients underwent multimodal imaging evaluation using structural optical coherence tomography (OCT), OCT-angiography (OCT-A), dynamic vessel analyzer (DVA) and microperimetry. No significant differences were disclosed comparing diabetics and controls for visual acuity, central macular thickness, and subfoveal choroidal thickness. On retinal nerve fiber layer and ganglion cell complex thickness, no significant differences were disclosed comparing each 3-mm-diameter macular and peripapillary subfield between two groups. Using OCT-A, deep capillary plexus perfusion density (PD) of diabetics was significantly lower compared to control group, whereas PD of other retinal/choriocapillaris plexuses and foveal avascular zone area did not show any significant difference. Using DVA, diabetic eyes revealed a significantly decreased vessel response to flicker light in comparison to controls. No differences were disclosed using microperimetry analysis. Taken together, these results suggest that vascular alterations could be the first detectable retinal change in the development of DR.

Intraoperative optical coherence tomography in the full-thickness macular hole surgery with internal limiting membrane inverted flap placement.

PURPOSE: To describe the helpfulness of using intraoperative optical coherence tomography (OCT) during surgery for full-thickness macular hole (FTMH). OBSERVATIONS: This observational case series identifies three patients with FTMH who were treated with vitrectomy, internal limiting membrane (ILM) peel with inverted ILM flap, which was tucked into the MH, and air with 18% Sulfur Hexafluoride (SF6) gas tamponade. Intraoperative OCT was used to confirm positioning of the ILM flap, even after complete air-fluid exchange. The patients were followed for three months after surgery and all reached a good morphological and functional outcome. CONCLUSIONS: If confirmed by a prospective longitudinal study, the intraoperative OCT might become an important tool in assisting FTMH surgery.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ASSESSMENT OF VASCULAR EFFECTS OCCURRING AFTER AFLIBERCEPT INTRAVITREAL INJECTIONS IN TREATMENT-NAIVE PATIENTS WITH WET AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To investigate vessel changes occurring after aflibercept injections in treatment-naive exudative age-related macular degeneration patients. METHODS: Fifteen eyes of 15 patients affected by wet age-related macular degeneration were enrolled in the study. All the patients had a diagnosis of Type 1 choroidal neovascularization and were treated with 3 monthly aflibercept intravitreal injections (IVI). Subjects were evaluated by means of optical coherence tomography angiography at baseline, the day after the first injection and one month after both the first and the second IVI. At last, all the patients were followed up to 2 months after the third IVI. RESULTS: Foveal superficial vascular plexus flow density was 29.01% (21.13-37.32%) at baseline and was significantly reduced as soon as 1 month after the first IVI (median: 20.78%; interquartile range: 14.75-23.13%; P = 0.017). Parafoveal superficial vascular plexus flow density was 47.09% (44.91-51.72%) at baseline and significantly decreased as soon as 1 month after the second IVI (median: 44.40%; interquartile range: 41.59-49.29%; P = 0.034). Choroidal neovascularization lesion area remained stable throughout the follow-up. Nevertheless, interestingly, choroidal neovascularization flow area was significantly reduced as soon as the next day the first IVI (median: 0.37 mm and interquartile range: 0.27-0.72 mm at baseline; median: 0.30 mm and interquartile range: 0.24-0.64 mm at 1 day after the first IVI; P = 0.047). CONCLUSION: Intravitreal aflibercept injections are associated with a significant change in native retinal and choroidal vasculature. Moreover, the treatment did not cause a reduction in lesion area, but rather reduced the flow in the choroidal neovascularization.