Multicolor Imaging for Detection of Retinal Nerve Fiber Layer Defect in Myopic Eyes With Glaucoma

Exploring retinal conditions through blue light reflectance imaging

Blue light reflectance (BLR) imaging offers a non-invasive, cost-effective method for evaluating retinal structures by analyzing the reflectance and absorption characteristics of the inner retinal layers. By leveraging blue light's interaction with retinal tissues, BLR enhances visualization beyond the retinal nerve fiber layer, improving detection of structures such as the outer plexiform layer and macular pigment. Its diagnostic utility has been demonstrated in distinct retinal conditions, including hyperreflectance in early macular telangiectasia, hyporeflectance in non-perfused areas indicative of ischemia, identification of pseudodrusen patterns (notably the ribbon type), and detection of peripheral retinal tears and degenerative retinoschisis in eyes with reduced retinal pigment epithelial pigmentation. Best practices for image acquisition and interpretation are discussed, emphasizing standardization to minimize variability. Common artifacts and mitigation strategies are also addressed, ensuring image reliability. BLR's clinical utility, limitations, and future research directions are highlighted, particularly its potential in automated image analysis and quantitative assessment. Different BLR acquisition methods, such as fundus photography, confocal scanning laser ophthalmoscopy, and broad line fundus imaging, are evaluated for their respective advantages and limitations. As research advances, BLR's integration into multimodal workflows is expected to improve early detection and precise monitoring of retinal diseases.

Blue light reflectance imaging in non-perfusion areas detection: insights from multimodal analysis

DESIGN

A retrospective, cross-sectional image analysis using a convenience sample.

SUBJECTS

Five cases selected based on the availability of comprehensive imaging data.

METHODS

This study involved a retrospective review of images from five cases, focusing on the use of retinal monochromatic blue light reflectance (BLR) imaging to detect non-perfusion areas. Two cases of sickle-cell retinopathy demonstrated peripheral retinal non-perfusion identified through widefield fluorescein angiography. Three other cases-one with branch retinal vein occlusion, one with branch retinal artery occlusion, and one presenting paracentral acute middle maculopathy showed focal macular non-perfusion detected by structural OCT and OCTA. The areas of nonperfused retinal tissue, confirmed by fluorescein angiography, OCT, and OCTA, were then correlated with findings from the BLR image. This correlation aimed to identify any potential associations between these imaging modalities.

MAIN OUTCOME MEASURES

Enhance understanding of the utilization of retinal monochromatic BLR images as a non-perfusion biomarker.

RESULTS

The perfusion defects identified through fluorescein angiography were qualitatively correlated with hypo-reflective regions observed in the BLR images. A notable correlation was also observed between the OCTA deep capillary plexus findings and the BLR images. Additionally, areas of retinal thinning identified on structural OCT thickness maps corresponded with the hypo-reflective regions in the BLR images. This indicates the potential of BLR in identifying non-perfused retinal areas.

CONCLUSIONS

This study reinforces the evidence, through OCT, OCTA, and angiographic correlation, that the BLR can effectively identify areas of retinal non-perfusion in a non-invasive manner. Further research is warranted to assess the method's sensitivity, specificity, and limitations. While the interaction of blue light with the retina, leading to specular reflections and scattering, is established, this research represents a pioneering effort in suggesting which specific retinal structures may be implicated in this phenomenon. This novel insight opens avenues for deeper exploration into the underlying mechanisms and potential clinical applications of utilizing the BLR imaging technique for assessing retinal vascular abnormalities.

Axial elongation in nonpathologic high myopia: Ocular structural changes and glaucoma diagnostic challenges

Axial elongation continues in highly myopic adult eyes, even in the absence of pathologic changes such as posterior staphyloma or chorioretinal atrophy. This ongoing axial elongation leads to structural changes in the macular and peripapillary regions, including chorioretinal thinning, reduced vascular perfusion and optic disc tilting and rotation, among others. These alterations can affect the acquisition and interpretation of optical coherence tomography, optical coherence tomography angiography and fundus photographs, potentially introducing artifacts and diminishing the accuracy of glaucoma diagnosis in highly myopic eyes. In this review, we compared the progression patterns of axial elongation across populations with varying demographic characteristics, genetic and environmental backgrounds and ocular features. We also discussed the implications of axial elongation-induced ocular structural changes for diagnosing glaucoma in nonpathologic high myopia. Finally, we highlighted the prospects for enhancing the diagnostic efficacy of glaucoma in nonpathologic highly myopic populations.

Retinal hyperspectral imaging in mouse models of Parkinson's disease and healthy aging

Retinal hyperspectral imaging (HSI) is a non-invasive in vivo approach that has shown promise in Alzheimer's disease. Parkinson's disease is another neurodegenerative disease where brain pathobiology such as alpha-synuclein and iron overaccumulation have been implicated in the retina. However, it remains unknown whether HSI is altered in in vivo models of Parkinson's disease, whether it differs from healthy aging, and the mechanisms which drive these changes. To address this, we conducted HSI in two mouse models of Parkinson's disease across different ages; an alpha-synuclein overaccumulation model (hA53T transgenic line M83, A53T) and an iron deposition model (Tau knock out, TauKO). In comparison to wild-type littermates the A53T and TauKO mice both demonstrated increased reflectivity at short wavelengths ~ 450 to 600 nm. In contrast, healthy aging in three background strains exhibited the opposite effect, a decreased reflectance in the short wavelength spectrum. We also demonstrate that the Parkinson's hyperspectral signature is similar to that from an Alzheimer's disease model, 5xFAD mice. Multivariate analyses of HSI were significant when plotted against age. Moreover, when alpha-synuclein, iron or retinal nerve fibre layer thickness were added as a cofactor this improved the R2 values of the correlations in certain groups. This study demonstrates an in vivo hyperspectral signature in Parkinson's disease that is consistent in two mouse models and is distinct from healthy aging. There is also a suggestion that factors including retinal deposition of alpha-synuclein and iron may play a role in driving the Parkinson's disease hyperspectral profile and retinal nerve fibre layer thickness in advanced aging. These findings suggest that HSI may be a promising translation tool in Parkinson's disease.

