Comparison Among Methods of Retinopathy Assessment (CAMRA) Study: Smartphone, Nonmydriatic, and Mydriatic Photography

Screening for vision-threatening diabetic retinopathy in South India: comparing portable non-mydriatic and standard fundus cameras and clinical exam

PurposeTo evaluate the sensitivity and specificity of a portable non-mydriatic fundus camera to diagnose vision-threatening diabetic retinopathy (VTDR).Patients and methodsA prospective, single-site, comparative instrument validation study was undertaken at the Aravind Eye Care System. Overall, 155 subjects with and without diabetes were recruited. Images from 275 eyes were obtained with the (1) non-mydriatic Smartscope, (2) mydriatic Smartscope, and (3) mydriatic table-top camera of the macular, nasal, and superotemporal fields. A retina specialist performed a dilated fundus examination (DFE), (reference standard). Two masked retina specialists graded the images. Sensitivity and specificity to detect VTDR with the undilated Smartscope was calculated compared to DFE.ResultsGraders 1 and 2 had a sensitivity of 93% (95% confidence interval (CI): 87-97%) and 88% (95% CI: 81-93%) and a specificity of 84% (95% CI: 77-89%) and 90% (95% CI: 84-94%), respectively, in diagnosing VTDR with the undilated Smartscope compared to DFE. Compared with the dilated Topcon images, graders 1 and 2 had sensitivity of 88% (95% CI: 81-93%) and 82% (95% CI: 73-88%) and specificity of 99% (95% CI: 96-100%) and 99% (95% CI: 95-100%).ConclusionsRemote graders had high sensitivity and specificity in diagnosing VTDR with undilated Smartscope images, suggesting utility where portability is a necessity.

Comparison of Smartphone Ophthalmoscopy With Slit-Lamp Biomicroscopy for Grading Vertical Cup-to-Disc Ratio

PURPOSE OF THE STUDY

The purpose of the study was to determine the agreement between smartphone ophthalmoscopy and slit-lamp indirect biomicroscopy when assessing vertical cup-to-disc ratios (VCDRs).

MATERIALS AND METHODS

This was a clinical-based, prospective, comparative instrument study performed in 110 patients with ocular hypertension (OH) or primary open angle glaucoma (POAG). Patients underwent estimation of VCDR by undilated smartphone ophthalmoscopy and slit-lamp biomicroscopy by 2 masked glaucoma specialists.

RESULTS

The differences between the mean VCDR estimations obtained by each techniques were not statistically significant. Overall exact agreement between the 2 modalities was found in 21 of 29 eyes (72.4%; simple κ=0.63, confidence interval, 0.52-0.73, P<0.001) in POAG patients and in 52 of 78 eyes (66.7%) in OH patients. The optic nerve head was not gradable with smartphone ophthalmoscopy in 1 eye with POAG and in 2 eyes with OH because of media opacities and/or small pupil diameter.

CONCLUSIONS

Smartphone ophthalmoscopy showed substantial agreement with slit-lamp examination for the estimation of the VCDR. The ubiquitous diffusion of the smartphones, together with their connectivity and portability features, enables an extensive benefit for this technology to be used in glaucoma screening, especially in low-resource settings.

Glaucoma Screening in Nepal: Cup-to-Disc Estimate With Standard Mydriatic Fundus Camera Compared to Portable Nonmydriatic Camera

PURPOSE

To compare cup-to-disc ratio (CDR) measurements from images taken with a portable, 45-degree nonmydriatic fundus camera to images from a traditional tabletop mydriatic fundus camera.

DESIGN

Prospective, cross-sectional, comparative instrument validation study.

METHODS

Setting: Clinic-based.

STUDY POPULATION

A total of 422 eyes of 211 subjects were recruited from the Tilganga Institute of Ophthalmology (Kathmandu, Nepal). Two masked readers measured CDR and noted possible evidence of glaucoma (CDR ≥ 0.7 or the presence of a notch or disc hemorrhage) from fundus photographs taken with a nonmydriatic portable camera and a mydriatic standard camera. Each image was graded twice.

MAIN OUTCOME MEASURES

Effect of camera modality on CDR measurement; inter- and intraobserver agreement for each camera for the diagnosis of glaucoma.

