The diagnosis of diabetic retinopathy. Ophthalmoscopy versus fundus photography

RELIABILITY OF CLINICAL GRADING OF DIABETIC RETINOPATHY COMPARED WITH GRADING OF ULTRA-WIDEFIELD IMAGES

PURPOSE

To evaluate the reliability of clinical grading of diabetic retinopathy (DR) severity compared with grading on ultra-widefield pseudocolor fundus (UWF-CF) and ultra-widefield fluorescein angiography (UWF-FA) images and their relative detection of sight-threatening DR and referable DR.

METHODS

A total of 184 diabetic eyes were analyzed. UWF-CF and UWF-FA images were graded based on the International Clinical Diabetic Retinopathy severity scale. Agreement between clinical and UWF-based severity grading was evaluated using Cohen's kappa coefficient. The rate of sight-threatening DR and referable DR was evaluated for each grading method.

RESULTS

Moderate agreement was found between clinical grading and UWF-CF (k = 0.456, P < 0.001) and between UWF-CF and UWF-FA (k = 0.443, P < 0.001). The agreement between clinical grading and UWF-FA was fair (k = 0.397, P < 0.001). UWF-based grading identified a higher DR grade in 56 eyes (30%) on UWF-CF and 85 eyes (46.2%) on UWF-FA. Compared with clinical grading, UWF-FA detected a higher rate of sight-threatening DR (44%; 81/184 vs. 22.3%; 41/184), while UWF-CF detected more referable eyes (58.1%; 107/184 vs. 45.65%; 84/184).

CONCLUSION

Ultra-widefield pseudocolor fundus is a valuable tool for identifying referable eyes and can be a useful, noninvasive adjunct to clinical grading. The results suggest that UWF-FA is particularly useful for detecting unsuspected sight-threatening DR in eyes with clinically referable DR.

Imaging Modalities Employed in Diabetic Retinopathy Screening: A Review and Meta-Analysis

INTRODUCTION

Urbanization has caused dramatic changes in lifestyle, and these rapid transitions have led to an increased risk of noncommunicable diseases, such as type 2 diabetes. In terms of cost-effectiveness, screening for diabetic retinopathy is a critical aspect in diabetes management. The aim of this study was to review the imaging modalities employed for retinal examination in diabetic retinopathy screening.

METHODS

The PubMed and Web of Science databases were the main sources used to investigate the medical literature. An extensive search was performed to identify relevant articles concerning "imaging", "diabetic retinopathy" and "screening" up to 1 June 2021. Imaging techniques were divided into the following: (i) mydriatic fundus photography, (ii) non-mydriatic fundus photography, (iii) smartphone-based imaging, and (iv) ultrawide-field imaging. A meta-analysis was performed to analyze the performance and technical failure rate of each method.

RESULTS

The technical failure rates for mydriatic and non-mydriatic digital fundus photography, smartphone-based and ultrawide-field imaging were 3.4% (95% CI: 2.3-4.6%), 12.1% (95% CI: 5.4-18.7%), 5.3% (95% CI: 1.5-9.0%) and 2.2% (95% CI: 0.3-4.0%), respectively. The rate was significantly different between all analyzed techniques (p < 0.001), and the overall failure rate was 6.6% (4.9-8.3%; I2 = 97.2%). The publication bias factor for smartphone-based imaging was significantly higher than for mydriatic digital fundus photography and non-mydriatic digital fundus photography (b = -8.61, b = -2.59 and b = -7.03, respectively; p < 0.001). Ultrawide-field imaging studies were excluded from the final sensitivity/specificity analysis, as the total number of patients included was too small.

CONCLUSIONS

Regardless of the type of the device used, retinal photographs should be taken on eyes with dilated pupils, unless contraindicated, as this setting decreases the rate of ungradable images. Smartphone-based and ultrawide-field imaging may become potential alternative methods for optimized DR screening; however, there is not yet enough evidence for these techniques to displace mydriatic fundus photography.

An automated microaneurysm detector as a tool for identification of diabetic retinopathy in rural optometric practice

BACKGROUND

With the increase in the prevalence of diabetes, rural optometric clinics stand to increase their patient load and assessment of diabetic eye disease. This study aimed to assess whether automated identification of diabetic retinopathy based on the presence of microaneurysms is an effective tool in clinical practice.

METHODS

We analysed 758 fundal images of 385 patients with diabetes attending the clinic obtained using a Canon CR5 with an EOS10 digital camera through a dilated pupil. Five optometrists employed in the clinic assessed the diabetic retinopathy using binocular indirect ophthalmoscopy. The sensitivity and specificity of the automated system used to analyse the retinal fundal images was determined by comparison with optometric and ophthalmologic assessment.

RESULTS

The optometrists achieved 97 per cent sensitivity at 88 per cent specificity with respect to the ophthalmic classification for detecting retinopathy.

CONCLUSION

The automated retinopathy detector achieved 85 per cent sensitivity at 90 per cent specificity at detecting retinopathy. The automated microaneurysm detector has a lower sensitivity compared to the optometrists but meets NHMRC guidelines. It may impact on the efficiency of rural optometric practices by early identification of diabetic retinopathy. Automated assessment can save time and be cost-effective, and provide a history of changes in the retinal fundus and the opportunity for instant patient education using the digital images.

