Nopasak Phasukkijwatana

Retinal Capillary Density and Foveal Avascular Zone Area Are Age-Dependent: Quantitative Analysis Using Optical Coherence Tomography Angiography.

Purpose The purpose of this study was to quantify retinal capillary density and the foveal avascular zone (FAZ) area in normal subjects according to age, using optical coherence tomography angiography (OCTA). Methods All eyes in this cross-sectional study underwent OCTA using RTVue XR Avanti with AngioVue. OCTA scans were analyzed and processed, and vessel density and FAZ dimensions were calculated. Results A total of 113 normal eyes from 70 subjects were included (30 males, 40 females; mean 48 ± 20 years of age). The mean vessel density and FAZ dimensions were significantly smaller in the superficial retinal capillary plexus (SCP) than in the deep retinal capillary plexus (DCP), using quantitative OCTA analysis (all P< 0.0001). With 3 × 3-mm scans, the mean vessel density was 13.431 ± 1.758 mm-1 in the SCP, 18.812 ± 1.796 mm-1 in the DCP, and 5.913 ± 1.308 mm-1 and 10.447 ± 1.262 mm-1 with 6 × 6-mm scans in the SCP and DCP, respectively. Mean FAZ areas were 0.289 ± 0.108 mm2 at the SCP and 0.614 ± 0.200 mm2 at the DCP. Age was a predictor of SCP and DCP vessel density and FAZ area in the SCP. Vessel density decreased 0.0393 mm-1 (0.26%) per year in the SCP and 0.0574 mm-1 (0.27%) per year in the DCP. FAZ areas increased 0.0014 mm2 (0.63%) and 0.0011 mm2 (0.20%) per year in the SCP and DCP, respectively. Conclusions SCP and DCP vessel density decreased with increasing age, while FAZ area increased with age. Normal age-matched measurements provide important standardized values that may facilitate management of retinal vascular disorders.

Quantitative OCT Angiography of the Retinal Microvasculature and the Choriocapillaris in Myopic Eyes

Purpose To study the retinal capillary microvasculature and the choriocapillaris (CC) in myopic eyes using quantitative optical coherence tomography angiography (OCTA) analysis. Methods Macular OCTA images of 3 × 3 mm were obtained using the RTVue-XR Avanti with AngioVue. Quantitative measurements of the retinal capillary microvascular layers and the CC were analyzed using en face projection images. Vessel density and fractal dimension of the superficial and deep retinal capillary plexus, and area and density of flow reduction in the CC were analyzed, quantified, and compared with an age-matched control group. Results Fifty eyes with myopia and 34 age-matched healthy eyes were included in this study. The vessel density and the vessel branching complexity using fractal dimension of the retinal capillary microvasculature were significantly lower in myopic eyes (P < 0.001 and P = 0.001). The total number of flow voids in the CC was lower (108.93 vs. 138.63, P = 0.001) but the total and average flow void area was significantly higher (total area 3.715 ± 0.257 vs. 3.596 ± 0.194 mm2, P = 0.026; average area 0.044 ± 0.029 vs. 0.028 ± 0.010 mm2, P = 0.002) compared with the healthy control group. Average choroidal thickness was lower in the myopic group versus the normal control cohort (123.538 ± 73.477 vs. 246.97 ± 41.745 μm, P < 0.05) and significantly reduced in eyes with lacquer cracks (LC) compared with myopic eyes without LC formation (P = 0.003). There was no correlation between choroidal thickness and quantitative parameters of the CC in the myopic eyes. Conclusions The density of the retinal capillary microvasculature is reduced and the area of flow deficit in the CC is increased in eyes with greater myopia. The relevance of microvascular alterations in the setting of myopia warrants further study.

Optical coherence tomography angiography of type 3 neovascularisation in age-related macular degeneration after antiangiogenic therapy

Background/aims To assess the microvascular response of type 3 neovascularisation secondary to age-related macular degeneration (AMD) after antivascular endothelial growth factor (anti-VEGF) therapy using optical coherence tomography angiography (OCTA). Methods Consecutive patients diagnosed with AMD and type 3 neovascularisation based on clinical examination, structural optical coherence tomography and fluorescein angiography when available were retrospectively evaluated. En face OCTA imaging (3×3 mm scans) with quantitative microvascular analysis was performed at baseline and after a single anti-VEGF intravitreal injection. Results 17 eyes of 14 patients underwent OCTA before and after anti-VEGF treatment. OCTA demonstrated significant regression of small calibre type 3 neovascular tufts in all eyes. Median lesion area was 0.061 mm2 (range 0.003–0.198 mm2) at baseline and 0.009 mm2 (range 0–0.085 mm2, p=0.0003) at follow-up. Cystoid macular oedema and/or subretinal fluid resolved in all cases after treatment. The type 3 lesions became undetectable with OCTA post-treatment in 5 of the 17 eyes. However, in 11 eyes, large feeder vessels were identified and remained unchanged after treatment. Conclusions The microvascular morphology of type 3 neovascularisation secondary to AMD was assessed at baseline and follow-up and showed significant regression in response to anti-VEGF therapy by OCTA. Quantitative OCTA analysis was also performed and confirmed remarkable regression in response to a single intravitreal anti-VEGF injection.

