Clinical evaluation of patients with diabetic retinopathy: accuracy of the Inoveon diabetic retinopathy-3DT system

One-field, two-field and five-field handheld retinal imaging compared with standard seven-field Early Treatment Diabetic Retinopathy Study photography for diabetic retinopathy screening

BACKGROUND/AIMS

To determine agreement of one-field (1F, macula-centred), two-field (2F, disc-macula) and five-field (5F, macula, disc, superior, inferior and nasal) mydriatic handheld retinal imaging protocols for the assessment of diabetic retinopathy (DR) as compared with standard seven-field Early Treatment Diabetic Retinopathy Study (ETDRS) photography.

METHODS

Prospective, comparative instrument validation study. Mydriatic retinal images were taken using three handheld retinal cameras: Aurora (AU; 50° field of view (FOV), 5F), Smartscope (SS; 40° FOV, 5F), and RetinaVue (RV; 60° FOV, 2F) followed by ETDRS photography. Images were evaluated at a centralised reading centre using the international DR classification. Each field protocol (1F, 2F and 5F) was graded independently by masked graders. Weighted kappa (Kw) statistics assessed agreement for DR. Sensitivity (SN) and specificity (SP) for referable diabetic retinopathy (refDR; moderate non-proliferative diabetic retinopathy (NPDR) or worse, or ungradable images) were calculated.

RESULTS

Images from 225 eyes of 116 patients with diabetes were evaluated. Severity by ETDRS photography: no DR, 33.3%; mild NPDR, 20.4%; moderate, 14.2%; severe, 11.6%; proliferative, 20.4%. Ungradable rate for DR: ETDRS, 0%; AU: 1F 2.23%, 2F 1.79%, 5F 0%; SS: 1F 7.6%, 2F 4.0%, 5F 3.6%; RV: 1F 6.7%, 2F 5.8%. Agreement rates of DR grading between handheld retinal imaging and ETDRS photography were (Kw, SN/SP refDR) AU: 1F 0.54, 0.72/0.92; 2F 0.59, 0.74/0.92; 5F 0.75, 0.86/0.97; SS: 1F 0.51, 0.72/0.92; 2F 0.60, 0.75/0.92; 5F 0.73, 0.88/0.92; RV: 1F 0.77, 0.91/0.95; 2F 0.75, 0.87/0.95.

CONCLUSION

When using handheld devices, the addition of peripheral fields decreased the ungradable rate and increased SN and SP for refDR. These data suggest the benefit of additional peripheral fields in DR screening programmes that use handheld retinal imaging.

Present and future screening programs for diabetic retinopathy: a narrative review

Diabetes is a prevalent global concern, with an estimated 12% of the global adult population affected by 2045. Diabetic retinopathy (DR), a sight-threatening complication, has spurred diverse screening approaches worldwide due to advances in DR knowledge, rapid technological developments in retinal imaging and variations in healthcare resources.Many high income countries have fully implemented or are on the verge of completing a national Diabetic Eye Screening Programme (DESP). Although there have been some improvements in DR screening in Africa, Asia, and American countries further progress is needed. In low-income countries, only one out of 29, partially implemented a DESP, while 21 out of 50 lower-middle-income countries have started the DR policy cycle. Among upper-middle-income countries, a third of 59 nations have advanced in DR agenda-setting, with five having a comprehensive national DESP and 11 in the early stages of implementation.Many nations use 2-4 fields fundus images, proven effective with 80-98% sensitivity and 86-100% specificity compared to the traditional seven-field evaluation for DR. A cell phone based screening with a hand held retinal camera presents a potential low-cost alternative as imaging device. While this method in low-resource settings may not entirely match the sensitivity and specificity of seven-field stereoscopic photography, positive outcomes are observed.Individualized DR screening intervals are the standard in many high-resource nations. In countries that lacks a national DESP and resources, screening are more sporadic, i.e. screening intervals are not evidence-based and often less frequently, which can lead to late recognition of treatment required DR.The rising global prevalence of DR poses an economic challenge to nationwide screening programs AI-algorithms have showed high sensitivity and specificity for detection of DR and could provide a promising solution for the future screening burden.In summary, this narrative review enlightens on the epidemiology of DR and the necessity for effective DR screening programs. Worldwide evolution in existing approaches for DR screening has showed promising results but has also revealed limitations. Technological advancements, such as handheld imaging devices, tele ophthalmology and artificial intelligence enhance cost-effectiveness, but also the accessibility of DR screening in countries with low resources or where distance to or a shortage of ophthalmologists exists.

Blood flow perfusion in visual pathway detected by arterial spin labeling magnetic resonance imaging for differential diagnosis of ocular ischemic syndrome

Background

Ocular ischemic syndrome (OIS), attributable to chronic hypoperfusion caused by marked carotid stenosis, is one of the important factors that cause ocular neurodegenerative diseases such as optic atrophy. The current study aimed to detect blood flow perfusion in a visual pathway by arterial spin labeling (ASL) and magnetic resonance imaging (MRI) for the differential diagnosis of OIS.

Methods

This diagnostic, cross-sectional study at a single institution was performed to detect blood flow perfusion in a visual pathway based on 3D pseudocontinuous ASL (3D-pCASL) using 3.0T MRI. A total of 91 participants (91 eyes) consisting of 30 eyes with OIS and 61 eyes with noncarotid artery stenosis-related retinal vascular diseases (39 eyes with diabetic retinopathy and 22 eyes with high myopic retinopathy) were consecutively included. Blood flow perfusion values in visual pathways derived from regions of interest in ASL images, including the retinal-choroidal complex, the intraorbital segments of the optic nerve, the tractus optics, and the visual center, were obtained and compared with arm-retinal circulation time and retinal circulation time derived from fundus fluorescein angiography (FFA). Receiver operating characteristic (ROC) curve analyses and the intraclass correlation coefficient (ICC) were performed to evaluate the accuracy and consistency.

Results

Patients with OIS had the lowest blood flow perfusion values in the visual pathway (all p < 0.05). The relative intraorbital segments of optic nerve blood flow values at post-labeling delays (PLDs) of 1.5 s (area under the curve, AUC = 0.832) and the relative retinal-choroidal complex blood flow values at PLDs of 2.5 s (AUC = 0.805) were effective for the differential diagnosis of OIS. The ICC of the blood flow values derived from the retinal-choroidal complex and the intraorbital segments of the optic nerve between the two observers showed satisfactory concordance (all ICC > 0.932, p < 0.001). The adverse reaction rates of ASL and FFA were 2.20 and 3.30%, respectively.

Conclusion

3D-pCASL showed that the participants with OIS had lower blood flow perfusion values in the visual pathway, which presented satisfactory accuracy, reproducibility, and safety. It is a noninvasive and comprehensive differential diagnostic tool to assess blood flow perfusion in a visual pathway for the differential diagnosis of OIS.

