Strategies of Digital Fundus Photography for Screening Diabetic Retinopathy in a Diabetic Population in Urban China

Validation of handheld fundus camera with mydriasis for retinal imaging of diabetic retinopathy screening in China: a prospective comparison study

OBJECTIVES

To investigate the clinical validity of using a handheld fundus camera to detect diabetic retinopathy (DR) in China.

DESIGN AND SETTINGS

Prospective comparison study of the handheld fundus camera with a standard validated instrument in detection of DR in hospital and a community screening clinic in Guangdong Province, China.

PARTICIPANTS

Participants aged 18 years and over with diabetes who were able to provide informed consent and agreed to attend the dilated eye examination with handheld tests and a standard desktop camera.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was the proportion of those with referable DR (R2 and above) identified by the handheld fundus camera (the index test) compared with the standard camera. Secondary outcome was the comparison of proportion of gradable images obtained from each test.

RESULTS

In this study, we examined 304 people (608 eyes) with each of the two cameras under mydriasis. The handheld camera detected 119 eyes (19.5%) with some level of DR, 81 (13.3%) of them were referable, while the standard camera detected 132 eyes (21.7%) with some level of DR and 83 (13.7%) were referable. It seems that the standard camera found more eyes with referable DR, although McNemar's test detected no significant difference between the two cameras.Of the 608 eyes with images obtained by desktop camera, 598 (98.4%) images were of sufficient quality for grading, 12 (1.9%) images were not gradable. By the handheld camera, 590 (97.0%) were gradable and 20 (3.2%) images were not gradable.The two cameras reached high agreement on diagnosis of retinopathy and maculopathy at all the levels of retinopathy.

CONCLUSION

Although it could not take the place of standard desktop camera on clinic fundus examination, the handheld fundus camera showed promising role on preliminary DR screening at primary level in China. To ensure quality images, mydriasis is required.

A Unique Experience of Retinal Diseases Screening in Nepal

Background

Recently, the number of retinal patients is increasing in Nepal. The retinal problems are the second common cause of blindness in Nepal. Retinal diseases are challenging to manage due to the lack of simple and cost-effective screening methods, limited human resources, poverty, and lack of awareness in Nepal. Hospital for Children, Eye, ENT & Rehabilitation Services (CHEERS), Nepal conducted retina screening camps and education in communities through Retina Eye Care of Nepal project (RECON) in the years 2017 and 2018.

Materials and Methods

We screened retinal patients with an indirect ophthalmoscope coupled with plus 20 Dioptre lens and portable fundus camera. We referred the patients needing interventions to the base hospital (CHEERS) using a screening algorithm, where they received retinal laser and surgery. Besides, we also provided on-site educational programs for retinal disease awareness to the community.

Results

Retinal problems found from two static outreach clinics (SORC) and a day screening and treatment service (DSTS) were 18.3%, 20%, and 20%, respectively, while from a remote rural health camp (RRHC) was 2.61%. Likewise, patients referred to CHEERS for retinal laser or other retinal interventions were 15%, 16.6%, 16%, and 1.96% from 2 SORCs, 1 DSTS, and 1 RRHC, respectively.

Conclusion

Retina camp is a cost-effective approach to early detection and referral for retinal-related vision impairment patients. It is also one opportunity to educate the community. The purpose of the project was to provide retina care to the community who otherwise could not afford it. We recommend a similar screening model on a large scale in a low-resource setting for the maximum benefits to the rural community.

[Screening for diabetic retinopathy by non-mydriatic fundus photography: First national campaign in Lebanon]

INTRODUCTION

Diabetic retinopathy (DR) is a leading cause of blindness worldwide. Non-mydriatic fundus photography (NMFP) has been adopted as a screening tool for this disease. We aim to determine the prevalence of DR through this method in Lebanese diabetic patients and to evaluate the impact of such screening in this population.

MATERIALS AND METHODS

This study explores data from an awareness and screening campaign conducted in Lebanon. Diabetic patients from multiple regions were referred by their endocrinologists to undergo NMFP using the Optomed SmartScope^® handheld fundus camera. Photographs were interpreted by a remote observer, and recommendations were given accordingly. The prevalence of DR was calculated, and statistical analyses were performed on the clinical characteristics, fundus findings and number of referrals to ophthalmologists.

RESULTS

The campaign lasted 11 months, during which 2205 patients were examined in 37 screening locations. Out of the 97.41% of patients with type 2 diabetes mellitus, 12.56% had signs of DR, with no significant difference between the regions. 6.28% of the photos were uninterpretable. Positive results were associated with a longer duration of diabetes (P<0.01), treatment with insulin (P<0.01), as well as the presence and chronicity of systemic hypertension (P=0.01). 25% of patients with positive testing were retrospectively asked about their follow-up; only one third had an ophthalmologic examination as per the recommendation, among whom 68.18% underwent treatment for proliferative DR and/or diabetic macular edema.

CONCLUSION

Tele-ophthalmology is useful in mass screening for DR. The importance of dilated fundus examinations still needs to be highlighted for diabetic patients, and better collaboration between endocrinologists and ophthalmologists is required to improve screening outcomes.

