Purpose: To determine if demographic factors and calculated areas of nonperfusion (NP) and neovascularization (NV) on ultrawidefield (UWF) fluorescein angiography (FA) in the eyes of patients with diabetes are associated with treatment with intravitreal injections (IVIs), panretinal photocoagulation (PRP), and diabetic retinopathy (DR) progression. Patients and Methods: This retrospective, cross-sectional study included 363 patients (651 eyes) treated at the University of Michigan Kellogg Eye Center between January 2009 and May 2018. Eligible participants were 18 years or older diagnosed with diabetes who received UWF FA. Patients with previous PRP or poor-quality images were excluded. Main outcome measures included comparison analyses of measured surface areas in millimeters squared (mm(2)) of total and regional retinal nonperfusion and neovascularization, number of IVIs and PRP treatments, and DR progression. Results: Our cohort received 3,041 IVIs and 878 PRP treatments with a mean follow-up of 915 days (SD +/- 714). IVIs were positively associated with posterior NP (difference, 1.15 mm(2); 0.43-1.86; P=0.0017). PRP treatments were positively associated with total NP (difference, 27.24 mm(2); 14.68-39.79; P<0.001) and total NV (difference, 1.75 mm(2); 0.84-2.65; P<0.001), as well as regional areas. While progression was not associated with NP/NV area, it was positively associated with a pre-existing diagnosis of type 2 as compared to type 1 diabetes (147% increase; 7-373% increase; p=0.03). Conclusion: Areas of NP and NV on UWF FA demonstrated associations with PRP and IVIs in DR patients.

Diabetic retinopathy is a leading cause of blindness in working-age adults worldwide. Neovascular leakage on fluorescein angiography indicates progression to the proliferative stage of diabetic retinopathy, which is an important distinction that requires timely ophthalmic intervention with laser or intravitreal injection treatment to reduce the risk of severe, permanent vision loss. In this study, we developed a deep learning algorithm to detect neovascular leakage on ultra-widefield fluorescein angiography images obtained from patients with diabetic retinopathy. The algorithm, an ensemble of three convolutional neural networks, was able to accurately classify neovascular leakage and distinguish this disease marker from other angiographic disease features. With additional real-world validation and testing, our algorithm could facilitate identification of neovascular leakage in the clinical setting, allowing timely intervention to reduce the burden of blinding diabetic eye disease.

Colloidal gold nanoparticles (GNPs) serve as promising contrast agents in photoacoustic (PA) imaging, yet their utility is limited due to their absorption peak in the visible window overlapping with that of hemoglobin. To overcome such limitation, this report describes an ultrapure chain-like gold nanoparticle (CGNP) clusters with a redshift peak wavelength at 650 nm. The synthesized CGNP show an excellent biocompatibility and photostability. These nanoparticles are conjugated with arginine-glycine-aspartic acid (RGD) peptides (CGNP clusters-RGD) and validated in 12 living rabbits to perform multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) for visualization of newly developed blood vessels in the sub-retinal pigment epithelium (RPE) space of the retina, named choroidal neovascularization (CNV). The PAM system can achieve a 3D PAM image via a raster scan of 256 × 256 pixels within a time duration of 65 s. Intravenous injection of CGNP clusters-RGD bound to CNV and resulted in up to a 17-fold increase in PAM signal and 176% increase in OCT signal. Histology indicates that CGNP clusters could disassemble, which may facilitate its clearance from the body.

The current study is presenting a non-invasive and high resolution multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) system for visualization of choroidal vascular lesions in living rabbits.

In the near-infrared optical window (NIR, 650 to 1000 nm), biological tissue generates a low intrinsic photoacoustic (PA) signal. This window can be utilized to reduce the background noise, and thus enhance visualization of contrast agents. Exogenous contrast agents have been investigated and co-applied with photoacoustic imaging such as organic materials (indocyanine green, astaxanthin, Prussian blue) and inorganic materials (gold nanorods, gold nanostars). However, these available contrast agents are usually associated with low thermal stability or large size, leading to unreliable photoacoustic signal. Conventional gold nanoparticles have an absorption peak of 520 nm, which corresponds to the absorption spectrum of hemoglobin. This study investigated the synthesis of novel ultrapure, biocompatible, and photostable chain-like gold nanoparticles (CGNPs), which shift the peak absorbance of GNPs from visible window (520 nm) to NIR window, while keeping the GNPs at a smaller size. These GNPs were fabricated by a femtosecond laser and were combined together with two organic polymers. The surface was then modified with PEG and conjugated with RGD ligands. The capacity of CGNPs for photoacoustic microscopy (PAM) and OCT were examined on 4 white New Zealand rabbits using a choroidal neovascularization (CNV) model. CNV was created by laser-induced retinal vein occlusion. Then, all animals were administered GNPs at concentration of 5 mg/mL. PAM and OCT were obtained before and after the injection at various time points, including 2 h, 4 h, 8 h, 24 h, days 2, 3, 5, 7, 9. 11, and 14. In vivo PAM and OCT imaging demonstrated that CNV was observed after the injection of CGNPs. In comparison with the signal before the injection, CGNPs produces 18- fold greater photoacoustic contrast and exhibits a 176 % increase in OCT signal, given the reduced background signal in the NIR window. The newly fabricated CGNPs have the capacity to improve visualization in living animals, while minimizing signal from hemoglobin and other endogenous contrast agents.

