Ultra-widefield retinal imaging: an update on recent advances

Quantitative Biomarkers of Diabetic Retinopathy Using Ultra-Widefield Fluorescein Angiography

Introduction

Diabetic retinopathy (DR) is a leading cause of blindness. Retinal imaging is an important tool to monitor the progression of DR. While seven-standard retinal fields are the traditional method for evaluating DR, ultra-widefield (UWF) imaging allows for improved visualization of peripheral areas of nonperfusion (NP) and neovascularization (NV), which could be used as biomarkers to monitor and predict progression of DR.

Methods

A retrospective, cross-sectional study was conducted on 651 eyes from 363 patients diagnosed with type 1 or type 2 diabetes who received UWF-FA over 10 years. Fluorescein Angiography (FA) images were segmented, and surface areas of NP and NV were analyzed using multivariate regression to determine if biomarkers of DR and DR severity are associated with increasing areas of NP and NV.

Results

Each additional year with a diagnosis of DR was associated with a 10.75 mm2 increase in the total NP (95% CI, 1.94-19.56; P = 0.02) and 7.87 mm2 increase in NP far-periphery (95% CI, 1.62-14.13; P = 0.01). A one-unit change in severity as defined by the Early Treatment of Diabetic Retinopathy Study (ETDRS) classification was associated with a 25.75 mm2 increase in total NP (95% CI, 11.16-40.33; P = 0.001), a 13.15 mm2 increase in mid-periphery NP (95% CI, 6.93-19.38; P < 0.0001), and a 12.29 mm2 increase in far-periphery NP (95% CI, 3.62-20.97; P = 0.01).

Discussion

Biomarkers identified through UWF imaging such as total and regional areas of NP can be used to monitor and predict the progression of DR. This may provide a quantitative method for prognostication in patients with DR.

Wide-field imaging with smartphone based fundus camera: grading of severity of diabetic retinopathy and locating peripheral lesions in diabetic retinopathy

AIM

To assess the performance of smartphone based wide-field retinal imaging (WFI) versus ultra-wide-field imaging (UWFI) for assessment of sight-threatening diabetic retinopathy (STDR) as well as locating predominantly peripheral lesions (PPL) of DR.

METHODS

Individuals with type 2 diabetes with varying grades of DR underwent nonmydriatic UWFI with Daytona Plus camera followed by mydriatic WFI with smartphone-based Vistaro camera at a tertiary care diabetes centre in South India in 2021-22. Grading of DR as well as identification of PPL (DR lesions beyond the posterior pole) in the retinal images of both cameras was performed by senior retina specialists. STDR was defined by the presence of severe non-proliferative DR, proliferative DR or diabetic macular oedema (DME). The sensitivity and specificity of smartphone based WFI for detection of PPL and STDR was assessed. Agreement between the graders for both cameras was compared.

RESULTS

Retinal imaging was carried out in 318 eyes of 160 individuals (mean age 54.7 ± 9 years; mean duration of diabetes 16.6 ± 7.9 years). The sensitivity and specificity for detection of STDR by Vistaro camera was 92.7% (95% CI 80.1-98.5) and 96.6% (95% CI 91.5-99.1) respectively and 95.1% (95% CI 83.5-99.4) and 95.7% (95% CI 90.3-98.6) by Daytona Plus respectively. PPL were detected in 89 (27.9%) eyes by WFI by Vistaro camera and in 160 (50.3%) eyes by UWFI. However, this did not translate to any significant difference in the grading of STDR between the two imaging systems. In both devices, PPL were most common in supero-temporal quadrant (34%). The prevalence of PPL increased with increasing severity of DR with both cameras (p < 0.001). The kappa comparison between the 2 graders for varying grades of severity of DR was 0.802 (p < 0.001) for Vistaro and 0.753 (p < 0.001) for Daytona Plus camera.

CONCLUSION

Mydriatic smartphone-based widefield imaging has high sensitivity and specificity for detecting STDR and can be used to screen for peripheral retinal lesions beyond the posterior pole in individuals with diabetes.

Retinal hemorrhages and damages from tractional forces associated with infantile abusive head trauma evaluated by wide-field fundus photography

We evaluated the distribution and types of retinal hemorrhages (RHs) and other damages in eyes with abusive head trauma (AHT). This retrospective, consecutive case series of AHT and non-AHT conditions involved 54 children with AHT, 43 children with head bruises, and 49 children with blunt eye trauma, each of non-AHT supported by reliable witness accounts. RHs and other damage were evaluated using ophthalmoscopy and wide-field fundus photography. A variety of RH types and other damage were identified in the AHT group but not in the non-AHT group. RHs in AHT extended from the posterior pole to the far periphery in 77% of eyes and on/near the veins in 86% and arteries in 85%, most of which were in the far periphery. Retinoschisis, white-dot lesions, and retinal folds were seen even in the far periphery. RHs on/near the veins and arteries, retinoschisis, and retinal folds suggest a traumatic mechanism of the tractional force of the vitreous that is attached to the entire retinal surface. Identifying the distribution and arterio and venous origins of RHs is a key factor in determining the association with trauma. Thus, wide-field fundus photography is useful to record and evaluate the origin of the RHs and other retinal damage.

Multispectral Fundus Photography of Choroidal Nevi With Trans-Palpebral Illumination

Purpose

The purpose of this study was to investigate the spectral characteristics of choroidal nevi and assess the feasibility of quantifying the basal diameter of choroidal nevi using multispectral fundus images captured with trans-palpebral illumination.

Methods

The study used a widefield fundus camera with multispectral (625 nm, 780 nm, 850 nm, and 970 nm) trans-palpebral illumination to examine eight subjects diagnosed with choroidal nevi. Geometric features of nevi, including border clarity, overlying drusen, and lesion basal diameter, were characterized. Clinical imagers, including scanning laser ophthalmoscopy (SLO), autofluorescence (AF), and optical coherence tomography (OCT), were utilized for comparative assessment.

Results

Fundus images depicted nevi as dark regions with high contrast against the background. Near-infrared (NIR) fundus images provided enhanced visibility of lesion borders compared to visible fundus images and SLO images. Lesion-background contrast measurements revealed 635 nm SLO at 11% and 625 nm fundus at 42%. Significantly enhanced contrasts were observed in NIR fundus images at 780 nm (73%), 850 nm (63%), and 970 nm (67%). For quantifying the diameter of nevi, NIR fundus images at 780 nm and 850 nm yielded a deviation of less than 10% when compared to OCT measurements.

Conclusions

NIR fundus photography with trans-palpebral illumination enhances nevi visibility and boundary definition compared to SLO. Agreement in diameter measurements with OCT validates the accuracy and reliability of this method for choroidal nevi assessment.

Translational Relevance

Multispectral fundus imaging with trans-palpebral illumination improves choroidal nevi visibility and accurately measures basal diameter, promising to enhance clinical practices in screening, diagnosis, and monitoring of choroidal nevi.

Using Deep Learning to Segment Retinal Vascular Leakage and Occlusion in Retinal Vasculitis

PURPOSE

Retinal vasculitis (RV) is characterised by retinal vascular leakage, occlusion or both on fluorescein angiography (FA). There is no standard scheme available to segment RV features. We aimed to develop a deep learning model to segment both vascular leakage and occlusion in RV.

METHODS

Four hundred and sixty-three FA images from 82 patients with retinal vasculitis were used to develop a deep learning model, in 60:20:20 ratio for training:validation:testing. Parameters, including deep learning architectures (DeeplabV3+, UNet++ and UNet), were altered to find the best binary segmentation model separately for retinal vascular leakage and occlusion, using a Dice score to determine the reliability of each model.

RESULTS

Our best model for vascular leakage had a Dice score of 0.6279 (95% confidence interval (CI) 0.5584-0.6974). For occlusion, the best model achieved a Dice score of 0.6992 (95% CI 0.6109-0.7874).

CONCLUSION

Our RV segmentation models could perform reliable segmentation for retinal vascular leakage and occlusion in FAs of RV patients.

