In acute CSCR, OCTA could be a potentially useful imaging modality for providing a real-time direct visualization of the blood flow in the SCP, DCP and CC in the process of self-resolve, contributing to provide theoretical basis for the mechanism of acute CSCR. In a previous study, based on dye angiography combined with SD-OCT, we were only able to identify subretinal fluid and leakage of RPE. However, in the present study, OCTA can enhance to detect the microvascular morphology and density of SCP, DCP and CC at baseline and 3 months. Although the key mechanisms of acute CSCR are choroidal vasodilation and leakage through the RPE, the choroidal circulation is not only for the choroid, but also for the RPE and as far as the lateral part of the retinal inner layer (ie, the deep capillary region).17,18 Birol et al. confirmed in an animal model that the deep capillary bed is conducive to the oxygen requirements of the photoreceptor layer.18 In their study, the primary oxygen supply to photoreceptor layers was derived from the choroidal circulation, but 10%–15% was derived from the retinal circulation.19 As oxygenation of the fovea is somewhat different from that of the perifoveal retina, it would be useful to discuss this and any other potentially relevant correlations regarding the foveal and perifoveal areas.18 From these results, the microvascular changes of DCP and choroicapillary could contribute to prognosis determination important target. In our study, the density of DCP and choroicapillary increased at 3 months, which proved the recovery of acute CSCR.
Chan et al20 retrospectively reported 12 eyes with CSCR presented foci high signal in choroicapillary layer by OCTA, demonstrating the dilated choroicapillary. It is concluded that OCTA can be used as an auxiliary tool to diagnose CSCR. In contrast, we observed changes in the vasoconstriction of the choroicapillary dilatation during the recovery of acute CSCR patients. Although the subretinal fluid was completely absorbed detected by OCT, choroicapillary with high signal can still be remained by OCTA. This phenomenon, related stimuli, such as smoking, alcoholism, staying up late and so on, explains why many patients with acute CSCR are prone to recurrence. Therefore, with the advantage of OCTA in the follow-up process, it is possible to extend the follow-up treatment time after the complete recovery of choroidal capillaries, which indicates that OCTA provides an effective reference for clinical follow-up treatment. Teussink et al21 compared 18 patients with chronic CSCR with 6 nomal controls who underwent FFA, ICGA and OCTA, illstrating the same presentation of choroicapillary by OCTA as the ones by ICGA. Refered to the aboved research, the main diagnosis were: less than 3 months of onset, subretinal fluid accumulation by OCT, and squamous high signal in choroicapillary layer presented by OCTA in our study.
The changes of microvascular density in different layers are diverse not only among various retinal diseases, but also the progress or efficacy of disease.22-25 For example, the extend of photoreceptor damage is related to the blood flow density of DCP in diabetic retinopathy.24,25 Moreover, another publication showed reduced microvascular density of SCP and the increased density of DCP in adult-onset foveomacular vitelliform dystrophy.23 At present, rare study is focus on the microvascular density in SCP, DCP and CC in acute CSCR episodes without treatment. Nelis et al27 compared 16 eyes with acute CSCR with contralateral eyes and normal eye, resulting in the much more density of SCP and much smaller of FAZ in eyes with acute CSCR than the contralateral and normal eyes. However, the higher density of DCP in 12 eyes with acute CSCR at 3 months compared with eyes at initial visit, but no significant differene in density and FAZ of SCP between at baseline and at 3months. At the same time, in spite of completely absorption of subretinal fluid, the photoreceptor layer need longer time to recovery. We could identify the disruption of IS/OS by en -face imaging, which is related with the visual acuity.
Elevation of RPE by OCT was found in 19-68% in acute CSCR patients,3 but few studies focus on the vascular changes of CC caused by flat PED in eyes with acute CSCR. In our study, two eyes with acute CSCR exhibited flat pigment epithelial detachment by OCT and OCTA demonstrated the formation of vascular in choroicapillary layer at 3 months.
Several improvements are needed: the larger sample size; OCTA underwent contemporaneously with FFA/ICGA in order to determine more accurately the relative sensitivities of each of these modalities;Longitudinal studies are needed to describe the microvascular changes of retina and choroid.