RESULTS

A total of 196 eyes (46.5%) were diagnosed with glaucoma by chart review; 41.2%-59.0% of eyes were remotely diagnosed with glaucoma over grader, repeat measurement, and camera modality. There was no significant difference in CDR measurement between cameras after adjusting for grader and measurement order (estimate = 0.004, 95% confidence interval [CI], 0.003-0.011, P = .24). There was moderate interobserver reliability for the diagnosis of glaucoma (Pictor: κ = 0.54, CI, 0.46-0.61; Topcon: κ = 0.63, CI, 0.55-0.70) and moderate intraobserver agreement upon repeat grading (Pictor: κ = 0.63 and 0.64, for graders 1 and 2, respectively; Topcon: κ = 0.72 and 0.80, for graders 1 and 2, respectively).

CONCLUSIONS

A portable, nonmydriatic, fundus camera can facilitate remote evaluation of disc images on par with standard mydriatic fundus photography.

Plenoptic Ophthalmoscopy: A Novel Imaging Technique

This prospective retinal imaging case series was designed to establish feasibility of plenoptic ophthalmoscopy (PO), a novel mydriatic fundus imaging technique. A custom variable intensity LED array light source adapter was created for the Lytro Gen1 light-field camera (Lytro, Mountain View, CA). Initial PO testing was performed on a model eye and rabbit fundi. PO image acquisition was then performed on dilated human subjects with a variety of retinal pathology and images were subjected to computational enhancement. The Lytro Gen1 light-field camera with custom LED array captured fundus images of eyes with diabetic retinopathy, age-related macular degeneration, retinal detachment, and other diagnoses. Post-acquisition computational processing allowed for refocusing and perspective shifting of retinal PO images, resulting in improved image quality. The application of PO to image the ocular fundus is feasible. Additional studies are needed to determine its potential clinical utility. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:1038-1043.].

Predictors of Photographic Quality with a Handheld Nonmydriatic Fundus Camera Used for Screening of Vision-Threatening Diabetic Retinopathy

PURPOSE

To analyze predictors of image quality for a handheld nonmydriatic fundus camera used for screening of vision-threatening diabetic retinopathy.

METHODS

An ophthalmic photographer at an Aravind Eye Hospital obtained nonmydriatic and mydriatic fundus images from 3 fields in 275 eyes of 155 participants over 13 months using a Smartscope camera (Optomed, Oulu, Finland) and a Topcon tabletop fundus camera (Topcon, Tokyo, Japan). Two fellowship-trained retina specialists graded the images. Repeated-measures logistic regression assessed predictors of the main outcome measure: gradability of the fundus images.

RESULTS

Of 2,475 images, 76.2% of the Smartscope nonmydriatic images, 90.1% of the Smartscope mydriatic images, and 92.0% of the Topcon mydriatic images were gradable. Eyes with vitreous hemorrhage (OR = 0.24, p < 0.0001) or advanced cataract (OR = 0.08, p < 0.0001) had decreased odds of image gradability. Excluding eyes with cataract or vitreous hemorrhage, nonmydriatic macular image gradability improved from 68.4% in the first set of 55 eyes to 94.6% in the final set of 55 eyes.

CONCLUSION

With sufficient training, paraprofessional health care staff can obtain high-quality images with a portable nonmydriatic fundus camera, particularly in patients with clear lenses and clear ocular media.

Telemedicine screening of retinal diseases with a handheld portable non-mydriatic fundus camera

Background

We modified and reconstructed a high image quality portable non-mydriatic fundus camera and compared it with the tabletop fundus camera to evaluate the efficacy of the new camera in detecting retinal diseases.

Methods

We designed and built a novel portable handheld fundus camera with telemedicine system. The image quality of fundus cameras was compared to that of existing commercial tabletop cameras by taking photographs of 364 eyes from the 254 patients. In all 800 fundus images taken by two camera types, 400 images per camera, were graded with the four image clarity classifications.

