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

A telemedicine program for diabetic retinopathy in a Veterans Affairs Medical Center--the Joslin Vision Network Eye Health Care Model

PURPOSE

To extend access to diabetic eye care and characterize the extent of diabetic retinopathy {DR) and other ocular findings using the Joslin Vision Network (JVN).

DESIGN

Retrospective observational cohort study.

METHODS

Outpatients at the Togus VA Medical Center with diabetes mellitus, impaired fasting glucose, or impaired glucose tolerance underwent JVN protocol imaging. Images were transmitted to the Joslin Diabetes Center for grading and recommended treatment plan.

RESULTS

The study included 1,219 patients (2,437 eyes); 1,536 eyes (63.0%) had no (DR), 389 (16.0%) had mild nonproliferative DR (NPDR), 105 (4.3%) moderate NPDR, 35 (1.4%) severe NPDR, 20 (0.8%) very severe NPDR, and 21 (0.9%) had proliferative DR (PDR). Regarding diabetic macular edema (DME), 1,907 eyes (78.3%) had no DME, 34 (1.4%) had early DME, and 16 (0.7%) had clinically significant macular edema (CSME). Of all patients, 354 (29.0%) had either no DR or mild NPDR in both eyes, no evidence of DME, and no significant nondiabetic findings; 679 (55.7%) had no DR in either eye, and 229 (18.8%) had mild NPDR in the more severe eye. Of the 908 patients (74.5%) with either no DR or mild NPDR in the more severe eye, 533 (58.7%) had at least one nondiabetic ocular finding necessitating referral. Finally, 320 eyes (13.1%) were ungradable for both DR and DME and 160 (6.6%) were ungradable for DME alone.

CONCLUSION

In a non-ophthalmic setting, JVN identifies the severity of DR and nondiabetic ocular conditions, permitting appropriate triage for eye care.

Telehealth practice recommendations for diabetic retinopathy

Telehealth holds the promise of increased adherence to evidenced-based medicine and improved consistency of care. Goals for an ocular telehealth program include preserving vision, reducing vision loss, and providing better access to medicine. Establishing recommendations for an ocular telehealth program may improve clinical outcomes and promote informed and reasonable patient expectations. This document addresses current diabetic retinopathy telehealth clinical and administrative issues and provides recommendations for designing and implementing a diabetic retinopathy ocular telehealth care program. The recommendations also form the basis for evaluating diabetic retinopathy telehealth techniques and technologies. Recommendations in this document are based on careful reviews of current evidence, medical literature and clinical practice. They do not, however, replace sound medical judgment or traditional clinical decision-making. "Telehealth Practice Recommendations for Diabetic Retinopathy" will be annually reviewed and updated to reflect evolving technologies and clinical guidelines.

Addition of primary care-based retinal imaging technology to an existing eye care professional referral program increased the rate of surveillance and treatment of diabetic retinopathy

OBJECTIVE

Digital retinal imaging is a relatively new technology that can be used to assess patients for diabetic retinopathy. We evaluated the impact of adding a primary care-based retinal imaging technology to an existing eye care professional referral process on the rate of surveillance and treatment of diabetic retinopathy in a large, well-defined patient population over a 5-year period.

RESEARCH DESIGN AND METHODS

We performed systematic performance evaluations using a computerized patient information system and a comprehensive procedure log to describe annually the patient population, the number of patients with diabetes, and the proportion of patients with diabetes who received appropriate eye care services, including surveillance and laser treatment for diabetic retinopathy before and after implementation of a digital retinal imaging system at the Phoenix Indian Medical Center Primary Care Medical Clinic.

RESULTS

The rate of annual retinal examinations increased from 50% (95% CI 44-56%) to 75% (70-80%; P < 0.000001), representing a 50% increase in the retinal examination rate. The rate of laser therapy increased from 19.6 per 1,000 patients with diabetes in 1999 to 29.5 per 1,000 in 2003 for a 51% increase in the laser treatment rate.

CONCLUSIONS

Implementing retinal imaging technology in a primary care setting resulted in a significant increase in the rate of diabetic retinopathy surveillance and a proportional increase in the rate of laser treatment for diabetic retinopathy for a large patient population. Application of this technology in primary care settings holds the potential to extend sight-preserving care by increasing access to appropriate retinal care.

Screening for diabetic retinopathy in Denmark: the current status

PURPOSE

To investigate the current status of screening for diabetic retinopathy in Denmark, focussing on organization, methods of screening and regional differences.

METHODS

A questionnaire was sent out in 2002 to 14 departments of ophthalmology and one ophthalmology practice, covering all 15 counties in Denmark.

RESULTS

Six counties reported having systematic screening, defined as organized screening, including a database; three reported having plans for systematic screening; two reported having undetermined plans for systematic screening and four reported having no plans for systematic screening. In counties with systematic screening, both the organization and the method of screening varied.

