We read with great interest the article by Nagel et al.,
1 “Comparison of a Novel Ultra-Widefield Three-Color Scanning Laser Ophthalmoscope to Other Retinal Imaging Modalities in Chorioretinal Lesion Imaging.” The study provides a comprehensive evaluation of the RGB ultra-widefield imaging modality and its diagnostic utility compared to RG and MCI systems. We commend the authors for their detailed analysis and would like to offer complementary insights into the interpretation of retinal imaging modalities, particularly concerning optical phenomena and the use of blue light reflectance (BLR).
Retinal imaging is fundamentally influenced by the interaction of light with retinal structures, where phenomena such as backscattering, frontscattering, polarization, and diffusion play pivotal roles.
2 Although the study effectively demonstrates the superior diagnostic accuracy of the RGB ultra-widefield modality for certain pathologies, it is crucial to acknowledge that the inherent characteristics of each imaging system—including confocality, light spectrum, and sensor type—uniquely contribute to the resulting images.
2 For instance, color fundus photography (CFP) captures a broader array of optical phenomena compared to confocal scanning laser ophthalmoscopy (cSLO), which predominantly emphasizes backscattering.
2 The information comparing the specific features of different imaging methods, as presented in the study by Nagel et al., is highly valuable. However, to minimize misinterpretation and enhance reader understanding, comparisons between imaging systems should also be contextualized within the scope of the specific optical information each modality provides.
Each wavelength interacts distinctively with ocular tissues, facilitating the selective imaging of various retinal layers and structures.
2 The inclusion of blue light in ultra-widefield imaging represents a significant advancement, because its clinical utility extends far beyond the evaluation of the retinal nerve fiber layer, epiretinal membranes, and retinal folds.
2–5 BLR is a powerful tool for identifying biomarkers of retinal nonperfusion.
2,4 Recent studies highlight that BLR reflects from the retinal plexiform layers and serves as a noninvasive biomarker for detecting alterations in these layers.
3 Additionally, its application in the early diagnosis and monitoring of several retinal conditions, including macular and peripheral pathologies, is well documented.
2 This aligns with the authors’ findings regarding the enhanced visualization of macular and midperipheral lesions with RGB ultra-widefield imaging.
1 However, its limitation in altering the appearance of melanocytic choroidal lesions, observed by Nagel et al.,
1 can be explained by the topographical location of these lesions (deeper within the tissue), coupled with the limited penetration of blue light into deeper layers due to its high absorption by melanin in the retinal pigment epithelium.
2,6 This underscores the importance of understanding the strengths and limitations of each wavelength used in imaging systems.
The practical implications of these observations are profound. Beyond providing a “true color” representation of retinal images, the incorporation of blue light in ultra-widefield imaging delivers noninvasive, reliable, and valuable information regarding numerous retinal conditions. Clinicians analyzing retinal images must remain cognizant of the unique properties of each imaging modality and adapt their interpretations accordingly. We commend the authors for their valuable contribution and emphasize the importance of the incorporation of blue light among retinal imaging systems.