New 200° Single-Capture Color Red-Green-Blue Ultra-Widefield Retinal Imaging Technology: First Clinical Experience

BACKGROUND AND OBJECTIVE

We investigated the additive clinical benefits of a new ultra-widefield (UWF) red-green-blue (RGB) imaging technology.

PATIENTS AND METHODS

This was a retrospective, observational, single-center study of 86 consecutive patients (172 eyes). UWF red-green (RG) and RGB images were taken using a new Optos California (Optos Plc). This scanning laser ophthalmoscope uses wavelengths of 635 nm, 532 nm, and 488 nm for the red (R), green (G), and blue laser (B), respectively. The same device can image both in UWF RG and RGB simultaneously.

RESULTS

The new Optos California provides a well-balanced, three-channel color image that is clinically useful in imaging and identifying vitreoretinal, retinal, and chorioretinal pathologies. The combination of the images captured by each laser source produces a final composite image that more accurately reflects the natural colors of the fundus. The addition of blue light provides additional detail to visualize the vitreoretinal interface and superficial retina, both within the posterior pole and in the periphery.

CONCLUSIONS

This new device allows for both RG and RGB imaging of the retina, providing valuable information on the anatomy of the vitreoretinal interface, retina, retinal pigment epithelium, and their abnormalities. Both techniques complement each other and can be useful in daily practice, allowing clinicians to choose the preferred imaging technique depending on specific findings and conditions. [Ophthalmic Surg Lasers Imaging Retina 2023;54:714-718.].

Prevalence of peripheral retinal findings in retinal patients using ultra-widefield pseudocolor fundus imaging

Ultra-widefield retinal imaging is increasingly used in ophthalmology and optometry practices to image patients identifying peripheral abnormalities. However, the clinical relevance of these peripheral retinal abnormalities is unclear. This cross-sectional study aims to firstly validate a new grading system, secondly, assess the prevalence of peripheral retinal abnormalities in retinal patients, and finally understand how peripheral findings may associate with retinal disease. Ultra-widefield pseudocolor fundus images were taken from the eyes of clinic patients. Demographic data and clinical diagnosis for each patient was noted. The grading system was validated using masked retinal specialists. Logistic regression identified associations between retinal disease and peripheral retinal findings. Using the grading system, inter-observer agreement was 76.1% with Cohen's Kappa coefficient 0.542 (p < 0.0001) and the test-retest agreement was 95.1% with Kappa 0.677(p < 0.0001). 971 images were included, with 625 eyes (64.4%) having peripheral abnormalities. Peripheral drusen was the most common abnormality (n = 221, 22.76%) and correlated with age-related macular degeneration (p < 0.001). Novel correlations were also identified between diabetic retinopathy and retinal pigmentation as well as pigmentary degeneration. This study provides a validated system for identifying peripheral abnormalities and adds to literature highlighting peripheral retinal associations with retinal disease which would benefit from further study.

Vascular abnormalities in fellow eyes of patients with unilateral coats' disease

Coats' disease is an idiopathic retinal vascular disorder, known to usually occur unilaterally; however, recent studies have highlighted vascular abnormalities in the fellow unaffected eyes. This retrospective study investigated the peripheral vascular features and macular vascular structure of unaffected fellow eyes in patients with unilateral Coats' disease using multimodal imaging tools. We analysed images of patients, including bilateral ultra-widefield imaging, fluorescein angiography (FA), ultra-widefield FA, or standard fundus photography. Available bilateral optical coherence tomography angiography (OCT-A) images were used for macular vascular structure analysis. OCT-A parameters, including foveal avascular zone (FAZ), perfusion index, and vessel density (VD) in the superficial and deep capillary plexuses (SCP, DCP), were calculated using Image J software. The mean age at diagnosis was 34.5 ± 17.9 years. The mean final best-corrected visual acuity of the affected eyes was logMAR 0.78 ± 0.79, while that of the fellow eyes was logMAR 0.04 ± 0.12. Ten fellow eyes had microaneurysms (47.6%), two had tortuous vessel abnormalities (9.5%), and 11(52.4%) had abnormal vascular findings on FA. Although there was a trend towards larger DCP FAZ (1.201 ± 0.086 vs. 1.072 ± 0.226), and lower DCP VD (8.593 ± 1.583 vs. 10.827 ± 3.392) in the affected eyes as measured by the Cirrus machine, the difference was not statistically significant between affected and fellow eyes when measured using the Zeiss Cirrus machine (P = 0.686, P = 0.343, respectively). However, when measured with the Spectralis machine, DCP FAZ was larger in affected eyes (0.828 ± 0.426 vs. 0.254 ± 0.092, P = 0.002) and DCP VD was lower in affected eyes (6.901 ± 2.634 vs. 17.451 ± 7.207, P = 0.002) compared to the fellow eyes, while other parameters showed no significant variations. These findings indicate that there may be subtle vascular abnormalities primarily located in the peripheral regions of the unaffected fellow eyes in patients with unilateral Coats' disease, while the macular microvasculature remains unaffected.

Evaluating spatial dependency of the spectral efficiency in trans-palpebral illumination for widefield fundus photography

Multi-spectral widefield fundus photography is valuable for the clinical diagnosis and management of ocular conditions that may impact both central and peripheral regions of the retina and choroid. Trans-palpebral illumination has been demonstrated as an alternative to transpupillary illumination for widefield fundus photography without requiring pupil dilation. However, spectral efficiency can be complicated due to the spatial variance of the light property through the palpebra and sclera. This study aims to investigate the effect of light delivery location on spectral efficiency in trans-palpebral illumination. Four narrow-band light sources, covering both visible and near infrared (NIR) wavelengths, were used to evaluate spatial dependency of spectral illumination efficiency. Comparative analysis indicated a significant dependence of visible light efficiency on spatial location, while NIR light efficiency is only slightly affected by the illumination location. This study confirmed the pars plana as the optimal location for delivering visible light to achieve color imaging of the retina. Conversely, spatial location is not critical for NIR light imaging of the choroid.

ASSESSMENT OF QUALITY AND ADEQUACY OF PANRETINAL PHOTOCOAGULATION IN PROLIFERATIVE DIABETIC RETINOPATHY USING ULTRA-WIDEFIELD IMAGING

PURPOSE

To assess the characteristics of completed panretinal photocoagulation (PRP), using ultra-widefield imaging in proliferative diabetic retinopathy.

METHODS

Quantitative assessment of ultra-widefield imaging images of 133 patients with proliferative diabetic retinopathy with completed PRP was made using ImageJ software. The parameters assessed included distance of laser spots from the optic disk, foveal center, superior and inferior arcades, and extent of the maximum width of laser. Areas assessed were total area of the image, area of the inner limit within which laser spots are restricted, minimum areas of unlasered patches, total area lasered, and ideal area to be covered by PRP.

RESULTS

Two hundred one images were assessed for the final analysis. The mean distance of laser spots was 4.2 ± 2.4 mm from the optic disk (nasal) and 6.6 ± 2.5 mm from the foveal center (temporal). The mean distance of laser spots from the superior arcade vessel was 3.2 ± 1.9 mm and 6.2 ± 4.4 mm from the inferior arcade. The mean area of the retina that should have been ideally lasered was found to be 900 ± 267 mm 2 , and the actual area lasered was found to be 681 ± 254.4 mm 2 .

CONCLUSION

Approximately one-quarter area of the retina continues to remain ischemic because of the lack of inadequate coverage of PRP. Further longitudinal studies are recommended, using ultra-widefield imaging to objectively assess the adequacy of PRP and its role in modulating the course of progression of the retinopathy.

The relationship of diabetic retinopathy severity scales with frequency and surface area of diabetic retinopathy lesions

PURPOSE

To assess the relationship between qualitative diabetic retinopathy (DR) scales with the precise numbers and surface area of DR lesions within the Early Treatment Diabetic Retinopathy Study (ETDRS) standard seven field (S7F) region on ultrawide-field (UWF) color fundus images.

METHODS

In this study, we collected UWF images from adult patients with diabetes. Poor-quality images and eyes with any pathology precluding assessment of DR severity were excluded. The DR lesions were manually segmented. DR severity was graded according to the International Clinical Diabetic Retinopathy (ICDR) and AA protocol by two masked graders within the ETDRS S7F. These lesions' numbers and surface area were computed and correlated against the DR scores using the Kruskal-Wallis H test. Cohen's Kappa was performed to determine the agreement between two graders.

