Comparison of optical coherence tomography in diabetic macular edema, with and without reading center manual grading from a clinical trials perspective

Mitigation of AI adoption bias through an improved autonomous AI system for diabetic retinal disease

Where adopted, Autonomous artificial Intelligence (AI) for Diabetic Retinal Disease (DRD) resolves longstanding racial, ethnic, and socioeconomic disparities, but AI adoption bias persists. This preregistered trial determined sensitivity and specificity of a previously FDA authorized AI, improved to compensate for lower contrast and smaller imaged area of a widely adopted, lower cost, handheld fundus camera (RetinaVue700, Baxter Healthcare, Deerfield, IL) to identify DRD in participants with diabetes without known DRD, in primary care. In 626 participants (1252 eyes) 50.8% male, 45.7% Hispanic, 17.3% Black, DRD prevalence was 29.0%, all prespecified non-inferiority endpoints were met and no racial, ethnic or sex bias was identified, against a Wisconsin Reading Center level I prognostic standard using widefield stereoscopic photography and macular Optical Coherence Tomography. Results suggest this improved autonomous AI system can mitigate AI adoption bias, while preserving safety and efficacy, potentially contributing to rapid scaling of health access equity. ClinicalTrials.gov NCT05808699 (3/29/2023).

A New Approach to Staging Diabetic Eye Disease: Staging of Diabetic Retinal Neurodegeneration and Diabetic Macular Edema

Topic

The goal of this review was to summarize the current level of evidence on biomarkers to quantify diabetic retinal neurodegeneration (DRN) and diabetic macular edema (DME).

Clinical relevance

With advances in retinal diagnostics, we have more data on patients with diabetes than ever before. However, the staging system for diabetic retinal disease is still based only on color fundus photographs and we do not have clear guidelines on how to incorporate data from the relatively newer modalities into clinical practice.

Methods

In this review, we use a Delphi process with experts to identify the most promising modalities to identify DRN and DME. These included microperimetry, full-field flash electroretinogram, spectral-domain OCT, adaptive optics, and OCT angiography. We then used a previously published method of determining the evidence level to complete detailed evidence grids for each modality.

Results

Our results showed that among the modalities evaluated, the level of evidence to quantify DRN and DME was highest for OCT (level 1) and lowest for adaptive optics (level 4).

Conclusion

For most of the modalities evaluated, prospective studies are needed to elucidate their role in the management and outcomes of diabetic retinal diseases.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Innovations in Diabetic Macular Edema Management: A Comprehensive Review of Automated Quantification and Anti-vascular Endothelial Growth Factor Intervention

Diabetic macular edema (DME) poses a significant threat to the vision and quality of life of individuals with diabetes. This comprehensive review explores recent advancements in DME management, focusing on integrating automated quantification techniques and anti-vascular endothelial growth factor (anti-VEGF) interventions. The review begins with an overview of DME, emphasizing its prevalence, impact on diabetic patients, and current challenges in management. It then delves into the potential of automated quantification, leveraging machine learning and artificial intelligence to improve early detection and monitoring. Concurrently, the role of anti-VEGF therapies in addressing the underlying vascular abnormalities in DME is scrutinized. The review synthesizes vital findings, highlighting the implications for the future of DME management. Promising outcomes from recent clinical trials and case studies are discussed, providing insights into the evolving landscape of personalized medicine approaches. The conclusion underscores the transformative potential of these innovations, calling for continued research, collaboration, and integration of these advancements into clinical practice. This review aims to serve as a roadmap for researchers, clinicians, and industry stakeholders, fostering a collective effort to enhance the precision and efficacy of DME management.

Update on current pharmacologic therapies for diabetic retinopathy

INTRODUCTION

Diabetic retinopathy is a major cause of visual loss worldwide. The most important clinical findings include diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR).

AREAS COVERED

PubMed was used for our literature review. Articles from 1995 to 2023 were included. Pharmacologic treatment of diabetic retinopathy generally involves the use of intravitreal anti-vascular endothelial growth factor (VEGF) therapy for DME and PDR. Corticosteroids remain important second-line therapies for patients with DME. Most emerging therapies focus on newly identified inflammatory mediators and biochemical signaling pathways involved in disease pathogenesis.