CONCLUSION

Approximately 43% of Danish patients with diabetes currently live in a county without systematic screening for diabetic retinopathy. Should all counties contemplating systematic screening implement their plans, this proportion will be reduced to approximately 17%.

Detection of diabetic retinopathy: a comparison between red-free digital images and colour transparencies

BACKGROUND

The aim of this study was to compare how diabetic retinopathy was detected from red-free digital images and colour transparencies.

METHODS

Two ophthalmologists graded two-field, nonstereoscopic, 60 degrees red-free digital images and colour transparencies utilizing an ETDRS-based grading scale, from 107 mainly type 2 diabetic patients. The discordantly scored eyes were graded by the graders together to obtain a consensus level of retinopathy for each method. The eyes with discordant consensus grading results were further graded using all available photographic material to reach a final consensus level of diabetic retinopathy. Intermethod variations were presented as percentages and using kappa (k) and weighted kappa (wk) statistics. The errors of the two consensus gradings with respect to the final consensus grading were compared using McNemar's test.

RESULTS

For the colour transparencies there was an agreement between the individual and the consensus grading results in 93% (k=0.90, wk=0.97) and 86% (k=0.79, wk 0.88) for grader 1 and grader 2. Corresponding figures for red-free digital images were 88% (k=0.83, wk=0.96) and 84% (k=0.78, wk 0.91). Agreement between methods was obtained in 76/107 eyes (71%; k=0.58 and wk=0.79). In the 31 discordantly graded eyes the level of retinopathy was underestimated in 20/31 (64%) vs 7/31 eyes (23%) and overestimated in 1/31 (3%) vs 3/31 eyes (10%) from colour transparencies and red-free digital images, respectively. The error tendencies were significantly lower when using red-free digital images (p<0.008).

CONCLUSIONS

Red-free digital images are comparable with two-field colour transparencies in the identification of mild to moderate nonproliferative diabetic retinopathy.

Single-field fundus photography for diabetic retinopathy screening: a report by the American Academy of Ophthalmology

OBJECTIVE

To evaluate whether single-field fundus photography can be used as a screening tool to identify diabetic retinopathy for referral for further ophthalmic care.

METHODS

A MEDLINE search of the peer-reviewed literature was conducted in June 2001 for the years 1968 to 2001 and updated in September 2003, yielding 145 articles. The search was limited to articles published in English. The Cochrane Library of clinical trials was also investigated. The authors reviewed the abstracts of these articles and selected 63 of possible clinical relevance for review by the panel. Of these 63 articles, the panel selected 32 for the panel methodologist to review and rate according to the strength of evidence.

RESULTS

Three of the 32 articles reviewed were classified as level I evidence, and 4 were classified as level II evidence. Evidence from level I studies demonstrates that as a tool to detect vision-threatening retinopathy, single-field fundus photography interpreted by trained readers has sensitivity ranging from 61% to 90% and specificity ranging from 85% to 97% when compared with the gold standard reference of stereophotographs of 7 standard fields. When compared with dilated ophthalmoscopy by an ophthalmologist, single-field fundus photography has sensitivity ranging from 38% to 100% and specificity ranging from 75% to 100%.

CONCLUSIONS

Single-field fundus photography is not a substitute for a comprehensive ophthalmic examination, but there is level I evidence that it can serve as a screening tool for diabetic retinopathy to identify patients with retinopathy for referral for ophthalmic evaluation and management. The advantages of single-field fundus photography interpreted by trained readers are ease of use (only one photograph is required), convenience, and ability to detect retinopathy. Further studies will be required to assess the implementation of single-field photography-based programs to confirm the clinical and cost-effectiveness of these techniques in improving population visual outcomes. Future research also should include establishing standardized protocols and satisfactory performance standards for diabetic retinopathy screening programs.

Cost-effectiveness analysis of telemedicine to evaluate diabetic retinopathy in a prison population

OBJECTIVE

A cost-effectiveness analysis was conducted to investigate the clinical and economic impact of teleophthalmology in evaluating diabetic retinopathy in prison inmates with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Based on a hypothetical teleophthalmology system to evaluate diabetic retinopathy patients with type 2 diabetes in a prison care setting, a Markov decision model was developed with probability and cost data derived primarily from published epidemiological and outcome studies. A 40-year-old African-American man with type 2 diabetes was used as a reference case subject. The number of quality-adjusted life-years (QALYs) gained was used as the clinical outcome, and the cost in U.S. dollars from the year 2003 was used as the economic outcome. Teleophthalmology and nonteleophthalmology strategies were compared using an expected QALYs calculation and two types of sensitivity analyses: probabilistic and traditional n-way sensitivity analyses.