RESULTS

One thousand five hundred and twenty eyes of 869 patients (294 females, 756 right eyes) with a mean age of 58.7 years were included. 47.4% were graded as no DR, 2.2% as mild non-proliferative DR (NPDR), 24.0% as moderate NPDR, 6.3% as severe NPDR, and 20.1% as proliferative DR (PDR). The area and number of DR lesions generally increased as the ICDR level increased up to severe NPDR, but decreased from severe NPDR to PDR. There was perfect intergrader agreement on the DR severity.

CONCLUSION

A quantitative approach reveals that DR lesions' number and area generally correlate with ICDR-based categorical DR severity levels with an increasing trend in the number and area of DR lesions from mild to severe NPDR and a decrease from severe NPDR to PDR.

Ultra-Widefield Imaging as a Teleophthalmology Screening Tool for Ocular Pathology

Background

Prior studies have validated ultra-widefield imaging as a remote screening tool for diabetic retinopathy. The aim of this study was to determine its use in screening for any fundus pathology in a routine patient population.

Methods

In this prospective randomized study, patients underwent both slit lamp indirect ophthalmoscopy and ultra-widefield imaging. Ultra-widefield images were independently reviewed by two optometrists, and discrepancies were adjudicated by a retina specialist. Clinical findings from slit-lamp examiners and image-reviewers were coded into themes and clinically meaningful findings were extracted. Cohen's kappa was used to estimate agreement for these findings between the two image-reviewers and between the image-reviewers and slit-lamp examiners.

Results

Nine-hundred eyes of 450 patients were examined and imaged, of which 616 eyes were analyzed. At least one abnormal fundus finding was present on ophthalmoscopy in 71 eyes (11%) and on adjudicated image interpretation in 166 eyes (27%). Agreement between the two image-reviewers was moderate to substantial for most clinically meaningful findings, including optic disc hemorrhage (κ = 0.8), macular exudates (κ = 0.7), and macular pigmentary changes (κ = 0.7). Agreement between examiners and image-reviewers was moderate to substantial for optic disc hemorrhage (κ = 1), indistinct optic disc margins (κ = 0.5), drusen (κ = 0.4), pigmentary changes (κ = 0.4), and hemorrhage (κ = 0.8). A total of 187 findings were detected by imaging but not examination, compared with 42 that were detected on examination but not imaging.

Conclusion

In a routine patient population, ultra-widefield imaging agreed with standard-of-care slit-lamp examinations and detected more fundus findings.

Retro-Mode in NIDEK Mirante: A Comparative Analysis with Other Imaging Modalities for AMD and CSR

BACKGROUND

Retro-mode is a novel technique capable of creating pseudo-3D images of the retina. However, its clinical utility remains unknown. This study aimed to evaluate the Nidek Mirante multimodal imaging platform for ocular assessment in patients with various retinal conditions.

METHODS

A total of 115 participants with central serous chorioretinopathy (CSR) and age-related macular degeneration (AMD) were included. Two experienced graders independently evaluated the images, and statistical analysis was performed to assess interclass correlation coefficients (ICC) between graders and modalities; Results: For CSR detection, retro-mode demonstrated exceptionally high ICC rates (ICC = 1; 100%), while color and autofluorescence (FAF) showed moderate coefficients (0.69 and 0.78, respectively). The detection of pigment epithelial detachment was high across all methods, with only retro-mode deviated right (DR) allowing detection in 69% of cases, while retro-mode DR and deviated left (DL) achieved 100% detection. FAF-green achieved a 95% detection rate. In detecting retinal atrophy, most modalities demonstrated high detection rates, with the lowest detection rates offered by retro-mode DL (ICC = 0.85) and DR (ICC = 0.89), while retro-mode ring aperture offered 0.97. Infra-red and fluorescein angiography imaging offered the highest detection rates among the tested modalities, with 97% and 100%, respectively.

CONCLUSION

Retro-mode showed promise for comprehensive ocular evaluation and diagnosis, with certain imaging modalities demonstrating higher accuracy in detecting specific retinal features.

A new diagnostic method for retinal breaks in patients with posterior vitreous detachment: Ultra-wide-field imaging with the Zeiss Clarus 700

PURPOSE

This study was performed with the aim of finding a more convenient and less time-consuming method to diagnose retinal breaks in posterior vitreous detachment (PVD) patients.

METHODS

A prospective double-blind observational case study was performed with patients who were admitted to the Eye Emergency Department Sahlgrenska University Hospital with PVD symptoms and approved to participate in the study (n = 128). Standard slit lamp examination was compared with images from a Zeiss Clarus 700 ultra-wide-field camera (UWFC). Patients were examined and photographed by an independent operator. Data and image review was performed by three independent reviewers with varying experience. Retinal break detection with the two different methods (detailed eye examination by well-trained ophthalmologist and UWFC evaluations) was analysed statistically.

RESULTS

After excluding diagnoses other than PVD as well as unclear images due to cataracts, vitreous bleeding, etc., a total of 103 eyes with PVD were evaluated. A total of 38 ruptures in 25 patients were detected by routine examination and were subjected to laser treatment. UWFC images were reviewed by three ophthalmology consultants and compared with routine examinations. Sensitivity values in detecting retinal ruptures in UWFC images of the three reviewers were 0.89, 0.87 and 0.79, and specificity values were 0.88, 0.86 and 0.93 (kappa values: 0.742, 0.689 and 0.728) respectively.

CONCLUSION

Although there have been rapid developments in imaging with UWFC in recent years and it is a very promising method for the future, routine clinical examination is still the only valid method for the detection of retinal tears today.

RETINAL VASCULITIS SEVERITY ASSESSMENT: Intraobserver and Interobserver Reliability of a New Scheme for Grading Wide-Field Fluorescein Angiograms in Retinal Vasculitis

PURPOSE

Wide-field fluorescein angiography is commonly used to assess retinal vasculitis (RV), which manifests as vascular leakage and occlusion. Currently, there is no standard grading scheme for RV severity. The authors propose a novel RV grading scheme and assess its reliability and reproducibility.

METHODS

A grading scheme was developed to assess both leakage and occlusion in RV. Wide-field fluorescein angiography images from 50 patients with RV were graded by four graders, and one grader graded them twice. An intraclass correlation coefficient (ICC) was used to determine intraobserver-interobserver reliability. Generalized linear models were calculated to associate the scoring with visual acuity.

RESULTS

Repeated grading by the same grader showed good intraobserver reliability for both leakage (ICC = 0.85, 95% CI 0.78-0.89) and occlusion (ICC = 0.82, 95% CI 0.75-0.88) scores. Interobserver reliability among four independent graders showed good agreement for both leakage (ICC = 0.66, 95% CI 0.49-0.77) and occlusion (ICC = 0.75, 95% CI 0.68-0.81) scores. An increasing leakage score was significantly associated with worse concurrent visual acuity (generalized linear models, β = 0.090, P < 0.01) and at 1-year follow-up (generalized linear models, β = 0.063, P < 0.01).

CONCLUSION

The proposed grading scheme for RV has good to excellent intraobserver and interobserver reliability across a range of graders. The leakage score related to present and future visual acuity.

