Conventional Fundus Photography Research Articles

Advances in Structural and Functional Retinal Imaging and Biomarkers for Early Detection of Diabetic Retinopathy.

Diabetic retinopathy (DR), a vision-threatening microvascular complication of diabetes mellitus (DM), is a leading cause of blindness worldwide that requires early detection and intervention. However, diagnosing DR early remains challenging due to the subtle nature of initial pathological changes. This review explores developments in multimodal imaging and functional tests for early DR detection. Where conventional color fundus photography is limited in the field of view and resolution, advanced quantitative analysis of retinal vessel traits such as retinal microvascular caliber, tortuosity, and fractal dimension (FD) can provide additional prognostic value. Optical coherence tomography (OCT) has also emerged as a reliable structural imaging tool for assessing retinal and choroidal neurodegenerative changes, which show potential as early DR biomarkers. Optical coherence tomography angiography (OCTA) enables the evaluation of vascular perfusion and the contours of the foveal avascular zone (FAZ), providing valuable insights into early retinal and choroidal vascular changes. Functional tests, including multifocal electroretinography (mfERG), visual evoked potential (VEP), multifocal pupillographic objective perimetry (mfPOP), microperimetry, and contrast sensitivity (CS), offer complementary data on early functional deficits in DR. More importantly, combining structural and functional imaging data may facilitate earlier detection of DR and targeted management strategies based on disease progression. Artificial intelligence (AI) techniques show promise for automated lesion detection, risk stratification, and biomarker discovery from various imaging data. Additionally, hematological parameters, such as neutrophil-lymphocyte ratio (NLR) and neutrophil extracellular traps (NETs), may be useful in predicting DR risk and progression. Although current methods can detect early DR, there is still a need for further research and development of reliable, cost-effective methods for large-scale screening and monitoring of individuals with DM.

Posterior segment optical coherence tomography: A diagnostic aid in posterior uveitis

Background: Patients with posterior uveitis can develop vision-threatening complications. Optical coherence tomography (OCT) plays an important role in the diagnosis and management of these complications. Aims: The objectives of this study were to describe different retinal morphological characteristics presenting on OCT in patients with posterior uveitis, with an aim to facilitate early diagnosis to initiate specific treatment and also to observe the response to treatment. Materials and Methods: A cross-sectional prospective non-randomized study was undertaken at a tertiary eye care hospital. The study included 30 eyes of 30 patients with posterior uveitis between the period of May 2016 and May 2018. All subjects underwent a set of systemic investigations for etiological diagnosis and complete ophthalmic examination, including OCT (Zeiss Cirrus machine (model number 5000)] imaging). Data were collected and analyzed. A P value of <0.05 was considered statistically significant. Results: The mean patient age was 33.1 ± 4.2 years. Infectious etiology was diagnosed in 13 patients (43.33%) of which toxoplasma chorioretinitis (36.66%) was the most common infection. Among 17 patients with noninfectious uveitis (56.66%), Vogt-Koyanagi-Harada (VKH) disease and multifocal choroiditis (16.67% each) were the most common causes. RPE-Bruch’s membrane abnormalities were seen in 96.67% of patients. Subretinal detachment (26.67%) was the most common type of macular edema on OCT. Significant differences in central foveal thickness posttreatment were noted in cases with VKH syndrome and toxoplasma retinochoroiditis (P < 0.05). Conclusion: OCT is a useful tool complementary to conventional fundus photography and fluorescein angiography in patients with posterior uveitis.

Graph-based multi-level feature fusion network for diabetic retinopathy grading using ultra-wide-field images

Diabetic Retinopathy (DR) grading plays an important role for early intervention in managing the disease. However, conventional grading methods predominantly rely on traditional color fundus photography, which may not fully capture crucial pathological information. In contrast, Ultra-wide-field (UWF) represents a novel non-contact and non-invasive modality, capable of generating images with an unprecedented field of view, ranging from 180∘ to 200∘. This offers distinct advantages over conventional color fundus photography for DR grading. Furthermore, given the subtle distinctions in imaging characteristics among adjacent levels of DR, the grading task becomes exceptionally challenging. Therefore, we propose a new multi-level feature fusion network based on the graph convolution to accomplish the DR grading task using UWF images. Specifically, we first use the progressive multi-level constraint module to iteratively refine features by imposing constraints on model features at different levels. This process serves to minimize the inter-individual distances within the intra-class feature space, ultimately reducing the overlap of feature spaces between adjacent classes. Subsequently, since features at different network levels exhibit distinct semantics and distributions, conventional aggregation techniques, such as splicing and summing, may introduce redundant information and noise interference. To address this issue, we introduce a graph-based feature fusion module, capable of capturing spatial relationships and effectively fusing multi-layered features. Experimental results evaluated on an in-house UWF dataset with 1234 images and a publicly available fundus dataset with 3662 images illustrate that the proposed approach outperforms the state-of-the-art methods and shows promise for DR grading, with a respective accuracy of 0.81 and 0.84.

