In this cross-sectional, case-control study with 82 eyes of eight-two subjects, we quantitatively assessed and compared the parameters of parafoveal microvasculature in eyes with treatment-naïve exudative CCH (n = 41) with those of age- and gender-controlled healthy eyes (n = 41) using OCTA. To the best our knowledge, this is the first cross-sectional, case-control study revealing the parafoveal microvasculature changes in eyes with exudative CCH compared with age- and gender-controlled healthy eyes. We found that not only the vessel density of the superficial vascular complex and deep vascular complex of retina but also the vessel density of choriocapillaris significantly decreased in eyes with exudative CCH compared with healthy eyes (P < 0.001). Although we found that the FAZ area in the exudative CCH group was larger than that of the healthy eye control group, however, no statistical significance was found between two groups (P = 0.164).
OCTA is a non-invasive procedure with depth resolved imaging technique which allows the visualization and quantitation of the CD of superficial and deep retinal capillary plexus as well as choriocapillaris[21, 22]. Although FA and ICGA remain invaluable in the diagnosis of many retinal and choroidal diseases, however, both FA and ICGA are invasive procedures need the injection of dye, which are time-consuming, and also carry the risk of complications, such as severe allergic reactions or even death. Compared with FA and ICGA, OCTA has many advantages: Firstly, it is a non-invasive procedure without the need of injection of dye, which could avoid the risk of related complications. Besides, OCTA is less time-consuming but could provide a great quantity of information such as CD of superficial and deep retinal capillary plexus, choriocapillaris which is not possible on FA or ICGA. Therefore, OCTA has become widely used clinically to diagnose a variety of ophthalmological diseases, such as age-related macular degeneration, diabetic retinopathy, artery and vein occlusions, and glaucoma.
Up to date, there are still only a few publications on retinal parafoveal microvasculature of choroidal tumors on OCTA. Valverde and colleagues reported in a retrospective comparative analysis that eyes with choroidal nevus showed no statistical significance on the CFT, superficial and deep FAZ, and CD of both superficial plexus and deep plexus compared with the contralateral eyes. In contrast, Valverde et al found that eyes with melanoma showed significant increase on CFT, enlarged superficial and deep FAZ, as well as the reduction in CD of superficial and deep plexus. Therefore, they suggested that OCTA could be a useful modality for the differential diagnosis between choroidal nevus and melanoma. Further, Li and her colleagues demonstrated that significant enlargement of deep FAZ and significant reduction in CD of superficial and deep plexus in the eyes with treatment-naive choroidal melanoma compared with fellow eyes, besides, they demonstrated that the parafoveal microvascular changes had an inverse correlation with the presence of SRF and the increasing tumor size. Interestingly, Sioufi and colleagues, for the first time, reported that eyes with previous or current CME and/or SRF had reduced CD of deep plexus in a retrospective chart review of 14 patients with CCH (9 patients had previous or current CME and/or SRF and 5 patients had no CME and/or SRF). In this retrospective chart review study, Sioufi reported that the CD of superficial plexus as well as the FAZ area of superficial and plexus had no statistical significance compared with the contralateral “normal” eyes among the 9 patients with CCH who had previous or current CME and/or SRF. However, some ophthalmologists considered that the contralateral “normal” eyes of patients with CCH are not absolutely normal[5, 18]. For example, Kim et al revealed that elevated choroidal thickness and increased risk of central serous chorioretinopathy in the fellow eyes of patients with CCH. Therefore, it is necessary to quantitative evaluation of parafoveal microvasculature changes in eyes with exudative CCH compared with healthy normal eyes. In our cross-sectional, case-control study with 82 eyes of eight-two subjects, we revealed that the CD of superficial plexus and deep plexus as well as choriocapillaris significantly decreased in eyes with exudative CCH compared with age- and gender-controlled healthy eyes (Table 2). To further know whether the decreased CD of retinal superficial plexus, deep plexus, and choriocapillaris as we as the FAZ area had correlation with baseline BCVA, the Pearson’s correlation analysis revealed that baseline BCVA was not correlated with any of the parameters including CD of retinal superficial plexus, deep plexus, choriocapillaris, or the FAZ area.
Specifically, our study for the first time revealed that the CD of choriocapillaris decreased in eyes with exudative CCH. As we know, retinal oxygen consumption is much higher in the macula[26–29]. The reduction in blood flow from choriocapillaris secondary to exudative CCH would lead to metabolic stress and ischemia, which would stimulate factors to promote tumor vascularization such as VEGF-A[30, 31]. As we know, VEGF-A may affect the permeability of blood vessels and cause macular edema or aggravate preexisting macular edema. Therefore, we speculated that CD of choriocapillaris might be used as an indicator of the effectiveness of treatments for exudative CCH. Further exploration of this hypothesis could reveal the correlation of parafoveal microvasculature changes and exudative CCH.
Limitations of this study included relatively small number of enrolled subjects. Besides, only exudative CCH which caused CME and/or SRF were included. We believed that future study including eyes with CCH without CME or SRF would provide more information about parafoveal microvasculature changes for various kinds of CCH. However, even with these limits, our age- and gender-controlled study provided some valuable information for the parafoveal microvasculature changes in eyes with exudative CCH compared with healthy eyes.