Joint conditional generative adversarial networks for eyelash artifact removal in ultra-wide-field fundus images

Background: Ultra-Wide-Field (UWF) fundus imaging is an essential diagnostic tool for identifying ophthalmologic diseases, as it captures detailed retinal structures within a wider field of view (FOV). However, the presence of eyelashes along the edge of the eyelids can cast shadows and obscure the view of fundus imaging, which hinders reliable interpretation and subsequent screening of fundus diseases. Despite its limitations, there are currently no effective methods or datasets available for removing eyelash artifacts from UWF fundus images. This research aims to develop an effective approach for eyelash artifact removal and thus improve the visual quality of UWF fundus images for accurate analysis and diagnosis. Methods: To address this issue, we first constructed two UWF fundus datasets: the paired synthetic eyelashes (PSE) dataset and the unpaired real eyelashes (uPRE) dataset. Then we proposed a deep learning architecture called Joint Conditional Generative Adversarial Networks (JcGAN) to remove eyelash artifacts from UWF fundus images. JcGAN employs a shared generator with two discriminators for joint learning of both real and synthetic eyelash artifacts. Furthermore, we designed a background refinement module that refines background information and is trained with the generator in an end-to-end manner. Results: Experimental results on both PSE and uPRE datasets demonstrate the superiority of the proposed JcGAN over several state-of-the-art deep learning approaches. Compared with the best existing method, JcGAN improves PSNR and SSIM by 4.82% and 0.23%, respectively. In addition, we also verified that eyelash artifact removal via JcGAN could significantly improve vessel segmentation performance in UWF fundus images. Assessment via vessel segmentation illustrates that the sensitivity, Dice coefficient and area under curve (AUC) of ResU-Net have respectively increased by 3.64%, 1.54%, and 1.43% after eyelash artifact removal using JcGAN. Conclusion: The proposed JcGAN effectively removes eyelash artifacts in UWF images, resulting in improved visibility of retinal vessels. Our method can facilitate better processing and analysis of retinal vessels and has the potential to improve diagnostic outcomes.

Ultra-Widefield OCT Angiography

Optical Coherence Tomography Angiography (OCTA), a functional extension of OCT, has the potential to replace most invasive fluorescein angiography (FA) exams in ophthalmology. So far, OCTA's field of view is however still lacking behind fluorescence fundus photography techniques. This is problematic, because many retinal diseases manifest at an early stage by changes of the peripheral retinal capillary network. It is therefore desirable to expand OCTA's field of view to match that of ultra-widefield fundus cameras. We present a custom developed clinical high-speed swept-source OCT (SS-OCT) system operating at an acquisition rate 8-16 times faster than today's state-of-the-art commercially available OCTA devices. Its speed allows us to capture ultra-wide fields of view of up to 90 degrees with an unprecedented sampling density and hence extraordinary resolution by merging two single shot scans with 60 degrees in diameter. To further enhance the visual appearance of the angiograms, we developed for the first time a three-dimensional deep learning based algorithm for denoising volumetric OCTA data sets. We showcase its imaging performance and clinical usability by presenting images of patients suffering from diabetic retinopathy.

Diabetic retinopathy screenings in West Virginia: an assessment of teleophthalmology implementation

BACKGROUND

The prevalence of diabetes in the state of West Virginia (WV) is amongst the highest in the United States, making diabetic retinopathy (DR) and diabetic macular edema (DME) a major epidemiological concern within the state. Several challenges exist regarding access to eye care specialists for DR screening in this rural population. A statewide teleophthalmology program has been implemented. We analyzed real-world data acquired via these systems to explore the concordance between image findings and subsequent comprehensive eye exams and explore the impact of age on image gradeability and patient distance from the West Virginia University (WVU) Eye Institute on follow-up.

METHODS

Nonmydriatic fundus images of diabetic eyes acquired at primary care clinics throughout WV were reviewed by retina specialists at the WVU Eye Institute. Analysis included the concordance between image interpretations and dilated examination findings, hemoglobin A1c (HbA1c) levels and DR presence, image gradeability and patient age, and distance from the WVU Eye Institute and follow-up compliance.

RESULTS

From the 5,512 fundus images attempted, we found that 4,267 (77.41%) were deemed gradable.  Out of the 289 patients whose image results suggested DR, 152 patients (52.6%) followed up with comprehensive eye exams-finding 101 of these patients to truly have DR/DME and allowing us to determine a positive predictive value of 66.4%. Patients within the HbA1c range of 9.1-14.0% demonstrated significantly greater prevalence of DR/DME (p < 0.01).  We also found a statistically significant decrease in image gradeability with increased age.  When considering distance from the WVU Eye Institute, it was found that patients who resided within 25 miles demonstrated significantly greater compliance to follow-up (60% versus 43%, p < 0.01).

CONCLUSIONS

The statewide implementation of a telemedicine program intended to tackle the growing burden of DR in WV appears to successfully bring concerning patient cases to the forefront of provider attention.  Teleophthalmology addresses the unique rural challenges of WV, but there is suboptimal compliance to essential follow-up with comprehensive eye exams. Obstacles remain to be addressed if these systems are to effectively improve outcomes in DR/DME patients and diabetic patients at risk of developing these sight-threatening pathologies.

Wide-field Fundus Imaging and Fluorescein Angiography Findings in Various Pseudoretinoblastoma Conditions

PURPOSE

To report wide-field fundus imaging and fluorescein angiography findings in conditions mimicking retinoblastoma (pseudoretinoblastoma).

METHODS

The clinical and imaging records of 28 patients (36 eyes) imaged with RetCam 3 (Clarity Medical Systems, Inc) wide-field fundus photography and fluorescein angiography who were diagnosed as having various pseudoretinoblastoma disorders between February 2020 and August 2021 were retrospectively evaluated.

RESULTS

Most patients were referred with suspicion of retinoblastoma. Other patients had unresolved eye conditions and received initial treatment elsewhere and they were referred later for exclusion of retinoblastoma. On RetCam fundus photography and fluorescein angiography, pseudoretinoblastoma conditions were diagnosed as Coats disease (9 eyes), congenital glaucoma (3 eyes), persistent fetal vasculature (3 eyes), familial exudative vitreoretinopathy (2 eyes), retinopathy of prematurity (2 eyes), myelinated retinal nerve fibers (2 eyes), optic nerve hypoplasia (2 eyes), oculocutaneous albinism (2 eyes), meridional fold (2 eyes), combined hamartoma of retina and retinal pigment epithelium (2 eyes), grouped congenital hypertrophy of the retinal pigment epithelium (1 eye), retinal astrocytic hamartoma (1 eye), morning glory syndrome (1 eye), optic glioma (1 eye), giant choroidal nevus (1 eye), vasculitis (1 eye), and chorioretinitis (1 eye). RetCam imaging and fluorescein angiography demonstrated telangiectasias, microaneurysms, submacular exudation/fibrosis, capillary non-perfusion, and exudation posterior to telangiectasias in Coats disease. Hypofluorescent optic discs, peripheral non-perfusion, and vascular leakage were observed in congenital glaucoma. Large areas of capillary non-perfusion, poor foveal morphology/formation, elongated ciliary processes with hyperfluorescent central core, and hyperfluorescent fibrovascular stalk at the posterior pole were hallmarks of persistent fetal vasculature.

CONCLUSIONS

RetCam wide-field fundus imaging and fluorescein angiography play an important role in the diagnosis of conditions simulating retinoblastoma. [J Pediatr Ophthalmol Strabismus. 2023;60(1):60-74.].

Ultra-wide-field fundus photography compared to ophthalmoscopy in diagnosing and classifying major retinal diseases

To analyze the performance of ultra-wide-field (UWF) fundus photography compared with ophthalmoscopy in identifying and classifying retinal diseases. Patients examined for presumed major retinal disorders were consecutively enrolled. Each patient underwent indirect ophthalmoscopic evaluation, with scleral depression and/or fundus biomicroscopy, when clinically indicated, and mydriatic UWF fundus imaging by means of CLARUS 500™ fundus camera. Each eye was classified by a clinical grader and two image graders in the following groups: normal retina, diabetic retinopathy, vascular abnormalities, macular degenerations and dystrophies, retinal and choroidal tumors, peripheral degenerative lesions and retinal detachment and myopic alterations. 7024 eyes of new patients were included. The inter-grader agreement for images classification was perfect (kappa = 0.998, 95% Confidence Interval (95%CI) = 0.997-0.999), as the two methods concordance for retinal diseases diagnosis (kappa = 0.997, 95%CI = 0.996-0.999) without statistically significant difference. UWF fundus imaging might be an alternative to ophthalmoscopy, since it allows to accurately classify major retinal diseases, widening the range of disorders possibly diagnosed with teleophthalmology. Although the clinician should be aware of the possibility that a minority of the most peripheral lesions may be not entirely visualized, it might be considered a first line diagnostic modality, in the context of a full ophthalmological examination.