Comparison of Color Fundus Photography and Multicolor Fundus Imaging for Detection of Lesions in Diabetic Retinopathy and Retinal Vein Occlusion.

To evaluate the agreement between conventional fundus photography (CFP) and multicolor fundus imaging (MFI) for the detection of lesions of diabetic retinopathy (DR) and retinal vein occlusion (RVO). Cross-sectional analysis of eyes with DR or RVO who underwent CFP and MFI. All images were independently analyzed by two observers (O1 and O2), and the evaluated lesions were classified as "present" or "absent". Then, a paired comparison between both exams of the same eye was performed, to assess which made it easier to detect the lesions. Considering DR, the agreement was substantial for cotton wool spots and photocoagulation scars for both observers (O1: κ=0.75 and κ=0.67; O2: κ=0.71 and κ=0.64, respectively) and for hard exudates for O1 (κ=0.80). These lesions were detected more frequently on MFI. Regarding RVO, the agreement was considered substantial for venous sheathing by O1 (κ=0.64) and moderate for optociliary shunts by O2 (κ=0.60). Optociliary shunts were detected more frequently in CPF by both observers and venous sheathing on MFI by O1. For microaneurysms, retinal hemorrhages, retinal neovascularization, and proliferative membranes, in DR, and retinal hemorrhages, venous engorgement, and retinal neovascularization in RVO, the agreement was almost perfect (κ>0.82). In the paired analysis, both observers considered that, in DR, microaneurysms and retinal hemorrhages were easier to detect on CFP and that retinal neovascularization, cotton wool spots, and photocoagulation scars were easier to identify on MFI. Regarding RVO, optocilliary shunts were easier to identify on CFP and venous engorgement on MFI. The agreement of MFI and CFP was substantial to almost perfect for most lesions. MFI seems better to detect cotton wool spots and photocoagulations scars in DR and venous sheathing in RVO. Optocilliary shunts seem easier to detect on CFP.

Predicting the severity of white matter lesions among patients with cerebrovascular risk factors based on retinal images and clinical laboratory data: a deep learning study.

As one common feature of cerebral small vascular disease (cSVD), white matter lesions (WMLs) could lead to reduction in brain function. Using a convenient, cheap, and non-intrusive method to detect WMLs could substantially benefit to patient management in the community screening, especially in the settings of availability or contraindication of magnetic resonance imaging (MRI). Therefore, this study aimed to develop a useful model to incorporate clinical laboratory data and retinal images using deep learning models to predict the severity of WMLs. Two hundred fifty-nine patients with any kind of neurological diseases were enrolled in our study. Demographic data, retinal images, MRI, and laboratory data were collected for the patients. The patients were assigned to the absent/mild and moderate-severe WMLs groups according to Fazekas scoring system. Retinal images were acquired by fundus photography. A ResNet deep learning framework was used to analyze the retinal images. A clinical-laboratory signature was generated from laboratory data. Two prediction models, a combined model including demographic data, the clinical-laboratory signature, and the retinal images and a clinical model including only demographic data and the clinical-laboratory signature, were developed to predict the severity of WMLs. Approximately one-quarter of the patients (25.6%) had moderate-severe WMLs. The left and right retinal images predicted moderate-severe WMLs with area under the curves (AUCs) of 0.73 and 0.94. The clinical-laboratory signature predicted moderate-severe WMLs with an AUC of 0.73. The combined model showed good performance in predicting moderate-severe WMLs with an AUC of 0.95, while the clinical model predicted moderate-severe WMLs with an AUC of 0.78. Combined with retinal images from conventional fundus photography and clinical laboratory data are reliable and convenient approach to predict the severity of WMLs and are helpful for the management and follow-up of WMLs patients.