Optical Coherence Tomography Angiography of Type 2 Neovascularization in Age-Related Macular Degeneration

Age-related macular degeneration continues to be the leading cause of severe central vision loss in older adults of European descent. Optical coherence tomography angiography (OCT-A) enables more accurate identification of type 1 neovascularization in age-related macular degeneration than traditional fluorescein and indocyanine green angiographies. In addition, OCT-A facilitates the morphological classification of type 1 lesions, including features characteristic of early, mature, and fibrotic lesions. Vessel complex analysis, including lesion area and capillary density quantification, can also be readily measured and monitored over time. Performing this analysis following anti-vascular endothelial growth factor therapy may lead to a better understanding of the efficacies and responses to such treatments. Although some limitations currently exist, OCT-A is a promising imaging modality that could prove to have profound implications if incorporated into regular clinical practice.

AN UPDATED STAGING SYSTEM OF TYPE 3 NEOVASCULARIZATION USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

Purpose: To comprehensively investigate spectral domain optical coherence tomography features associated with Type 3 neovascularization and determine the prevalence of each feature and to develop an updated staging system for Type 3 neovascularization based on spectral domain optical coherence tomography findings. Methods: The authors retrospectively analyzed 34 eyes with new-onset Type 3 neovascularization. Spectral domain optical coherence tomography images at onset of Type 3 neovascularization, immediately after the first injection, and at the final quiescent visit were analyzed for the presence of specific optical coherence tomography features. In addition, when available, optical coherence tomography images from the visit before onset were studied. Results: Among 18 eyes with preonset optical coherence tomography, 77.8% had preexisting intraretinal hyperreflective foci (precursor lesion). In the same group of eyes, 44.4% and 27.8% exhibited outer plexiform layer disruption and outer plexiform layer downward deflection, respectively. At the onset of detectable Type 3 neovascularization, all 34 eyes demonstrated a hyperreflective focus with cystoid macular edema and 85.3% exhibited disruption of the retinal pigment epithelium. Serous pigment epithelial detachment and subretinal fluid were present in 67.6% and 23.5% of eyes at onset, respectively. The rate of cystoid macular edema decreased from 100% to 17.6% after a single injection. At the final quiescent visit, focal atrophy at the site of Type 3 lesions, as evidenced by outer retinal and retinal pigment epithelium disruption developed in 88.2% and 52.9% of eyes, respectively. Conclusion: An updated staging system of Type 3 lesions was developed based on spectral domain optical coherence tomography findings. A precursor stage consists of a punctate hyperreflective focus in the outer retina. The subtle detection of associated outer plexiform layer disruption and downward deflection may indicate that this precursor lesion is more likely to progress to an active Type 3 neovascular lesion. Stage 1 consists of a larger intraretinal hyperreflective lesion associated with cystoid macular edema but without outer retinal disruption. Stage 2 is notable for outer retinal disruption that occurs with retinal pigment epithelium disruption in most of the cases. Stage 3 is defined by an intraretinal hyperreflective lesion that extends through the retinal pigment epithelium to vascularize a drusenoid pigment epithelial detachment creating a serous component of the pigment epithelial detachment.

Optical Coherence Tomography Angiography in Fovea Plana.

Fovea plana is characterized by the anatomical absence of the foveal pit in eyes with normal visual function. The authors have analyzed three cases of idiopathic fovea plana with optical coherence tomography angiography (OCTA). As previously reported, the authors found the absence of a foveal avascular zone in all cases with OCTA; however, a preserved fusion of both the superficial and the deep capillary plexuses was found around the foveal center. This novel observation cannot be detected with conventional dye-based angiography, in which the deep capillary plexus is not visualized. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:670-673.].

Optical Coherence Tomography Angiography of Deep Capillary Ischemia

Paracentral acute middle maculopathy (PAMM) is defined by the spectral-domain optical coherence tomography (OCT) finding of paracentral hyper-reflective band-like lesions of the inner nuclear layer (INL) of the macula that progress to corresponding areas of severe INL thinning. En face analysis has enabled more detailed analyses and quantifications of these lesions and has provided insights into the pathogenesis of this abnormality. While there is a wealth of demographic and anatomical data indicating that these PAMM lesions are the result of an INL infarct, OCT angiography is the first modality to provide direct evidence. Several studies have recently shown that old PAMM lesions are indeed associated with ischemia of the deep capillary retinal plexus, while acute lesions may or may not show initial perfusion of the deep capillary retinal plexus.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF A29 BIRDSHOT CHORIORETINOPATHY COMPLICATED BY RETINAL NEOVASCULARIZATION