The Role of Different Retinal Imaging Modalities in Predicting Progression of Diabetic Retinopathy: A Survey

Diabetic retinopathy (DR) is a devastating condition caused by progressive changes in the retinal microvasculature. It is a leading cause of retinal blindness in people with diabetes. Long periods of uncontrolled blood sugar levels result in endothelial damage, leading to macular edema, altered retinal permeability, retinal ischemia, and neovascularization. In order to facilitate rapid screening and diagnosing, as well as grading of DR, different retinal modalities are utilized. Typically, a computer-aided diagnostic system (CAD) uses retinal images to aid the ophthalmologists in the diagnosis process. These CAD systems use a combination of machine learning (ML) models (e.g., deep learning (DL) approaches) to speed up the diagnosis and grading of DR. In this way, this survey provides a comprehensive overview of different imaging modalities used with ML/DL approaches in the DR diagnosis process. The four imaging modalities that we focused on are fluorescein angiography, fundus photographs, optical coherence tomography (OCT), and OCT angiography (OCTA). In addition, we discuss limitations of the literature that utilizes such modalities for DR diagnosis. In addition, we introduce research gaps and provide suggested solutions for the researchers to resolve. Lastly, we provide a thorough discussion about the challenges and future directions of the current state-of-the-art DL/ML approaches. We also elaborate on how integrating different imaging modalities with the clinical information and demographic data will lead to promising results for the scientists when diagnosing and grading DR. As a result of this article's comparative analysis and discussion, it remains necessary to use DL methods over existing ML models to detect DR in multiple modalities.

Practice Guidelines for Ocular Telehealth-Diabetic Retinopathy, Third Edition

Contributors The following document and appendices represent the third edition of the Practice Guidelines for Ocular Telehealth-Diabetic Retinopathy. These guidelines were developed by the Diabetic Retinopathy Telehealth Practice Guidelines Working Group. This working group consisted of a large number of subject matter experts in clinical applications for telehealth in ophthalmology. The editorial committee consisted of Mark B. Horton, OD, MD, who served as working group chair and Christopher J. Brady, MD, MHS, and Jerry Cavallerano, OD, PhD, who served as cochairs. The writing committees were separated into seven different categories. They are as follows: 1.Clinical/operational: Jerry Cavallerano, OD, PhD (Chair), Gail Barker, PhD, MBA, Christopher J. Brady, MD, MHS, Yao Liu, MD, MS, Siddarth Rathi, MD, MBA, Veeral Sheth, MD, MBA, Paolo Silva, MD, and Ingrid Zimmer-Galler, MD. 2.Equipment: Veeral Sheth, MD (Chair), Mark B. Horton, OD, MD, Siddarth Rathi, MD, MBA, Paolo Silva, MD, and Kristen Stebbins, MSPH. 3.Quality assurance: Mark B. Horton, OD, MD (Chair), Seema Garg, MD, PhD, Yao Liu, MD, MS, and Ingrid Zimmer-Galler, MD. 4.Glaucoma: Yao Liu, MD, MS (Chair) and Siddarth Rathi, MD, MBA. 5.Retinopathy of prematurity: Christopher J. Brady, MD, MHS (Chair) and Ingrid Zimmer-Galler, MD. 6.Age-related macular degeneration: Christopher J. Brady, MD, MHS (Chair) and Ingrid Zimmer-Galler, MD. 7.Autonomous and computer assisted detection, classification and diagnosis of diabetic retinopathy: Michael Abramoff, MD, PhD (Chair), Michael F. Chiang, MD, and Paolo Silva, MD.

Screening Intervals for Diabetic Retinopathy and Implications for Care

PURPOSE OF REVIEW

The purpose of this study is to review the evidence that lower risk groups who could safely be screened less frequently for sight-threatening diabetic retinopathy (DR) than annually.

RECENT FINDINGS

Data have demonstrated that people with no DR in either eye are at a low risk of progression to sight-threatening DR over a 2-year period (event rate 4.8 per 1000 person years), irrespective of whether the screening method is one-field non-mydriatic or two-field mydriatic digital photography. Low risk has been defined as no retinopathy on two consecutive screening episodes or no retinopathy on one screening episode combined with risk factor data. The risk of an extension to 2 years is less than 5 per 1000 person years in a population with a national screening programme, and the general standard of diabetes care is relatively good, whether low risk is defined as no retinopathy on two consecutive screening episodes or no retinopathy on one screening episode combined with other risk factor data. The definition used in different populations is likely to depend on the availability of data.

Screening for diabetic retinopathy using new mydriasis-free, full-field flicker ERG recording device

Diabetic retinopathy (DR) is a leading cause of blindness among working-age adults. Therefore, it is important to detect DR accurately during mass screening. The purpose of this study was to determine whether a small, hand-held, mydriasis-free, full-field flicker electroretinographic (ERGs) device called RETeval can be used to screen for DR. To accomplish this, we recorded full-field flicker ERGs with this device from 48 normal eyes and 118 eyes with different severities of DR in patients with diabetes mellitus (DM). This system delivered a constant flash retinal luminance by adjusting the flash luminance that compensated for changes in the pupil size. Our results showed that there were significant correlations between the severity of DR and the implicit times (P < 0.001; r = 0.55) and the amplitudes (P = 0.001; r = −0.29). When the implicit time was used for the index, the area under the receiver operating characteristic curve was 0.84 for the detection of DR, and was 0.89 for the detection of DR requiring ophthalmic treatments. These results suggest that the implicit times of the flicker ERGs recorded by the small, mydryasis-free ERG system can be used as an adjunctive tool to screen for DR.

Retinal Imaging Techniques for Diabetic Retinopathy Screening

Due to the increasing prevalence of diabetes mellitus, demand for diabetic retinopathy (DR) screening platforms is steeply increasing. Early detection and treatment of DR are key public health interventions that can greatly reduce the likelihood of vision loss. Current DR screening programs typically employ retinal fundus photography, which relies on skilled readers for manual DR assessment. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of automated retinal image analysis software that may potentially alleviate this burden cost-effectively. Furthermore, current screening programs based on 2-dimensional fundus photography do not effectively screen for diabetic macular edema (DME). Optical coherence tomography is becoming increasingly recognized as the reference standard for DME assessment and can potentially provide a cost-effective solution for improving DME detection in large-scale DR screening programs. Current screening techniques are also unable to image the peripheral retina and require pharmacological pupil dilation; ultra-widefield imaging and confocal scanning laser ophthalmoscopy, which address these drawbacks, possess great potential. In this review, we summarize the current DR screening methods using various retinal imaging techniques, and also outline future possibilities. Advances in retinal imaging techniques can potentially transform the management of patients with diabetes, providing savings in health care costs and resources.

