Clinical application of multicolour scanning laser imaging in diabetic retinopathy

Multimodal imaging in diabetic retinopathy and macular edema: An update about biomarkers

Diabetic macular edema (DME), defined as retinal thickening near, or involving the fovea caused by fluid accumulation in the retina, can lead to vision impairment and blindness in patients with diabetes. Current knowledge of retina anatomy and function and DME pathophysiology has taken great advantage of the availability of several techniques for visualizing the retina. Combining these techniques in a multimodal imaging approach to DME is recommended to improve diagnosis and to guide treatment decisions. We review the recent literature about the following retinal imaging technologies: optical coherence tomography (OCT), OCT angiography (OCTA), wide-field and ultrawide-field techniques applied to fundus photography, fluorescein angiography, and OCTA. The emphasis will be on characteristic DME features identified by these imaging technologies and their potential or established role as diagnostic, prognostic, or predictive biomarkers. The role of artificial intelligence in the assessment and interpretation of retina images is also discussed.

Effectiveness of dexamethasone implants in treating diabetic macular edema with hard exudates: a clinical observation

OBJECTIVE

This study seeks to explain the relationship between systemic conditions and hard exudate formations in diabetic macular edema patients. Besides, the study aimed to quantitatively examine changes in the area, location, and impact on visual function of hard exudates following intravitreal dexamethasone implant injections.

METHODS

A retrospective analysis was conducted, including 40 patients (40 eyes) diagnosed with non-proliferative diabetic retinopathy and concurrent macular edema between January 1, 2022, and January 1, 2024. Preoperative evaluations included glycated hemoglobin, lipid profile, and renal function examinations. Based on the location of HE, patients were divided into two groups: Group A, with HE in 1 mm of the central fovea, and Group B, with HE outside 1 mm of the central fovea. Selected eyes were subject to pre- and postoperative examinations, including best-corrected visual acuity (BCVA), intraocular pressure, slit-lamp biomicroscopy, scanning laser ophthalmoscopy (SLO), optical coherence tomography, and multifocal electroretinography. Following screening and examination, patients received an immediate intravitreal injection of the DEX implant, with an injection administered at the four-month mark. Hard exudate (HE) areas were measured utilizing SLO fundus imaging.

RESULTS

Total cholesterol, low-density lipoprotein, and triglyceride levels were found to be positively correlated with the presence of HE. Following surgical intervention, all patients demonstrated an improvement in BCVA. The mean BCVA increased from a preoperative measurement of 0.79 ± 0.04 to 0.39 ± 0.02 at the 6 month follow-up, indicating a statistically significant difference (p < 0.001). The baseline HE area for the entire patient cohort was 2.28 ± 0.22. One month post-operation, the HE area exhibited a slight increase to 2.27 ± 0.22. However, by the 6 month follow-up, the HE area had significantly decreased to 0.8 ± 0.87, representing a 35.09% reduction from the baseline measurement (p < 0.001). It is worth noting that Patient P1 did not exhibit a statistically significant difference between preoperative and six-month postoperative HE area (p = 0.032). Preoperative BCVA measurements for Group A and Group B were 0.81 ± 0.03 and 0.77 ± 0.03, respectively, with no statistically significant intergroup difference (p = 0.333). The baseline HE area for Group A was 2.61 ± 0.16, which decreased to 0.38 ± 0.20 at the six-month follow-up, representing a 14.60% reduction from the baseline total area. For Group B, the baseline HE area was measured at 1.95 ± 0.09, then decreasing to 1.21 ± 0.13 at the six-month follow-up, indicating a 62.05% reduction from the baseline total area. A statistically significant difference in the postoperative 6 month HE area was observed between Group A and Group B (p < 0.001). In Group A, the reduction in HE area (initial HE area-final HE area) was positively correlated with the improvement in P1 (initial P1-final P1) (r = 0.610, p = 0.004). In Group B, a similar positive correlation was found (initial HE area-final HE area with initial P1-final P1) (r = 0.488, p = 0.029). In Group B, the reduction in HE area (initial HE area-final HE area) correlated positively with the improvement in BCVA (initial BCVA-final BCVA) (r = 0.615, p = 0.004). Additionally, in Group B, the reduction in HE area (initial HE area-final HE area) was positively correlated with the improvement in CMT (initial CMT-final CMT) (r = -0.725, p< 0.001). Aggravated cataracts were observed in thirteen eyes during a follow-up examination 6 months later.

