Pachychoroid diseases are a series of clinical entities that share some characteristic findings in the retina or the choroid 1–3. The most important finding is a focally or diffusely thickened choroid that contains dilated choroidal vessels and attenuated choriocapillaris accompanied with abnormalities of the retinal pigment epithelium (RPE) 1. The lesion is often characterized by choroidal vascular hyper permeability (CVH) revealed by indocyanine green angiography (ICGA). The clinical entities include pachychoroid pigment epitheliopathy (PPE) 4,5, chronic central serous chorioretinopathy (CSC), pachychoroid neovasculopathy 6,7, polypoidal choroidal vasculopathy (PCV) 6,7, and pachychoroid geographic atrophy 8–11. During the course of these diseases, they present exudative changes such as serous detachment of the retina or the RPE with or without choroidal neovascularization (CNV) and atrophic changes at the choriocapillaris, the RPE, or the sensory retina. The area of CVH has been reported to be anatomically linked with these changes 12,13. To date, increasing evidence has suggested that pachychoroid diseases should be distinguished from age-related macular degeneration (AMD), which exhibits similar exudative or atrophic changes in the posterior retina 14.
Recent advancement of imaging technology, especially that of optical coherence tomography angiography (OCTA), has contributed to increased detection of CNV or macular neovascularization (MNV), especially quiescent or nonexudative CNV or nonexudative MNV, i.e., neovascular tissue not accompanied with exudative changes. In a previous review, nonexudative MNV was detected in 6–27% of the fellow eyes with AMD 15. Nonexudative MNV could be a precursor for exudative AMD, but it may retard the growth of geographic atrophy and could have a protective effect on retinal function, probably at least in the stage where the lesion was quiescent 15,16.
Meanwhile, several studies have reported the presence of nonexudative CNV in pachychoroid diseases 17,18. The presence of nonexudative CNV could also be a risk factor for the development of exudative changes in CSC 19 and PCV 20. However, whether nonexudative CNV affects the retinal function is not clearly understood.
A previous study 21 showed that eyes with chronic CSC complicated with CNV demonstrated worse visual or reading acuity than those without CNV. However, considering that the lesion does not necessarily involve the fovea, it is important to not only compare visual acuity but also analyze retinal sensitivity (RS) at the lesion area. Nevertheless, to the best of our knowledge, there has been no published report investigating the association between RS and the presence or absence of quiescent CNV.
Therefore, in the present study, we investigated RS by microperimetry in eyes with pachychoroid diseases. We then evaluated the local function corresponding to within or outside the lesion area. In addition, we examined the association between the presence or absence of CNV and the changes in RS.