EXPERT OPINION

Emerging anti-VEGF modalities, integrin antagonists, and anti-inflammatory agents have the potential to improve outcomes with reduced treatment burdens.

A systematic evaluation of human expert agreement on optical coherence tomography biomarkers using multiple devices

OBJECTIVES

To assess the agreement in evaluating optical coherence tomography (OCT) variables in the leading macular diseases such as neovascular age-related macular degeneration (nAMD), diabetic macular oedema (DMO) and retinal vein occlusion (RVO) among OCT-certified graders.

METHODS

SD-OCT volume scans of 356 eyes were graded by seven graders. The grading included presence of intra- and subretinal fluid (IRF, SRF), pigment epithelial detachment (PED), epiretinal membrane (ERM), conditions of the vitreomacular interface (VMI), central retinal thickness (CRT) at the foveal centre-point (CP) and central millimetre (CMM), as well as height and location of IRF/SRF/PED. Kappa statistics (κ) and intraclass correlation coefficient (ICC) were used to report categorical grading and measurement agreement.

RESULTS

The overall agreement on the presence of IRF/SRF/PED was κ = 0.82/0.85/0.81; κ of VMI condition was 0.77, that of ERM presence 0.37. ICC for CRT measurements at CP and CMM was excellent with an ICC of 1.00. Height measurements of IRF/SRF/PED showed robust consistency with ICC = 0.85-0.93. There was substantial to almost perfect agreement in locating IRF/SRF/PED with κ = 0.67-0.86. Between diseases, κ of IRF/SRF presence was 0.69/0.80 for nAMD, 0.64/0.83 for DMO and 0.86/0.89 for RVO.

CONCLUSION

Even in the optimized setting, featuring certified graders, standardized image acquisition and the use of a professional reading platform, there is a disease dependent variability in biomarker evaluation that is most pronounced for IRF in nAMD as well as DMO. Our findings highlight the variability in the performance of human expert OCT grading and the need for AI-based automated feature analyses.

Foundational Considerations for Artificial Intelligence Using Ophthalmic Images

IMPORTANCE

The development of artificial intelligence (AI) and other machine diagnostic systems, also known as software as a medical device, and its recent introduction into clinical practice requires a deeply rooted foundation in bioethics for consideration by regulatory agencies and other stakeholders around the globe.

OBJECTIVES

To initiate a dialogue on the issues to consider when developing a bioethically sound foundation for AI in medicine, based on images of eye structures, for discussion with all stakeholders.

EVIDENCE REVIEW

The scope of the issues and summaries of the discussions under consideration by the Foundational Principles of Ophthalmic Imaging and Algorithmic Interpretation Working Group, as first presented during the Collaborative Community on Ophthalmic Imaging inaugural meeting on September 7, 2020, and afterward in the working group.

FINDINGS

Artificial intelligence has the potential to improve health care access and patient outcome fundamentally while decreasing disparities, lowering cost, and enhancing the care team. Nevertheless, substantial concerns exist. Bioethicists, AI algorithm experts, as well as the Food and Drug Administration and other regulatory agencies, industry, patient advocacy groups, clinicians and their professional societies, other provider groups, and payors (i.e., stakeholders) working together in collaborative communities to resolve the fundamental ethical issues of nonmaleficence, autonomy, and equity are essential to attain this potential. Resolution impacts all levels of the design, validation, and implementation of AI in medicine. Design, validation, and implementation of AI warrant meticulous attention.

CONCLUSIONS AND RELEVANCE

The development of a bioethically sound foundation may be possible if it is based in the fundamental ethical principles of nonmaleficence, autonomy, and equity for considerations for the design, validation, and implementation for AI systems. Achieving such a foundation will be helpful for continuing successful introduction into medicine before consideration by regulatory agencies. Important improvements in accessibility and quality of health care, decrease in health disparities, and lower cost thereby can be achieved. These considerations should be discussed with all stakeholders and expanded on as a useful initiation of this dialogue.