CONCLUSION

HE formation is associated with lipid levels. Dexamethasone implants demonstrate effectiveness in reducing HE areas in the short term, reducing macular edema, improving retinal structure, and enhancing visual function. The incidence of postoperative complications such as cataracts and glaucoma remains low.

Comparison of Color Fundus Photography and Multicolor Fundus Imaging for Detection of Lesions in Diabetic Retinopathy and Retinal Vein Occlusion

Purpose

To evaluate the agreement between conventional fundus photography (CFP) and multicolor fundus imaging (MFI) for the detection of lesions of diabetic retinopathy (DR) and retinal vein occlusion (RVO).

Methods

Cross-sectional analysis of eyes with DR or RVO who underwent CFP and MFI. All images were independently analyzed by two observers (O1 and O2), and the evaluated lesions were classified as "present" or "absent". Then, a paired comparison between both exams of the same eye was performed, to assess which made it easier to detect the lesions.

Results

Considering DR, the agreement was substantial for cotton wool spots and photocoagulation scars for both observers (O1: κ=0.75 and κ=0.67; O2: κ=0.71 and κ=0.64, respectively) and for hard exudates for O1 (κ=0.80). These lesions were detected more frequently on MFI. Regarding RVO, the agreement was considered substantial for venous sheathing by O1 (κ=0.64) and moderate for optociliary shunts by O2 (κ=0.60). Optociliary shunts were detected more frequently in CPF by both observers and venous sheathing on MFI by O1. For microaneurysms, retinal hemorrhages, retinal neovascularization, and proliferative membranes, in DR, and retinal hemorrhages, venous engorgement, and retinal neovascularization in RVO, the agreement was almost perfect (κ>0.82). In the paired analysis, both observers considered that, in DR, microaneurysms and retinal hemorrhages were easier to detect on CFP and that retinal neovascularization, cotton wool spots, and photocoagulation scars were easier to identify on MFI. Regarding RVO, optocilliary shunts were easier to identify on CFP and venous engorgement on MFI.

Conclusion

The agreement of MFI and CFP was substantial to almost perfect for most lesions. MFI seems better to detect cotton wool spots and photocoagulations scars in DR and venous sheathing in RVO. Optocilliary shunts seem easier to detect on CFP.

Quantitative approaches in multimodal fundus imaging: State of the art and future perspectives

When it first appeared, multimodal fundus imaging revolutionized the diagnostic workup and provided extremely useful new insights into the pathogenesis of fundus diseases. The recent addition of quantitative approaches has further expanded the amount of information that can be obtained. In spite of the growing interest in advanced quantitative metrics, the scientific community has not reached a stable consensus on repeatable, standardized quantitative techniques to process and analyze the images. Furthermore, imaging artifacts may considerably affect the processing and interpretation of quantitative data, potentially affecting their reliability. The aim of this survey is to provide a comprehensive summary of the main multimodal imaging techniques, covering their limitations as well as their strengths. We also offer a thorough analysis of current quantitative imaging metrics, looking into their technical features, limitations, and interpretation. In addition, we describe the main imaging artifacts and their potential impact on imaging quality and reliability. The prospect of increasing reliance on artificial intelligence-based analyses suggests there is a need to develop more sophisticated quantitative metrics and to improve imaging technologies, incorporating clear, standardized, post-processing procedures. These measures are becoming urgent if these analyses are to cross the threshold from a research context to real-life clinical practice.