Visualization of retinal breaks on ultra-widefield fundus imaging using a digital green filter

PURPOSE

We compare the ability of resident physicians to identify retinal breaks on ultra-widefield color fundus photos using the traditional image compared to an image with a green filter overlay.

METHODS

Residents were shown fundus photos of 10 eyes with either a retinal tear or hole. Participants were shown each photo twice-once with traditional color settings and once with a green filter overlay. Participants were scored on whether the break was correctly identified and timed on how long it took to identify the pathology.

RESULTS

Residents were able to correctly identify more retinal breaks on fundus photos with a green filter overlay compared to photos with traditional settings (P = 0.02). Residents were also able to identify breaks on fundus photos more quickly on images with a green filter overlay compared to the traditional images (P < 0.001).

CONCLUSIONS

The application of a green filter overlay may help in identifying retinal breaks.

Risk factors for the development or progression of diabetic retinopathy in pregnancy: Meta‐analysis and systematic review

BACKGROUND

Diabetic retinopathy (DR) is the leading cause of blindness in the working-age population, and it increases in severity during pregnancy.

METHODS

Systematic review of literature from PubMed, Cochrane Library and Web of Science using keywords 'diabetic retinopathy' and 'pregnancy' and 'progression' from inception to 2021 was completed. Included studies were (1) peer-reviewed observational studies addressing progression/development of DR in pregnancy, (2) provided the number of diabetic patients that developed/progressed in DR during pregnancy, and (3) included differential data on variables between progression and non-progression groups. This was applied by two independent researchers and referred to a third researcher as necessary. Twenty-seven of the original 138 studies met this criterion. Data were pooled and analysed using fixed-effects in meta-analysis.

RESULTS

From 27 studies, 2537 patients were included. Pre-eclampsia [Risk Ratio (RR) 2.62 (95% CI = 1.72, 4.00)] and hypertension treatment during pregnancy [RR 2.74 (95% CI = 1.72, 4.00)] were significantly associated with the development/progression of DR. HbA1c at baseline [MD 0.82 (95% CI = 0.59, 1.06)], duration of diabetes [mean difference (MD) 5.97 (95% CI = 5.38, 6.57)], and diastolic blood pressure at baseline [MD 3.29 (95% CI = 0.46, 6.12)] were all significantly higher in the progression group while only mean birth weight [MD -0.17 (95% CI = -0.31, -0.03)] was significantly higher in the non-progression group.

CONCLUSIONS

This study fills a gap in the literature and provide physicians with more information on the risk factors associated with the progression of DR in pregnancy and how to counsel this vulnerable patient population appropriately.

Light color efficiency-balanced trans-palpebral illumination for widefield fundus photography of the retina and choroid

A wide-field fundus camera, which can selectively evaluate the retina and choroid, is desirable for better detection and treatment evaluation of eye diseases. Trans-palpebral illumination has been demonstrated for wide-field fundus photography, but its application for true-color retinal imaging is challenging due to the light efficiency delivered through the eyelid and sclera is highly wavelength dependent. This study is to test the feasibility of true-color retinal imaging using efficiency-balanced visible light illumination, and to validate multiple spectral imaging (MSI) of the retina and choroid. 530 nm, 625 nm, 780 nm and 970 nm light emission diodes (LED)s are used to quantitatively evaluate the spectral efficiency of the trans-palpebral illumination. In comparison with 530 nm illumination, the 625 nm, 780 nm and 970 nm light efficiencies are 30.25, 523.05, and 1238.35 times higher. The light efficiency-balanced 530 nm and 625 nm illumination control can be used to produce true-color retinal image with contrast enhancement. The 780 nm light image enhances the visibility of choroidal vasculature, and the 970 nm image is predominated by large veins in the choroid. Without the need of pharmacological pupillary dilation, a 140° eye-angle field of view (FOV) is demonstrated in a snapshot fundus image. In coordination with a fixation target, the FOV can be readily expanded over the equator of the eye to visualize vortex ampullas.

Advances in OCT Imaging in Myopia and Pathologic Myopia

Advances in imaging with optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) technology, including the development of swept source OCT/OCTA, widefield or ultra-widefield systems, have greatly improved the understanding, diagnosis, and treatment of myopia and myopia-related complications. Anterior segment OCT is useful for imaging the anterior segment of myopes, providing the basis for implantable collamer lens optimization, or detecting intraocular lens decentration in high myopic patients. OCT has enhanced imaging of vitreous properties, and measurement of choroidal thickness in myopic eyes. Widefield OCT systems have greatly improved the visualization of peripheral retinal lesions and have enabled the evaluation of wide staphyloma and ocular curvature. Based on OCT imaging, a new classification system and guidelines for the management of myopic traction maculopathy have been proposed; different dome-shaped macula morphologies have been described; and myopia-related abnormalities in the optic nerve and peripapillary region have been demonstrated. OCTA can quantitatively evaluate the retinal microvasculature and choriocapillaris, which is useful for the early detection of myopic choroidal neovascularization and the evaluation of anti-vascular endothelial growth factor therapy in these patients. In addition, the application of artificial intelligence in OCT/OCTA imaging in myopia has achieved promising results.

Comparison between Deep-Learning-Based Ultra-Wide-Field Fundus Imaging and True-Colour Confocal Scanning for Diagnosing Glaucoma

In this retrospective, comparative study, we evaluated and compared the performance of two confocal imaging modalities in detecting glaucoma based on a deep learning (DL) classifier: ultra-wide-field (UWF) fundus imaging and true-colour confocal scanning. A total of 777 eyes, including 273 normal control eyes and 504 glaucomatous eyes, were tested. A convolutional neural network was used for each true-colour confocal scan (Eidon AF™, CenterVue, Padova, Italy) and UWF fundus image (Optomap™, Optos PLC, Dunfermline, UK) to detect glaucoma. The diagnostic model was trained using 545 training and 232 test images. The presence of glaucoma was determined, and the accuracy and area under the receiver operating characteristic curve (AUC) metrics were assessed for diagnostic power comparison. DL-based UWF fundus imaging achieved an AUC of 0.904 (95% confidence interval (CI): 0.861−0.937) and accuracy of 83.62%. In contrast, DL-based true-colour confocal scanning achieved an AUC of 0.868 (95% CI: 0.824−0.912) and accuracy of 81.46%. Both DL-based confocal imaging modalities showed no significant differences in their ability to diagnose glaucoma (p = 0.135) and were comparable to the traditional optical coherence tomography parameter-based methods (all p > 0.005). Therefore, using a DL-based algorithm on true-colour confocal scanning and UWF fundus imaging, we confirmed that both confocal fundus imaging techniques had high value in diagnosing glaucoma.

Towards standardizing retinal optical coherence tomography angiography: a review

The visualization and assessment of retinal microvasculature are important in the study, diagnosis, monitoring, and guidance of treatment of ocular and systemic diseases. With the introduction of optical coherence tomography angiography (OCTA), it has become possible to visualize the retinal microvasculature volumetrically and without a contrast agent. Many lab-based and commercial clinical instruments, imaging protocols and data analysis methods and metrics, have been applied, often inconsistently, resulting in a confusing picture that represents a major barrier to progress in applying OCTA to reduce the burden of disease. Open data and software sharing, and cross-comparison and pooling of data from different studies are rare. These inabilities have impeded building the large databases of annotated OCTA images of healthy and diseased retinas that are necessary to study and define characteristics of specific conditions. This paper addresses the steps needed to standardize OCTA imaging of the human retina to address these limitations. Through review of the OCTA literature, we identify issues and inconsistencies and propose minimum standards for imaging protocols, data analysis methods, metrics, reporting of findings, and clinical practice and, where this is not possible, we identify areas that require further investigation. We hope that this paper will encourage the unification of imaging protocols in OCTA, promote transparency in the process of data collection, analysis, and reporting, and facilitate increasing the impact of OCTA on retinal healthcare delivery and life science investigations.