Choroidal Thickness After Dexamethasone Implant or Aflibercept in Patients with Diabetic Macular Edema Persistent to Ranibizumab

Purpose: This study aims to compare subfoveal choroidal thicknesses (SFCTs) after intravitreal dexamethasone (IVD) or intravitreal aflibercept (IVA) treatment in patients with persistent diabetic macular edema (DME) unresponsive to intravitreal ranibizumab (IVR). Methods: The study consisted of patients with DME unresponsive to IVR treatment in which 37 were administered 1 dose IVD (group A) and 34 patients who were administered 3 doses of IVA (group B), as well as 35 healthy individuals (group C). Detailed ophthalmological examination and optical coherence tomography parameters of group A and group B, including central retinal thickness and SFCT, were retrospectively evaluated before and after treatment. Results from preinjection, and 1, 2, and 3 months after injection were analyzed. Results of group A and group B were compared within themselves and also compared with group C. Results: SFCT measurements were compared within group A and group B (1 = preinjection; 2 = 1 month postinjection; 3 = 2 months postinjection; 4 = 3 months postinjection). There was significant thinning in SFCT between 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4 time intervals within both group A and group B (both P < 0.001). Comparison of SFCT measurements showed preinjection, 1-, and 2-month values of group A were significantly thicker than those of group C (P < 0.001), whereas there was no significant difference between 3-month values (P = 0.09). Preinjection, 1-, and 2-month values of group B were significantly thicker than those of group C (P < 0.001), whereas there was no significant difference between 3-month values (P = 0.06). Conclusions: Three month follow-up showed thinning in SFCT measurements in patients with persistent DME unresponsive to IVR who were applied IVD or IVA treatment.

Current and Future Pharmacologic Therapies for Diabetic Retinopathy

Background:

Currently, diabetic retinopathy is the leading cause of permanent visual loss in workingage adults in industrialized nations. The chronic microangiopathic changes associated with diabetic retinopathy lead to the most common causes of severe permanent visual loss: diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). Multiple studies have evaluated different pharmacotherapies for different levels of retinopathy.

Methods:

A review of the pathophysiology of diabetic retinopathy and current and emerging pharmacotherapies for diabetic retinopathy.

Results:

Historically, DME has been the primary focus of treatment in patients with nonproliferative diabetic retinopathy (NPDR). Due to the rapidly increasing number of agents and treatment options, management algorithms for DME have become increasingly complex. Furthermore, spectral domain optical coherence tomography (OCT) has allowed unparalleled sensitivity and specificity for detecting macular edema. All available intravitreal vascular endothelial growth factor (VEGF) inhibitors have demonstrated efficacy in the treatment of patients with DME and PDR. Intravitreal triamcinolone acetonide has also proven beneficial in diabetic retinopathy. Most recently, various corticosteroids have been designed as sustained-release intraocular implants in order to reduce the burden and risks associated with retreatment. Current research is focused on providing new agents that target alternate pathways and signaling molecules to provide patients with additional therapeutic tools, especially in patients who have an incomplete response to the current medications.

Conclusion:

Anti-VEGF therapy has revolutionized the medical management of diabetic retinopathy. The most important existing challenges in the treatment of diabetic retinopathy are improving visual outcomes and decreasing the treatment burden associated with repeated intravitreal injections. Combination therapy with anti-VEGF and corticosteroids with other previously available treatments, such as panretinal photocoagulation, may be a reasonable clinical strategy to reduce the intravitreal injections burden. Many exciting novel drugs that target newly discovered pathways hold clinical promise. The results of ongoing randomized clinical trials will answer the important concerns surrounding new drugs and delivery devices: safety and visual outcomes.

Evaluation of a combination digital retinal camera with spectral-domain optical coherence tomography (SD-OCT) that might be used for the screening of diabetic retinopathy with telemedicine: A pilot study

AIMS

Pilot study to determine whether an instrument combining a non-mydriatic retinal camera and spectral domain optical coherence tomography (SD-OCT) is effective for screening patients with diabetic retinopathy (DR).

METHODS

Case series conducted between 2012 and 2013. DR imaged with a retinal camera/SD-OCT instrument viewed remotely was compared to a dilated examination by a retina specialist.