Strategies to Screen for Diabetic Retinopathy in Chinese Patients with Newly Diagnosed Type 2 Diabetes: A Cost-Effectiveness Analysis

To investigate the cost-effectiveness of different screening intervals for diabetic retinopathy (DR) in Chinese patients with newly diagnosed type 2 diabetes mellitus (T2DM). Chinese healthcare system.Chinese general clinical setting. A cost-effectiveness model was developed to simulate the disease course of Chinese population with newly diagnosed with diabetes. Different DR screening programs were modeled to project economic outcomes. To develop the economic model, we calibrated the progression rates of DR that fit Chinese epidemiologic data derived from the published literature. Costs were estimated from the perspective of the Chinese healthcare system, and the analysis was run over a lifetime horizon. One-way and probabilistic sensitivity analyses were performed. Total costs, vision outcomes, costs per quality-adjusted life year (QALY), the incremental cost-effectiveness ratio (ICER) of screening strategies compared to no screening. DR screening is effective in Chinese patients with newly diagnosed T2DM, and screen strategies with ≥4-year intervals were cost-effective (ICER <$7,485 per QALY) compared to no screening. Screening every 4 years produced the greatest increase in QALYs (11.066) among the cost-effective strategies. The screening intervals could be varied dramatically by age at T2DM diagnosis. Probabilistic sensitivity analyses demonstrated the consistency and robustness of the cost-effectiveness of the 4-year interval screening strategy. The findings suggest that a 4-year interval screening strategy is likely to be more cost-effective than screening every 1 to 3 years in comparison with no screening in the Chinese setting. The screening intervals might be tailored according to the age at T2DM diagnosis.

Telemedicine for detecting diabetic retinopathy: a systematic review and meta-analysis

Objective

To determine the diagnostic accuracy of telemedicine in various clinical levels of diabetic retinopathy (DR) and diabetic macular oedema (DME).

Methods

PubMed, EMBASE and Cochrane databases were searched for telemedicine and DR. The methodological quality of included studies was evaluated using the Quality Assessment for Diagnostic Accuracy Studies (QUADAS-2). Measures of sensitivity, specificity and other variables were pooled using a random effects model. Summary receiver operating characteristic curves were used to estimate overall test performance. Meta-regression and subgroup analyses were used to identify sources of heterogeneity. Publication bias was evaluated using Stata V.12.0.

Results

Twenty articles involving 1960 participants were included. Pooled sensitivity of telemedicine exceeded 80% in detecting the absence of DR, low- or high-risk proliferative diabetic retinopathy (PDR), it exceeded 70% in detecting mild or moderate non-proliferative diabetic retinopathy (NPDR), DME and clinically significant macular oedema (CSME) and was 53% (95% CI 45% to 62%) in detecting severe NPDR. Pooled specificity of telemedicine exceeded 90%, except in the detection of mild NPDR which reached 89% (95% CI 88% to 91%). Diagnostic accuracy was higher with digital images obtained through mydriasis than through non-mydriasis, and was highest when a wide angle (100–200°) was used compared with a narrower angle (45–60°, 30° or 35°) in detecting the absence of DR and the presence of mild NPDR. No potential publication bias was detected.

Conclusions

The diagnostic accuracy of telemedicine using digital imaging in DR is overall high. It can be used widely for DR screening. Telemedicine based on the digital imaging technique that combines mydriasis with a wide angle field (100–200°) is the best choice in detecting the absence of DR and the presence of mild NPDR.

Telemedicine for evaluation of retinopathy of prematurity

Retinopathy of prematurity (ROP) remains a significant threat to vision for extremely premature infants despite the availability of therapeutic modalities capable, in most cases, of managing this disorder. It has been shown in many controlled trials that application of therapies at the appropriate time is essential to successful outcomes in premature infants affected by ROP. Bedside binocular indirect ophthalmoscopy has been the standard technique for diagnosis and monitoring of ROP in these patients. However, implementation of routine use of this screening method for at-risk premature infants has presented challenges within our existing care systems, including relative local scarcity of qualified ophthalmologist examiners in some locations and the remote location of some NICUs. Modern technology, including the development of wide-angle ocular digital fundus photography, coupled with the ability to send digital images electronically to remote locations, has led to the development of telemedicine-based remote digital fundus imaging (RDFI-TM) evaluation techniques. These techniques have the potential to allow the diagnosis and monitoring of ROP to occur in lieu of the necessity for some repeated on-site examinations in NICUs. This report reviews the currently available literature on RDFI-TM evaluations for ROP and outlines pertinent practical and risk management considerations that should be used when including RDFI-TM in any new or existing ROP care structure.

Utility of hard exudates for the screening of macular edema

PURPOSE

The purpose of this study was to determine whether hard exudates (HEs) within one disc diameter of the foveola is an acceptable criterion for the referral of diabetic patients suspected of clinically significant macular edema (CSME) in a screening setting.

METHODS

One hundred forty-three adults diagnosed as having diabetes mellitus were imaged using a nonmydriatic digital fundus camera at the Alameda County Medical Center in Oakland, CA. Nonstereo fundus images were graded independently for the presence of HE near the center of the macula by two graders according to the EyePACS grading protocol. The patients also received a dilated fundus examination on a separate visit. Clinically significant macular edema was determined during the dilated fundus examination using the criteria set forth by the Early Treatment Diabetic Retinopathy Study. Subsequently, the sensitivity and specificity of HEs within one disc diameter of the foveola in nonstereo digital images used as a surrogate for the detection of CSME diagnosed by live fundus examination were calculated.

RESULTS

The mean (±SD) age of 103 patients included in the analysis was 56 ± 17 years. Clinically significant macular edema was diagnosed in 15.5% of eyes during the dilated examination. For the right eyes, the sensitivity of HEs within one disc diameter from the foveola as a surrogate for detecting CSME was 93.8% for each of the graders; the specificity values were 88.5 and 85.1%. For the left eyes, the sensitivity values were 93.8 and 75% for each of the two graders, respectively; the specificity was 87.4% for both graders.

CONCLUSIONS

This study supports the use of HE within a disc diameter of the center of the macula in nonstereo digital images for CSME detection in a screening setting.

Teleophthalmology in Diabetic Retinopathy

Over the past decade, there have been rapid strides in progress in the fields of telecommunication and medical imaging. There is growing evidence regarding use of teleophthalmology for screening of diabetic retinopathy. This article highlights some pertinent questions regarding use of telescreening for diabetic retinopathy. It deals with evidence regarding accuracy of diagnosis, patients satisfaction and cost-effectiveness. The American Telemedicine Association have given certain guidelines for teleheath practices for diabetic retinopathy. The article discusses regarding these guidelines. Finally, a working model for diabetic retinopathy screening through teleophthalmology has been described. Telescreening for diabetic retinopathy seems to be a cost-effective, accurate, and reliable method for screening for diabetic retinopathy. The American Telemedicine Association has set up guidelines for telescreening that should be adhered to provide quality screening services to people with diabetes.

Nonmydriatic ultra-wide-field scanning laser ophthalmoscopy (Optomap) versus two-field fundus photography in diabetic retinopathy

The purpose of this study was to investigate the diagnostic properties of a 2-laser wavelength nonmydriatic 200° ultra-wide-field scanning laser ophthalmoscope (SLO) versus mydriatic 2-field 45° color fundus photography (EURODIAB standard) for assessing diabetic retinopathy (DR). A total of 143 consecutive eyes of patients with different levels of DR were graded regarding DR level and macular edema based on 2-field color photographs or 1 Optomap Panoramic 200 SLO image. All SLO images were nonmydriatic and all photographs mydriatic. Grading was performed masked to patient and clinical data. Based on photography, 20 eyes had no DR, 44 had mild, 18 moderate and 42 severe nonproliferative DR, and 19 eyes had proliferative DR. Overall correlation for grading DR level compared to Optomap SLO was moderate with kappa 0.54 (p < 0.001), fair-to-moderate in macular edema grading with kappa 0.39 (p < 0.001), and substantial for grading clinically significant macular edema (kappa 0.77). The wide-field SLO offers a wider field of view and can potentially better differentiate lesions by applying the 2 laser wavelengths. However, these advantages over 2-field fundus photography need to be confirmed in further studies.