Portable widefield fundus camera with high dynamic range imaging capability.

Fundus photography is indispensable for the clinical detection and management of eye diseases. Low image contrast and small field of view (FOV) are common limitations of conventional fundus photography, making it difficult to detect subtle abnormalities at the early stages of eye diseases. Further improvements in image contrast and FOV coverage are important for early disease detection and reliable treatment assessment. We report here a portable, wide FOV fundus camera with high dynamic range (HDR) imaging capability. Miniaturized indirect ophthalmoscopy illumination was employed to achieve the portable design for nonmydriatic, widefield fundus photography. Orthogonal polarization control was used to eliminate illumination reflectance artifacts. With independent power controls, three fundus images were sequentially acquired and fused to achieve HDR function for local image contrast enhancement. A 101° eye-angle (67° visual-angle) snapshot FOV was achieved for nonmydriatic fundus photography. The effective FOV was readily expanded up to 190° eye-angle (134° visual-angle) with the aid of a fixation target without the need for pharmacologic pupillary dilation. The effectiveness of HDR imaging was validated with both normal healthy and pathologic eyes, compared to a conventional fundus camera.

Choroidal Melanocytic Hamartoma.

We report on a case series that revealed flat, choroidal lesions on optical coherence tomography (OCT) and on enface MultiColor® (MCI) imaging of the fundus but were not noticeable on clinical examination or conventional color fundus images. This observational study included 12 eyes from 11 patients who had distinct, orange-colored lesions on MCI. Retinal imaging was conducted using conventional color fundus photography and OCT. On the color fundus images and the blue and green reflectance channels of MCI, each of the lesions was difficult to distinguish. On the infrared channel, the lesion was identified as bright white in color and bright orange on the multicolor image. The lesion was identified on OCT as a flat, homogeneous hyperreflective lesion involving the choroid, with an intact overlying retinal pigment epithelium and retinal layers. A comparison of the clinical and imaging features with other known entities led to the conclusion that the lesion was a distinct clinical entity. The presence of melanin in the lesion was confirmed based on the retinal imaging findings and the light absorption properties of melanin. As a result, the lesion was named as ‘choroidal melanocytic hamartoma’. A longer follow-up is required to confirm the benign nature of this clinical entity.

Incomplete Retinal Pigment Epithelial and Outer Retinal Atrophy: Longitudinal Evaluation in Age-Related Macular Degeneration

To examine the association between incomplete retinal pigment epithelial and outer retinal atrophy (iRORA) on OCT imaging and the subsequent risk of developing geographic atrophy (GA) defined on conventional color fundus photography (CFP) and to compare this with the specific features that define nascent GA (nGA). Retrospective analysis of data from a longitudinal study. A total of 280 eyes from 140 participants with bilateral large drusen without specific nGA-defining features or late age-related macular degeneration (AMD) at baseline. OCT imaging and CFP were performed at baseline and then at 6-month intervals for up to 36 months. Eyes that developed neovascular AMD were censored on the day it was detected. OCT volume scans were graded for the presence of iRORA and nGA separately, and CFP images were graded for the presence of GA. Association with and variance explained in time to GA development. A total of 58 eyes (21%) from 46 participants (33%) had iRORA at baseline, and a further 87 eyes (31%) developed iRORA over the follow-up period. Time-to-event analyses demonstrated that prevalent orincident iRORA was associated with an increased rate of GA development (adjusted hazard ratio [HR], 12.1; P= 0.021), as was incident nGA (adjusted HR, 78.6; P < 0.001). However, only the specific nGA features (adjusted P < 0.001), and not iRORA (adjusted P= 0.520), were associated with an increased rate of GA development when both features were included in the same multivariable model. The proportion of variance explained in the time to GA development by iRORA itself (R2= 43%) was significantly lower than explained by nGA alone (R2= 91%; P= 0.010). In this cohort, iRORA is a significant risk factor for GA development, but its association with GA development appears to be accounted for by the development of the specific features that define nGA. Although requiring replication, these findings provide useful guidance on the relative utility of nGA and iRORA as risk factors for GA and as potential surrogate end points for future interventional studies in the early stages of AMD.

MULTICOLOR CONFOCAL SCANNING LASER OPHTHALMOSCOPE IMAGING IN POSTERIOR UVEITIS.