Investigating the Fractal Dimension of the Foveal Microvasculature in Relation to the Morphology of the Foveal Avascular Zone and to the Macular Circulation in Patients With Type 2 Diabetes Mellitus

In this study, we examined the relationship between the fractal dimension (FD), the morphology of the foveal avascular zone (FAZ) and the macular circulation in healthy controls and patients with type 2 diabetes mellitus (T2DM) with and with no diabetic retinopathy (DR). Cross-sectional data of 47 subjects were analyzed from a 5-year longitudinal study using a multimodal optical imaging approach. Healthy eyes from nondiabetic volunteers (n = 12) were selected as controls. Eyes from patients with T2DM were selected and divided into two groups: diabetic subjects with mild DR (MDR group, n = 15) and subjects with DM but without DR (DM group, n = 20). Our results demonstrated a higher FD in the healthy group (mean, 1.42 ± 0.03) than in the DM and MDR groups (1.39 ± 0.02 and 1.35 ± 0.03, respectively). Also, a bigger perimeter, area, and roundness of the FAZ were found in MDR eyes. A significant difference in area and perimeter (p ≤ 0.005) was observed for the MDR group supporting the enlargement of the FAZ due to diabetic complications in the eye. A moderate positive correlation (p = 0.014, R² = 43.8%) between the FD and blood flow rate (BFR) was only found in the healthy control group. The BFR calculations revealed the lowest values in the MDR group (0.98 ± 0.27 μl/s vs. 1.36 ± 0.86 μl/s and 1.36 ± 0.57 μl/sec in the MDR, DM, and healthy groups, respectively, p = 0.2). Our study suggests that the FD of the foveal vessel arborization could provide useful information to identify early morphological changes in the retina of patients with T2DM. Our results also indicate that the enlargement and asymmetry of the FAZ might be related to a lower BFR because of the DR onset and progression. Interestingly, due to the lack of FAZ symmetry observed in the DM and MDR eyes, it appears that the distribution of flow within the retinal vessels loses complexity as the vascular structures distributing the flow are not well described by fractal branching. Further research could determine how our approach may be used to aid the diagnosis of retinal neurodegeneration and vascular impairment at the early stage of DR.

Venous beading in two or more quadrants might not be a sensitive grading criterion for severe nonproliferative diabetic retinopathy

Purpose

To determine whether venous beading (VB) in two or more quadrants is an appropriate grading criterion for severe nonproliferative diabetic retinopathy (NPDR).

Methods

A hospital-based, retrospective, cross-sectional study. A total of 806 patients admitted with diabetic retinopathy (DR) from January 2014 to April 2017 were included in this study. DR severity was graded by the international grading criterion. The status of VB, intraretinal microvascular abnormalities (IRMA), capillary nonperfusion, arteriovenous nicking, and diabetic macular edema was evaluated based on fundus fluorescein angiography.

Results

The prevalence of VB in eyes with proliferative diabetic retinopathy (PDR), severe NPDR, and moderate NPDR was 41.3% (327/791), 5.9% (31/526), and 0% (0/295), respectively (p < 0.001). Moreover, the proportion of VB in two or more quadrants was even lower (27.1% for PDR and 2.1% for severe NPDR, p < 0.001), and among the total of 225 eyes with VB in two or more quadrants, 214 eyes (95.1%) were graded as PDR. Furthermore, VB formation was significantly correlated with capillary nonperfusion, duration of diabetes (both p < 0.001), and smoking (p < 0.05). After adjusting for age, sex, and other possible factors, VB (OR = 7.479, p < 0.001) and IRMA (OR = 2.433, p < 0.001) were determined as independent risk factors for developing PDR.

Conclusions

Our study suggested that VB in two or more quadrants might not be a sensitive grading criterion for severe NPDR among a Chinese population with type 2 diabetes. Nevertheless, VB has a great specificity to define an advanced form of DR.

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.

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.

SDOCT imaging to identify macular pathology in patients diagnosed with diabetic maculopathy by a digital photographic retinal screening programme

Introduction

Diabetic macular edema (DME) is an important cause of vision loss. England has a national systematic photographic retinal screening programme to identify patients with diabetic eye disease. Grading retinal photographs according to this national protocol identifies surrogate markers for DME. We audited a care pathway using a spectral-domain optical coherence tomography (SDOCT) clinic to identify macular pathology in this subset of patients.

Methods

A prospective audit was performed of patients referred from screening with mild to moderate non-proliferative diabetic retinopathy (R1) and surrogate markers for diabetic macular edema (M1) attending an SDOCT clinic. The SDOCT images were graded by an ophthalmologist as SDOCT positive, borderline or negative. SDOCT positive patients were referred to the medical retina clinic. SDOCT negative and borderline patients were further reviewed in the SDOCT clinic in 6 months.

Results

From a registered screening population of 17 551 patients with diabetes mellitus, 311 patients met the inclusion criteria between (March 2008 and September 2009). We analyzed images from 311 patients’ SDOCT clinic episodes. There were 131 SDOCT negative and 12 borderline patients booked for revisit in the OCT clinic. Twenty-four were referred back to photographic screening for a variety of reasons. A total of 144 were referred to ophthalmology with OCT evidence of definite macular pathology requiring review by an ophthalmologist.

Discussion

This analysis shows that patients with diabetes, mild to moderate non-proliferative diabetic retinopathy (R1) and evidence of diabetic maculopathy on non-stereoscopic retinal photographs (M1) have a 42.1% chance of having no macular edema on SDOCT imaging as defined by standard OCT definitions of DME when graded by a retinal specialist. SDOCT imaging is a useful adjunct to colour fundus photography in screening for referable diabetic maculopathy in our screening population.

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.

Comparison of dilated fundus examinations with seven-field stereo fundus photographs in the Veterans Affairs Diabetes Trial

OBJECTIVE

The Veterans Affairs Diabetes Trial (VADT) is a 20-medical center, prospective, randomized study of 1792 Type 2 diabetic individuals primarily aimed at determining whether intensive glycemic control prevents macrovascular events. We report a comparison of fundus photographs and ophthalmologic examination at baseline, permitting an evaluation of multiple settings similar to common clinical practice.

RESEARCH DESIGN AND METHODS

A 340-patient subset had both local dilated fundus examinations and centrally read seven-field stereo fundus photographs completed within 60 days of each other (median 28 days). Local examiners were unaware of the stereo photographs.