Retinal imaging biomarkers of neurodegenerative diseases

The timely detection of neurodegenerative diseases is central to improving clinical care as well as enabling the development and deployment of disease-modifying therapies. Retinal imaging is emerging as a method to detect features of a number of neurodegenerative diseases, given the anatomical and functional similarities between the retina and the brain. This review provides an overview of the current status of retinal imaging biomarkers of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Lewy body dementia, frontotemporal dementia, Huntington's disease and multiple sclerosis. Whilst research findings are promising, efforts to harmonise study designs and imaging methods will be important in translating these findings into clinical care. Doing so may mean that eye care providers will play important roles in the detection of a variety of neurodegenerative diseases in future.

Assessing Choroidal Nevi, Melanomas and Indeterminate Melanocytic Lesions Using Multimodal Imaging—A Retrospective Chart Review

Using multimodal imaging, the literature proposed the following risk factors for choroidal nevus growth into melanoma: increased tumor thickness, subretinal fluid, decreased visual acuity, presence of orange pigment, ultrasound acoustic hollowness, and increased tumor diameter. This study investigated the presence of the mentioned risk factors in choroidal nevi, choroidal melanomas, and indeterminate choroidal melanocytic lesions. This retrospective, single-center chart review assessed choroidal melanocytic tumors with multimodal imaging. We defined our primary outcome as the cumulative presence of mentioned risk factors. Further, we evaluated various optical coherence tomography (OCT), ultrasound, and autofluorescence findings. We analyzed 51 tumors from 49 patients during the period from April 2008 to June 2021. The median (IQR) age was 64.0 (56.0 to 70.5) years, with 23 of 49 (46.9%) patients being female. The follow-up time for all tumors was median (IQR) 25.0 (12.0 to 39.0) months. The choroidal nevi had a median (range) risk score of 0.0 (0.0 to 3.0), and the choroidal melanoma of 5.0 (3.0 to 6.0), with statistically significant different ratings (p < 0.001). Multimodal imaging creates a score that may help to distinguish choroidal nevi from choroidal melanomas objectively.

Assessing the Utility and Patient Satisfaction of Virtual Retina Clinics During COVID-19 Pandemic

Purpose

To explore whether the virtual retina clinic (VRC) has been a useful and safe platform for monitoring retinal diseases during the COVID-19 pandemic and assessing patient satisfaction.

Methods

A prospective observational study was conducted for patients with stable retinal diseases in Donostia University Hospital’s Ophthalmology Service during the pandemic. All patients were assessed in the VRC with optical coherence tomography of the macula and widefield retinography, plus visual field tests in hydroxychloroquine retinopathy screenings. The VRC´s effectiveness was evaluated with repeat blind assessments and patient satisfaction with an adapted SERVQUAL scale.

Results

The most common diseases were diabetic retinopathy (30.3%) and age-related macular degeneration (21.8%). Most patients (74%) were eligible to continue in the VRC, 19.3% were referred to face-to-face (F2F) appointments and 6.6% were discharged. Patients underwent repeat blind assessments in F2F appointments to monitor VRC performance in 23.7% of the cases. The sensitivity to detect disease progression was 100%. The specificity was 80.1%. The VRC took half the time. The patient overall satisfaction rating was 9.8/10.

Conclusion

The VRC, as an additional platform, supports F2F appointments. Almost three-quarters of patients could continue being safely seen in the VRC. The virtual approach decreases SARS-CoV-2 exposure. Patient satisfaction is very good.

Translational Relevance

The VRC enables us to attend patients safely with decreased SARS-CoV-2 exposure.

Ultra-Widefield Fundus Fluorescein Angiography Findings in Patients with Fuchs' Uveitis Syndrome

Background

The aim of this study was to evaluate ultra-widefield (UWF) fundus fluorescein angiography (FFA) findings in patients with Fuchs' uveitis syndrome (FUS).

Materials and Methods

This cross-sectional study was conducted in patients with FUS. All the patients underwent a complete ophthalmologic examination, and FFA was carried out with Optos UWF retinal imaging. Standard FFA and image acquisition consisted of early phase (15-45 s) images, and late-phase (5-10 min) images were also obtained for both eyes.

Results

Forty eyes from twenty unilateral FUS patients, including 11 females (55%), who had a mean age of 38.50 ± 6.97 years, were enrolled. Eighty-five percent of the FUS eyes had optic disc hyperfluorescence (ODH) in the FFA. A significant relationship was observed between ODH and iris heterochromia (P = 0.004). ODH was seen in all the patients with iris heterochromia (n = 16). Peripheral vascular leakage (PVL), capillary nonperfusion, chorioretinal scar, and vascular sheathing were observed in 3, 3, 2, and 8 of the patients' eyes, respectively.

Conclusion

UWF FFA imaging seemed to be mandatory for evaluating the prognosis of the FUS patients, and another investigation may require to be conducted to evaluate the effect of antivascular endothelial growth factor agents for the management of PVL in these patients.

Quantitative Analysis of Retinal Vasculature in Rhegmatogenous Retinal Detachment Based on Ultra-Widefield Fundus Imaging

Purpose

To quantitatively analyze retinal vascular morphological features, such as vascular density, caliber, and tortuosity, in rhegmatogenous retinal detachment (RRD).

Methods

A total of 244 patients with RRD and 400 healthy controls (HC) were included. Retinal fundus images were collected using OPTOS PLC Daytona P200T. Retinal images were divided into RRD and non-RRD regions of interest (ROIs). All visible retinal fundus vessels were then extracted mainly based on edge detection within ROI to form the whole-vascular image. Retinal vasculature parameters, such as vascular density, caliber, and tortuosity, were calculated.

Results

For the absolute density, the mean rank (MR) value of normal controls was significantly higher than that in non-RRD (p < 0.001). A consistent tendency of significant vascular density was increased from non-RRD to RRD (p < 0.001). The average and median diameters of normal controls were both significantly larger than RRD (p < 0.001). The average and median diameters were also appeared significantly thinner in non-RRD. Unweighted and width-inversely-weighted vascular tortuosity in RRD and non-RRD comparison exhibited non-significant differences. All types of tortuosity calculated from HC were significantly larger (p < 0.001) in values compared to RRD. All types of tortuosity values of HC were significantly higher than non-RRD. Compared with non-RRD, RRD was significantly larger in area-weighted, length-weighted, and width-weighted vascular tortuosity.

Conclusions

This study showed that RRD affects both the quantity and morphology of retinal vasculature, such as RRD and non-RRD areas. Smaller average and medium vascular diameters and tortuosity values were found in RRD. However, the absolute vascular density, the average and median diameter, and tortuosity values were also reduced in non-RRD although the retina is still attached. This work indicates that RRD may affect the retinal vasculature beyond the detached retina.

[Technical and optical aspects of smartphone-based fundus photography : Possibilities and limitations in practice]

BACKGROUND

Smartphone-based adapters for fundus photography offer a cost-effective alternative to traditional fundus cameras. The various offers vary widely in design, size, purchasing costs, user-friendliness, and image quality when compared to each other and to traditional fundus cameras.

OBJECTIVE

The aim is to enable the reader to understand the technical and optical aspects of fundus photography and therefore to evaluate the various offers of traditional fundus cameras and adaptors for smartphone-based fundus photography with respect to their personal requirements.

MATERIAL AND METHODS

The technical and optical principles and aspects of fundus photography are explained and the various approaches to illumination, imaging, image capture and alignment are discussed. The association between field of view, pupil size, mydriasis and image quality are discussed as well as the challenges and difficulties of aligning the fundus camera relative to the patient's eye.

RESULTS

The most important technical aspects of a fundus camera are the avoidance of disturbing reflections when taking photographs, an acceptable field of view angle, the user-friendliness during alignment, success rate of imaging and the question whether mydriasis is necessary.

CONCLUSION

The development of adapters for smartphone-based fundus photography has resulted in interesting offers, which make fundus photography available to a wider user spectrum at low purchase costs. The offers on the market vary widely. It is therefore difficult to reach a definitive evaluation; however, smartphone-based adapters mostly have limitations with respect to user-friendliness, the size of the field of view and image quality.

Trans-scleral Illumination - The Future of Retinal Imaging?