To study the utility of MultiColor confocal scanning laser ophthalmoscope imaging (MCI) in identifying the morphology of uveitic lesions compared with conventional color fundus photography (CFP) in patients with posterior uveitis. In this prospective observational study, subjects with posterior uveitis underwent MCI and CFP. The images obtained by the two modalities were analyzed by two independent reviewers for vitreoretinal surface abnormalities, retinal fluid and hemorrhages, and depth/location of lesions. These findings were compared with the clinical findings and other imaging techniques. Sixty-nine eyes of 43 patients (25 men) with mean age of 33.5 ± 13.9 years were studied. MultiColor imaging had better sensitivity and specificity in detecting vitreoretinal interface abnormalities, such as epiretinal membrane and inner retinal striae, compared with CFP. MultiColor imaging failed to detect retinochoroiditis lesions in 5 of 6 eyes (83%) and choroiditis in 9 46 eyes (20%), which were detected on CFP and clinical examination. Also, MCI showed a high false-positive rate of 34% in detecting intraretinal hemorrhages. Retinochoroidal lesions in posterior uveitis may be poorly identified on MCI compared with CFP and clinical examination. One must exercise caution in commenting on disease morphology based on MCI alone.

Role of Ultra-widefield Imaging in the evaluation of Long-term change of highly myopic fundus.

To evaluate the impact of posterior staphyloma identified using ultra-widefield fundus imaging on the long-term progression of myopic maculopathy in highly myopic patients. In this observational cohort study, highly myopic patients who were followed up for at least 5 years using ultra-widefield fundus imaging were analysed for fundus abnormalities and the progression of myopic maculopathy based on the International Meta-analysis of Pathologic Myopia classification. This study included 390 eyes (210 patients) with the mean follow-up period of 69.2 ± 7.5 months (range, 60-88). Posterior staphyloma was identified in 198 eyes (50.8%) in the baseline ultra-widefield fundus images. The border of staphyloma was not identified within 50° view circle corresponding to conventional fundus photography in 42 eyes (21.2%) with staphyloma, most of that were wide macular type. Progression of myopic maculopathy during follow-up was observed in 202 eyes (51.8%), and eyes with staphyloma were more likely to show progression compared to those without (142/198 [71.7%] versus 60/192 [31.3%]; p < 0.001). In multivariable regression analysis, the presence of posterior staphyloma was an independent risk factor for the progression of myopic maculopathy (p = 0.005). One or more peripheral retinal lesions were observed in 302 eyes (77.4%) and 321 eyes (82.3%) in the baseline and final ultra-widefield fundus images, respectively. Posterior staphyloma was associated with the long-term progression of myopic maculopathy. With a wider field of view, ultra-widefield fundus imaging is useful for identifying the posterior staphyloma and monitoring the progression of myopic maculopathy in highly myopic patients.

Recent Advances and Clinical Application of Color Scanning Laser Ophthalmoscope.

Scanning laser ophthalmoscopes (SLOs) have been available since the early 1990s, but they were not commonly used because their advantages were not enough to replace conventional color fundus photography. In recent years, color SLOs have improved significantly, and the colored SLO images are obtained by combining multiple SLO images taken by lasers of different wavelengths. A combination of these images of different lasers can create an image that is close to that of the real ocular fundus. One advantage of the advanced SLOs is that they can obtain images with a wider view of the ocular fundus while maintaining a high resolution even through non-dilated eyes. The current SLOs are superior to the conventional fundus photography in their ability to image abnormal alterations of the retina and choroid. Thus, the purpose of this review was to present the characteristics of the current color SLOs and to show how that can help in the diagnosis and the following of changes after treatments. To accomplish these goals, we will present our findings in patients with different types of retinochoroidal disorders.

Early detection of diabetic retinopathy based on deep learning and ultra-wide-field fundus images

Visually impaired and blind people due to diabetic retinopathy were 2.6 million in 2015 and estimated to be 3.2 million in 2020 globally. Though the incidence of diabetic retinopathy is expected to decrease for high-income countries, detection and treatment of it in the early stages are crucial for low-income and middle-income countries. Due to the recent advancement of deep learning technologies, researchers showed that automated screening and grading of diabetic retinopathy are efficient in saving time and workforce. However, most automatic systems utilize conventional fundus photography, despite ultra-wide-field fundus photography provides up to 82% of the retinal surface. In this study, we present a diabetic retinopathy detection system based on ultra-wide-field fundus photography and deep learning. In experiments, we show that the use of early treatment diabetic retinopathy study 7-standard field image extracted from ultra-wide-field fundus photography outperforms that of the optic disc and macula centered image in a statistical sense.