RESULTS

Overall, agreement within one step was 76% and exact agreement between ophthalmoscopy and central gradings of fundus photographs on a five-step retinopathy severity scale was 43% (weighted kappa 0.42, CI 0.35-0.48). In about 90% of disagreements the severity level was higher by photographic grading. The sensitivity for ophthalmoscopy compared to grading of fundus photographs for the detection of any retinopathy was 51% and specificity was 91%. For proliferative diabetic retinopathy (PDR), sensitivity was 61% and specificity 98%. Only one eye was high-risk PDR, and it was detected by both methods. For clinically significant macular edema, these measures were 24% and 98%, respectively. The disagreements were of possible clinical importance in three cases (<1%).

CONCLUSION

Most disagreements occurred in eyes rated near the milder end of a category and/or resulted from small differences between the ophthalmoscopic and photographic definitions used in classifying severity. There were reasonably few disagreements of possible clinical significance.

Global complication rates of type 2 diabetes in Indigenous peoples: A comprehensive review

INTRODUCTION AND OBJECTIVE

The world's Indigenous peoples are experiencing an unprecedented epidemic of type 2 diabetes [T2DM] but little has been published describing the complications burden. The objective of this paper was to conduct a systematic review of T2DM complications in Indigenous populations worldwide.

METHODS

A literature review was conducted using PubMed and EMBASE to examine available complications data. Country, Indigenous population, authors, publication year, total sample size, Indigenous sample size, age, methodology, and prevalence of nephropathy, end-stage renal disease, retinopathy, neuropathy, lower extremity amputations, cardiovascular disease, hospitalizations and mortality due to diabetes were recorded.

RESULTS

One-hundred and eleven studies were selected. Results revealed a disproportionate burden of disease complications among all Indigenous peoples regardless of their geographic location. Complication rates were seen to vary widely across Indigenous groups.

DISCUSSION

Gaps were found in the published literature on complications among Indigenous populations, especially those living in underdeveloped countries. These gaps may be in part due to the challenges caused by varying operational practices, research methodologies, and definitions of the term Indigenous, making documentation of rates among these peoples problematic. Comprehensive surveillance applying standardized definitions and methodologies is needed to design targeted prevention and disease management strategies for Indigenous peoples with T2DM.

Retinal vascular lesions in patients of Caucasian and Asian origin with type 2 diabetes: baseline results from the ADVANCE Retinal Measurements (AdRem) study

OBJECTIVE

The objective of this study was to describe prevalent vascular retinal lesions among patients with type 2 diabetes enrolled in the ADVANCE Retinal Measurements (AdRem) study, a substudy of the Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation (ADVANCE) trial.

RESEARCH DESIGN AND METHODS

Seven-field stereoscopic photographs of both eyes were obtained at the baseline assessment of the ADVANCE trial. All photographs were graded in a central reading center. Gradable retinal images were received from 1,605 patients.

RESULTS

The number of patients with any retinopathy (Early Treatment of Diabetic Retinopathy Study [ETDRS] score > or = 20) was 645 (40.2% [95% CI 37.8-42.6]); of these, 35 (2.2% [1.6-3.0]) had severe diabetic retinopathy (ETDRS score > or = 50). Focal arterial narrowing, venous beading, and arteriovenous nicking were present in 3.8, 5.1, and 9.8% of participants, respectively. Among participants included in this study, Chinese and South-Asian patients had more retinopathy than Caucasians, as defined both by ETDRS score (49.4, 46.0, and 31.3%, respectively; P < 0.001, adjusted for age, sex, A1C, systolic blood pressure, and duration of diabetes) and specific vascular lesions (e.g., arteriovenous nicking 12.3, 8.5, and 7.5%, respectively; adjusted P < 0.005). A1C, duration of diabetes, and systolic blood pressure were similarly associated with increased retinal lesions in Chinese, South-Asian, and Caucasian patients.

CONCLUSIONS

Using a sensitive diagnostic procedure, more than one-third of patients with type 2 diabetes enrolled in the AdRem study had retinal lesions at baseline. Despite differences in prevalence and severity of retinopathy among Chinese, South-Asian, and Caucasian patients included in this study, the cross-sectional associations among established risk factors for retinopathy and retinal lesions were similar across ethnic groups.

Rationale and design of the AdRem study: Evaluating the effects of blood pressure lowering and intensive glucose control on vascular retinal disorders in patients with type 2 diabetes mellitus

The ADVANCE Retinal Measurements (AdRem) Study is a large intervention study evaluating the effects of target driven intensive glucose control and placebo controlled blood pressure lowering on retinal vascular changes. AdRem is a sub-study of the ADVANCE Study (Action in Diabetes and Vascular disease), a 2x2 factorial randomized controlled trial with an ACE inhibitor-diuretic combination (perindopril-indapamide) and a gliclazide MR-based regimen in patients with type 2 diabetes mellitus. The AdRem study is based on seven-field stereoscopic retinal photographs of both eyes. These are taken within 3 months after randomization in ADVANCE (baseline), at the biennial and at the final visit. The primary outcome is progression of two or more steps in ETDRS classification. Secondary outcomes include progression of retinal vascular lesions and distortion of retinal vascular geometry. Retinal photographs are made on film and digitized at a central laboratory. The AdRem study uses fully digitized quality control and grading. Between August 2002 and January 2004 1978 patients were included in the AdRem study, from 39 centers in 14 countries. Approximately 85% comply with the strict AdRem quality requirements. Publication of the results is expected in early 2008. The AdRem study is designed to provide reliable evidence on the effects of intensive glucose control and blood pressure lowering on both diabetic retinopathy and abnormalities of retinal vasculature in patients with type 2 diabetes mellitus.

Feasibility Study on Computer-Aided Screening for Diabetic Retinopathy

PURPOSE

To conduct a feasibility study of computer-aided screening for diabetic retinopathy by developing a computerized program to automatically detect retinal changes from digital retinal images.

METHODS

The study was carried out in three steps. Step 1 was to collect baseline retinal image data of 600 eyes of normal subjects with normal fundi and data of 300 eyes of diabetic patients with diabetic retinopathy. All data were recorded by digital fundus camera. Step 2 was to analyse all retinal images for normal and abnormal features. By this method, the automated computerized screening program was developed. The program preprocesses colour retinal images and recognizes the main retinal components (optic disc, fovea, and blood vessels) and diabetic features such as exudates, haemorrhages, and microaneurysms. All of the accumulated information is interpreted as normal, abnormal, or unknown. Step 3 was to evaluate the sensitivity and specificity of the computerized screening program by testing the program on diabetic patients and comparing the program's results with the results of screening by retinal specialists.