Current status and future possibilities of retinal imaging in diabetic retinopathy care applicable to low- and medium-income countries

Diabetic retinopathy (DR) is a leading cause of blindness among adults and the numbers are projected to rise. There have been dramatic advances in the field of retinal imaging since the first fundus image was captured by Jackman and Webster in 1886. The currently available imaging modalities in the management of DR include fundus photography, fluorescein angiography, autofluorescence imaging, optical coherence tomography, optical coherence tomography angiography, and near-infrared reflectance imaging. These images are obtained using traditional fundus cameras, widefield fundus cameras, handheld fundus cameras, or smartphone-based fundus cameras. Fluorescence lifetime ophthalmoscopy, adaptive optics, multispectral and hyperspectral imaging, and multicolor imaging are the evolving technologies which are being researched for their potential applications in DR. Telemedicine has gained popularity in recent years as remote screening of DR has been made possible. Retinal imaging technologies integrated with artificial intelligence/deep-learning algorithms will likely be the way forward in the screening and grading of DR. We provide an overview of the current and upcoming imaging modalities which are relevant to the management of DR.

Sensitivity and specificity of MultiColor imaging in detecting proliferative diabetic retinopathy

PURPOSE

To evaluate the accuracy of MultiColor imaging (MC) compared to fluorescein angiography (FA) in detecting proliferative diabetic retinopathy (PDR) and associated diabetic retinopathy features.

METHODS

Fifty-nine eyes from 38 PDR patients were included. MC images were reviewed by 2 independent masked graders. A qualitative analysis based on the following features was performed: neovascular complexes (NVC), disc neovascularization (NVD), neovascularization elsewhere (NVE), microaneurysm (MA), intraretinal hemorrhage (IRH), vitreous hemorrhage (VH), preretinal hemorrhage (PRH), fibrosis, hard exudates (HE), epiretinal membrane (ERM), diabetic macular edema (DME), ischemia and laser spots (LS). Measures of diagnostic accuracy compared to FA were determined.

RESULTS

The sensitivity for the detection of NVC using MC was 95.1%, with a specificity of 40.0%, positive predictive value (PPV) of 92.9% and negative predictive value (NPV) of 50.0%. Sensitivity and specificity were higher in detecting NVD (88.9% and 76.9%) while NVE registered higher PPV (88.9%). MC was highly sensitive in detecting IRH, HE, ERM and LS (100%), MA (98.0%) and fibrosis (95.5%). Highest specificity was found for VH (100.0%), DME (100.0%), PRH (98.1%) and LS (89.5%). The area under the receiver-operating characteristic analysis of MC was excellent in NVD (0.83, 95% confidence interval (CI), 0.71-0.95, p < 0.001), IRH (0.89, 95% CI 0.74-1.00, p < 0.001), VH (0.81, 95% CI 0.60-1.00, p = 0.005) and PRH (0.89, 95% CI 0.68-1.00, p = 0.004) and outstanding in LS detection (0.95, 95% CI 0.87-1.00, p < 0.001). These results are likely due to the contrast and quality of the MC since better discrimination is enabled by the green wavelength.

CONCLUSION

MC is useful in evaluation of PDR patients and can complement noninvasive imaging. MC detected some PDR features more accurately than FA such as NVD, IRH, VH, PRH, and LS.

Quantitative evaluation of hard exudates in diabetic macular edema by multicolor imaging and their associations with serum lipid levels

AIMS

To quantify hard exudates (HEs) by multicolor imaging (MCI) and traditional color fundus photography (CFP) in diabetic macular edema (DME), and study their associations with serum lipid levels.

METHODS

Observational study. DME patients with HEs were recruited. The HE area and location both by MCI and CFP were measured by ImageJ software. Multivariate regression models were used to analyze the associations of serum lipid levels with the total HE area and HE location.

