Artificial intelligence (AI) based on deep learning (DL) has sparked tremendous global interest in recent years. DL has been widely adopted in image recognition, speech recognition and natural language processing, but is only beginning to impact on healthcare. In ophthalmology, DL has been applied to fundus photographs, optical coherence tomography and visual fields, achieving robust classification performance in the detection of diabetic retinopathy and retinopathy of prematurity, the glaucoma-like disc, macular oedema and age-related macular degeneration. DL in ocular imaging may be used in conjunction with telemedicine as a possible solution to screen, diagnose and monitor major eye diseases for patients in primary care and community settings. Nonetheless, there are also potential challenges with DL application in ophthalmology, including clinical and technical challenges, explainability of the algorithm results, medicolegal issues, and physician and patient acceptance of the AI ‘black-box’ algorithms. DL could potentially revolutionise how ophthalmology is practised in the future. This review provides a summary of the state-of-the-art DL systems described for ophthalmic applications, potential challenges in clinical deployment and the path forward.

Optical coherence tomography (OCT) provides non-contact, rapid in vivo imaging of ocular structures, and has become a key part of evaluating the anterior segment of the eye. Over the years, improvements to technology have increased the speed of capture and resolution of images, leading to the increasing impact of anterior segment OCT imaging on clinical practice. In this review, we summarize the historical development of anterior segment OCT, and provide an update on the research and clinical applications of imaging the ocular surface, cornea, anterior chamber structures, aqueous outflow system, and most recently anterior segment vessels. We also describe advancements in anterior segment OCT technology that have improved understanding with greater detail, such as tear film in dry eye disease evaluation, intra-operative real-time imaging for anterior segment surgery, and aqueous outflow with angle assessment for glaucoma. Improvements to image processing and software have also improved the ease and utility of interpreting anterior segment OCT images in everyday clinical practice. Future developments include refinement of assessing vascular networks for the anterior segment, in vivo ultra-high resolution anterior segment optical coherence tomography with histology-like detail, en-face image with 3-dimensional reconstruction as well as functional extensions of the technique.

We interfaced color Doppler Fourier domain optical coherence tomography (CD-FDOCT) with a commercial OCT system to perform in vivo studies of human retinal blood flow in real time. FDOCT does not need reference arm scanning and records one full depth and Doppler profile in parallel. The system operates with an equivalent A-scan rate of 25 kHz and allows real time imaging of the color encoded Doppler information together with the tissue morphology at a rate of 2-4 tomograms (40 x 512 pixel) per second. The recording time of a single tomogram (160 x 512 data points) is only 6,4ms. Despite the high detection speed we achieve a system sensitivity of 86dB using a beam power of 500microW at the cornea. The fundus camera allows simultaneous view for selection of the region of interest. We observe bi-directional blood flow and pulsatility of blood velocity in retinal vessels with a Doppler detection bandwidth of 12.5 kHz and a longitudinal velocity sensitivity in tissue of 200microm/s.

and is inventor for US patents and patent applications on artificial intelligence, imaging and deep learning, as well as on foreign patents. Drs NM Bressler and P Burlina are the co-inventor and patent holders for a deep learning system for retinal diseases.

The purpose of the present study was to investigate the contribution of basal nitric oxide (NO) on retinal vascular tone in humans. In addition, we set out to elucidate the role of NO in flicker-induced retinal vasodilation in humans. Twelve healthy young subjects were studied in a three-way crossover design. Subjects received an intravenous infusion of either placebo or NG-monomethyl-L-arginine (L-NMMA; 3 or 6 mg/kg over 5 min), an inhibitor of NO synthase. Thereafter, diffuse luminance flicker was consecutively performed for 16, 32, and 64 s at a frequency of 8 Hz. The effect of L-NMMA on retinal arterial and venous diameter was assessed under resting conditions and during the hyperemic flicker response. Retinal vessel diameter was measured with a Zeiss retinal vessel analyzer. L-NMMA significantly reduced arterial diameter (3 mg/kg: -2%; 6 mg/kg: -4%, P < 0.001) and venous diameter (3 mg/kg: -5%; 6 mg/kg: -8%, P < 0.001). After placebo infusion, flicker induced a significant increase in retinal vessel diameter (P < 0.001). At a flicker duration of 64 s, arterial diameter increased by 4% and venous diameter increased by 3%. L-NMMA did not abolish these hyperemic responses but blunted venous vasodilation (P = 0.017) and arterial vasodilation (P = 0.02) in response to flicker stimulation. Our data indicate that NO contributes to basal retinal vascular tone in humans. In addition, NO appears to play a role in flicker-induced vasodilation of the human retinal vasculature.

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OBJECTIVE -Impaired endothelial function of resistance and conduit arteries can be detected in patients with type 1 diabetes. We studied whether a persistent improvement of endothelial function can be achieved by regular physical training.RESEARCH DESIGN AND METHODS -The study included 26 patients with type 1 diabetes of 20 Ϯ 10 years' duration and no overt angiopathy; 18 patients (42 Ϯ 10 years old) participated in a bicycle exercise training program, and 8 patients with type 1 diabetes (33 Ϯ 11 years old) served as control subjects. Vascular function of conduit arteries was assessed by flow-mediated and endothelium-independent dilation of the brachial artery and of resistance vessels by the response of ocular fundus pulsation amplitudes to intravenous N G -monomethyl-L-arginine (L-NMMA) at baseline, after 2 and 4 months of training, and 8 months after cessation of regular exercise.RESULTS -Training increased peak oxygen uptake (VO 2max ) by 13% after 2 months and by 27% after 4 months (P ϭ 0.04). Flow-mediated dilation (FMD) of the brachial artery increased from 6.5 Ϯ 1.1 to 9.8 Ϯ 1.1% (P ϭ 0.04) by training. L-NMMA administration decreased fundus pulsation amplitude (FPA) by 9.1 Ϯ 0.9% before training and by 13.4 Ϯ 1.5% after 4 months of training (P ϭ 0.02). VO 2max , FMD, and FPA were unchanged in the control group. Vascular effects from training were abrogated 8 months after cessation of exercise.CONCLUSIONS -Our study demonstrates that aerobic exercise training can improve endothelial function in different vascular beds in patients with long-standing type 1 diabetes, who are at considerable risk for diabetic angiopathy. However, the beneficial effect on vascular function is not maintained in the absence of exercise.

In adults with treated systemic hypertension, retinal capillary density reduced with higher BP and poorer eGFR. These findings highlight the potential role of OCT-A to study early microvascular changes because of systemic hypertension.This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0.