RESULTS

The combination instrument was better than the retina specialist in detecting more severe retinopathy, primarily because of the SD-OCT. For severe retinopathy (grade ≥ 3), the image grader had better sensitivity (87.3% [95% CI: 75.5%, 94.7%]) than the retina examiner (76.4% [95% CI: 63.0%, 86.8%]). Specificities were similar between the instrument grader (96.0% [95% CI: 86.3%, 99.5%]) and retina examiner (100.0% [95% CI: 92.9%, 100.0%]). When identifying diabetic macular edema (ME), the retina examiner only identified 47.6% (20/42) of eyes with ME detected by SD-OCT. The instrument was better than a dilated retinal examination in detecting ME and not as good at detecting mild or proliferative retinopathy.

CONCLUSIONS

As used in this study, the instrument was more effective in identifying DR than was the current recommendation of a dilated and comprehensive eye examination. SD-OCT is needed to accurately identify DR in a screening setting.

Management of diabetic macular edema patients in clinical practice in Spain

Purpose:

Diabetic macular edema is the main cause of blindness in diabetic patients. Vascular endothelial growth factor is involved in diabetic macular edema pathogenesis. Vascular endothelial growth factor inhibitors are an important option in diabetic macular edema therapy. This survey investigates actual clinical practice in diabetic macular edema in Spain.

Methods:

An expert advisory panel of 17 Spanish ophthalmologists developed a 30-item anonymous questionnaire about diagnosis, treatment, and follow-up in diabetic macular edema. A total of 137 ophthalmologists from 10 Spanish regions completed the questionnaire online.

Results:

Almost all of the respondents (99.3%) record the measured visual acuity and perform biomicroscopic anterior (94.9%) and posterior (91.2%) segment examinations. Similarly, 100% of responding ophthalmologists always/almost always or frequently perform optical coherence tomography. Most respondents (65%) always/almost always or frequently perform a retinography. More than 50% rarely perform fluorescein angiography. Nearly, all (96.4%) of the specialists responded that, in center-involved diabetic macular edema, the first treatment is an anti–vascular endothelial growth factor drug. For corticosteroids, the first choice of most respondents (91.2%) was the dexamethasone implant. In the follow-up, almost all (96.4%) specialists record the measured visual acuity and most also perform biomicroscopic anterior (82.5%) and posterior (83.2%) segment examination.

Conclusion:

This survey shows the actual clinical practice in diabetic macular edema in Spain, finding that anti–vascular endothelial growth factor therapy is frequently used, and that diagnosis, treatments, and follow-up examinations used by specialists are homogeneous and according to diabetic macular edema guidelines.

EXTREME DIURNAL VARIATION OF CENTRAL MACULAR THICKNESS IN DIABETIC MACULAR EDEMA

PURPOSE

Spectral domain optical coherence tomography is an established modality to quantify diabetic macular edema (DME). Change in central subfield thickness exceeding 3% to 6% in DME is likely to be significant. In this case of DME, we describe an extreme bilateral variation in central macular thickness on spectral domain optical coherence tomography over two consecutive days without any treatment.

METHODS

The patient with DME and nonproliferative diabetic retinopathy underwent visual acuity testing, slit-lamp biomicroscopy, and dilated fundus examination. The patient also underwent spectral domain optical coherence tomography and digital fluorescence angiography. Findings are described in case report.

RESULTS

There was an overnight decrease of central subfield thickness from 360 microns to 291 microns (69 [∼19%] microns) in the right eye and from 404 microns to 293 microns (111 [∼27%] microns) in the left eye.

CONCLUSION

Extreme fluctuations in retinal thickness in central involving DME are unusual, and the exact mechanism of this fluctuation is poorly understood.

En face Integrated Central Avascular Zone (EFICAZ): a noninvasive tool for correlating morphological and functional damage in central diabetic macular edema

BACKGROUND

As numerous factors account for diabetic maculopathy, retinal thickness alone is poorly correlated to visual function in diabetic macular edema. En face optical coherence tomography (OCT) enables assessing retinal changes at specific layers. By averaging several planes, overall changes can be better appreciated.

