New Frontiers in Retina: highlights of the 2020 angiogenesis, exudation and degeneration symposium.

We summarize the most important findings presented at the 2020 angiogenesis, exudation and degeneration symposium in five topic areas: (1) epidemiology of retinal vascular disease and macular degeneration; (2) dry AMD and geographic atrophy; (3) neovascular age-related macular degeneration; (4) drug delivery and devices and (5) diabetic retinopathy.

Decreased severity of age-related macular degeneration in amblyopic eyes.

AIM: To evaluate whether people with age-related macular degeneration (AMD) and a history of amblyopia have equal severity of AMD in both eyes. METHODS: Billing records were used to locate all people with a history of amblyopia and AMD evaluated between 1 January 2003 and 1 June 2015 at a single ophthalmology institute. Two ophthalmic graders blinded to amblyopia status determined the severity of AMD in each eye using fundus photos and a validated grading scale. RESULTS: A total of 14 people were found to have AMD and a documented history of amblyopia. Average patient age was 77.0 years and average best corrected visual acuity was 20/160 in eyes with a history of amblyopia and 20/40 in fellow eyes without amblyopia. Eyes with a history of amblyopia were found to have a lower AMD severity score (mean lower score: -1.38; paired t-test P=0.019). Of the 11 people with asymmetric disease severity, 10 individuals had worse AMD in the non-amblyopic eye while one person had worse AMD in the amblyopic eye (P=0.0067). CONCLUSIONS: Our pilot study suggests that eyes with a history of amblyopia may manifest decreased severity of AMD compared with non-ambylopic eyes in the same patient. Further research is warranted to investigate this clinical observation.

Quantitative microvascular analysis of retinal venous occlusions by spectral domain optical coherence tomography angiography.

PURPOSE: To quantitatively evaluate the retinal microvasculature in human subjects with retinal venous occlusions (RVO) using optical coherence tomography angiography (OCTA). DESIGN: Retrospective, cross-sectional, observational case series. PARTICIPANTS: Sixty subjects (84 eyes) were included (20 BRVO, 14 CRVO, 24 unaffected fellow eyes, and 26 controls). METHODS: OCTA was performed on a prototype, spectral domain-OCTA system in the 3x3mm central macular region. Custom software was used to quantify morphology and density of retinal capillaries using four quantitative parameters. The vasculature of the segmented retinal layers and nonsegmented whole retina were analyzed. MAIN OUTCOME MEASURES: Fractal dimension (FD), vessel density (VD), skeletal density (SD), and vessel diameter index (VDI) within the segmented retinal layers and nonsegmented whole retina vasculature. RESULTS: Nonsegmented analysis of RVO eyes demonstrated significantly lower FD (1.64±0.01 vs 1.715±0.002; p<0.001), VD (0.32±0.01 vs 0.432±0.002; p<0.001), and SD (0.073±0.004 vs 0.099±0.001; p<0.001) compared to controls. Compared to the fellow eye, FD, VD and SD were lower (p<0.001), and VDI was higher (p<0.001). FD, VD, and SD progressively decreased as the extent (or type) of RVO increased (control vs BRVO vs CRVO; p<0.001). In the unaffected fellow eye FD, VD and SD showed significant differences when compared to control eyes or affected RVO eyes (p<0.001). CONCLUSIONS: Quantitative OCTA of the central 3x3mm macular region demonstrates significant differences in capillary density and morphology among subjects with BRVO and CRVO compared to controls or unaffected fellow eyes in all vascular layers. The unaffected fellow eyes also demonstrate significant differences when compared to controls. OCTA allows for noninvasive, layer-specific, quantitative evaluation of RVO-associated microvascular changes.

Quantifying Retinal Microvascular Changes in Uveitis Using Spectral-Domain Optical Coherence Tomography Angiography.

PURPOSE: To quantify retinal capillary density and morphology in uveitis using spectral-domain optical coherence tomography angiography (SD-OCTA). DESIGN: Cross-sectional, observational study. METHODS: Healthy and uveitic subjects were recruited from 2 tertiary care eye centers. Prototype SD-OCTA devices (Cirrus; Carl Zeiss Meditec, Inc, Dublin, California, USA) were used to generate 3 × 3-mm2 OCTA images centered on the fovea. Subjects were placed into 3 groups based on the type of optical microangiography (OMAG) algorithm used for image processing (intensity and/or phase) and type of retinal segmentation (automatic or manual). A semi-automated method was used to calculate skeleton density (SD), vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI). Retinal vasculature was assessed in the superficial retinal layer (SRL), deep retinal layer (DRL), and nonsegmented retinal layer (NS-RL). A generalized estimating equations model was used to analyze associations between the OCTA measures and disease status within each retinal layer. A P value < .05 was accepted as significant. Reproducibility and repeatability were assessed using the intraclass correlation coefficient (ICC). RESULTS: The SD, VD, and FD of the parafoveal capillaries were lower in uveitic eyes compared with healthy eyes in all retinal segments. In addition, SD and VD were significantly lower in the DRL of subjects with uveitic macular edema. There was no correlation in any capillary parameters and anatomic classification of uveitis. CONCLUSIONS: Quantitative analysis of parafoveal capillary density and morphology in uveitis demonstrates significantly lower capillary density and complexity. SD-OCTA algorithms are robust enough to detect these changes and can provide a novel diagnostic index of disease for uveitis subjects.