Systematic review and meta-analysis of diagnostic accuracy of detection of any level of diabetic retinopathy using digital retinal imaging

BACKGROUND

Visual impairment from diabetic retinopathy (DR) is an increasing global public health concern, which is preventable with screening and early treatment. Digital retinal imaging has become a preferred choice as it enables higher coverage of screening. The aim of this review is to evaluate how different characteristics of the DR screening (DRS) test impact on diagnostic test accuracy (DTA) and its relevance to a low-income setting.

METHODS

We conducted a systematic literature search to identify clinic-based studies on DRS using digital retinal imaging of people with DM (PwDM). Summary estimates of different sub-groups were calculated using DTA values weighted according to the sample size. The DTA of each screening method was derived after exclusion of ungradable images and considering the eye as the unit of analysis. The meta-analysis included studies which measured DTA of detecting any level of DR. We also examined the effect on detection from using different combinations of retinal fields, pupil status, index test graders and setting.

RESULTS

Six thousand six hundred forty-six titles and abstracts were retrieved, and data were extracted from 122 potentially eligible full reports. Twenty-six studies were included in the review, and 21 studies, mostly from high-income settings (18/21, 85.7%), were included in the meta-analysis. The highest sensitivity was observed in the mydriatic greater than two field strategy (92%, 95% CI 90-94%). The highest specificity was observed in greater than two field methods (94%, 95% CI 93-96%) where mydriasis did not affect specificity. Overall, there was no difference in sensitivity between non-mydriatic and mydriatic methods (86%, 95% CI 85-87) after exclusion of ungradable images. The highest DTA (sensitivity 90%, 95% CI 88-91%; specificity 95%, 95% CI 94-96%) was observed when screening was delivered at secondary/tertiary level clinics.

CONCLUSIONS

Non-mydriatic two-field strategy could be a more pragmatic approach in starting DRS programmes for facility-based PwDM in low-income settings, with dilatation of the pupils of those who have ungradable images. There was insufficient evidence in primary studies to draw firm conclusions on how graders' background influences DTA. Conducting more context-specific DRS validation studies in low-income and non-ophthalmic settings can be recommended.

Diabetic Retinopathy in the Asia-Pacific

Diabetic retinopathy (DR), the most common complication of diabetes mellitus, is the leading cause of new cases of blindness in middle-aged and elderly in the Asia-Pacific. It has been estimated that 51% of all those with blindness due to DR globally (n = 424,400) and 56% of those with visual impairment due to DR (2.1 million) come from the Asia-Pacific. Prevalence of DR among those with diabetes ranged from 10% in India to 43% in Indonesia within the Asia-Pacific. Awareness of DR among persons with diabetes ranged from 28% to 84%. Most common modifiable risk factors for DR in the Asia-Pacific were hyperglycemia, blood pressure, dyslipidemia, and obesity. Implementation of systematic screening programs for DR and advancement in telemedicine screening methods have increased patient coverage and cost-effectiveness, though there are still numerous factors impeding screening uptake in the low-middle income regions of the Asia-Pacific. Management and treatment of DR in the Asia-Pacific is mainly limited to traditional laser retinopexy, but it is suboptimal despite new clinical approaches such as use of intravitreal anti.vascular endothelial growth factor and steroids due to limited resources. Further research and data are required to structure a more cost-effective public healthcare program and more awareness-building initiatives to increase the effectiveness of DR screening programs.

Predictors for attending annual eye screening for diabetic retinopathy amongst patients with diabetes in an urban community of Beijing

AIM

To gain a better understanding of possible factors that may influence the decision of diabetes persons to participate in annual eye screening in an urban community setting of China.

METHODS

A structured interview including questions on attendance of eye screening, knowledge and awareness of diabetic retinopathy was conducted. The presence and degree of retinopathy were assessed using two field non-mydriatic retinal photography.

RESULTS

Totally 720 diabetes persons were recruited and 519 were enrolled in this cross-sectional study. In this urban setting of Beijing, among diabetes patients of average of 10y duration, 77% confirmed having undergone at least one eye examination and 61% reported having at least one eye examination with dilated pupil. As for the last 12mo, the number decreased to 210 (47%) and 131 (30%) separately. Most of the participants (95%) were aware that diabetes could affect their vision and that regular eye examination was necessary. Very few of them (12%) however were aware that the early stages of diabetic retinopathy presented without symptoms of vision loss. Having attended patient education on diabetes was effective in building awareness about diabetic eye disease and was a significant positive predictor for attending eye screening [education in a year, Adj. OR=0.47 (0.29-0.74), P<0.001, education years ago, Adj. OR=0.56 (0.33-0.96), P=0.036]. The duration of disease also increased the likelihood of having undergone eye screening (Adj. OR=0.96, P<0.05).

CONCLUSION

Being exposed to education about the complications of diabetes increases the probability of attending diabetic eye screening. An appropriate patient knowledge building strategy should be made available to patients from the time of diagnosis.