RESULTS

Sixty-two patients (74 eyes) were enrolled to quantify HEs in DME. The total HE area by MCI was larger than that by CFP (P = 0.004), and the distance between the fovea and the nearest HE by MCI was shorter than that by CFP (P = 0.003). The percentage of patients with HEs involving the central macula by MCI was significantly higher than that by CFP (P < 0.001). Furthermore, 62 eyes of 62 patients were included to analyze the associations of HE parameters with serum lipid levels. In both MCI and CFP, the HE areas were positively associated with triglyceride level (P = 0.016, P = 0.022, respectively). HEs involving the central macula were positively associated with triglyceride and low-density cholesterol levels in MCI (P = 0.028, P = 0.046, respectively), while no significant association was found between serum lipid levels and HE location in CFP.

CONCLUSIONS

MCI is superior to traditional CFP for the detection of HEs and the analysis of associations between HEs and serum lipid levels in DME.

CLINICAL APPLICATION OF MULTICOLOR IMAGING IN CENTRAL SEROUS CHORIORETINOPATHY

PURPOSE

To characterize features of central serous chorioretinopathy (CSC) using multicolor (MC) imaging and to compare the efficacy of using MC imaging and traditional color fundus photography (CFP) for detecting features of CSC.

METHODS

A retrospective review of 75 eyes of 69 participants with CSC from the Eye Center of the Renmin Hospital of Wuhan University. The patients underwent same-day CFP, fundus fluorescein angiography (FFA), spectral domain optical coherence tomography (SD-OCT), and MC imaging (including infrared reflectance (IR), green reflectance (GR), blue reflectance (BR), combined standard MC image, and green-blue-enhanced image). Positive CSC lesions were evaluated using FFA and SD-OCT. Features in images of CFP, standard MC, green-blue-enhanced, IR, GR, and BR were analyzed and calculated.

RESULTS

Among the 75 eyes of 69 patients, 75 eyes with subretinal fluid (SRF) and retinal pigment epithelial (RPE) leakage point, and 43 eyes with RPE damage were observed by FFA and SD-OCT. The detection rate of SRF was significantly higher with the standard MC image (92.0%), green-blue-enhanced image (92.0%), IR (88.0%), and GR (88.0%) than that with CFP (66.7%) (P < 0.05). Blue reflectance (45.3%) was associated with lower rate of SRF detection compared to CFP (P < 0.05). The standard MC image (84.0%), green-blue-enhanced image (84.0%), IR (78.7%), and GR (80%) delineated the boundaries of SRF more effectively than CFP (44%). The abnormal areas corresponding to RPE leakage points on FFA were observed with the standard MC image, green-blue-enhanced image, and IR at detection rates of 90.7, 82.7, and 90.7%, respectively, which were significantly higher than with CFP (29.3%) (P < 0.05). However, the detection rates of the abnormalities corresponding to leakage on FFA were lower with GR (5.3%) and BR (1.3%) than those with CFP (P < 0.05). Areas of RPE damage on FFA were observed at the same locations with the standard MC image, green-blue-enhanced image, and IR at detection rates of 97.7, 93.0, and 95.3%, respectively, which were significantly higher than with CFP (41.9%) (P < 0.05). Compared with CFP, the detectable rates of RPE damage on GR (14.0%) and BR (9.3%) were lower (P < 0.05).

CONCLUSION

As an adjunct to SD-OCT, the MC image can delineate the extent or boundaries of SRF more effectively than CFP. As an adjunct to FFA, the MC image can identify foci of leakage more effectively than CFP. The MC image, particularly the IR channel, can identify areas of RPE damage more effectively than CFP. Therefore, the MC image may be a useful adjunct to FFA and OCT for detecting or monitoring CSC.

Differences in the multicolour imaging features between the superficial and deep vascular occlusions

Purpose To describe the multicolour imaging (MI) findings in superficial and deep vascular plexus occlusions.