Widefield OCT Findings of a Patient With Stellate Nonhereditary Idiopathic Foveomacular Retinoschisis.

The authors report extensive peripheral retinoschisis in a patient with stellate nonhereditary idiopathic foveomacular retinoschisis (SNIFR) detected by widefield optical coherence tomography (OCT). A 64-year-old woman diagnosed with foveomacular retinoschisis 3 years prior presented for evaluation after being seen by multiple other retina specialists. Standard macular spectral-domain OCT (6 mm) revealed typical foveomacular schisis involving only the outer retina. However, widefield OCT (12 mm) revealed diffuse bilateral retinoschisis involving both inner and outer retinal layers in the macula and midperiphery. Widefield imaging is important to evaluate and monitor complex peripheral retinoschisis that may be otherwise undetectable using conventional techniques. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:774-777.].

Quantifying Microvascular Density and Morphology in Diabetic Retinopathy Using Spectral-Domain Optical Coherence Tomography Angiography.

PURPOSE: To quantify changes in retinal microvasculature in diabetic retinopathy (DR) by using spectral-domain optical coherence tomography angiography (SD-OCTA). METHODS: Retrospective, cross-sectional, observational study of healthy and diabetic adult subjects with and without DR. Retinal microvascular changes were assessed by using SD-OCTA images and an intensity-based optical microangiography algorithm. A semiautomated program was used to calculate indices of microvascular density and morphology in nonsegmented and segmented SD-OCTA images. Microvascular density was quantified by using skeleton density (SD) and vessel density (VD), while vessel morphology was quantified as fractal dimension (FD) and vessel diameter index (VDI). Statistical analyses were performed by using the Student's t-test or analysis of variance with post hoc Tukey honest significant difference tests for multiple comparisons. RESULTS: Eighty-four eyes with DR and 14 healthy eyes were studied. Spearman's rank test demonstrated a negative correlation between DR severity and SD, VD, and FD, and a positive correlation with VDI (ρ = -0.767, -0.7166, -0.768, and +0.5051, respectively; P < 0.0001). All parameters showed high reproducibility between graders (ICC = 0.971, 0.962, 0.937, and 0.994 for SD, VD, FD, and VDI, respectively). Repeatability (κ) was greater than 0.99 for SD, VD, FD, and VDI. CONCLUSIONS: Vascular changes in DR can be objectively and reliably characterized with SD, VD, FD, and VDI. In general, decreasing capillary density (SD and VD), branching complexity (FD), and increasing average vascular caliber (VDI) were associated with worsening DR. Changes in capillary density and morphology were significantly correlated with diabetic macular edema.

Forming a Consensus: Data and Guidance for Physicians Treating Diabetic Macular Edema.

The diabetic macular edema (DME) treatment paradigm has evolved as the understanding of the disease pathology has grown. Since 2012, four pharmacotherapies have been approved by the U.S. Food and Drug Administration for the treatment of DME. First-line treatment of DME with anti-vascular endothelial growth factor [VEGF] agents has become the gold standard; however, an appreciable percentage of patients do not respond to anti-VEGF therapies. In patients who inadequately respond to anti-VEGF therapies, the underlying disease pathology may be mediated by a multitude of growth factors and inflammatory cytokines. For these patients, corticosteroids are an attractive treatment option because they not only downregulate VEGF, but also an array of cytokines. The phase 3 MEAD and FAME trials demonstrated significant visual acuity improvements associated with dexamethasone and fluocinolone acetonide, respectively, in patients with DME; however, class-specific adverse events, including increased intraocular pressure and cataract development, must be considered before use. A panel of experts gathered during the 2015 annual meeting of the American Academy of Ophthalmology for a roundtable discussion focused on patient selection and adverse event management associated with the use of the 0.19 mg fluocinolone acetonide intravitreal implant.

Improving Outcomes for Patients With Diabetic Macular Edema.

Diabetic macular edema (DME) is one of the most common causes of vision loss in patients who have diabetes, and all of these patients are at risk for developing DME. The onset is often painless, difficult to detect, and can occur at any stage of diabetes. Ideally, DME is preventable, but treatment must be considered when preventative methods fail. Although physicians have several different treatment options for patients with DME, some patients who receive treatment can respond poorly and may even lose vision. Until recently, laser photocoagulation was regarded as the standard of care for DME; however, pharmaceutical treatments are rapidly replacing this standard as the desire to maximize systemic treatment of DME increases. A panel of experts gathered during the 2015 annual meeting of the Association for Research in Vision and Ophthalmology for a roundtable discussion designed to focus on improving outcomes for patients with DME using pharmaceutical treatment, including the use of anti-VEGFs and corticosteroids, based on the most current research and clinical data.