RESULTS

Diabetic patients (182 patients, 336 eyes) were examined by retinal specialists; 221 eyes had a normal fundus and 115 eyes had nonproliferative diabetic retinopathy. Digital retinal images were taken of these 336 eyes and interpreted by the automated screening program. The program had a sensitivity and specificity of 74.8% and 82.7%, respectively.

CONCLUSIONS

The automated screening program was able to differentiate between the normal fundus and the diabetic retinopathy fundus. The program may be beneficial for use in screening for diabetic retinopathy. Further development of the program may provide higher sensitivity.

Use of telemedicine in screening for diabetic retinopathy

BACKGROUND

A diabetic retinopathy screening program was introduced in September 2000 at a university-affiliated hospital in Montreal to meet the demands of an overburdened health care system. In this article we describe our initial experience with this program.

METHODS

A Canon CR6-45NM nonmydriatic 45 degrees camera was installed in the outpatient endocrinology clinic of the hospital. All patients who visited the clinic between September 2000 and January 2001 agreed to participate in the program. For each patient, a short questionnaire (age, sex, type of diabetes mellitus, time since diagnosis, prior retinal laser therapy and presence of end-organ involvement) was filled in. Subsequently at least two photographs were obtained of each eye. The photographs were sent via the hospital intranet to a retinal specialist within the hospital. The specialist reviewed the images unchanged and sent a report (grading of the level of diabetic retinopathy, presence or absence of macular hard exudates, quality of the images obtained and follow-up recommendations) via the hospital intranet to the endocrinology service. If the images were judged to be of poor quality and could not be read by the retina specialist, the patient was asked to see his or her regular ophthalmologist.

RESULTS

Images of 830 eyes of 415 patients (211 men and 204 women with a mean age of 57.5 years) were obtained. Most (83.6%) had type 2 diabetes. The average duration of disease was 13.3 years. Macular hard exudates were observed in 50 eyes (6.0%). Nonproliferative diabetic retinopathy was noted in 117 eyes (14.1%) and proliferative diabetic retinopathy in 15 eyes (1.8%). Unexpected findings included epiretinal membranes (in three eyes), macular holes (in two), bilateral cotton-wool spots (in one patient) and central retinal vein occlusion (in one eye). Overall, 10% of the patients were referred to a retina specialist based on the screening photographs. The main difficulty encountered with the screening program was image inconsistency. Overall, 35% of the images graded were felt to be of poor quality, the most common reason being poor exposure (84.4%). The quality of the images improved significantly over the study period (p < 0.01). Images obtained from patients aged 65 years or more were consistently poorer than those obtained from patients less than 65 years of age (p < 0.001).

INTERPRETATION

Despite the imperfections of such a system, our experience was favourable, allowing us to screen large numbers of patients in a cost-effective, reliable manner.

Evaluation of a new non-mydriatic digital camera for detection of diabetic retinopathy

AIMS

To compare the results of fundus photography using a new non-mydriatic digital camera with the results of reference standard of Early Treatment Diabetic Retinopathy Study (ETDRS) retinal photographs, for the detection of diabetic retinopathy (DR).

METHODS

Fundus colour photographs were taken with a Topcon non-mydriatic camera of 147 eyes of 74 diabetic patients, without pupillary dilation (five overlapping fields of 45 degrees; posterior pole, nasal, temporal, superior and inferior). Three retinal specialists classified the photographs in a masked fashion, as showing no DR or mild non-proliferative DR (NPDR) not requiring referral, moderate or more severe NPDR and/or macular oedema, or as non-gradable image requiring referral. ETDRS 35-mm colour slides served as reference images for DR detection.

RESULTS

For moderately severe to severe DR, the sensitivities of detection reported by the three observers were 92, 100 and 92%, respectively, and the specificities, 87, 85, and 88%. For four levels of DR severity (none or mild NPDR, moderate NPDR, severe NPDR and proliferative DR), the percentages of exact agreement between the three observers on the retinopathy grades assigned to the non-mydriatic photographs and to the ETDRS reference slides were 94.6, 93 and 87.6%, respectively (kappa 0.60-0.80). Sixteen eyes of nine patients (11%) were judged ungradable by at least one observer. In a second series of 110 patients, evaluated in the setting of a screening procedure, fewer photographs were ungradable (< 6%).

CONCLUSION

These results suggest that fundus photographs taken by the Topcon TRC-NW6S non-mydriatic camera, without pupillary dilation, are suitable for DR screening.

Changing times for the management of diabetic retinopathy

Laser photocoagulation has led a revolution in the management of diabetic retinopathy. Scatter photocoagulation and focal photocoagulation has been shown to be effective in reducing vision loss. Just as dramatic as laser photocoagulation, medical treatment has led another revolution in the treatment of diabetic retinopathy. Good glycemic, blood pressure, and lipid control have contributed to further reduce vision loss and laser photocoagulation. In the very near future, there will be significant advances in pharmacologic treatment of diabetic retinopathy. Treatment with antioxidants, agents inhibiting hyperglycemia-induced protein kinase activity, and other agents will likely prevent the development/progression of retinopathy. Because pharmacologic agents are aimed at the prevention of retinopathy, patients with retinopathy will need to be examined earlier to diagnose retinopathy at earlier stages. To maximize the opportunity for earlier diagnosis, ophthalmologist may need to adopt screening strategies to identify patients most likely to benefit from these new treatments.