Measuring ocular torsion and its variations using different nonmydriatic fundus photographic methods.

PurposeTo compare the variations in ocular torsion measurements made using different fundus photographic methods.MethodsWe enrolled subjects with three conditions: (1) patients with intermittent exotropia (IXT) (n = 44), (2) patients with unilateral superior oblique palsy (SOP) (n = 10), and (3) normal subjects as controls (n = 85). Ocular torsion was measured by disc-center–fovea angle (DFA) using three different imaging modalities: (1) conventional fundus photography (CFP) with a 45° field of view (FV), (2) wide-field fundus photography (WFP) with a 200° FV, and (3) optical coherence tomography (OCT) with a 55° FV.ResultsIn the IXT group, the DFAs in the right and left eyes were 5.70±3.35° and 6.37±3.36°, respectively, for CFP, 8.39±5.24° and 8.61±3.67° for WFP, and 5.73±3.61° for 6.16±3.50° for OCT. In the SOP group, the DFAs in paretic and nonparetic eyes were 12.19±1.69° and 6.71±1.09°, respectively, for CFP, 14.29±2.36° and 8.23±3.31° for WFP, and 12.12±1.73° and 6.91±1.12° for OCT. In the control group, the DFAs in the right and left eyes were 5.39±2.65° and 5.71±3.16°, respectively, for CFP, 8.77±5.56° and 8.90±6.24° for WFP, and 5.27±2.67° and 5.72±3.20° for OCT. There was no difference between the results from CFP and OCT among the three groups. However, the torsional angle was larger when measured using WFP than the other two photographic methods (CFP and OCT) in all three groups (all p<0.05).ConclusionThe ocular torsion measurement varies with the fundus photographic method used to measure it. Clinicians should be careful to avoid overestimating ocular extorsion when it is evaluated using WFP.

Clinical features of ocular toxocariasis: a comparison between ultra-wide-field and conventional camera imaging.

The purpose of this study is to compare the lesion detection rates of ocular toxocariasis (OT) between ultra-wide-field scanning laser ophthalmoscopy (UWF-SLO) and conventional fundus photography (CFP), and to evaluate the potential diagnostic ability of UWF-SLO in OT. A total of 56 patients with serological/immunological confirmed unilateral OT were enrolled. The presence of OT characteristic features included the posterior granuloma (postG), peripheral granuloma (periG), tractional retinal detachment (TRD), retinal folds (RF), and vitreous strands (VS) and was analyzed in 36 patients with UWF-SLO and 56 patients with CFP. Diagnostic tests were employed using the clinical examination as gold standard. In total of the 56 OT eyes, granulomas were identified in 91.1% (51/56) of eyes, including postG in 46.4% (26/56) of eyes, periG in 41.1% (23/56) of eyes, and combined granulomas in 3.6% (2/56) of eyes. TRD, RF, and VS were found in 28.6% (16/56), 51.8% (29/56), and 83.9% (47/56) of patients, respectively. Although the specificities of the diagnosis in clinical features were similar by the diagnostic tests, the sensitivities of postG, periG, TRD, RF, and VS using UWF-SLO were 100%, 100%, 66.7%, 95%, and 81.8%, respectively, which were significantly higher those of CFP (72.2%, 31.3%, 11.1%, 55%, and 48.5%). Additionally, the extent of vitreous haze was milder graded by UWF-SLO compared to CFP (p = 0.0099). The diagnostic ability of UWF-SLO was superior to CFP using clinical examination as gold standard for the ascertainment of the characteristic manifestations of OT, especially for granulomas and RF.

ULTRAWIDEFIELD PSEUDOCOLOR RETINAL IMAGING VERSUS REAL-COLOR FUNDUS PHOTOGRAPHY FOR DETECTION OF INTRARETINAL PIGMENT MIGRATION IN AGE-RELATED MACULAR DEGENERATION.