Diagnostic performance of wide-field optical coherence tomography angiography for high myopic glaucoma

Diagnosing and monitoring glaucoma in high myopic (HM) eyes are becoming very important; however, it is challenging to diagnose this condition. This study aimed to evaluate the diagnostic ability of wide-field optical coherence tomography angiography (WF-OCTA) maps for the detection of glaucomatous damage in eyes with HM and to compare the diagnostic ability of WF-OCTA maps with that of conventional imaging approaches, including swept-source optical coherence tomography (SS-OCT) wide-field maps. In this retrospective observational study, a total 62 HM-healthy eyes and 140 HM eyes with open-angle glaucoma were included. Patients underwent a comprehensive ocular examination, including SS-OCT wide-field and 12 × 12 WF-OCTA scans. The WF-OCTA map represents the peripapillary and macular superficial vascular density maps. Glaucoma specialists determined the presence of glaucomatous damage in HM eyes by reading the WF-OCTA map and comparing its sensitivity and specificity with those of conventional SS-OCT images. The sensitivity and specificity of 12 × 12 WF-OCTA scans for HM-glaucoma diagnosis were 87.28% and 86.94%, respectively, while, the sensitivity and specificity of SS-OCT wide-field maps for HM-glaucoma diagnosis were 87.49% and 80.51%, respectively. The specificity of the WF-OCTA map was significantly higher than that of the SS-OCT wide-field map (p < 0.05). The sensitivity of the WF-OCTA map was comparable with that of the SS-OCT wide-field map (p = 0.078). The WF-OCTA map showed good diagnostic ability for discriminating HM-glaucomatous eyes from HM-healthy eyes. As a complementary method to an alternative imaging modality, WF-OCTA mapping can be a useful tool for the detection of HM glaucoma.

Multicolor imaging compared with red-free fundus photography in the detection of glaucomatous retinal nerve fiber layer thinning

BACKGROUND

To compare the ability of multicolor imaging (MCI) with red-free fundus photography (RFP) to detect glaucomatous retinal nerve fiber layer (RNFL) thinning.

METHODS

A total of 127 eyes of 79 patients with glaucoma underwent MCI using blue light, RFP, and circumpapillary optical coherence tomography (OCT) scanning on the same day. Angular location and width of the RNFL defects (RNFLDs) identified on the MCI and RFP were independently measured, and compared with those of RNFL thinning indicated by abnormal color codes on OCT.

RESULTS

The angular location and width of the RNFLDs determined by both MCI and RFP were well correlated with those of RNFL thinning determined by OCT (all P ≤ 0.013). The correlation of angular width with OCT was significantly stronger for MCI than for RFP (R = 0.708 vs. R = 0.616, P = 0.009). The superiority of MCI to RFP in the detection of OCT-determined RNFL thinning was significant in the inferior (P = 0.025) and marginally significant in the superior (P = 0.084) hemisectors. Thinner RNFL and longer axial length were significantly associated with better visualization of RNFLD by MCI than by RFP, respectively in the superior (OR = 0.948, P = 0.048) and inferior (OR = 1.490, P = 0.012) hemisectors.

CONCLUSIONS

RNFLD on MCI correlated well with OCT measurement of RNFL thinning in eyes with glaucoma. MCI performed better than conventional RFP in the detection of OCT-determined RNFL thinning, specifically in eyes with thinner RNFL and those with myopia. MCI may be more useful than conventional RFP in evaluating glaucomatous RNFL thinning.

Clinical application of multicolor imaging in Leber hereditary optic neuropathy

Purpose

To characterize features of retinal never fiber in Leber Hereditary Optic Neuropathy (LHON) using multicolor (MC) imaging and color fundus photography (CFP).

Methods

Ninety-two eyes of patients with LHON underwent MC imaging, optic disc spectral domain optical coherence tomography (SD-OCT), and CFP. Two independent observers graded RNFL visibility scores and two other experts determined never fiber bundle defects from four-quadrant readings. CFP, standard MC, infrared reflectance (IR), green reflectance (GR), blue reflectance (BR), and green-blue-enhanced (BG) imaging were compared.

Results

Agreement on never fiber bundle defects was substantial for CFP, standard MC, GR, BR, and BG images relative to IR. It was shown that BR (2.71 ± 0.55) had the best mean RNFL visibility score, BG (2.69 ± 0.52), GR (2.69 ± 0.56), standard MC (2.04 ± 0.79), CFP (1.80 ± 0.82), and IR (0.45 ± 0.59) followed. Agreement on temporal area defects was relatively improved. Youden's indices for CFP (78.21%), standard MC (84.48%), GR (90.92%), BR (89.64%), and BG (90.99%) indicated good detection of defects in the papillomacular bundle (PMB)/ high suspicion of patients with LHON, particularly for BG and GR. According to the proportion of never fiber bundle defects, standard MC, GR, BR, and BG can roughly determine the LHON clinical stage, especially in subacute and chronic stages, and standard MC is superior for patients with LHON of all stages. The stage judged by MC was consistent with the course inferred by pRNFL thickness.

Conclusion

As an adjunct to SD-OCT, the MC image, particularly the GR and BG can delineate RNFL more effectively than CFP. The MC image may be a useful adjunct to OCT for detecting or monitoring never fiber bundle defects, providing inexpensive and rapid methods that can quickly identify patients with high suspicion of LHON.