Purpose: To describe the quantitative optical coherence tomography angiography analysis of the superficial and deep retinal capillary plexus in a case of A29 birdshot chorioretinopathy (BCR) complicated by retinal neovascularization. Methods: Multimodal retinal imaging, including optical coherence tomography angiography with quantitated vessel density analysis of the superficial and deep retinal capillary plexus, was performed in a case of A29 BCR. Capillary density (mm−1) was defined as the total vessel length (mm) per area (mm2). Results: A 39-year-old healthy white man presented with vitreous hemorrhage and retinal neovascularization at baseline. Clinical presentation was consistent with BCR and human leukocyte antigen testing confirmed A29 positivity. Optical coherence tomography angiography was performed 6 years after the diagnosis and revealed capillary density reduction in the superficial and especially in the deep retinal capillary plexus. Quantitative vessel density analysis was compared with the mean capillary density of 11 age-matched normal eyes and demonstrated 6% and 18% reduction of the superficial plexus in the right and left eyes of our patient, respectively. For the deep plexus, a reduction of 25% and 32% was found in the right and left eyes, respectively. Conclusion: In this patient with BCR, capillary density reduction was most marked at the deep retinal capillary plexus level and may explain the development of retinal neovascularization in this case. Quantitative optical coherence tomography angiography may be a useful tool to study and to monitor retinal microvascular changes in patients with BCR and should be further explored as a biomarker of therapeutic response.

Quantitative Analysis of Three Distinct Retinal Capillary Plexuses in Healthy Eyes Using Optical Coherence Tomography Angiography

Purpose To identify and quantify the three distinct retinal capillary plexuses and the foveal avascular zone (FAZ) in healthy subjects according to age using optical coherence tomography angiography (OCTA) with novel projection artifact removal (PAR) software and improved segmentation. Methods All eyes in this cross-sectional study underwent OCTA imaging using RTVue XR Avanti with novel PAR AngioVue software. OCTA scans were analyzed and the three main parafoveal retinal capillary plexuses were segmented and vessel density and FAZ area were calculated. Results A total of 152 normal eyes from 95 subjects (39 males, 56 females, mean age 42 ± 25 years) were included. The mean vessel density was 15.48 ± 2.04 mm-1 in the superficial retinal capillary plexus (SCP), 15.28 ± 1.82 mm-1 in the intermediate retinal capillary plexus (ICP), and 16.33 ± 2.32 mm-1 in the deep retinal capillary plexus (DCP) for 3 × 3-mm OCTA images. Analysis of 3 × 3-mm scans yielded a mean FAZ area of 0.270 ± 0.101 mm2. The average reduction in vessel density per year of age with 3 × 3-mm OCTA scans was 0.04 mm-1 (0.22%) in the SCP, 0.05 mm-1 (0.27%) in the ICP, and 0.06 mm-1 (0.30%) in the DCP. The average increase in FAZ area per year of age was 0.0015 mm2 (0.72%). Conclusions Novel PAR software may provide improved visualization of all three major parafoveal retinal capillary plexuses including the ICP. Using this technology, SCP, ICP, and DCP vessel density decreased with increasing age while FAZ area increased with age.

BIOMARKERS OF NEOVASCULAR ACTIVITY IN AGE-RELATED MACULAR DEGENERATION USING OCT ANGIOGRAPHY

Purpose: To study the qualitative and quantitative features of choroidal neovascular (NV) membranes in age-related macular degeneration using optical coherence tomography angiography in patients with active and quiescent NV lesions before and after treatment with anti–vascular endothelial growth factor. Methods: Macular optical coherence tomography angiography images were obtained using RTVue XR Avanti with AngioVue. Morphologic features and quantitative measurements of the NV lesion were analyzed using en face projection images. The NV lesion was subdivided into inner segment and outer fringe for further fractal dimension analysis. Results: In a series of 31 eyes, 11 eyes with active NV lesions at baseline and after consecutive follow-up after treatment with anti–vascular endothelial growth factor therapy and 20 eyes with quiescent NV lesions were included in this study. Morphologically, all the quiescent NV lesions versus 63.6% of the active NV lesions demonstrated a prominent central vessel and active leasions demonstrated a greater rate of small vessels branching (82%) and peripheral arcades (82%) than quiescent lesions (30% and 40% respectively) and this was statistically significant. The lesion area and vessel density was not statistically significantly different after treatment or versus quiescent lesions although the latter lesions were reduced in area. Lesion pattern complexity measured by the fractal dimension was statistically significantly lower in the inner part of the lesion after treatment and statistically significantly lower in the total lesion of the quiescent NV compared with the active NV. Conclusion: Optical coherence tomography angiography is a new, noninvasive imaging modality that can be used to perform qualitative and quantitative analyses of NV lesions. In the future, OCT angiography may provide biomarkers of activity and guide the evaluation and treatment and monitoring of neovascularization in age-related macular degeneration.