METHODS

In this retrospective observational study, patients diagnosed with central retinal artery and branch retinal artery occlusion, cotton-wool spot, paracentral acute middle maculopathy and acute macular neuroretinopathy between January 2018 and June 2019 were included. Colour fundus photograph, optical coherence tomography and MI of these patients were analysed.

RESULTS

A total of 41 eyes of 40 patients were included in this study. In eyes with central retinal artery occlusion, MI showed white areas in the retina with orange foveal centre. In eyes with branch retinal artery occlusion, MI showed white area along the affected retinal quadrant without an orange foveal centre. In pure superficial vascular plexus occlusions as in cotton-wool spots, the lesion was identified on MI as a white lesion. On MI, paracentral acute middle maculopathy showed parafoveal white areas with orange foveal centre while acute macular neuroretinopathy on MI parafoveal greyish-white areas with normal foveal centre.

CONCLUSION

En-face images using MI technology can provide yet another way to identify the level of retinal vasculature involvement which complements the existing gold standard of optical coherence tomography imaging.

Validation of Multicolor Imaging of Diabetic Retinopathy Lesions Vis a Vis Conventional Color Fundus Photographs

BACKGROUND AND OBJECTIVE

To analyze the visibility of various diabetic retinopathy lesions in multicolor imaging (MCI) and compare them to corresponding color fundus photography (CFP).

PATIENTS AND METHODS

Retrospective review of 130 eyes of 65 consecutive patients with diabetic retinopathy who underwent multicolor confocal scanning laser ophthalmoscopy and CFP.

RESULTS

Hard exudates (Hex) were seen in 74 eyes (71.2%). In all 74 eyes, Hex were visible on both CFP and MCI. Among other color channels, Hex were picked up most in green reflectance (GR) images in 73 eyes (70.2%). Cotton-wool spots (CWS) were picked up in 29 eyes (27.9%) on MCI and in 27 eyes (26%) on CFP. In both GR and blue reflectance (BR) imaging, they were equally picked up in 29 eyes (27.9%). Retinal hemorrhages were picked up in 83 eyes (79.8%) on MCI and in 82 eyes (72.8%) on CFP. Among other channels, they were picked up most in GR images in 81 (77.9%) eyes. Hex, CWS, and hemorrhages were seen better on MCI and in GR images as compared to CFP, BR, and infrared imaging, respectively. With CFP as the comparator, the sensitivity and specificity of MCI to detect of these lesions were more than 90%.

CONCLUSIONS

The authors' pilot study validates the efficacy of MCI in picking up lesions of DR vis a vis CFP. MCI has potential to replace CFP in clinical and DR screening setting. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:8-15.].

Clinical application of multicolor optical coherence tomography in the diagnosis of retinal pathologies

Objective:

To assess the clinical application of multicolor optical coherence tomography (OCT) using confocal scanning laser ophthalmoscopy (cSLO) in different retinal pathologies.

Methods:

This observational study was conducted at the Layton Rahmatullah Benevolent Trust (LRBT), Free Base Eye Hospital, Karachi, from April 2018 to June 2018. It includes 36 patients suffering from different retinal pathologies including diabetic retinopathy, age related macular degeneration, and vitreomacular interface disorders using multicolor optical coherence tomography as a screening tool.

Results:

It was found that automated eye tracking system of this new version tool enables ophthalmologists to take high-resolution cSLO reflectance images. The light scatter can be avoided with the use of confocal optics. Appearances of pigment changes and hemorrhages were some of the differences found when compared to the conventional CFP. About 20% in AMD, 37.5% with diabetes and 100% patients with vitreomacular interface disorders could have be easily missed by CFP.

Conclusions:

Multicolor OCT can provide information and figures far more authoritatively than the conventional CFP, which is highly affected by media opacities. To interpret Multicolor OCT ophthalmologists should be watchful with plenty of understanding.