Feasibility of telemedicine in detecting diabetic retinopathy and age-related macular degeneration

Age-related macular degeneration and diabetic retinopathy are important causes of visual impairment and blindness in the world. Because of recent advances and newly available treatment modalities along with the devastating consequences associated with late stages of these diseases, much attention has been paid to the importance of early detection and improving patient access to specialist care. Telemedicine or, more specifically, digital retinal imaging utilizing telemedical technology has been proposed as an important alternative screening and management strategy to help meet this demand. In this paper, we perform a literature review and analysis that evaluates the validity and feasibility of telemedicine in detecting diabetic retinopathy and age-related macular degeneration. Understanding both the progress and barriers to progress that have been demonstrated in these two areas is important for future telemedicine research projects and innovations in telemedicine technology.

Evaluation of telemedicine for screening of diabetic retinopathy in the Veterans Health Administration

OBJECTIVE

To explore the cost-effectiveness of telemedicine for the screening of diabetic retinopathy (DR) and identify changes within the demographics of a patient population after telemedicine implementation.

DESIGN

A retrospective medical chart review (cohort study) was conducted.

PARTICIPANTS

A total of 900 type 1 and type 2 diabetic patients enrolled in a medical system with a telemedicine screening program for DR.

METHODS

The cost-effectiveness of the DR telemedicine program was determined by using a finite-horizon, discrete time, discounted Markov decision process model populated by parameters and testing frequency obtained from patient records. The model estimated the progression of DR and determined average quality-adjusted life years (QALYs) saved and average additional cost incurred by the telemedicine screening program.

MAIN OUTCOME MEASURES

Diabetic retinopathy, macular edema, blindness, and associated QALYs.

RESULTS

The results indicate that telemedicine screening is cost-effective for DR under most conditions. On average, it is cost-effective for patient populations of >3500, patients aged <80 years, and all racial groups. Observable trends were identified in the screening population since the implementation of telemedicine screening: the number of known DR cases has increased, the overall age of patients receiving screenings has decreased, the percentage of nonwhites receiving screenings has increased, the average number of miles traveled by a patient to receive a screening has decreased, and the teleretinal screening participation is increasing.

CONCLUSIONS

The current teleretinal screening program is effective in terms of being cost-effective and increasing population reach. Future screening policies should give consideration to the age of patients receiving screenings and the system's patient pool size because our results indicate it is not cost-effective to screen patients aged older than 80 years or in populations with <3500 patients.

The challenge of screening for retinopathy of prematurity

Screening for retinopathy of prematurity (ROP) and the optimum treatment of sight-threatening disease requires detailed understanding of the infants at risk and timely identification. Despite a plethora of guidelines, not all populations and situations are adequately covered, so that what should be preventable visual disability still occurs. This article considers the design of screening guidelines and the possibility of a global guideline, although in certain parts of the world manpower for ROP screening is not available. Algorithms linked to the increase in weight of preterm infants over time may refine the number of babies needing to undergo treatment.

Ultra-wide field retinal imaging in detection, classification, and management of diabetic retinopathy

Current ultra-wide field (UWF) retinal imaging systems utilize scanning laser ophthalmoscope technology combined with an ellipsoidal mirror to capture up to 200 degrees of the retina in a single image. When compared with mydriatic ETDRS-protocol, 7 standard field photographs and clinical examination, nonmydriatic UWF images appear to have excellent agreement in allowing the detection and classification of diabetic retinopathy (DR), although larger, definitive validation studies are still forthcoming. UWF imaging and angiography allow visualization of peripheral retinal nonperfusion, vascular leakage and neovascularization in patients with DR that may not be captured on 7 standard fields. Prospective randomized controlled trials are needed to evaluate whether modified laser treatment algorithms based on improved visualization of the retinal periphery might improve patient outcomes. Nonmydriatic UWF imaging has potential applications for ocular diabetic telehealth programs, but validation of newer, more portable, and more affordable UWF imaging models is needed.

Telemedicine and ocular health in diabetes mellitus

Teleretinal/teleophthalmological programs that use existing health information technology infrastructure solutions for people with diabetes increase access to and adherence to appropriate eye care. Teleophthalmological studies indicate that the single act of patients viewing their own retinal images improves self-management behaviour and clinical outcomes. In some settings this can be done at lower cost and with improved visual outcomes compared with standard eye care. Cost-effective and sustainable teleretinal surveillance for detection of diabetic retinopathy requires a combination of an inexpensive portable device for taking low light-level retinal images without the use of pharmacological dilation of the pupil and a computer-assisted methodology for rapidly detecting and diagnosing diabetic retinopathy. A more holistic telehealth-care paradigm augmented with the use of health information technology, medical devices, mobile phone and mobile health applications and software applications to improve health-care co-ordination, self-care management and education can significantly impact a broad range of health outcomes, including prevention of diabetes-associated visual loss. This approach will require a collaborative, transformational, patient-centred health-care program that integrates data from medical record systems with remote monitoring of data and a longitudinal health record. This includes data associated with social media applications and personal mobile health technology and should support continuous interactions between the patient, health-care team and the patient's social environment. Taken together, this system will deliver contextually and temporally relevant decision support to patients to facilitate their well-being and to reduce the risk of diabetic complications.

Nonmydriatic ultrawide field retinal imaging compared with dilated standard 7-field 35-mm photography and retinal specialist examination for evaluation of diabetic retinopathy

PURPOSE

To compare nonmydriatic stereoscopic Optomap ultrawide field images with dilated stereoscopic Early Treatment Diabetic Retinopathy Study 7-standard field 35-mm color 30-degree fundus photographs (ETDRS photography) and clinical examination for determining diabetic retinopathy (DR) and diabetic macular edema (DME) severity.

DESIGN

Single-site, prospective, comparative, instrument validation study.

METHODS

One hundred three diabetic patients (206 eyes) representing the full spectrum of DR severity underwent nonmydriatic ultrawide field 100-degree and 200-degree imaging, dilated ETDRS photography, and dilated fundus examination by a retina specialist. Two independent readers graded images to determine DR and DME severity. A third masked retina specialist adjudicated discrepancies.

RESULTS

Based on ETDRS photography (n = 200), the results were as follows: no DR (n = 25 eyes [12.5%]), mild nonproliferative DR (NPDR; 47 [23.5%]), moderate NPDR (61 [30.5%]), severe NPDR (11 [5.5%]), very severe NPDR (3 [1.5%]), and proliferative DR (52 [2.5%]). One (0.5%) eye was ungradable and 6 eyes did not complete ETDRS photography. No DME was found in 114 eyes (57.0%), DME was found in 28 eyes (14.0%), and clinically significant DME was found in 47 eyes (23.5%), and 11 (5.5%) eyes were ungradable. Exact DR severity agreement between ultrawide field 100-degree imaging and ETDRS photography occurred in 84%, with agreement within 1 level in 91% (K(W) = 0.85; K = 0.79). Nonmydriatic ultrawide field images exactly matched clinical examination results for DR in 70% and were within 1 level in 93% (K(W) = 0.71; K = 0.61). Nonmydriatic ultrawide field imaging acquisition time was less than half that of dilated ETDRS photography (P < .0001).