To compare pseudocolor Optos ultrawidefield (UWF) retinal images with conventional real-color fundus photography (CFP) for detecting macular hyperpigmentary changes in intermediate age-related macular degeneration. This retrospective study included 50 patients diagnosed with intermediate age-related macular degeneration. All patients underwent Optos imaging and CFP. The overall accuracy to visualize hyperpigmentation and its morphologic features was graded by two independent readers using a standardized grid. Structural and en face optical coherence tomography images were correlated with UWF and CFP images to determine spatial correspondence of pigment clumping on fundus images and hyperreflective foci on optical coherence tomography. One hundred eyes of 50 patients had hyperpigmentary changes on funduscopic examination and were included. The intragraders and intergraders agreements were high for all measurements (P < 0.001). At least one hyperpigmentary changes within the standardized grid was detected in 93% using CFP and 100% using UWF camera (P = 0.02). The total area of hyperpigmentation measured on UWF images was significantly higher than on CFP images (P < 0.001). There was a significant correlation between the presence of hyperpigmentary changes on both CFP and UWF images and hyperreflective foci on structural optical coherence tomography (P < 0.001). Ultrawidefield fundus images allow high detection and accurate quantification of macular hyperpigmentary changes in intermediate age-related macular degeneration compared with conventional CFP.

Smartphone-Based Fundus Imaging-Where Are We Now?

With the advent of smartphone-based fundus imaging (SBFI), a low-cost alternative to conventional digital fundus photography has become available. SBFI allows for a mobile fundus examination, is applicable both with and without pupil dilation, comes with built-in connectivity and post-processing capabilities, and is relatively easy to master. Furthermore, it is delegable to paramedical staff/technicians and, hence, suitable for telemedicine. Against this background a variety of SBFI applications have become available including screening for diabetic retinopathy, glaucoma, and retinopathy of prematurity and its applications in emergency medicine and pediatrics. In addition, SBFI is convenient for teaching purposes and might serve as a surrogate for direct ophthalmoscopy. First wide-field montage techniques are available and the combination of SBFI with machine learning algorithms for image analyses is promising. In conclusion, SBFI has the potential to make fundus examinations and screenings for patients particularly in low- and middle-income settings more accessible and, therefore, aid tackling the burden of diabetic retinopathy, glaucoma, and retinopathy of prematurity screening. However, image quality for SBFI varies substantially and a reference standard for grading appears prudent. In addition, there is a strong need for comparison of different SBFI approaches in terms of applicability to disease screening and cost-effectiveness.

Cyclotorsion Measurement on Scanning Laser Ophthalmoscopy Imaging Compared With Fundus Photography in Patients With Fourth Nerve Palsy and Healthy Controls: CySLO-IV Study.

The purpose of the study is to evaluate the agreement of the foveopapillary angle (FPA) on conventional fundus photography (c-FPA) with the FPA on scanning laser ophthalmoscopy (SLO) imaging (SLO-FPA) in patients with fourth nerve palsy and healthy controls (HCs). The FPA was measured in both eyes of 25 patients and 25 HCs in synedra View (c-FPA) and with the integrated algorithm of the Heidelberg Spectralis OCT (SLO-FPA). The primary endpoint was the agreement of both measurements. Furthermore, we evaluated the influence of the eye tracker, the influence of fixation on objective torsion, and the FPA cutoff between patients and HCs. The mean SLO-FPA in patients (6/25 acquired palsies) was 11.3 ± 3.6° and 6.4 ± 2.1° in HCs. The mean c-FPA was 11.4 ± 4.0° and 5.8 ± 2.2°, respectively. The Bland-Altman plot of c-FPA vs SLO-FPA in patients and HCs shows no systematic bias (mean of -0.28°). Limits of agreement were -6.58 and 6.02°. Using the eye tracker had no systematic effect. There was no evidence for an immediate shift of torsion with change of fixation (24/25 patients and 23/25 HCs). Discrimination between patients and HCs by the SLO-FPA is very good with an area under the curve = 0.92 (95% confidence interval: 0.84-0.99). SLO-FPA measurement allows convenient and consistent assessment of objective cyclotorsion. There was no systematic bias in the difference between SLO-FPA and traditional c-FPA; thus, SLO-FPA is a valuable alternative to the commonly used c-FPA. Using the eye tracker is recommended for proper centering of the ring scan.