Importance Quantification of nonperfusion (NP) and neovascularization (NV) in diabetic retinopathy (DR) may identify better biomarkers of disease progression. Objective To identify demographic risk factors and markers of advanced DR that are associated with increased areas of NP and NV in eyes with disease ranging from no DR but diagnosed as having diabetes to proliferative DR (PDR) and to calculate a threshold total area of NP that may be associated with an increased risk of PDR. Design, Setting, and Participants This retrospective case series was performed on ultrawidefield fluorescein angiography (UWF FA) images from January 2009 to May 2018 at the University of Michigan Kellogg Eye Center. A total of 363 participants (651 eyes) diagnosed as having type 1 or 2 diabetes receiving UWF FA were included. Exclusion criteria included previous panretinal photocoagulation (PRP) and poor-quality images (eg, vitreous hemorrhage and significant cataract). Main Outcomes and Measures The surface areas in millimeters squared of the foveal avascular zone; total NP; NP at posterior pole, midperiphery, and far periphery; total NV; NV at posterior pole, midperiphery, and far periphery were measured. Results Of 363 patients, most were male (205 patients [56.5%]) and white (247 [68%]) or black (77 [21.2%]). The mean (SD) age was 59.4 (13.7) years. Seventy-six eyes with no DR, 92 with mild NPDR, 144 with moderate NPDR, 101 with severe NPDR, 220 with PDR, and 18 with DR of unknown severity were included. Male sex had a positive association with total NP (difference, 15.72; 95% CI, 4.83-26.61; P = .005); black race/ethnicity with total NV (difference, 2.32; 95% CI, 0.09-4.55; P = .04); and vitreous hemorrhage with total NP (difference, 30.00; 95% CI, 5.26-54.75; P = .02). A threshold total NP area of 77.48 mm2 (95% CI, 54.24-92.66 mm2) was identified, at greater than which patients may have an increased risk of developing PDR (sensitivity of 59.5% and specificity of 73.6%). Conclusions and Relevance Our results indicate NP and NV can be quantified on UWF FA. These biomarkers interpreted with demographic risk factors may help predict disease progression. Conclusions are limited by ascertainment and information biases because the results are from retrospective data.

PURPOSE:The aim of this study is to investigate the efficacy of a mobile platform that combines smartphone-based retinal imaging with automated grading for determining the presence of referral-warranted diabetic retinopathy (RWDR).METHODS:A smartphone-based camera (RetinaScope) was used by non-ophthalmic personnel to image the retina of patients with diabetes. Images were analyzed with the Eyenuk EyeArt® system, which generated referral recommendations based on presence of diabetic retinopathy (DR) and/or markers for clinically significant macular oedema. Images were independently evaluated by two masked readers and categorized as refer/no refer. The accuracies of the graders and automated interpretation were determined by comparing results to gold standard clinical diagnoses.RESULTS:A total of 119 eyes from 69 patients were included. RWDR was present in 88 eyes (73.9%) and in 54 patients (78.3%). At the patient-level, automated interpretation had a sensitivity of 87.0% and specificity of 78.6%; grader 1 had a sensitivity of 96.3% and specificity of 42.9%; grader 2 had a sensitivity of 92.5% and specificity of 50.0%. At the eye-level, automated interpretation had a sensitivity of 77.8% and specificity of 71.5%; grader 1 had a sensitivity of 94.0% and specificity of 52.2%; grader 2 had a sensitivity of 89.5% and specificity of 66.9%.DISCUSSION:Retinal photography with RetinaScope combined with automated interpretation by EyeArt achieved a lower sensitivity but higher specificity than trained expert graders. Feasibility testing was performed using non-ophthalmic personnel in a retina clinic with high disease burden. Additional studies are needed to assess efficacy of screening diabetic patients from general population.

This report describes a novel multimodal photoacoustic microscopy (PAM) and spectral-domain optical coherence tomography (SD-OCT) imaging setup for evaluation of the degree of retinal ischemia in living rabbits.

Although photoacoustic microscopy (PAM) and optical coherence tomography (OCT) allow visualization of the retinal microvasculature, distinguishing early neovascularization from adjacent vessels remains challenging. Herein, gold nanostars (GNSs) functionalized with an RGD peptide were utilized as multimodality contrast agents for both PAM and OCT. GNSs have great absorption and scattering characteristics in the near-infrared region where most vasculature and tissue generates a less intrinsic photoacoustic signal while having a small size, excellent biocompatibility in vivo, and great photostability under nanosecond pulsed laser illumination. This enabled visualization and differentiation of individual microvasculature in vivo using multimodal PAM and OCT imaging. Detailed three-dimensional imaging of GNSs was achieved in an important choroidal neovascularization model in living rabbits. Through the administration of GNSs, PA contrast increased up to 17-fold and OCT intensities increased 167%. This advanced molecular-imaging platform with GNSs provides a unique tool for detailed mapping of the pathogenesis of the microvasculature.