CONCLUSIONS

Nonmydriatic ultrawide field images compare favorably with dilated ETDRS photography and dilated fundus examination in determining DR and DME severity; however, they are acquired more rapidly. If confirmed in broader diabetic populations, nonmydriatic ultrawide field imaging may prove to be beneficial in DR evaluation in research and clinical settings.

Telehealth practice recommendations for diabetic retinopathy, second edition

Ocular telemedicine and telehealth have the potential to decrease vision loss from DR. Planning, execution, and follow-up are key factors for success. Telemedicine is complex, requiring the services of expert teams working collaboratively to provide care matching the quality of conventional clinical settings. Improving access and outcomes, however, makes telemedicine a valuable tool for our diabetic patients. Programs that focus on patient needs, consider available resources, define clear goals, promote informed expectations, appropriately train personnel, and adhere to regulatory and statutory requirements have the highest chance of achieving success.

Accuracy and reliability of telemedicine for diagnosis of cytomegalovirus retinitis

PURPOSE

To determine the feasibility of remote diagnostic screening for cytomegalovirus (CMV) retinitis among HIV patients in northern Thailand.

DESIGN

Prospective, observational cross-sectional study.

METHODS

One hundred eighty-two eyes from 94 consecutive patients with HIV seen in 2008 and 2009 at a tertiary university-based medical center were photographed using a digital retinal camera. Individual and composite images were uploaded to a secure web site. Three expert graders accessed the electronic images and graded each image for signs of CMV retinitis. Results of remote expert grading were compared with on-site patient examination by local expert ophthalmologists.

RESULTS

On-site ophthalmologists diagnosed CMV retinitis in 89 (48.9%) of 182 eyes. Trained ophthalmic photographers obtained digital retinal images for all 182 eyes. As compared with the on-site examinations, the sensitivity for detecting CMV retinitis by remote readers using composite retinal images ranged from 89% to 91%. The specificity for detecting CMV retinitis by remote readers ranged from 85% to 88%. Intrarater reliability was high, with each grader achieving a κ value of 0.93. Interrater reliability among the 3 graders also was high, with a κ value of 0.86.

CONCLUSIONS

Remote diagnostic screening for CMV retinitis among HIV-positive patients may prove to be a valuable tool in countries where the burden of HIV exceeds the capacity of the local eye care providers to screen for ocular opportunistic infections.

The cost-effectiveness of three screening alternatives for people with diabetes with no or early diabetic retinopathy

OBJECTIVE

To determine whether biennial eye evaluation or telemedicine screening are cost-effective alternatives to current recommendations for the estimated 10 million people aged 30-84 with diabetes but no or minimal diabetic retinopathy.

DATA SOURCES

United Kingdom Prospective Diabetes Study, National Health and Nutrition Examination Survey, American Academy of Ophthalmology Preferred Practice Patterns, Medicare Payment Schedule.

STUDY DESIGN

Cost-effectiveness Monte Carlo simulation.

DATA COLLECTION/EXTRACTION METHODS

Literature review, analysis of existing surveys.

PRINCIPAL FINDINGS

Biennial eye evaluation was the most cost-effective treatment option when the ability to detect other eye conditions was included in the model. Telemedicine was most cost-effective when other eye conditions were not considered or when telemedicine was assumed to detect refractive error. The current annual eye evaluation recommendation was costly compared with either treatment alternative. Self-referral was most cost-effective up to a willingness to pay (WTP) of U.S.$37,600, with either biennial or annual evaluation most cost-effective at higher WTP levels.

CONCLUSIONS

Annual eye evaluations are costly and add little benefit compared with either plausible alternative. More research on the ability of telemedicine to detect other eye conditions is needed to determine whether it is more cost-effective than biennial eye evaluation.

General retinal vessel segmentation using regularization-based multiconcavity modeling

Detecting blood vessels in retinal images with the presence of bright and dark lesions is a challenging unsolved problem. In this paper, a novel multiconcavity modeling approach is proposed to handle both healthy and unhealthy retinas simultaneously. The differentiable concavity measure is proposed to handle bright lesions in a perceptive space. The line-shape concavity measure is proposed to remove dark lesions which have an intensity structure different from the line-shaped vessels in a retina. The locally normalized concavity measure is designed to deal with unevenly distributed noise due to the spherical intensity variation in a retinal image. These concavity measures are combined together according to their statistical distributions to detect vessels in general retinal images. Very encouraging experimental results demonstrate that the proposed method consistently yields the best performance over existing state-of-the-art methods on the abnormal retinas and its accuracy outperforms the human observer, which has not been achieved by any of the state-of-the-art benchmark methods. Most importantly, unlike existing methods, the proposed method shows very attractive performances not only on healthy retinas but also on a mixture of healthy and pathological retinas.

Telemedical diagnosis of retinopathy of prematurity: accuracy of expert versus non-expert graders

BACKGROUND/AIMS

To assess accuracy of telemedical retinopathy of prematurity (ROP) diagnosis by trained non-expert graders compared with expert graders.

METHODS

Eye examinations (n=248) from 67 consecutive infants were captured using wide-angle retinal photography (RetCam-II, Clarity Medical Systems, Pleasanton, California, USA). Non-expert graders attended two 1-h training sessions on image-based ROP diagnosis. Using a web-based telemedicine system, 14 non-expert and three expert graders provided a diagnosis for each eye: no ROP, mild ROP, type 2 pre-threshold ROP or treatment-requiring ROP. All diagnoses were compared with a reference standard of dilated indirect ophthalmoscopy by an experienced paediatric ophthalmologist.

RESULTS

For detection of type 2 or worse ROP, the mean (range) sensitivities and specificities were 0.95 (0.94-0.97) and 0.93 (0.91-0.96) for experts, 0.87 (0.71-0.97) and 0.73 (0.39-0.95) for resident non-experts, and 0.73 (0.41-0.88) and 0.91 (0.84-0.96) for student non-experts, respectively. For detection of treatment-requiring ROP, the mean (range) sensitivities and specificities were 1.00 (1.00-1.00) and 0.93 (0.88-0.96) for experts, 0.88 (0.50-1.00) and 0.84 (0.71-0.98) for resident non-experts, and 0.82 (0.42-1.00) and 0.92 (0.83-0.97) for student non-experts, respectively.

CONCLUSIONS

Mean sensitivity and specificity of trained non-experts were lower than that of experts, although several non-experts had high accuracy. Development of methods for training non-expert graders may help support telemedical ROP evaluation.

Ocular telehealth initiatives in diabetic retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes mellitus and a leading cause of new-onset vision loss in adults worldwide. Current medical and surgical evidence-based care, including laser photocoagulation, is effective in preserving vision. This care is most effective prior to the onset of ocular or visual symptoms, but many diabetic persons do not receive the recommended annual eye examination for the evaluation of the retina for level of DR. With diabetes incidence and prevalence increasing at epidemic rates and the prediction that 370 million people worldwide will have diabetes by the year 2030, human and fiscal resources will be unable to meet the visual needs with current acute care methods. Appropriate and validated telemedicine programs for DR hold the promise of both enrolling patients into appropriate eye care programs and, more importantly, providing more effective, high-quality diabetes eye care based on current and developing technology.