Results

Using the portable fundus camera, 63% (252/400) images were graded as excellent overall quality, 20.5% (82/400) were good, 11.75% (47/400) were fair, and 4.75% (19/400) were inadequate. Using the tabletop fundus camera, 70.75% (283/400) images were graded as excellent overall quality, 20.4% (51/400) were good, 13.25% (53/400) were fair, and 3.25% (13/400) were inadequate. Common retinal diseases were easily identified from fundus images obtained from the portable fundus camera.

Conclusion

The new type of non-mydriatic portable fundus camera was qualified to have professional quality of fundus images. The revolutionary screening camera provides a foundational platform which can potentially improve the accessibility of retinal screening programmes.

A Portable, Inexpensive, Nonmydriatic Fundus Camera Based on the Raspberry Pi® Computer

Purpose. Nonmydriatic fundus cameras allow retinal photography without pharmacologic dilation of the pupil. However, currently available nonmydriatic fundus cameras are bulky, not portable, and expensive. Taking advantage of recent advances in mobile technology, we sought to create a nonmydriatic fundus camera that was affordable and could be carried in a white coat pocket. Methods. We built a point-and-shoot prototype camera using a Raspberry Pi computer, an infrared-sensitive camera board, a dual infrared and white light light-emitting diode, a battery, a 5-inch touchscreen liquid crystal display, and a disposable 20-diopter condensing lens. Our prototype camera was based on indirect ophthalmoscopy with both infrared and white lights. Results. The prototype camera measured 133mm × 91mm × 45mm and weighed 386 grams. The total cost of the components, including the disposable lens, was $185.20. The camera was able to obtain good-quality fundus images without pharmacologic dilation of the pupils. Conclusion. A fully functional, inexpensive, handheld, nonmydriatic fundus camera can be easily assembled from a relatively small number of components. With modest improvements, such a camera could be useful for a variety of healthcare professionals, particularly those who work in settings where a traditional table-mounted nonmydriatic fundus camera would be inconvenient.

Clinical Components of Telemedicine Programs for Diabetic Retinopathy

Diabetic retinopathy is a leading cause of new-onset vision loss worldwide. Treatments supported by large clinical trials are effective in preserving vision, but many persons do not receive timely diagnosis and treatment of diabetic retinopathy, which is typically asymptomatic when most treatable. Telemedicine evaluation to identify diabetic retinopathy has the potential to improve access to care, but there are no universal standards regarding camera choice or protocol for ocular telemedicine. We review the literature regarding the impact of imaging device, number and size of retinal images, pupil dilation, type of image grader, and diagnostic accuracy on telemedicine assessment for diabetic retinopathy. Telemedicine assessment of diabetic retinopathy has the potential to preserve vision, but further development of telemedicine specific technology and standardization of operations are needed to better realize its potential.

Evidence for Telemedicine for Diabetic Retinal Disease

According to current projections, the number of Americans with diabetes mellitus will increase from 27.8 million in 2007 to 60.7 million in 2030. With the increasing gap between demand for eye care and supply of ophthalmologists and optometrists, and the non-uniform distribution of eye care providers in US counties, barriers to eye examinations will likely increase. Telemedicine assessment of diabetic retinal disease through remote retinal imaging and diagnosis has the potential to meet these growing demands. To establish evidence for a telemedicine program as an effective modality for diabetic retinopathy (DR) assessment, the interpretation of teleretinal images should compare favorably with Early Treatment Diabetic Retinopathy Study film or digital photographs. We review the current evidence on the critical features and characteristics of ocular telehealth programs for DR in the following categories: image gradability, mydriasis, sensitivity and specificity, cost-effectiveness, long-term effectiveness, patient comfort and satisfaction, and improvement of patient related outcomes.

Clinical Validation of a Smartphone-Based Adapter for Optic Disc Imaging in Kenya

IMPORTANCE

Visualization and interpretation of the optic nerve and retina are essential parts of most physical examinations.

OBJECTIVE

To design and validate a smartphone-based retinal adapter enabling image capture and remote grading of the retina.