Photoacoustic microscopy (PAM) is a novel and hybrid optical and acoustic technique for imaging. This modality can be used for label-free imaging of the retinal microvasculature with ultrahigh resolution and excellent image contrast. However, it is hard to distinguish newly developed microvasculature from native vessels. An exogenous photoabsorber contrast agent can boost the sensitivity and enhance the PAM image contrast. The focus of this study is to investigate the potential application of gold nanostars (GNS) as a contrast agent for multimodal PAM and OCT. GNS were validated on Rose Bengal laser-induced retinal vein occlusion choroidal neovascularization (CNV) rabbit model. Four New Zealand white rabbits were administrated with Rose Bengal (5 mg/kg) followed by laser illumination at a power of 300 mW. CNV developed at day 28 post laser illumination. The rabbit model before and after treatment was monitored by a multimodal imaging system including OCT, PAM, color fundus photographs, fluorescein angiography, (FA) and indocyanine green angiography (ICGA). At day 28 post laser treatment, the rabbits received an intravenous injection of 400 mu L GNS at a concentration of 2.5 mg/mL. Multimodal PAM and OCT monitored the GNS at various time points: 1 h, 2 h, 8 h, 24 h, 48 h, 72 h, day 4, day 7, day 9, day 11 and day 14. The experimental results show that the PA signal was enhanced 24-fold and OCT intensity increased 184% 24 h post injection. Histological analysis and TUNEL assay show no evidence of any change in cell nuclear morphology suggesting no damage or cell death. In addition, the liver function tests showed normal liver and kidney function, indicating that GNS induced no toxicity in the rabbit at the treated concentration. Therefore, GNS may provide a safe and potential contrast agent for the detection of the microvasculature in the eye.

Photoacoustic microscopy (PAM) can be an effective imaging modality to visualize retinal vein occlusion during laserinduced photocoagulation on major retinal veins. Developments in the vessels could be observed before and after laser irradiation due to the change of the optical absorption spectrum of the target vessels. However, the suitable wavelength to achieve high contrast PAM images of occluded vessels is unclear. This study evaluates the effect of wavelength on PAM imaging to evaluate the photocoagulation lesions on the rabbit to optimize the wavelength for imaging. Retinal vein occlusion (RVO) was created using a 532 nm millisecond pulse duration green light with concurrent intravenous administration of Rose Bengal (5 mg/kg) in New Zealand rabbits. Imaging was acquired by the PAM system at various wavelengths ranging from 520 nm to 590 nm. In addition, the thermal lesion was also confirmed using optical coherence tomography (OCT). A group of 20 retinal veins was irradiated for 0.5 s at a laser fluence of 850 W/cm2 (power = 150 mW, beam diameter = 75 μm). Twenty shots of the laser were applied to each major vein. PAM results showed that the thermal lesion was obviously visualized and exhibited lower contrast in comparison with untreated vessels posttreatment. Photoacoustic spectroscopy exhibited that the highest PA contrast of vessels treated with Rose Bengal laserinduced RVO occurred at a wavelength of 563, 570, and 578 nm, which was higher than the PA amplitude at lower and longer wavelengths respectively. The use of multi-wavelength PAM can provide a better method for visualization and evaluation of retinal vein occlusions.

Inadequate screening of treatment-warranted retinopathy of prematurity (ROP) can lead to devastating visual outcomes. Especially in resource-poor communities, the use of an affordable, portable, and easy to use smartphone-based non-contact fundus photography device may prove useful for screening for high-risk ROP. This study evaluates the feasibility of screening for high-risk ROP using a novel smartphone-based fundus photography device, RetinaScope. Retinal images were obtained using RetinaScope on a cohort of prematurely born infants during routine examinations for ROP. Images were reviewed by two masked graders who determined the image quality, the presence or absence of plus disease, and whether there was retinopathy that met predefined criteria for referral. The agreement between image-based assessments was compared to the gold standard indirect ophthalmoscopic assessment. Fifty-four eyes of 27 infants were included. A wide-field fundus photograph was obtained using RetinaScope. Image quality was acceptable or excellent in 98% and 95% of cases. There was substantial agreement between the gold standard and photographic assessment of presence or absence of plus disease (Cohen’s κ = 0.85). Intergrader agreement on the presence of any retinopathy in photographs was also high (κ = 0.92). RetinaScope can capture digital retinal photographs of prematurely born infants with good image quality for grading of plus disease.

The current study demonstrates the potential application of gold nanorods (GNRs) as theranostic agents for photoacoustic microscopy (PAM) and optical coherence tomography (OCT) imaging enhancement and photodynamic therapy (PDT) of retinal neovascularization (RNV) in rabbits in vivo.

This study evaluates the potential of indocyanine green as an organic contrast agent for multimodal photoacoustic microscopy (PAM) and planar fluorescence imaging to non-invasively visualize choroidal neovascularization in rabbits.