Diabetic Retinopathy Screening Using Smartphone-Based Fundus Imaging in India

Early detection and treatment can prevent irreversible blindness from diabetic retinopathy (DR), which is the leading cause of visual impairment among working-aged adults worldwide. Some 80% of affected persons live in low- and middle-income countries, yet lack of resources has largely prevented DR screening implementation in these world regions. Smartphone-based fundus imaging (SBFI) allows for low-cost mobile fundus examination using an adapter on a smartphone; however, key aspects such as image quality, diagnostic accuracy, and comparability of different approaches have not been systematically assessed to date. Evaluation of diagnostic technology. A total of 381 eyes of 193 patients with diabetes were recruited at outreach eye clinics in South India. We compared 4 technically different approaches of SBFI (3 approaches based on direct and 1 approach based on indirect ophthalmoscopy) in terms of image quality and diagnostic accuracy for DR screening. Image quality (sharpness/focus, reflex artifacts, contrast, and illumination), field-of-view, examination time, and diagnostic accuracy for DR screening were analyzed against conventional fundus photography and clinical examination. Smartphone-based fundus imaging based on indirect ophthalmoscopy yielded the best image quality (P < 0.01), the largest field-of-view, and the longest examination time (111 vs. 68-86 seconds, P < 0.0001). Agreement with the reference standard (Cohen's kappa 0.868) and sensitivity/specificity to detect DR were highest for the indirect SBFI approach (0.79/0.99 for any DR and 1.0/1.0 for severe DR, 0.79/1.0 for diabetic maculopathy). Smartphone-based fundus imaging can meet DR screening requirements in an outreach setting; however, not all devices are suitable in terms of image quality and diagnostic accuracy. Smartphone-based fundus imaging might aid in alleviating the burden of DR screening in low- and middle-income countries, and these results will allow for a better selection of SBFI devices in field trials for DR screening.

Correlation of multicolor images and conventional color fundus photographs with foveal autofluorescence patterns in diabetic macular edema.

Purpose:The aim of this study is to assess the ability of multicolour imaging (MCI) to detect foveal cysts in diabetic macular edema (DME) and compare it with conventional color fundus photography (CFP) and foveal autofluorescence (FAF) pattern.Methods:It was a retrospective review of 112 eyes of 84 DME patients with central foveal thickness ≥250 μ who underwent MCI, CFP and shortwave autofluorescence imaging. MCI was performed with Sepctralis spectral domain optical coherence tomography (SDOCT) (Heidelberg Engineering, Germany).Results:97 (86.6%) eyes had cystoid increased autofluorescence (cystoid iFAF), 9 (8%) had spot iFAF and 6 (5.35%) had irregular decreased FAF (dFAF). Among eyes with cystoid iFAF, OCT detected DME cysts in 93 (95.6%) eyes, MCI in 75 (77.3%) and CFP in 5 (5.15%) eyes. In all these eyes, the location of cysts on OCT and MCI corresponded with the location of cystoid iFAF, whereas none of the eyes with cyst seen on CFP correlated with the location of cystoid iFAF.Conclusion:MCI was superior to CFP in detecting DME cysts at fovea. It also correlated with hyperautofluorescence pattern in these eyes. MCI may have a potential role in diabetic retinopathy screening by segregating eyes with DME which would require treatment. Our findings need to be further validated in a larger and prospective study design.

Undilated versus dilated monoscopic smartphone-based fundus photography for optic nerve head evaluation

Smartphone-based fundus photography (SBFP) allows for a cheap and mobile fundus examination with the potential to revolutionize eye care especially in low income settings. The purpose of this study was to assess the impact of pupil dilation on image quality in optic nerve head (ONH) imaging and vertical cup-to-disc ratio (vCDR) evaluation with SBFP. Eyes with glaucoma or suspected to have glaucoma were imaged with conventional digital fundus photography (CFP) and SBFP undilated and following dilation, all monoscopically. SBFP was possible in 74% of eyes without dilation and in 98% following dilation. Better image quality on SBFP was achieved with dilation and complete visualization of the optic disc rim was possible in 46% of images without dilation and on 94% of images with dilation. VCDR measurements on images obtained following dilation highly correlated with measurements on CFP (coefficient of correlation r = 0.91, p < 0.001), whereas vCDR on images obtained without dilation correlated less well with CFP (r = 0.70, p < 0.001). SBFP for ONH evaluation is promising, however dilation appears mandatory to achieve results comparable to optic disc evaluation on CFP. ONH imaging with smartphones without dilation might bear the risk of underestimating the CDR and hence overlooking patients at risk for glaucoma.