Fundus imaging and the telemedical management of diabetes

Diabetes is the major preventable form of blindness among people of working age in the Western world, despite the improvements in laser photocoagulation treatments. It is known that regular glycaemic control and annual retinal screening of people with diabetes can reduce its incidence. Effective treatment needs to be available but also screening methods which are simple to perform and cost-effective should be implemented. It will be important in future to integrate digital images of the fundus into the health records of diabetic patients. Screening programmes for the detection of diabetic retinopathy aided by image-processing software for processing fundus images will save manpower and increase quality. Before this can happen, we need more clinical studies of store-and-forward techniques, so that they can be standardized and their effectiveness established against that of traditional analogue screening.

The sensitivity and specificity of single-field nonmydriatic monochromatic digital fundus photography with remote image interpretation for diabetic retinopathy screening: a comparison with ophthalmoscopy and standardized mydriatic color photography

PURPOSE

To evaluate single-field digital monochromatic nonmydriatic fundus photography as an adjunct in the screening of diabetic retinopathy.

DESIGN

Prospective, comparative, observational case series.

METHODS

Patients with type I and type II diabetes mellitus (n = 197) were sequentially evaluated by three different techniques: single-field digital monochromatic nonmydriatic photography; dilated ophthalmoscopy by an ophthalmologist; and seven Early Treatment Diabetic Retinopathy Study (ETDRS) standardized 35-mm color stereoscopic mydriatic images. The seven stereoscopic color photographs served as the reference standard and were compared with either ophthalmoscopy or a single digital photograph transmitted electronically to a reading site. Levels of agreement were determined by kappa analyses. The sensitivity and specificity of the three methods were compared based on a threshold for referral to further ophthalmologic evaluation (ETDRS level > or =35).

RESULTS

There was highly significant agreement (kappa = 0.97, P =.0001) between the degree of retinopathy detected by a single nonmydriatic monochromatic digital photograph and that seen in seven standard 35-mm color stereoscopic mydriatic fields. The sensitivity of digital photography compared with color photography was 78%, with a specificity of 86%. Agreement was poor (kappa = 0.40, P =.0001) between mydriatic ophthalmoscopy and the seven-field standard 35-mm color photographs. Sensitivity of ophthalmoscopy compared with color photography was 34%, with a specificity of 100%.

CONCLUSION

A single nonmydriatic monochromatic wide-field digital photograph of the disk and macula was more sensitive for diabetic retinopathy screening than mydriatic ophthalmoscopy, the currently accepted screening method. When adjudicated by standard seven-field color photographs, the higher sensitivity of digital photography primarily reflected the reduced sensitivity of ophthalmoscopy in detecting early retinopathy.

The detection of diabetic retinopathy by Australian optometrists

BACKGROUND

Diabetes mellitus is a systemic disease affecting approximately 750,000 Australians of whom more than 70,000 are Queenslanders. It can have serious ocular consequences and patients with diabetes require regular eye examinations to determine the degree of ocular involvement and the stage of retinopathy, if present. It is important that optometrists detect diabetic retinal changes and refer appropriately. We sought to determine the proficiency of optometrists at detecting retinal changes caused by diabetes.

METHODS

The study comprised four parts: 1. Nineteen randomly recruited Australian optometrists practising in Queensland completed a questionnaire on their experiences seeing patients with diabetes. 2. They examined the ocular fundi of 10 patients. 3. They viewed retinal slides of 12 additional cases. 4. They attended a follow-up seminar on diabetes and the cases. They were informed that the patients did not necessarily have diabetes and instructed not to discuss the condition with the patient or their colleagues. The optometrists were allowed seven minutes per station to examine the patient or the slides and write down their responses before moving to the next station.

RESULTS

When the slides and patients were considered together, cases where diabetic retinopathy was present were correctly identified by 94.0 per cent of the optometrists and cases where retinopathy was not present were correctly identified by 93.6 per cent of the optometrists. When all assessments were considered together, the correct detection/differential diagnosis rate was 88.3 per cent. Sub-classification of diabetic retinopathy severity agreed with that of the reference examiners in 58.3 per cent of assessments and there was agreement on management in 79.4 per cent of cases. Of the 22 assessments undertaken by each optometrist, there were, on average, 2.5 errors.

CONCLUSION

Randomly selected Australian optometrists are able to detect and grade diabetic retinal changes solely by retinal examination and refer the patients requiring specialist care.

High-resolution stereoscopic digital fundus photography versus contact lens biomicroscopy for the detection of clinically significant macular edema

PURPOSE

The purpose of this study was to compare high-resolution stereoscopic digital photography to contact lens biomicroscopy (CLBM) for the diagnosis of clinically significant macular edema.

STUDY DESIGN

Comparative, prospective, observational case series.

PARTICIPANTS

One hundred twenty diabetic patients.

METHODS

Patients underwent clinical retinal examination with CLBM by a retinal specialist. On the same day as clinical grading, patients received high-resolution stereoscopic digital imaging of the macula. The stereoscopic digital images were viewed using liquid crystal shutter goggles at least 2 months after clinical examination by a single masked grader for the presence or absence of diabetic retinopathy.

MAIN OUTCOME MEASURES

Presence or absence of the Early Treatment of Diabetic Retinopathy Study criteria for clinically significant macular edema (CSME) overall, CSME 1, CSME 2, CSME 3, macular edema, microaneurysms, intraretinal hemorrhage, and hard exudate.

RESULTS

Two hundred seven eyes of 105 patients had complete data sets from both diagnostic modalities. Exact agreement was high for all identified pathologic conditions: CSME overall, 83.6%; CSME 1, 83.6%; CSME 2, 96.1%; CSME 3, 88.5%; macular edema, 75.0%; microaneurysms, 77.9%; intraretinal hemorrhage, 83.7%; and hard exudate, 73.1%. Sensitivity ranged from 50.0% (CSME 2) to 90.6% (CSME overall). Specificity ranged from 90.0% (macular edema) to 99.0% (CSME 2).

CONCLUSIONS

High-resolution stereoscopic digital photography is both sensitive and specific when identifying CSME and correlates well with the accepted standard of CLBM for the diagnosis of CSME.