EyePACS: an adaptable telemedicine system for diabetic retinopathy screening

BACKGROUND

Annual retinal screening of patients with diabetes is the standard clinical practice to prevent visual impairment and blindness from diabetic retinopathy. Telemedicine-based diabetic retinopathy screening (DRS) in primary care settings can effectively detect sight-threatening retinopathy and significantly increase compliance with annual retinal exams. EyePACS is a license-free Web-based DRS system designed to simplify the process of image capture, transmission, and review. The system provides a flexible platform for collaboration among clinicians about diabetic retinopathy.

METHODS

Primary clinic personnel (i.e., nursing, technical, or administrative staff) are trained and certified by the EyePACS program to acquire retinal images from standard digital retinal cameras. Relevant clinical data and eight high-resolution images per patient (two external and six retinal images) are encrypted and transmitted to a secure Internet server, using a standard computer and Web browser. Images are then interpreted by certified EyePACS reviewers or local eye care providers who are certified through the EyePACS Retinopathy Grading System. Reports indicating retinopathy level and referral recommendations are transmitted back to primary care providers through the EyePACS Web site or through interfaces between EyePACS and Health Level 7-compliant electronic medical records or chronic disease registries.

RESULTS

The pilot phase of the EyePACS DRS program in California (2005-2006) recorded 3562 encounters. Since 2006, EyePACS has been expanded to over 120 primary care sites throughout California and elsewhere recording over 34,000 DRSs. The overall rate of referral is 8.21% for sight-threatening retinopathy and 7.83% for other conditions (e.g., cataract and glaucoma).

CONCLUSION

The use of license-free Web-based software, standard interfaces, and flexible protocols has allowed primary care providers to adopt retinopathy screening with minimal effort and resources.

Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP): 18-month experience with telemedicine screening

PURPOSE

To report the 18-month experience of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) telemedicine initiative.

DESIGN

Retrospective analysis of the SUNDROP archival data between 1 December 2005 and 30 May 2007, evaluating this new diagnostic technology for ROP screening.

PARTICIPANTS

All 97 consecutively enrolled infants in the SUNDROP network.

METHODS

All patients were screened using the RetCam II, and evaluated by the SUNDROP reading center at Stanford University. Nurses were trained to obtain five images in each eye. All patients were screened by an ophthalmologist trained in diagnosing ROP within 1 week of discharge from the hospital.

MAIN OUTCOME MEASURES

Outcomes included referral-warranted disease, need for treatment, and anatomic outcomes. Referral-warranted disease was defined as any Early Treatment Retinopathy of Prematurity Disease Type 2 or greater, threshold disease, any plus disease, and any stage 4 or higher disease.

RESULTS

In the initial 18-month period, the SUNDROP telemedicine screening initiative has not missed any referral-warranted disease for ROP. A total of 97 infants (194 eyes) were enrolled, resulting in 443 unique examinations and 4,929 unique images. The mean birth weight of the infants was 1,186.9 grams, with a mean gestational age at birth of 28.9 weeks. Seven infants were identified with referral-warranted disease; six patients underwent laser photocoagulation and completely regressed. The one remaining patient regressed spontaneously, and did not require intervention. Calculated sensitivity and specificity was 100% and 98.9% respectively. No patient progressed to retinal detachment or other adverse outcome. Inadequate exposure, artifact, poor visualization of the periphery, and lack of a complete standardized image set in some patients were identified as areas requiring further assessment.

CONCLUSIONS

The SUNDROP telemedicine screening initiative for ROP has proven to have a high degree of sensitivity and specificity for identification of referral-warranted disease. Training was easily implemented. All cases of referral-warranted disease were captured. There were no adverse outcomes.

OPHDIAT: a telemedical network screening system for diabetic retinopathy in the Ile-de-France

OBJECTIVE

International and national guidelines recommend an annual funduscopic examination for all diabetic patients, but such annual fundus examinations are not sufficiently performed in France. Non-mydriatic fundus photography is a valid method of evaluation for diabetic retinopathy (DR) and a viable alternative to ophthalmoscopy. After two pilot studies demonstrated the feasibility of telemedical screening for diabetic retinopathy in both hospital and primary-care settings, we developed a regional telemedical network, OPHDIAT, designed to facilitate access to regular annual evaluations of patients with diabetes while saving medical time.

MATERIALS AND METHODS

OPHDIAT comprises peripheral screening centres equipped with non-mydriatic cameras, where fundus photographs are taken by technicians linked by telemedicine to a reference centre, where ophthalmologists grade the images. Currently in the Ile-de-France region, 16 screening centres are linked through a central server to an ophthalmologic reading centre and includes 11 centres located in the diabetes departments of 11 hospitals, one diabetic retinopathy screening centre located in northern Paris, three in healthcare centres and one in a prison.

RESULTS

During the 28-month evaluation period, 15,307 DR screening examinations were performed. Retinal photographs of at least one eye could not be graded in 1332 patients (9.7%) and diabetic retinopathy was detected in 3350 patients (23.4%). After the screening examination, 3478 patients (25.2%) were referred to an ophthalmologist for either DR, cataract and/or non-gradable photographs.

CONCLUSION

Fundus photography combined with telemedicine has the potential to improve the regular annual evaluation for diabetic retinopathy. The organization of the network around a central reading centre serves to guarantee quality control.

A sorting system for hierarchical grading of diabetic fundus images: a preliminary study

Diabetic retinopathy is a leading cause of blindness in developed countries. Diabetic patients can prevent severe visual loss by attending regular eye examinations and receiving timely treatments. In the United States, standard protocols have been developed and refined for years to provide better screening and evaluation procedures of the fundus images. Due to the emerging number of diabetic retinopathy cases, accurate and efficient evaluations of the fundus images have become a serious burden for the ophthalmologists or care providers. While diabetic retinopathy remains too complicated to call for an automatic diagnosis system, an efficient tool to facilitate the grading process with a limited number of personnel is in great demand. The current study is to develop a sorting system with a user-friendly interface, based upon the standardized early treatment diabetic retinopathy study (ETDRS) protocol, to assist the professional graders. The raw fundus images will be screened and assigned to different graders according to their skill levels and experiences. The developed hierarchical sorting process will greatly support the graders and enhance their efficiency and throughput. The proposed hybrid intelligent system with multilevel knowledge representation is used to construct this sorting system. A preliminary case study is conducted using only the features of the spot lesion group coupled with the ETDRS standard to demonstrate its feasibility and performance. The results obtained from the case study show a promising future.