DESIGN, SETTING, AND PARTICIPANTS

This validation study compared the grading of optic nerves from smartphone images with those of a digital retinal camera. Both image sets were independently graded at Moorfields Eye Hospital Reading Centre. Nested within the 6-year follow-up (January 7, 2013, to March 12, 2014) of the Nakuru Eye Disease Cohort in Kenya, 1460 adults (2920 eyes) 55 years and older were recruited consecutively from the study. A subset of 100 optic disc images from both methods were further used to validate a grading app for the optic nerves. Data analysis was performed April 7 to April 12, 2015.

MAIN OUTCOMES AND MEASURES

Vertical cup-disc ratio for each test was compared in terms of agreement (Bland-Altman and weighted κ) and test-retest variability.

RESULTS

A total of 2152 optic nerve images were available from both methods (also 371 from the reference camera but not the smartphone, 170 from the smartphone but not the reference camera, and 227 from neither the reference camera nor the smartphone). Bland-Altman analysis revealed a mean difference of 0.02 (95% CI, -0.21 to 0.17) and a weighted κ coefficient of 0.69 (excellent agreement). The grades of an experienced retinal photographer were compared with those of a lay photographer (no health care experience before the study), and no observable difference in image acquisition quality was found.

CONCLUSIONS AND RELEVANCE

Nonclinical photographers using the low-cost smartphone adapter were able to acquire optic nerve images at a standard that enabled independent remote grading of the images comparable to those acquired using a desktop retinal camera operated by an ophthalmic assistant. The potential for task shifting and the detection of avoidable causes of blindness in the most at-risk communities makes this an attractive public health intervention.

Current and Next Generation Portable Screening Devices for Diabetic Retinopathy

Diabetic retinopathy (DR) is the leading cause of legal blindness in the United States, and with the growing epidemic of diabetes, a global increase in the incidence of DR is inevitable, so it is of utmost importance to identify the most cost-effective tools for DR screening. Emerging technology may provide advancements to offset the burden of care, simplify the process, and provide financially responsible methods to safely and effectively optimize care for patients with diabetes mellitus (DM). We review here currently available technology, both in production and under development, for DR screening. Preliminary results of smartphone-based devices, "all-in-one" devices, and alternative technologies are encouraging, but are largely pending verification of utility when used by nonophthalmic personnel. Further research comparing these devices to current nonportable telemedicine strategies and clinical fundus examination is necessary to validate these techniques and to potentially overcome the poor compliance around the globe of current strategies for DR screening.

Cost-effectiveness of Different Diabetic Retinopathy Screening Modalities

Current screening strategies aimed at detection of diabetic retinopathy (DR) historically have poor compliance, but advancements in technology can enable improved access to care. Nearly 80% of all persons with diabetes live in low- and middle-income countries (LMICs), highlighting the importance of a cost effective screening program. Establishing mechanisms to reach populations with geographic and financial barriers to access is essential to prevent visual disability. Teleretinal programs leverage technology to improve access and reduce cost. The quality of currently employed screening modalities depends on many variables including the instrument used, use of pupillary mydriasis, number of photographic fields, and the qualifications of the photographer and image interpreter. Recent telemedicine and newer technological approaches have been introduced, but data for these technologies is yet limited. We present results of a systematic review of studies evaluating cost-effectiveness of DR screening, and discuss potential relevance for LMICs.

The Diabetic Retinopathy Screening Workflow: Potential for Smartphone Imaging

Complications of diabetes mellitus, namely diabetic retinopathy and diabetic maculopathy, are the leading cause of blindness in working aged people. Sufferers can avoid blindness if identified early via retinal imaging. Systematic screening of the diabetic population has been shown to greatly reduce the prevalence and incidence of blindness within the population. Many national screening programs have digital fundus photography as their basis. In the past 5 years several techniques and adapters have been developed that allow digital fundus photography to be performed using smartphones. We review recent progress in smartphone-based fundus imaging and discuss its potential for integration into national systematic diabetic retinopathy screening programs. Some systems have produced promising initial results with respect to their agreement with reference standards. However further multisite trialling of such systems' use within implementable screening workflows is required if an evidence base strong enough to affect policy change is to be established. If this were to occur national diabetic retinopathy screening would, for the first time, become possible in low- and middle-income settings where cost and availability of trained eye care personnel are currently key barriers to implementation. As diabetes prevalence and incidence is increasing sharply in these settings, the impact on global blindness could be profound.