Two-field photography can identify patients with vision-threatening diabetic retinopathy: a screening approach in the primary care setting

OBJECTIVE

To compare the effectiveness of two 45 degrees photographic fields per eye in the screening for diabetic retinopathy with the routine ophthalmologist's examination and to study the effectiveness of visual acuity measurement in the detection of diabetic macular edema.

RESEARCH DESIGN AND METHODS

Type 1 and 2 diabetic patients without a known history of more than minimal retinopathy (n = 469) had a routine examination by an ophthalmologist, including visual acuity measurement, indirect retinoscopy, and biomicroscopy. At the same time, two-field nonstereoscopic retinal photographs were made of both eyes and assessed in a masked fashion by a retinal specialist. The results were compared.

RESULTS

The prevalence was 4.3% for vision-threatening retinopathy and 24% for any retinopathy. The sensitivity of two-field photography in identifying diabetic patients with sight-threatening retinopathy was 95% (specificity 99%) and sensitivity for detecting any retinopathy was 83% (specificity 88%). The percentage of referrals to an ophthalmologist was 6.2%. All patients with macular edema detected by biomicroscopy were classified as having vision-threatening retinopathy on the photographs.

CONCLUSIONS

Two-field retinal photography is a promising alternative to the routine ophthalmologist's examination in the screening for diabetic retinopathy. Visual acuity measurement is not a sensitive tool for the detection of macular edema. Screening for diabetic retinopathy using two-field retinal photography is feasible in a primary care setting and can substantially lower the number of ophthalmic referrals.

Costs of mobile screening for diabetic retinopathy: a practical framework for rural populations

Australia's rural and remote residents experience considerably higher hospitalisation and death rates due to diabetes than their metropolitan counterparts. There is clearly a need for improved diabetes care services in these areas and interventions that target conditions associated with diabetes will yield beneficial results for the community. All people with diabetes are at risk for diabetic retinopathy, which can cause vision loss and blindness. Although vision loss and blindness due to diabetes is nearly 100% preventable through regular eye examinations, 35% of Victoria's rural population with diabetes do not have their eyes examined on a regular basis. A pilot, mobile screening program for the early detection of diabetic eye disease was conducted in rural Victoria and proved to be a successful model of adjunct eye care for people with diabetes. Actual costs from the pilot screening were applied to a permanent model for rural eye care. At A$41 per participant, costs for mobile screening were competitive with Medicare rebate costs for eye examinations. The model addresses barriers of accessibility and availability, targets a portion of the rural population with diabetes that is not otherwise having eye examinations, and is cost-saving to the Government.

Performance characteristics of digital fundus photography as a screening test for diabetic retinopathy in a low-risk population

The purpose of the present study was to estimate the sensitivity and specificity of reviewers' assessments of digital fundus photography (DFP) images, using the findings from comprehensive ophthalmologic examination as the criterion standard. One hundred and fifty-two patients with diabetes underwent comprehensive ophthalmologic examination by an active duty U.S. Air Force (ADAF) staff ophthalmologist, and the examination findings were used as the criterion standard for the present study. Eight other ophthalmologists (M.D.'s) and 10 optometrists (O.D.'s), all ADAF providers, each evaluated seven nonstereo standard field DFP images from the left and right eyes (14 images per patient) of the 152 diabetic patients, assessing each patient for evidence of diabetic retinopathy (yes, no, not sure). The sensitivity, specificity, and proportion of "not sure" responses were computed separately for MD and OD reviewers and then compared. O.D. reviewers gave "not sure" responses more frequently than M.D.'s. With "not sure" responses treated as correct (i.e., identical to the results of ophthalmologic examination), both types of providers had 100% sensitivity for cases that are usually treated and 83% sensitivity for cases that are not usually treated but require close follow-up. Specificity (for any diabetic retinopathy) was 92% for M.D.'s and 93% for O.D.'s. With M.D.'s as photographic reviewers, DFP-based screening required only 27 ophthalmologic examinations per 100 patients screened; with O.D.'s as photographic reviewers, 31 ophthalmologic examinations were required per 100 patients screened. Using either ophthalmologists or optometrists as photographic reviewers, DFP-based screening for diabetic retinopathy has very good sensitivity and excellent specificity.

Telemedicine screening of glaucoma

OBJECTIVES

Glaucoma is a major cause of blindness. More than 80,000 Americans suffer permanent vision loss from the disease. Widespread screening is fundamental in limiting the incidence of glaucoma-associated blindness. This pilot study explored the use of stereo digital images taken at a primary care center for telemedicine review by an off-site specialist as a means of screening for glaucoma.

MATERIALS AND METHODS

Thirty-two diabetic patients were screened at a family medicine clinic. None had previously been diagnosed with glaucoma. A senior optometry student took stereoscopic digital and 35-mm optic disc photographs with a nonmydriatic retinal camera. The digital images were forwarded to a remote ophthalmologist for review. The conventional color stereo slide pairs of the same eyes were subsequently reviewed for comparison. Agreement on signs of glaucomatous disc changes between the two imaging systems was analyzed.

RESULTS

Twenty-six of 32 eyes' digital and 35-mm photographs were analyzed. Six of 32 eyes (18.8%) could not be compared due to lack of matching 35-mm slides or digital images. Out of 26 eyes, lamina cribosa visibility was undeterminable in 8 eyes' digital images and 3 other eyes' 35-mm slides. Agreement among digital images and 35-mm slides of the remaining eyes was: 100%-vertical elongation, barring of vessels, bayoneting of vessels, and drance hemorrhage; 96.2%-focus notching of rim and rim pallor; 93.3%-lamina cribosa visability; 92. 3%-overpass cupping; 88.5%-focal enlargement; 84.6%-parapapillary halo; 80%-nerve fiber visibility; 65.4%-parapapillary atrophy. Parapapillary halo (p = 0.046) and nerve fiber layer visibility (p = 0.18) were detected on some 35-mm slides but not seen on matching digital views.