Detection of anatomic structures in human retinal imagery

The widespread availability of electronic imaging devices throughout the medical community is leading to a growing body of research on image processing and analysis to diagnose retinal disease such as diabetic retinopathy (DR). Productive computer-based screening of large, at-risk populations at low cost requires robust, automated image analysis. In this paper we present results for the automatic detection of the optic nerve and localization of the macula using digital red-free fundus photography. Our method relies on the accurate segmentation of the vasculature of the retina followed by the determination of spatial features describing the density, average thickness, and average orientation of the vasculature in relation to the position of the optic nerve. Localization of the macula follows using knowledge of the optic nerve location to detect the horizontal raphe of the retina using a geometric model of the vasculature. We report 90.4% detection performance for the optic nerve and 92.5% localization performance for the macula for red-free fundus images representing a population of 345 images corresponding to 269 patients with 18 different pathologies associated with DR and other common retinal diseases such as age-related macular degeneration.

New microscopic pushbroom hyperspectral imaging system for application in diabetic retinopathy research

To aid ophthalmologists in determining the pathogenesis of diabetic retinopathy and in evaluating the effects of medication, a microscopic pushbroom hyperspectral imaging system is developed. 40 healthy Wistar rats of half gender are selected in this study. They are divided into three groups (six rats failed to be models). 10 normal rats as the normal control group, 12 diabetic rats without any treatment as the model control group, and another 12 diabetic rats treated with LCVS1001 as the LCVS1001 group. The microscopic hyperspectral image of each retina section is collected and processed. Some typical spectrum curves between 400 and 800 nm of the outer nuclear layer are extracted, and images at various wavelengths are analyzed. The results show that a small trough appears near 522.2 nm in the typical spectrum curve of the model control group, and the transmittance of it is higher than that of the normal control group. In addition, the spectrum of the LCVS1001 group changes gradually to the normal spectrum after treatment with LCVS1001. Our findings indicate that LCVS1001 has some therapeutic effect on the diabetic retinopathy of rats, and the microscopic pushbroom hyperspectral imaging system can be used to study the pathogenesis of diabetic retinopathy.

Web-Based Grading of Compressed Stereoscopic Digital Photography versus Standard Slide Film Photography for the Diagnosis of Diabetic Retinopathy

PURPOSE

To evaluate the ability of Joint Photographic Experts Group (JPEG) compressed, stereoscopic, digital photography to identify clinical levels of diabetic retinopathy, detect clinically significant macular edema (CSME), and make appropriate referral recommendations as compared with Early Treatment Diabetic Retinopathy Study (ETDRS) standard film photography.

DESIGN

Prospective, clinic-based, comparative photographic format validation study.

PARTICIPANTS

Two hundred four eyes from 102 consecutive, new, diabetic patients with a median duration of diabetes of 12.5 years were enrolled and analyzed.

METHODS

After pupillary dilation, a trained ophthalmic photographer obtained 2 sets of images: standard ETDRS, stereoscopic 7-field 35-mm film photographs and high-resolution, digital images of the same 7 standard fields (stereoscopic images of fields 1 and 2). Two masked readers graded both sets of images. The 35-mm film photographs were graded by hand using a written template. Digital photographs were compressed, uploaded to a web site, and graded by a web-based, computer-assisted ETDRS algorithm. The ETDRS level of diabetic retinopathy, presence of retinal thickening, and referral recommendation based on these 2 diagnoses were recorded and compared.

MAIN OUTCOME MEASURES

The presence of CSME, ETDRS level of diabetic retinopathy, and referral threshold diabetic retinopathy.

RESULTS

Film and compressed digital grading levels were compared using a simplified ETDRS categorization scheme. Film and digital gradings were highly correlated with exact agreements for level of diabetic retinopathy, CSME, and referral thresholds >87% and kappa levels >0.71. McNemar's testing found no statistically significant difference between compressed digital images and film when comparing referral thresholds (defined as the presence of CSME and/or ETDRS level > or = 61; P = 0.76).

CONCLUSIONS

A modified ETDRS protocol (stereoscopic images of fields 1 and 2 only) with 16:1 JPEG image compression and computer-assisted ETDRS grading algorithm has excellent reproducibility when compared to standard ETDRS stereoscopic slide-film photography. An internet-based teleophthalmology system can correctly and reliably (kappa = 0.78) identify patients requiring referral for CSME and proliferative diabetic retinopathy (PDR; ETDRS level > or = 61).

Accuracy of digital images for assessing diabetic retinopathy

BACKGROUND

To determine the accuracy of diabetic retinopathy status assessments with and without pupil dilation using digital fundus photographs acquired by a clinic staff person and interpreted remotely by ophthalmologists.

METHOD

Using early treatment diabetic retinopathy study (EDTRS) grading criteria, diabetic retinopathy status assessments were made by an experienced (nonphysician) retinal grader (NPG) based on seven standard field 35-mm stereoscopic slides acquired by an experienced ophthalmic photographer. These assessments were compared with those of the same eyes made by two ophthalmologists and the NPG using digital photographs acquired by a clinic staff person using a high-resolution (800 x 600) digital color camera system.

RESULTS

Based on 35-mm slides, 38% of 244 diabetic patients had ETDRS > or =35 in at least one eye and 5% had vision-threatening diabetic retinopathy (ETDRS > or =53 or macular edema). The proportion of ungradable images was significantly greater for nonmydriatic than mydriatic assessments (30% versus 10% ungradable as determined by the NPG). For ETDRS level > or =35, specificity ranged from moderate to high (0.70 to 0.96) for the three graders, while sensitivity was poor to moderate (0.38 to 0.71), and the area under the receiver-operating characteristic curves was less than satisfactory (0.67 to 0.71).

CONCLUSIONS

The low sensitivity of the digital assessments indicates a significant proportion of patients in need of referral would not have been referred. These findings suggest that implementation of a simplified screening system using nonphotographer clinic staff acquiring nonmydriatic images, with interpretation by an ophthalmologist, should take place with an understanding of potential limitations.

Interobserver Agreement in the Interpretation of Single-Field Digital Fundus Images for Diabetic Retinopathy Screening

PURPOSE

To assess agreement among a group of ophthalmic care providers, including ophthalmologists and trained nonphysician personnel, in the interpretation of single-field digital fundus images for diabetic retinopathy screening.

DESIGN

Interobserver reliability study.

PARTICIPANTS

Twelve ophthalmic care personnel, including 3 retina specialists, 3 general ophthalmologists, 3 ophthalmic nurses, and 3 ophthalmic photographers.

METHODS

All participants were to read 400 good single-field digital fundus images of diabetic patients from a community hospital. The nonphysician personnel group read the images 1 month after attending a 2-day intensive instruction course regarding diabetic retinopathy screening. The ophthalmologists read the images without additional training. The 3 retina specialists read the images again together 2 months later to form a consensus regarding retinopathy severity and macular edema for each case. All readers used the Early Treatment Diabetic Retinopathy Study standard photographs as guidelines.

MAIN OUTCOME MEASURES

The kappa statistic was used for the reliability assessment of the diabetic retinopathy severity and macular edema, and for the identification of cases that needed referral to ophthalmologists.

RESULTS

There is only fair agreement among all readers. The multirater kappa coefficient for retinopathy severity is 0.34; for macular edema, 0.27; and for referral cases, 0.28. Retina specialists have the best agreement among all groups (kappa = 0.58 for retinopathy severity or macular edema, kappa = 0.63 for referrals). There is also fair agreement when all readers are compared with the consensus of retina specialists (kappas = 0.35, 0.28, and 0.29 for retinopathy severity, macular edema, and referrals, respectively), and the retina specialist group also has the best agreement (kappas = 0.63, 0.65, and 0.67 for retinopathy severity, macular edema, and referrals).