We report how illumination of the retina through the sclera enables the recording of high-contrast reflectance and fluorescence images of the retina, free of the cornea and lens glare and autofluoresence that degrades images recorded using traditional illumination through the pupil.

Ultra-Widefield Swept-Source Optical Coherence Tomography Findings of Peripheral Retinal Degenerations and Breaks

PURPOSE

To investigate whether ultra-widefield (UWF) swept-source optical coherence tomography (SSOCT) system (Silverstone, Nikon Healthcare Japan, Inc, Tokyo, Japan) can obtain OCT images of peripheral retinal degenerations and breaks.

METHODS

Thirty-seven eyes of 31 consecutive cases (16 men, 15 women; mean age 51 years) who had peripheral retinal degenerations and underwent a UWF-SSOCT imaging were enrolled. The convenience and usefulness were investigated.

RESULTS

In all eyes, OCT images were capable and interpretable without any special techniques. The respective findings on OCT were retinal degeneration in 16 eyes: lattice degeneration in 8 eyes, paving stone degeneration in 4 eyes, and unclassified in 4 eyes, retinal tear in 12 eyes, and retinal hole in 9 eyes. The respective locations of the retinal degenerations or breaks were the posterior pole in 0 eyes, mid-periphery in 23 eyes, and far-periphery in 14 eyes. Fifteen eyes had a rhegmatogenous retinal detachment (RRD), one of which was preoperative and the other 14 eyes were postoperative. A buckle was placed in 8 eyes for RRD repair. Subretinal fluid was observed in 9 of 21 eyes with retinal break or retinal hole. Vitreoretinal traction was observed in 10 of 27 eyes without a history of vitrectomy. Inverted artifacts on OCT images were observed in 20 of 37 eyes, which were not related to the location or axial length, but were supposed to be due to the limited scan depth.

CONCLUSION

The UWF-SSOCT system could capture the OCT images of peripheral retinal degenerations and breaks without any special technique.

Perspective Distortion Correction for Multi-Modal Registration between Ultra-Widefield and Narrow-Angle Retinal Images

Multi-modal retinal image registration between 2D Ultra-Widefield (UWF) and narrow-angle (NA) images has not been well-studied, since most existing methods mainly focus on NA image alignment. The stereographic projection model used in UWF imaging causes strong distortions in peripheral areas, which leads to inferior alignment quality. We propose a distortion correction method that remaps the UWF images based on estimated camera view points of NA images. In addition, we set up a CNN-based registration pipeline for UWF and NA images, which consists of the distortion correction method and three networks for vessel segmentation, feature detection and matching, and outlier rejection. Experimental results on our collected dataset shows the effectiveness of the proposed pipeline and the distortion correction method.

Current and novel multi-imaging modalities to assess retinal oxygenation and blood flow

Retinal ischemia characterizes the underlying pathology in a multitude of retinal diseases that can ultimately lead to vision loss. A variety of novel imaging modalities have been developed to characterize retinal ischemia by measuring retinal oxygenation and blood flow in-vivo. These technologies offer valuable insight into the earliest pathophysiologic changes within the retina and provide physicians and researchers with new diagnostic and monitoring capabilities. Future retinal imaging technologies with the capability to provide affordable, noninvasive, and comprehensive data on oxygen saturation, vasculature, and blood flow mechanics are needed. This review will highlight current and future trends in multimodal imaging to assess retinal blood flow and oxygenation.

Comparison of Two Ultra-Widefield Cameras With High Image Resolution and Wider View for Identifying Diabetic Retinopathy Lesions

Purpose

To compare the effectiveness of the Optos P200dTx and Zeiss Clarus 500 fundus cameras in detecting diabetic retinopathy (DR) lesions.

Methods

A cross-sectional study was conducted among 243 patients with clinically diagnosed diabetes mellitus who were referred for an eye examination from two tertiary eye care centers in Chennai, India. Patients underwent DR screening based on mydriatic fundal images acquired by both fundal cameras. Fundal images from the two separate devices for each eye were compared based on accurately identified pathological retinal lesions with respect to type and location.

Results

When studying lesions of the central retina, they were better identified by the Zeiss Clarus compared with the Optos P200dTx, with six out of eight being statistically significant (P < 0.05). However, lesions of the mid-peripheral retina and peripheral retina were better identified by the Optos P200dTx than the Zeiss Clarus, with three out of eight lesions and five out of eight lesions being statistically significant (P < 0.05), respectively. Based on the color and size of lesions, the Optos P200dTx had a higher chance (59.6%) of missing white lesions than did the Zeiss Clarus (17%) (P < 0.0001). Consequently, small- and medium-sized lesions were missed more by the Optos P200dTx (30.72% and 32.63%, respectively) than the Zeiss Clarus (22.3% and 19.30%, respectively).

Conclusions

The capability of detecting or missing a particular DR lesion among diabetics differed between the two cameras based on effective field of view, resolution, and the retinal zone being imaged.

Translational Relevance

The choice of which ultra-widefield camera to be used for screening DR can be based on the greater prevalence of central versus peripheral retinal lesions noted in the patient population seen in a clinical practice.

A Novel, Smartphone-Based, Teleophthalmology-Enabled, Widefield Fundus Imaging Device With an Autocapture Algorithm

Purpose

Widefield imaging can detect signs of retinal pathology extending beyond the posterior pole and is currently moving to the forefront of posterior segment imaging. We report a novel, smartphone-based, telemedicine-enabled, mydriatic, widefield retinal imaging device with autofocus and autocapture capabilities to be used by non-specialist operators.

Methods

The Remidio Vistaro uses an annular illumination design without cross-polarizers to eliminate Purkinje reflexes. The measured resolution using the US Air Force target test was 64 line pairs (lp)/mm in the center, 57 lp/mm in the middle, and 45 lp/mm in the periphery of a single-shot retinal image. An autocapture algorithm was developed to capture images automatically upon reaching the correct working distance. The field of view (FOV) was validated using both model and real eyes. A pilot study was conducted to objectively assess image quality. The FOVs of montaged images from the Vistaro were compared with regulatory-approved widefield and ultra-widefield devices.

Results

The FOV of the Vistaro was found to be approximately 65° in one shot. Automatic image capture was achieved in 80% of patient examinations within an average of 10 to 15 seconds. Consensus grading of image quality among three graders showed that 91.6% of the images were clinically useful. A two-field montage on the Vistaro was shown to exceed the cumulative FOV of a seven-field Early Treatment Diabetic Retinopathy Study image.

Conclusions

A novel, smartphone-based, portable, mydriatic, widefield imaging device can view the retina beyond the posterior pole with a FOV of 65° in one shot.

Translational Relevance

Smartphone-based widefield imaging can be widely used to screen for retinal pathologies beyond the posterior pole.

Peripheral Manifestations in Age Related Macular Degeneration: A Review of Imaging and Findings

Purpose: To review novel findings in research with ultra-widefield imaging for analysis of peripheral manifestations in macular degeneration (AMD). We introduce the evolving widefield imaging modalities while summarizing the analytical techniques used in data collection of peripheral retinal findings thus far. Our review provides a summary of advancements to date and a commentary on future direction for AMD research. Methods: This is a literature review of all significant publications focused on the relationship between AMD and the retinal periphery conducted within the last two decades. Results and Conclusion: Promising research has been undertaken to elucidate peripheral retinal manifestations in macular degeneration using novel methodology. Advancements in ultra-widefield imaging and fundus autofluorescence have allowed us to elucidate peripheral retinal pigmentary changes, drusen deposition, and much more. Novel grid overlay techniques have been introduced to aid in analyzing these changes for pattern recognition and grouping of findings. This review discusses these findings in detail, providing evidence for the pan-retinal manifestations of AMD. Inter-study discordance in analytical approach highlights a need for more systematic future study.

The Role of Ultra-Widefield Fundus Imaging and Fluorescein Angiography in Diagnosis and Treatment of Diabetic Retinopathy

PURPOSE OF REVIEW

Early detection and treatment are important for preventing vision loss from diabetic retinopathy. Historically, the gold standard for grading diabetic retinopathy has been based on 7-field 30-degree color fundus photographs that capture roughly the central third of the retina. Our aim was to review recent literature on the role of ultra-widefield (allowing capture of up to 82% of the retina in one frame) fundus imaging in screening, prognostication, and treatment of diabetic retinopathy.