METHODS

Retrospective analysis of a consecutive group of 16 patients (30 eyes) with diabetic macular edema in at least one eye, was compared to a control group of 17 healthy subjects (34 eyes). Healthy volunteers and diabetic patients being seen as part of their regular care underwent swept source OCT fundus imaging. En face Integrated Central Avascular Zone (EFICAZ) was manually determined and measured on images obtained by swept-source optical coherence tomography (OCT). EFICAZ was then compared between both populations and, for diabetic patients, correlated with best corrected visual acuity, as measured by the Snellen chart.

RESULTS

In healthy subjects, a moderate correlation was found between age and EFICAZ (Pearson's coefficient = 0.45, P = 0.01). In age-matched populations (mean age of 63 ± 3.8 years for eight healthy subjects and 62.7 ± 8.9 years for diabetic patients; P = 0.9), EFICAZ was significantly higher in diabetic than non-diabetic eyes (2.92 ± 1.10 mm² versus 1.86 ± 0.53 mm²; P < 0.01). In diabetic patients, correlation between the size of EFICAZ and visual acuity (Pearson's correlation coefficient = -0 .72, P < 0.001) was stronger than between OCT measured central subfield retinal thickness and visual acuity (Pearson's correlation coefficient = -0.02, N.S).

CONCLUSIONS

EFICAZ increases with age in normal subjects. It is significantly larger in diabetic than in non-diabetic subjects. It offers a better way to determine visual acuity than OCT measurement of central retinal thickness. This new approach, which takes into account several factors involved in diabetic maculopathy, could be useful in monitoring response to therapy. It can easily be combined with other modalities.

Retinal Imaging Techniques for Diabetic Retinopathy Screening

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

Reading Center Characterization of Central Retinal Vein Occlusion Using Optical Coherence Tomography During the COPERNICUS Trial

PURPOSE

To determine the impact of segmentation error correction and precision of standardized grading of time domain optical coherence tomography (OCT) scans obtained during an interventional study for macular edema secondary to central retinal vein occlusion (CRVO).

METHODS

A reading center team of two readers and a senior reader evaluated 1199 OCT scans. Manual segmentation error correction (SEC) was performed. The frequency of SEC, resulting change in central retinal thickness after SEC, and reproducibility of SEC were quantified. Optical coherence tomography characteristics associated with the need for SECs were determined. Reading center teams graded all scans, and the reproducibility of this evaluation for scan quality at the fovea and cystoid macular edema was determined on 97 scans.

RESULTS

Segmentation errors were observed in 360 (30.0%) scans, of which 312 were interpretable. On these 312 scans, the mean machine-generated central subfield thickness (CST) was 507.4 ± 208.5 μm compared to 583.0 ± 266.2 μm after SEC. Segmentation error correction resulted in a mean absolute CST correction of 81.3 ± 162.0 μm from baseline uncorrected CST. Segmentation error correction was highly reproducible (intraclass correlation coefficient [ICC] = 0.99-1.00). Epiretinal membrane (odds ratio [OR] = 2.3, P < 0.0001), subretinal fluid (OR = 2.1, P = 0.0005), and increasing CST (OR = 1.6 per 100-μm increase, P < 0.001) were associated with need for SEC. Reading center teams reproducibly graded scan quality at the fovea (87% agreement, kappa = 0.64, 95% confidence interval [CI] 0.45-0.82) and cystoid macular edema (92% agreement, kappa = 0.84, 95% CI 0.74-0.94).

CONCLUSIONS

Optical coherence tomography images obtained during an interventional CRVO treatment trial can be reproducibly graded. Segmentation errors can cause clinically meaningful deviation in central retinal thickness measurements; however, these errors can be corrected reproducibly in a reading center setting.

TRANSLATIONAL RELEVANCE

Segmentation errors are common on these images, can cause clinically meaningful errors in central retinal thickness measurement, and can be corrected reproducibly in a reading center setting.

Optical coherence tomography evaluation in the Multicenter Uveitis Steroid Treatment (MUST) trial

PURPOSE

To describe the evaluation of optical coherence tomography (OCT) scans in the Muliticenter Uveitis Steroid Treatment (MUST) trial and report baseline OCT features of enrolled participants.