CONCLUSIONS

Without additional training, retina specialists may be the most reliable personnel to interpret single-field digital fundus images for diabetic retinopathy screening. For other ophthalmic care personnel to achieve comparable reliability, a comprehensive instruction course with specific continuing education is essential. Authorized nonphysician interpreters should be experts, and new standard photographs for single-field digital fundus image interpretation may also be required to improve interobserver reliability.

Results of Implementation of the DigiScope for Diabetic Retinopathy Assessment in the Primary Care Environment

Approximately 50% of patients with diabetes in the United States do not undergo recommended ocular evaluations for diabetic retinopathy. The DigiScope (EyeTel Imaging, Inc., Columbia, MD) was developed as a cost-effective and practical telemedicine digital imaging system to screen for diabetic retinopathy in the primary care physician's (PCP) office. The DigiScope has been validated against seven-field stereo color fundus photography for the detection of diabetic retinopathy. This study reports on the implementation of the DigiScope for diabetic retinopathy assessment in the primary care environment. In PCP's offices, patients with diabetes who had not undergone an eye examination in the past year were imaged with the DigiScope. The images were transmitted to a reading center where the need for referral to an ophthalmologist was determined. Nonurgent referral was recommended for patients with diabetic retinopathy greater than a few micro-aneurysms, other ocular pathology, or unreadable images. Referral was deemed "urgent" for patients with sight-threatening disease and evaluation by an ophthalmologist within 72 hours was recommended. Between October 1, 2002 and March 31, 2771 patients with diabetes underwent DigiScope imaging at multiple sites. Nonurgent referral was recommended for 468 patients (17%). Urgent referral was recommended for 71 patients (3%). The images were unreadable in 295 cases (11%). This study indicates that implementation of the DigiScope in the primary care setting is practical and allows screening of patients with diabetes who are otherwise not receiving recommended eye examinations.

Accuracy and reliability of teleophthalmology for diagnosing diabetic retinopathy and macular edema: a review of the literature

Using teleophthalmology for the delivery of routine eye care for patients with diabetes mellitus is becoming an increasingly common practice. Paramount in the consideration of any new diagnostic test is an analysis of its diagnostic accuracy and reliability and how that compares with conventional care. This review summarizes existing data on the diagnostic accuracy and reliability of teleophthalmology and conventional clinic-based eye care for detecting diabetic retinopathy and diabetes mellitus. The sensitivity of ophthalmoscopy for detecting diabetic retinopathy performed by eye care clinicians has varied widely, with point estimates ranging from 0% to 96%. Alternatively, specificity has been universally high. The sensitivity of teleophthalmology for detecting diabetic retinopathy has been shown to be comparable, if not better, than clinic-based examinations. Sensitivity values have ranged from 50% to 93%. The specificity of teleophthalmology, like clinic-based examinations, has been consistently high. High levels of diagnostic reliability, analyzed by both simple agreement and kappa values, have been found between ophthalmoscopy and teleophthalmology for detecting and classifying diabetic retinopathy. Evaluating the accuracy of macular edema detection requires the use of dual gold standards, the clinical examination using slit-lamp biomicroscopy and stereoscopic photography. Teleophthalmology, compared with both gold standards, has, overall, been a highly sensitive and specific test. Reliability studies that compared the two gold standards with one another have found moderate to substantial levels of agreement. Based on existing data, teleophthalmology appears to be an accurate and reliable test for detecting diabetic retinopathy and macular edema.

Retinal image analysis: concepts, applications and potential

As digital imaging and computing power increasingly develop, so too does the potential to use these technologies in ophthalmology. Image processing, analysis and computer vision techniques are increasing in prominence in all fields of medical science, and are especially pertinent to modern ophthalmology, as it is heavily dependent on visually oriented signs. The retinal microvasculature is unique in that it is the only part of the human circulation that can be directly visualised non-invasively in vivo, readily photographed and subject to digital image analysis. Exciting developments in image processing relevant to ophthalmology over the past 15 years includes the progress being made towards developing automated diagnostic systems for conditions, such as diabetic retinopathy, age-related macular degeneration and retinopathy of prematurity. These diagnostic systems offer the potential to be used in large-scale screening programs, with the potential for significant resource savings, as well as being free from observer bias and fatigue. In addition, quantitative measurements of retinal vascular topography using digital image analysis from retinal photography have been used as research tools to better understand the relationship between the retinal microvasculature and cardiovascular disease. Furthermore, advances in electronic media transmission increase the relevance of using image processing in 'teleophthalmology' as an aid in clinical decision-making, with particular relevance to large rural-based communities. In this review, we outline the principles upon which retinal digital image analysis is based. We discuss current techniques used to automatically detect landmark features of the fundus, such as the optic disc, fovea and blood vessels. We review the use of image analysis in the automated diagnosis of pathology (with particular reference to diabetic retinopathy). We also review its role in defining and performing quantitative measurements of vascular topography, how these entities are based on 'optimisation' principles and how they have helped to describe the relationship between systemic cardiovascular disease and retinal vascular changes. We also review the potential future use of fundal image analysis in telemedicine.

Comparison of stereoscopic digital imaging and slide film photography in the identification of macular degeneration

BACKGROUND

This study compared the sensitivity and specificity of stereoscopic digital photography of the retina through a dilated pupil with a 45 degrees nonmydriatic camera and Joint Photographic Experts Group (JPEG) compression of the images with the sensitivity and specificity of 35-mm slide film photography in the identification of age-related macular degeneration (AMD).

METHODS

Consecutive patients with a diagnosis of AMD were enrolled. Stereoscopic retinal images of the disc, macula and temporal macula were captured with a digital 45 degrees nonmydriatic camera (then compressed into JPEG format) and with a standard fundus camera and slide film. A single retinal specialist graded both image formats in masked fashion, at least 1 month apart, using a modified Age-Related Eye Disease Study (AREDS) severity scale. The digital images were displayed on a monitor and viewed with the use of liquid crystal display shutter glasses and stereo imaging software. The film images were mounted on a light box and graded with the use of a stereoviewer. Primary outcome measures included the presence or absence of AMD pathological features. Positive and negative predictive values (PPVs and NPVs), sensitivity, specificity and weighted kappaw statistics were calculated.

RESULTS

We photographed 203 eyes (of 103 patients) with both digital and slide film cameras. Correlation of the 2 image formats was substantial in identifying AREDS level 3a or greater (kappaw=0.64, standard error=0.08, PPV=0.95, NPV=0.66, sensitivity=0.93, specificity=0.74) and excellent in identifying level 4b or greater (kappaw=0.83, standard error=0.05, PPV=0.81, NPV=0.98, sensitivity=0.94, specificity=0.94).

INTERPRETATION

High-resolution stereoscopic, mydriatic, 45 degrees digital images captured with a nonmydriatic camera and JPEG compressed correlate well with stereoscopic slide film photographs in the identification of moderate to advanced AMD (AREDS level 3a or greater).