Multimodal Imaging in Non-Exudative Choroidal Neovascularization: a Pilot Study of Status of Retinal Pigment Epithelium

Abstract Purpose: To study the status of retinal pigment epithelium (RPE) in non-exudative and active choroidal neovascularization (CNV) in neovascular age-related macular degeneration (nAMD). Methods: Only treatment-naïve nAMD patients were enrolled in this prospective case-control study, including 17 eyes with non-exudative CNV (six males and 11 females, 74.9 ± 10.0 years) and 28 eyes with active CNV (eight males and 20 females, 69.3 ± 6.8 years). All patients received a comprehensive ophthalmic examination, optical coherence tomography (OCT), dark-field scanning laser ophthalmoscopy (DF-SLO), and fundus autofluorescence (FAF). The status of RPE was assessed with ImageJ software as the brightness of the CNV region on transillumination OCT, DF-SLO, and FAF images. CNV vessel density was measured based on OCT angiography. Results: The brightness of CNV region in non-exudative CNV was statistically significantly lower than in active CNV with both OCT transillumination (p = 0.004) and DF-SLO (p = 0.0015). No difference in brightness of CNV region between non-exudative and active CNV was found based on FAF (p = 0.44). The vessel density of non-exudative CNV was statistically significantly higher than that of active CNV with a median value of 64.5% (95% confidential interval (CI) 53.4 – 79.0 %) and 55.3% (95% CI 52.2 – 60.0%), respectively (p = 0.05). Conclusion: Multimodal imaging revealed substantial alteration of RPE in active CNV but not in non-exudative CNV which correlates with the higher vessel density of non-exudative CNV.