METHODS

Time-domain OCTs acquired by certified photographers using a standardized scan protocol were evaluated at a reading center. Accuracy of retinal thickness data was confirmed with quality evaluation, and caliper measurement of centerpoint thickness (CPT) was performed when retinal thickness data were unreliable. Morphological evaluation included cysts, subretinal fluid, epiretinal membranes (ERMs), and vitreomacular traction.

RESULTS

Of the 453 OCTs evaluated, automated retinal thickness was accurate in 69.5% of scans, caliper measurement was performed in 26%, and 4% were ungradable. Intraclass correlation was.98 for reproducibility of caliper measurement. Macular edema (centerpoint thickness ≥ 240 μm) was present in 36%. Cysts were present in 36.6% of scans and ERMs in 27.8%, predominantly central. Intergrader agreement ranged from 78 to 82% for morphological features.

CONCLUSION

Retinal thickness data can be retrieved in a majority of OCT scans in clinical trial submissions for uveitis studies. Small cysts and ERMs involving the center are common in intermediate and posterior/panuveitis requiring systemic corticosteroid therapy.

Optical coherence tomography grading reproducibility during the Comparison of Age-related Macular Degeneration Treatments Trials

OBJECTIVE

To report reading center reproducibility during grading of Stratus optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA) images obtained during the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT).

DESIGN

Prospective, clinical trial.

PARTICIPANTS

Independent reading teams reevaluated 270 OCT scans randomly sampled from the first 2 years of CATT enrollment. To assess temporal drift, a cohort of 23 scans submitted during the initial portion of the CATT study was longitudinally followed with serial reproducibility analysis.

INTERVENTION

The CATT readers performed standardized grading of OCT images. A reader team, composed of 2 independent readers and a senior reader, evaluated each scan. Grading included the CATT OCT end points of total thickness at the foveal center point and intraretinal fluid (IRF), subretinal fluid (SRF), and subretinal pigment epithelium (RPE) fluid. Independent reading teams masked to the results of initial grading reevaluated scans to determine the reproducibility of qualitative grading and measurements.

MAIN OUTCOME MEASURES

Categorical grading agreement was reported using percent agreement and kappa statistic, and measurement agreement was reported using intraclass correlations and paired differences.

RESULTS

Reading center teams reproducibly graded IRF (percent agreement = 73%, kappa = 0.48; 95% confidence interval [CI], 0.38-0.58), SRF (percent agreement = 90%; kappa = 0.80; 95% CI, 0.73-0.87), and sub-RPE fluid (percent agreement 88%; kappa = 0.75; 95% CI, 0.67-0.83). For independent reading center team measurements of total thickness at the foveal center point, the intraclass correlation was 0.99 (95% CI, 0.99-0.99), and the mean paired difference between reading center teams was 4 μm (95% limits of agreement, -55 to 47 μm). There was no qualitative or quantitative grading drift.

CONCLUSIONS

The standardized protocols used to evaluate OCT scans from the CATT study were reproducible. The methods used are suitable to monitor OCT imaging data from a large, neovascular age-related macular degeneration, interventional, multicenter study.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Screening for diabetic retinopathy and diabetic macular edema in the United Kingdom

Despite advances in screening for and treatment of diabetes, diabetic retinopathy and maculopathy are still major causes of visual loss around the world. Systematic screening programs for diabetic eye disease have been developed in many countries. The main aim of these services is to reduce diabetes-related blindness and ease the burden of illness on the patients and their families. In the United Kingdom (UK), the NHS Diabetic Eye Screening Program offers annual digital fundus photography for all patients with diabetes over the age of 12 years regardless of their socio-economic status or ethnicity. In 2010-2011 a nationwide uptake of 79% was achieved. If disease is identified, referral to a specialized eye unit for further assessment and treatment are organized to take place within a pre-specified time frame. Internal and external quality assurance ensures efficacy and safety. This paper aims to summarize the current situation of diabetic retinopathy screening in the UK and outlines the challenges ahead.

Use of nonmydriatic spectral-domain optical coherence tomography for diagnosing diabetic macular edema

PURPOSE

To evaluate the accuracy of 3 spectral-domain (SD) optical coherence tomography (OCT) devices (Topcon 3D-1000 [Topcon]; Cirrus HD [Carl Zeiss Meditec, Inc], and Spectralis OCT [Heidelberg Engineering]) before and after mydriasis for the diagnosis of diabetic macular edema.

