Central serous chorioretinopathy (CSC) is an idiopathic disease of the posterior pole of the retina, which often appears as serous retinal detachment accompanied by leakage of altered retinal pigment epithelium (RPE). Mechanical stress resulting from increased intra-choroidal pressure reduces RPE adhesion and alters hydro-ionic RPE regulation, which in turn causes PED. EDR is often associated with a mechanical abrasion resulting from an active flow through a break in the RPE.
The most common manifestation of B-Scan imaging in acute CSC is ERD. The neurosensory of retina uplift, there is a dark area of fluid accumulation beneath it. A high reflective light band at the bottom is the retinal pigment epithelial layer. Most reports mention the presence of ERD (9, 10), 100% of our patients have this sign. Most of the ERD areas of CSC are non-reflective dark areas, but there are few reports of membrane-like structure (11). Our study found that nearly 10% of the patients had this characteristic. CSC's membrane -like structure is localized, well-defined, and has some relationship with PED or RPE protuberances (12, 13). Fujimoto et al. (14) Study the leakage point of CSC found that half of the leakage point has a membrane-like structure. Many studies hold the view on the membrane -like structure of CSC as cellulose exudation. We hypothesized that the membrane -like structure in CSC should also be associated with local inflammation,
We found dot-like precipitates in two eyes in the retinal neurosensory detachment area of CSC. It has been reported that up to 65% of the EDR areas of CSC eyes have precipitates (15, 16). This neoplasm can be attached to the retina or in the retinal detachment area (17, 18). There is a lot of speculation about this precipitates. The main idea is that the outer segment of the photoreceptor cells precipitates in the subretinal space. It may also be the accumulation of fibrin or lipid, and the macrophages that remove these debris.
PED is the separation of the RPE from Bruch’s membrane or choroid membrane. Upon OCT, PED usually manifests as dome-shaped RPE protrusions stretching towards the retina, usually with a uniform low reflection area behind it (19, 20). PED is very common in CSC, and sometimes occurs with ERD, and sometimes it appears separately (20). RPE bulges, sometimes described as rough RPE (19), show slight protrusions in the RPE layer, with no clear low-reflex region behind them (21). This small bulge is common in CSC. Montero et al. (22) reported this small bulge in 35 of 39 eyes, but most of the reports were 30ཞ40% (21, 23). PED and bulge were both associated with the leakage point found by FFA examination (10, 14). Some people believed that bulge was associated with hyperplasia of pigment epithelium (21). On OCT images, we found that some bulges were not distinguishable from PEDs, and we speculated that some bulges were small PEDs.
Focal choroidal excavation (FCE) is a newly discovered disease. In 2006, Jampol et al. (24) first reported a case of choroidal excavation found in time domain OCT. In 2010, Abe et al. and Wakabayashi et al. (25, 26) reported 4 cases of monocular focal choroidal excavation with SD-OCT. Among the 3 cases reported by Wakabayashi et al. (26), there were two lesions in one eye. Margolis et al. (27) reviewed the focal choroidal excavation in 12 patients and named it focal choroidal excavation (FCE) defined as macular area Choroidal excavation, without posterior staphyloma or scleral bulge, without trauma, uveitis, retinal or choroidal vascular disease or infection, and had been divided into two types, conforming focal choroidal excavation C-FCE and nonconforming focal choroidal excavation NC-FCE. In the former, the top of photoreceptor cells and retinal pigment epithelium were not separated, the photoreceptor cell layer was thicker than that in the area not affected by depression, and the junction between inner and outer segments and pigment epithelium were not disturbed. In NC-FCE, the top of the photoreceptor is separated from the posterior RPE, accompanied by a low reflex region that may represent the subretinal serum. In these types, the pigment epithelium and inner segment/ outer segment connections are usually disturbed. Then Katome et al. reported two cases of C-FCE detected by EDI-OCT in three eyes in 2012 (28), one of which was binocular with two lesions in the left eye and the other with choroidal neovascularization (CNV). Kobayashi et al. (29) also reported a case of NC-FCE with CNV. Say et al. (30) reported a case of subretinal hemorrhage at the infratemporal arch with macular involvement. The report on FCE gradually increased (31, 32). In the study of CSC and FCE, Wang et al. (31), 17 cases (19 eyes, 21 FCEs) were found in 351 patients with CSC. The etiology of FCE is not clear. The latest study suggests that choroidal abnormalities occur (32). They found that the FCE corresponds to an increase in the inner choroidal reflex, unclear vascular development, the outer choroidal traction by the inner choroidal cavity, visible superior choroidal cavity, choroidal scleral interface is still smooth. However, the relationship between CSC and FCE is uncertain, Liu et al. (32) and other discussions suggest that there is no final conclusion, but Wang et al. (31) believes that the abnormality of choroidal vessels in FCE is related to the occurrence of CSC.
Fluctuation of internal limiting membrane (FI) was observed in one eye. FI was found in OCT of VKH before (21, 33). Our previous studies of VKH also found FI, and speculated that there is a certain relationship with retinal Radial stripes (34). Dusheng et al. (21) speculated that FI was associated with inflammation. Considering that the inflammation of CSC was not common, we believe that this change was due to mechanical traction caused by changes in the retina and choroids.
Both ILM-RPE map and Shadowgram of OCT are similar to fundus photography in that they observe the shape of the retina directly from the front and can quickly determine the location, extent and basic shape of the lesion. They complement each other with B-Scan and are indispensable for the diagnosis of diseases.
The ILM-RPE Map feature of CSC is very obvious. The lesion is typically round or round like with some very regular shapes; the uplift is uniform, the thickest in the center, slightly thickened at the edge of the detachment zone, and then excessive to normal. This is very consistent with the appearance of CSC seen under ophthalmoscope, and the FFA examination of the dye slowly leaking symmetrically in all directions (3). In some CSC, the lesions are large or deviate from the macular center. We can see only a round-like part of the lesion in the 6 × 6 mm2 range. With the improvement of OCT and the enlargement of the scope of examination, the ILM-RPE Map of OCT will be more convenient to observe CSC. The ILM-RPE Map does not show the contour of the inner limiting membrane surface, but the thickness between ILM and RPE, so the RPE uplift on the ILM-RPE Map is an excavation, and the FCE is a protrusion. The macular fovea itself is thinner and sometimes shows small excavation on the topographic map.
The Shadowgram of CSC has good contrast between black and white, it is convenient for clinical observation. Typical round or round like lesions, or part of the lesion round like, is very consistent with the scope of the lesions on ILM-RPE Map, and is very consistent with neurosensory detachment or RPE lesions. The range of lesions is easily estimated accurately.
OCT scanning light source wavelength 840 nm, belongs to infrared light, Shadowgram is similar to the black-and-white fundus photography taken with this wavelength. Zhou et al. (35) studied the NIR images of CSC with similar wavelengths (820 nm). Results Neuroepithelial detachment showed elliptical dark areas on NIR images with clear boundaries, and PED showed circular dark areas with clear boundaries on NIR images, which were consistent with fundus photography, FFA and ICGA. Comparing NIR images with OCT's Shadowgram, we found that they were very similar, but our Shadowgram had better contrast and was easier to distinguish the lesions.
RPE Surface is a surface morphology of RPE. RPE Surface of CSC shows a special shallow plate depression. This may be related to the mechanical separation of CSC's RPE and photoreceptor cells and the uniform thinning of RPE. RPE Surface's small uplift is very common in CSC, and is consistent with B-Scan's PED and bulge positions. Despite the presence of choroidal thickening (6, 36), the RPE Surface of CSC remained smooth without undulation.