RESULTS

The teleophthalmology strategy dominates in the cost-effectiveness analysis for the reference case subject: 16,514/18.73 dollars QALYs for teleophthalmology and 17,590/18.58 dollars QALYs for nonteleophthalmology. Ninety percent of the Monte Carlo simulations showed cost effectiveness (annual cost/QALYs < or = 50,000 dollars) in the teleophthalmology strategy based on an assumed inmate population. Teleophthalmology is the better strategy if the number of diabetic inmates in the prison community is >500.

CONCLUSIONS

Our cost-effectiveness analysis demonstrates that teleophthalmology holds great promise to reduce the cost of inmate care and reduce blindness caused by diabetic retinopathy in type 2 diabetic patients.

Effectiveness and safety of screening for diabetic retinopathy with two nonmydriatic digital images compared with the seven standard stereoscopic photographic fields

BACKGROUND

The use of nonmydriatic cameras, which offer ease of screening and 45 degrees immediate imaging of the fundus, is gaining increasing acceptance for screening programs tailored to diverse conditions. We performed a study to evaluate the effectiveness and safety of screening for diabetic retinopathy with two nonmydriatic camera images compared with the seven standard stereoscopic 30 degrees fields (7SF). We also wished to determine whether safe screening guidelines could be established to identify patients needing referral to an ophthalmologist.

METHODS

In this prospective masked cross-sectional study, we evaluated agreement in the assessment of the severity of diabetic retinopathy by means of two 45 degrees images centred on the optic disc and on the macula obtained with the Topcon CRW6 nonmydriatic camera and by means of 7SF photography and ophthalmologic slit-lamp biomicroscopy, both performed with pupil dilation. Between November 2000 and June 2001, 98 adult patients known to have type 1 or 2 diabetes mellitus who presented for the first time to the diabetic retinopathy clinic of a tertiary care centre in Montreal were enrolled consecutively. Thus, patient recruitment was weighted toward more severe retinopathy to ensure sufficient representation of less frequent but more severe levels. Each patient underwent nonmydriatic fundus photography of both eyes, followed by a complete ophthalmologic examination with pupil dilation by a single retina specialist and 7SF photography of both eyes with pupil dilation. The level of retinopathy was graded independently in each eye from the 7SF photographs according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale by two graders; an independent retina specialist adjudicated the rare instances of interreader disagreement in a masked fashion. Two months later, two graders independently graded the nonmydriatic images in a blinded fashion according to the ETDRS scale; a third observer adjudicated the rare instances of interreader disagreement. We measured concordance between grading results with the various screening techniques using the weighted and unweighted kappa statistic. We used sensitivity and specificity indices to determine safe screening guidelines to identify patients needing referral to an ophthalmologist.

RESULTS

There was substantial agreement in the grading of retinopathy with nonmydriatic camera imaging and with 7SF photography, both for all eyes (kappa = 0.626 [standard deviation (SD) 0.045]) and for the eye with more severe disease (kappa = 0.654 [SD 0.063]). With nonmydriatic camera imaging, screening thresholds for patient referral to an ophthalmologist of very mild retinopathy (ETDRS grade 20), mild retinopathy (ETDRS grade 35) and moderate retinopathy (EDTRS grade 43) had sensitivity values of 97.9%, 97.1% and 53.3% respectively and specificity values of 81.3%, 95.5% and 96.9% respectively. Screening thresholds of very mild or mild retinopathy both correctly identified 100% of eyes with severe nonproliferative or proliferative retinopathy. With a screening threshold of mild retinopathy, screening with the nonmydriatic camera would lead to referral to an ophthalmologist of 37.8% of patients because of detected disease and of an additional 17.3% because of insufficient image quality in at least one eye, for a total of 55.1%. The overall sensitivity and specificity of a two-field nonmydriatic screening strategy with a threshold of mild retinopathy for referral of patients with insufficient image quality in at least one eye are 97.7% and 84.0% respectively.

INTERPRETATION

Our results suggest that two-field nonmydriatic camera imaging is a safe screening strategy that may identify the patients with diabetes most in need of ophthalmologic care.

Diabetic retinopathy

Diabetic retinopathy is the principal cause of irreversible blindness in patients of working age in the industrialized world (1,2). For some types of retinopathy (e.g., proliferative disease), effective treatment in the form of laser photocoagulation has been available for more than 20 years, but many patients seek help too late when treatment is no longer effective. Macular edema, which is much more common in patients with type 2 diabetes mellitus, may be the presenting sign and therefore may already be established at diagnosis. If vision is significantly reduced, current treatment options are often ineffective. Screening of diabetic persons for early signs of retinopathy, which are treatable, improves the visual prognosis. Medical factors such as good blood glucose control, management of hypertension, and regulation of blood lipid levels are also considered to be of major importance.