DESIGN

Cross-sectional study.

METHODS

Sixty-two eyes of 62 consecutive patients with diabetes without recent loss of vision referred for retinal control were assessed. Two scans were performed for each SD OCT instrument. Central retinal thickness was measured before and after pupil dilation. Pupil dynamic was studied using pMetrics pupillometer (iVIS Technologies), and lens opacity was measured by Pentacam densitometry (Oculus). The diagnostic accuracy of SD OCT devices was assessed by sensitivity, specificity, and area under the receiver operating characteristic curve. Logistic regression analysis was used to assess the effect of pupil size and lens opacity on the reliability of SD OCT in the acquisition of adequate images.

RESULTS

The area under the receiver operating characteristic curve for the Topcon 3D OCT device was 0.84, that for the Cirrus HD OCT device was 0.93, and that for the Spectralis OCT device was 0.91. Significant differences in area under the receiver operating characteristic curve before and after pupillary dilatation were not found. Sensitivity and specificity associated with the cutoff value for the best performance were 82% and 74% for the Topcon 3D OCT device, 90% and 87% for the Cirrus HD OCT device, and 90% and 84% for the Spectralis OCT device, respectively. The Topcon 3D OCT device had an 11.3% segmentation algorithm failure rate for the central millimeter of the fovea, and the nuclear lens density was significantly greater in these eyes than in those without failure (17.1 ± 1.1 mm vs 10.4 ± 0.2 mm; P < .05).

CONCLUSIONS

SD OCT is a useful tool to detect and to measure diabetic macular edema without the need for pupil dilatation.

Effect of OCT volume scan density on thickness measurements in diabetic macular edema

PURPOSE

To evaluate the impact of reducing B-scan frame-sampling density on retinal thickness measurements using spectral domain optical coherence tomography (SD-OCT) in eyes with diabetic macular edema (DME).

METHODS

We retrospectively collected OCT data for 64 eyes of 43 patients undergoing imaging for DME using the Cirrus HD-OCT 512 × 128 macular cube protocol. For each case, raw OCT data were imported into the 3D-OCTOR software, and retinal thickness maps were generated using all 128 B-scans and for lower densities of B-scans ranging from every other scan to only four scans (every 30-s B-scan). Maps were generated before and after manual correction of retinal boundary segmentation errors. The foveal central subfield (FCS) and total macular volume (TMV) values were used to compare thickness maps of varying densities.

RESULTS

The mean difference in FCS retinal thickness and TMV increased as the B-scan density was reduced, particularly when the density was reduced to fewer than 16 B-scans over 6 mm. At a density of 16 B-scans, the mean absolute difference in FCS thickness was 2.43 μm (0.79%), with a maximum of 10.1 μm (4.09%). At this density, the mean difference in TMV was 0.012 mm(3) (0.13%), with a maximum difference of 0.04 mm(3) (0.47%). Manual correction of OCT segmentation errors resulted in a difference in FCS thickness of ≥ 10 μm in only 12.5% of cases, with a maximum difference of 115.7 μm.

CONCLUSION

A minimum of 16 equally spaced B-scans appear necessary to generate retinal thickness measurements similar to those produced using all 128 B-scans in eyes with DME. Manual correction of segmentation errors appeared to have a clinically meaningful effect in a small minority of cases. These results may have implications for the design of SD-OCT imaging and grading protocols in clinical trials of DME, particularly when using multiple SD-OCT instruments that acquire varying numbers of B-scans.

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.

Relationship between optical coherence tomography retinal parameters and visual acuity in diabetic macular edema

PURPOSE

To investigate the relationship between optical coherence tomography (OCT)-derived measurements of retinal morphology and visual acuity in patients with diabetic macular edema.

DESIGN

Retrospective cross-sectional study.

PARTICIPANTS

A total of 67 consecutive patients (67 eyes) with diabetic macular edema (DME) who underwent Stratus OCT imaging (Carl Zeiss Meditec, Inc., Dublin, CA).