Optical Coherence Tomography Angiography of Diabetic Retinopathy in Human Subjects.

BACKGROUND AND OBJECTIVE: Optical coherence tomography angiography (OCTA) is a novel, non-invasive OCT technique capable of imaging the retinal vasculature. This study aims to evaluate the retinal microvasculature in diabetic human subjects with OCTA and assess potential clinical applications. PATIENTS AND METHODS: Cross-sectional study of 33 subjects with diabetic retinopathy. OCTA was performed on 3 mm × 3 mm sections using a swept-source OCTA prototype and a phase- and intensity-based contrasting algorithm. OCT angiograms were studied with corresponding clinical examination and fluorescein angiograms, when available, to assess accuracy and clinical utility. RESULTS: OCTA was able to demonstrate most clinically relevant vascular changes in subjects with diabetic retinopathy, including microaneurysms, impaired vascular perfusion, some forms of intraretinal fluid, vascular loops, intraretinal microvascular abnormalities, neovascularization, and cotton-wool spots that were largely consistent with fluorescein angiography. CONCLUSION: OCTA generates high-resolution angiograms that illustrate many of the clinically relevant findings in diabetic retinopathy and offers a novel complement or alternative to fluorescein angiography. Although currently an investigational technique, OCTA in combination with standard OCT imaging is at least as good as fluorescein angiography in the evaluation of the macular complications of diabetic retinopathy.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF RETINAL VENOUS OCCLUSION.

PURPOSE: To noninvasively evaluate the retinal microvasculature in human subjects with retinal venous occlusions using optical coherence tomography angiography and assess potential clinical applications. METHODS: This was a prospective, observational study of adult human subjects with clinical and imaging findings demonstrating retinal venous occlusion. Subjects underwent complete ophthalmic examination and fluorescein angiography as appropriate for their standard of care. Optical coherence tomography angiography was performed on a prototype spectral domain-OCTA system in 3 mm × 3 mm and 6 mm × 6 mm regions centered on the fovea and parafoveal areas. Retinal vasculature was assessed within three horizontal slabs consisting of the superficial, middle, and deep retina. The vasculature within each slab was reconstructed using intensity contrast-based algorithms and visualized as en-face images. Optical coherence tomography angiograms were manually segmented to verify the accuracy of the automated segmentation algorithms. RESULTS: Optical coherence tomography angiography was able to demonstrate almost all of the clinically relevant findings in 25 subjects with acute and chronic retinal venous occlusion. These findings were consistent with clinical, anatomic, and fluorescein angiographic findings including areas of impaired vascular perfusion, retinal atrophy, vascular dilation, shunt vessels, and some forms of intraretinal edema. CONCLUSION: Optical coherence tomography angiography is an investigational method that generates high-resolution, noninvasive angiograms that qualitatively illustrate most of clinically relevant findings in retinal venous occlusion. Optical coherence tomography angiography corresponds well with fluorescein angiograms and in many cases provides more detailed anatomic and blood flow information. Optical coherence tomography angiography, in conjunction with standard spectral domain-OCT, is at least equally as effective as fluorescein angiography for evaluation and management of the macular complications of retinal venous occlusions.

Depth-resolved rhodopsin molecular contrast imaging for functional assessment of photoreceptors.

Rhodopsin, the light-sensing molecule in the outer segments of rod photoreceptors, is responsible for converting light into neuronal signals in a process known as phototransduction. Rhodopsin is thus a functional biomarker for rod photoreceptors. Here we report a novel technology based on visible-light optical coherence tomography (VIS-OCT) for in vivo molecular imaging of rhodopsin. The depth resolution of OCT allows the visualization of the location where the change of optical absorption occurs and provides a potentially accurate assessment of rhodopsin content by segmentation of the image at the location. Rhodopsin OCT can be used to quantitatively image rhodopsin distribution and thus assess the distribution of functional rod photoreceptors in the retina. Rhodopsin OCT can bring significant impact into ophthalmic clinics by providing a tool for the diagnosis and severity assessment of a variety of retinal conditions.

Optical coherence photoacoustic microscopy for in vivo multimodal retinal imaging.

We developed an optical coherence photoacoustic microscopy (OC-PAM) system, which can accomplish optical coherence tomography (OCT) and photoacoustic microscopy (PAM) simultaneously by using a single pulsed broadband light source. With a center wavelength of 800 nm and a bandwidth of 30 nm, the system is suitable for imaging the retina. Generated from the same group of photons, the OCT and PAM images are intrinsically registered in the lateral directions. To test the capabilities of the system on multimodal ophthalmic imaging, we imaged the retina of pigmented rats. The OCT images showed the retinal structures with quality similar to conventional OCT, while the PAM images revealed the distribution of absorbers in the retina. Since the absorption of hemoglobin is relatively weak at around 800 nm, the NIR PAM signals are generated mainly from melanin in the posterior segment of the eye, thus providing melanin-specific imaging of the retina.