RECENT FINDINGS

Ultra-widefield fundus imaging can capture peripheral retinal lesions outside the traditional 7-field photographs that may correlate with increased risk of diabetic retinopathy progression. The speed and ability to image through undilated pupils make ultra-widefield imaging attractive for tele-ophthalmology screening. Ultra-widefield fluorescein angiography may help guide targeted laser treatment in eyes with proliferative diabetic retinopathy. Ultra-widefield imaging has potential to help shape new diabetic retinopathy screening, staging, and treatment protocols.

Ultra-widefield retinal imaging for adjunctive resident training in retinal break detection

We evaluated the clinical utility of ultra-widefield imaging as an adjunctive tool for training resident ophthalmologists in the detection of retinal breaks. This was a prospective study conducted at a secondary health care center (Tri-Service General Hospital) in Taiwan. Participants were 44 patients (53 eyes) who were referred to our hospital after being diagnosed with retinal breaks. Patients first underwent an indirect ophthalmoscopy examination of the total fundus without scleral depression by our junior (first and second year) or senior (third and fourth year) resident ophthalmologist and then underwent an ultra-widefield imaging examination with a central image and four gaze-steered (up, down, nasal, and temporal) images to determine the number of retinal breaks in the total fundus and the four quadrants. Of the total 53 eyes, 31 were examined by junior residents and 22 were examined by senior residents. In the group of junior residents, ultra-widefield imaging was significantly better at detecting retinal breaks of the total fundus (49 vs. 33 retinal breaks, p < 0.001) and the temporal quadrant (17 vs. 10 retinal breaks, p = 0.018) than indirect ophthalmoscopy. In the group of senior residents, there was no significant difference in the ability to detect retinal breaks in the total fundus or each of the four quadrants with ultra-widefield imaging or indirect ophthalmoscopy. Our results indicate that, compared to indirect ophthalmoscopy, ultra-widefield imaging with a central image and four gaze-steered images has a better performance and is a useful adjunct tool for the detection of retinal breaks in junior resident training. Additionally, it could be a useful method for teaching indirect ophthalmoscopy examination to junior residents.

Novel utilisation of ultrawide-field fundus photography for detecting retinal nerve fibre layer defects in glaucomatous eyes

BACKGROUND/AIMS

Evaluation of the retinal nerve fibre layer (RNFL) is important for identifying glaucomatous damage. Ultrawide-field fundus photography (UWP) imaging is increasingly used in the ophthalmological field; however, it is unknown whether it can be used for detecting RNFL defects (RNFLDs). We investigated whether RNFLD can be detected with UWP images and compared the clinical effectiveness of three types of images for detecting RNFLD: conventional red-free RNFL photography (RFP), non-mydriatic UWP and digitally converted green separation of non-mydriatic UWP (G-UWP).

METHODS

Eyes with glaucoma or glaucoma suspect and normal control eyes meeting the eligibility criteria were consecutively enrolled from September 2019 to April 2020. Their conventional RFP, non-mydriatic UWP and G-UWP images were assessed for detecting RNFLD to evaluate the sensitivity and specificity for detecting RNFLD.

RESULTS

Three image sets of 196 participants (84 normal control, 25 glaucoma suspect and 87 glaucoma) were obtained. The sensitivity of G-UWP (94.6%; 95% CI 88.7 to 98.0) and RFP (92.9%; 95% CI 86.4 to 96.9) was higher than that of UWP (82.1%; 95% CI 73.8 to 88.7; p<0.05). The sensitivities of G-UWP and RFP are comparable. The specificity of G-UWP (78.6%; 95% CI 68.3 to 86.8) and UWP (75.0%; 95% CI 64.4 to 83.8) was comparable, but both were lower than that of RFP (98.8%; 95% CI 93.5 to 100.0; p<0.05).

CONCLUSION

Non-mydriatic UWP images can be used to detect RNFLD. Non-mydriatic G-UWP showed comparable sensitivity but lower specificity to conventional RFP. Non-mydriatic G-UWP could be used as a convenient and useful diagnostic tool for screening glaucoma in clinical settings.

Ultra-Widefield Imaging for Evaluation of the Myopic Eye

Topic: Ultra-widefield (UWF) imaging of the myopic eye. Clinical Relevance: Myopes, and particularly high and pathologic myopes, present a unique challenge in fundoscopic imaging. Critical pathology is often located in the anteriormost portion of the retina, variations in posterior segment contour are difficult to capture in two-dimensional images, and extremes in axial length make simply focusing imaging devices difficult. Methods: We review the evolution of modalities for ophthalmic imaging (color fundus photography [CFP], optical coherence topography [OCT], angiography, artificial intelligence [AI]) to present day UWF technology and its impact on our understanding of myopia. Results: Advances in UWF technology address many of the challenges in fundoscopic imaging of myopes, providing new insights into the structure and function of the myopic eye. UWF CFP improves our ability to detect and document anterior peripheral pathology prevalent in approximately half of all high myopes. UWF OCT better captures the staphylomatous contour of the myopic eye, providing enhanced visualization of the vitreoretinal interface and progressive development of myopic traction maculopathy. UWF angiography highlights the posterior vortex veins, thin choriocapillaris, far peripheral avascularity, and peripheral retinal capillary microaneurysms more prevalent in the myopic eye. Researchers have demonstrated the ability of AI algorithms to predict refractive error, and great potential remains in the use of AI technology for the screening and prevention of myopic disease. Conclusion: We note significant progress in our ability to capture anterior pathology and improved image quality of the posterior segment of high and pathologic myopes. The next jump forward for UWF imaging will be the ability to capture a high quality ora to ora multimodal fundoscopic image in a single scan that will allow for sensitive AI-assisted screening of myopic disease.

Multimodal imaging in pediatric uveitis

Pediatric uveitis accounts for up to 10% of all uveitis cases, so special attention must be paid to ensure early diagnosis as well as treatment and follow-up of these young patients in order to decrease the risk of possible ocular complications and consequently vision loss. Multimodal imaging has been an effective and important adjunct in the diagnoses and management of uveitis, especially in children. Reviewed here are the currently utilized modalities, advances, as well as their applications in juvenile idiopathic arthritis-associated uveitis, pars planitis, retinal vasculitis, tubulointerstitial nephritis and uveitis syndrome, Behçet disease, Blau syndrome, and Vogt-Koyanagi-Harada syndrome.

Comparison of two ultra-widefield imaging for detecting peripheral retinal breaks requiring treatment

AIM

To compare the sensitivity of Optomap Panoramic 200 and Clarus 500 in detecting peripheral retinal breaks that required treatment.

METHODS

This prospective study enrolled consecutive patients undergoing laser for treatment-requiring peripheral retinal breaks from May 2019 to July 2019. The patients first underwent indirect ophthalmoscopy examination with scleral indentation by a retinal consultant and then ultra-widefield imaging by a single trained technician on Optomap 200 and Clarus 500 in all nine ocular gazes. The images were analysed by two independent investigators to look for the number and location of the breaks. The sensitivity of each platform was calculated as the number of treatment-requiring breaks identified by the system divided by the number of breaks identified on clinical examination.

RESULTS

Clinical examination of 49 eyes (41 patients) showed 116 treatment-requiring breaks. Overall sensitivity for identifying such breaks for Optomap and Clarus was 80.2% (n = 93) and 74.1% (n = 86) respectively (p = 0.274). The sensitivities in superior (p = 0.665), temporal (p = 0.146) and inferior (p = 0.889) quadrants were statistically similar for both the platforms. The sensitivity of Optomap was slightly higher than Clarus in emmetropic (p = 0.046) and phakic (p = 0.061) eyes, but similar in myopic (p = 0.448) and pseudophakic (p = 0.191) eyes.

CONCLUSION

The ability to detect treatment-requiring retinal breaks is similar for both Optomap and Clarus systems.