CONCLUSION

Evaluations of cup-to-disc ratio (C/D) using both methods were in general agreement. However, some digital images were noted as too dark for assessing fine glaucomatous disc changes. Stereo digital images taken with a nonmydriatic camera by nonophthalmic photographers is a promising alternative for glaucoma screening in primary care settings. Telemedicine offers efficient communications with off-site glaucoma specialists. A larger study population is necessary to determine the overall effectiveness of using stereo digital imagery and teleophthalmology for glaucoma screening.

Risk factors for diabetic retinopathy among Saudi diabetics

PURPOSE

To describe the incidence of, and risk factors associated with, diabetic retinopathy in diabetic persons assessed at a Saudi diabetes centre.

METHODS

Five hundred and two patients with diabetes mellitus assessed by our service were studied. There were 174 patients (34.7%) with insulin-dependent diabetes mellitus (IDDM) and 328 patients (65.3%) with non-insulin-dependent diabetes mellitus (NIDDM).

RESULTS

The incidence of retinopathy was 157/502 (31.3%). The incidence was 42.5% in patients with IDDM and 25.3% in those with NIDDM. By logistic regression analysis, it was shown that old age (>60 years), insulin use, long duration of diabetes (>10 years), poor diabetes control, and the presence of nephropathy were significantly associated with the incidence of retinopathy. On the basis of the magnitudes of the regression coefficients in the hazard function, long duration of diabetes was the most important independent risk factor for the development of retinopathy; the presence of nephropathy, age >60 years, poor diabetes control, and use of insulin were less important (regression coefficients: 1.9, 1.71, 1.331, 0.8508 and 0.6178, respectively). The incidence of macular oedema was significantly associated with the presence of hypertension and high cholesterol levels in patients with IDDM. Polycotomous regression analysis showed that the presence of nephropathy was the only factor significantly associated with the severity of retinopathy.

CONCLUSIONS

The significant associations with poor control and duration of diabetes provide further strong evidence for the benefits of optimal glycaemic control. Other potentially modifiable risk factors for retinopathy may be important, including elevated blood pressure and serum cholesterol.

Automated localisation of the optic disc, fovea, and retinal blood vessels from digital colour fundus images

AIM

To recognise automatically the main components of the fundus on digital colour images.

METHODS

The main features of a fundus retinal image were defined as the optic disc, fovea, and blood vessels. Methods are described for their automatic recognition and location. 112 retinal images were preprocessed via adaptive, local, contrast enhancement. The optic discs were located by identifying the area with the highest variation in intensity of adjacent pixels. Blood vessels were identified by means of a multilayer perceptron neural net, for which the inputs were derived from a principal component analysis (PCA) of the image and edge detection of the first component of PCA. The foveas were identified using matching correlation together with characteristics typical of a fovea-for example, darkest area in the neighbourhood of the optic disc. The main components of the image were identified by an experienced ophthalmologist for comparison with computerised methods.

RESULTS

The sensitivity and specificity of the recognition of each retinal main component was as follows: 99.1% and 99.1% for the optic disc; 83.3% and 91.0% for blood vessels; 80.4% and 99.1% for the fovea.

CONCLUSIONS

In this study the optic disc, blood vessels, and fovea were accurately detected. The identification of the normal components of the retinal image will aid the future detection of diseases in these regions. In diabetic retinopathy, for example, an image could be analysed for retinopathy with reference to sight threatening complications such as disc neovascularisation, vascular changes, or foveal exudation.

The role of digital fundus photography in diabetic retinopathy screening. Digital Diabetic Screening Group (DDSG)

PURPOSE

The role of digital monochromatic nonmydriatic fundus photography as an adjunct in the diagnosis of diabetic retinopathy is evaluated.

METHODS

197 patients were sequentially evaluated by three different techniques: dilated ophthalmoscopy by an experienced ophthalmologist, performance of 7 standard color mydriatic stereo fields, and a single digital monochromatic nonmydriatic image incorporating the disc and macula. Stereo color photographs served as the reference standard and were compared to either ophthalmoscopy performed by a physician, or a single digital photograph transmitted electronically to a reading site and evaluated by a trained non-physician grader. Sensitivity and specificity of the three methods were compared. The decision as to whether or not to refer to an ophthalmologist for potential treatment (Kaiser modified ETDRS level > 21) was then chosen for analysis.

RESULTS

A single nonmydriatic monochromatic digital photograph appeared equivalent to standard color photography and more sensitive than mydriatic ophthalmoscopy in the detection of diabetic retinopathy in this patient population. Sensitivity of digital photography compared with color photography was 78%, and the specificity 86% contrasted with comparable ratios of 34% and 100% for ophthalmoscopy versus color photography. No patient identified by ophthalmoscopy alone for referral based on retinopathy level of > 21 would have been missed by a single digital monochromatic photographic image.

CONCLUSION

A single nonmydriatic monochromatic wide field digital photograph of the disc and macula in diabetic patients is a sensitive and cost-effective means for detecting diabetic retinopathy in high-risk populations.

Screening for diabetic retinopathy using a non-mydriatic retinal camera in rural Victoria

PURPOSE

To develop a screening programme for the early detection of diabetic retinopathy using non-mydriatic retinal photography.

METHODS

A community based screening service was offered to all people with known diabetes mellitus in selected townships in the LaTrobe and Goulburn Valleys in Victoria. At the local examination centre, basic sociodemographic information was collected as well as details of previous use of eye care services for the early detection of diabetic retinopathy. The examination included visual acuity (VA), glycosylated haemoglobin level and Polaroid photographs of each fundus using a Canon CR5-45NM non-mydriatic retinal camera (Canon, Tochigiken, Japan). Dilating drops were not used. Photographs were subsequently reviewed and letters were sent to all participants (with copies to their general practitioners) with recommendations for appropriate follow up.

RESULTS

A total of 1177 people with diabetes attended the screening service, which is estimated to be 40% of the total population with known diabetes in the study area. The mean age was 65 years (range 20-94 years); 559 (48%) people reported not having a dilated fundus examination within the past 2 years; 345 (29%) people had never had a dilated fundus examination. Of the 2354 eyes, 2126 (90%) of the photographs were gradable. A total of 704 people (60%) had normal VA and no evidence of diabetic retinopathy, 209 people (18%) had diabetic retinopathy, 101 people (9%) had evidence of other fundus pathology, 42 people (3%) had reduced acuity (< 6/18) in one or both eyes (with no fundus pathology evident) and 121 people (10%) had ungradable photographs in one or both eyes.