METHODS

Best-corrected Snellen visual acuity was recorded for each patient. Raw exported Stratus OCT images for each patient were analyzed using custom software entitled "OCTOR," which allows the precise positioning of prespecified boundaries on individual B-scans. Thickness, volume, and intensity were calculated for neurosensory retina and subretinal fluid. In addition, photoreceptor outer segment (POS) thickness was quantified.

MAIN OUTCOME MEASURES

Optical coherence tomography-derived measurements of retinal morphology and visual acuity.

RESULTS

The Spearman coefficient values (r) of the correlation between OCTOR-derived measurements of central subfield thickness, intensity, subretinal fluid volume, and POS thickness and the logarithm of the minimum angle of resolution visual acuities were 0.3428 (P = 0.005), -0.2658 (P = 0.03), -0.2683 (P = 0.38), and -0.3703 (P = 0.002), respectively. Multivariate models with stepwise selection revealed a cumulative R(2) of 0.4305 in the total study population, with R(2) of 0.4999 and 0.7628 in the untreated and prior focal laser groups, respectively.

CONCLUSIONS

Subanalysis and quantification of OCT features in eyes with DME seem to be of value. In particular, POS thickness seems to be an important predictor of function and visual acuity in patients with DME.

The Standard Care vs Corticosteroid for Retinal Vein Occlusion (SCORE) study system for evaluation of optical coherence tomograms: SCORE study report 4

OBJECTIVE

To describe grading procedures for optical coherence tomographic (OCT) images of participants in the Standard Care vs Corticosteroid for Retinal Vein Occlusion (SCORE) Study.

METHODS

Optical coherence tomograms were taken at clinical sites with the Stratus OCT using fast macular and crosshair scan protocols. Paper prints of images were evaluated at a central reading center. Quality evaluation identified the accuracy of OCT-measured retinal thickness data and was categorized as good, fair, borderline, or ungradable. Manual measurement of center point thickness was performed on borderline images. Morphological evaluation identified cystoid spaces, subretinal fluid, and vitreoretinal interface abnormalities. Reproducibility of grading was assessed through formal quality control exercises.

RESULTS

A randomly selected set of 106 images was identified for quality control. The first 2 annual regrades showed 91% and 89% intergrader agreement for OCT quality. Intraclass correlation for manually measured center point thickness was 0.99 per year. For morphological variables, intergrader agreement for cystoid spaces was 83% and 76%. Reproducibility for subretinal fluid and vitreoretinal interface abnormalities could not be interpreted owing to their limited presence in the sample.

CONCLUSION

Optical coherence tomogram evaluation procedures used in the SCORE Study are reproducible and can be used for multicenter longitudinal studies of retinal vein occlusion.

Impact of scanning density on measurements from spectral domain optical coherence tomography

PURPOSE

To investigate the relationship between B-scan density and retinal thickness measurements obtained by spectral domain optical coherence tomography (SDOCT) in eyes with retinal disease.

METHODS

Data were collected from 115 patients who underwent volume OCT imaging with Cirrus HD-OCT using the 512 x 128 horizontal raster protocol. Raw OCT data, including the location of the automated retinal boundaries, were exported from the Cirrus HD-OCT instrument and imported into the Doheny Image Reading Center (DIRC) OCT viewing and grading software, termed "3D-OCTOR." For each case, retinal thickness maps similar to those produced by Cirrus HD-OCT were generated using all 128 B-scans, as well as using less dense subsets of scans, ranging from every other scan to every 16th scan. Retinal thickness measurements derived using only a subset of scans were compared to measurements using all 128 B-scans, and differences for the foveal central subfield (FCS) and total macular volume were computed.

RESULTS

The mean error in FCS retinal thickness measurement increased as the density of B-scans decreased, but the error was small (<2 microm), except at the sparsest densities evaluated. The maximum error at a density of every fourth scan (32 scans spaced 188 microm apart) was <1%.

CONCLUSIONS

B-scan density in volume SDOCT acquisitions can be reduced to 32 horizontal B-scans (spaced 188 microm apart) with minimal change in calculated retinal thickness measurements. This information may be of value in design of scanning protocols for SDOCT for use in future clinical trials.