CONCLUSIONS

The present study demonstrates the usefulness of a screening programme with non-mydriatic retinal photography as an adjunct to current eye care services for the early detection of diabetic retinopathy.

Use of focus groups to identify health promotion strategies for the early detection of diabetic retinopathy

BACKGROUND

People with diabetes do not regularly utilise eye services for the early prevention of vision loss due to diabetic eye disease. A community-based screening program has been initiated in Victoria to address this issue. To encourage people to take preventive eye health care measures, the most effective health promotion strategies were identified.

METHODS

Thirty-three health professionals were invited to attend focus groups. A sample of 35 people with diabetes was approached by their GPs or diabetes educators because of their motivation to participate in diabetes activities. Each group consisted of 10 members. Discussion points included the type of education messages available to people with diabetes; use of eye services among the participants with diabetes; and strategies required promoting the screening service.

RESULTS

Five focus groups were conducted. The discussions highlighted that a great deal could be achieved by using local community networks to promote the benefits of early detection of diabetic retinopathy and local screening program. The group members recommended that particular attention be directed to general practitioners and their distribution of materials to patients. Key issues for planning and implementing the program were highlighted. The groups urged development of strategies to encourage people with diabetes in rural Victoria to participate in a program for the early detection of diabetic retinopathy.

Automatic detection of diabetic retinopathy using an artificial neural network: a screening tool

AIMS

To determine if neural networks can detect diabetic features in fundus images and compare the network against an ophthalmologist screening a set of fundus images.

METHODS

147 diabetic and 32 normal images were captured from a fundus camera, stored on computer, and analysed using a back propagation neural network. The network was trained to recognise features in the retinal image. The effects of digital filtering techniques and different network variables were assessed. 200 diabetic and 101 normal images were then randomised and used to evaluate the network's performance for the detection of diabetic retinopathy against an ophthalmologist.

RESULTS

Detection rates for the recognition of vessels, exudates, and haemorrhages were 91.7%, 93.1%, and 73.8% respectively. When compared with the results of the ophthalmologist, the network achieved a sensitivity of 88.4% and a specificity of 83.5% for the detection of diabetic retinopathy.

CONCLUSIONS

Detection of vessels, exudates, and haemorrhages was possible, with success rates dependent upon preprocessing and the number of images used in training. When compared with the ophthalmologist, the network achieved good accuracy for the detection of diabetic retinopathy. The system could be used as an aid to the screening of diabetic patients for retinopathy.

Detection of diabetic macular edema: Nidek 3Dx stereophotography compared with fundus biomicroscopy

PURPOSE

To assess the use of the Nidek 3Dx simultaneous stereophotography camera in diabetic patients, comparing the detection of clinically significant macular edema by fundus biomicroscopy to detection by the Nidek 3Dx simultaneous fundus stereophotograph.

METHODS

Two hundred eight eyes of 123 diabetic patients at the Wilmer Retinal Vascular Center were examined for this prospective study between August 1993 and October 1993. Each patient was examined by one of three retina specialists by contact lens biomicroscopy for clinically significant macular edema and foveal center thickening. Nidek 3Dx fundus stereophotographs were obtained and graded independently for clinically significant macular edema and foveal center thickening by a fourth ophthalmologist masked from the clinical examination findings. Percent agreement, kappa statistic, and weighted kappa statistic were determined for the two diagnostic methods.

RESULTS

One hundred eighty-four (88%) of the 208 stereophotographs were of sufficient quality to detect clinically significant macular edema; 175 (84%) of the 208 stereophotographs detected foveal center thickening. The agreement between the clinician and the photographic grading, measured by weighted kappa, was 0.52 for clinically significant macular edema and 0.58 for foveal center thickening, representing fair to good agreement beyond chance. Agreement was improved when normal fundus Nidek stereophotographs were available as standards for comparison.

CONCLUSIONS

The Nidek 3Dx camera is suitable for photographic detection of clinically significant macular edema and may have a potential advantage over conventional cameras by achieving good-quality, gradable stereophotographs in a large proportion of photographed eyes.

Adding retinal photography to screening for diabetic retinopathy: a prospective study in primary care

OBJECTIVE

To evaluate whether adding retinal photography improved community screening for diabetic retinopathy.

SETTING

Mobile screening unit at rural and urban general practices in south west England.

SUBJECTS

1010 diabetic patients from primary care.

DESIGN

Prospective study; patients were examined by ophthalmoscopy by general practitioners or opticians without fundal photographs and again with photographs, and assessments were compared to those of an ophthalmologist.

MAIN OUTCOME MEASURES

Whether fundal photography improved the sensitivity of detection of retinopathy and referrable diabetic retinopathy, and whether this sensitivity could be improved by including a review of the films by the specialist.

RESULTS

Diabetic retinopathy was detected by the ophthalmologist in 205 patients (20.5%) and referrable retinopathy in 49 (4.9%). The sensitivity of the general practitioners and opticians for referrable retinopathy with ophthalmoscopy was 65%, and improved to 84% with retinal photographs. General practitioners' sensitivity in detecting background retinopathy improved with photographs from 22% to 65%; opticians' sensitivity in detecting background retinopathy improved from 43% to 71%. The sensitivity of detecting referrable retinopathy by general practitioners improved from 56% to 80% with photographs; for opticians it improved from 75% to 88%.

CONCLUSIONS

Combining modalities of screening by providing photography with specialist review of all films in addition to direct ophthalmoscopy through dilated pupils improves assessment and referral for diabetic retinopathy by general practitioners and opticians. With further training and experience, primary care screeners should be able to achieve a sensitivity that will achieve an effective, acceptable, and economical community based screening programme for this condition.