Structural Changes of Inner and Outer Choroid in Central Serous Chorioretinopathy Determined by Optical Coherence Tomography

Abstract

Purpose: To determine the structural changes of the choroid in eyes with central serous chorioretinopathy (CSC) by enhanced depth imaging optical coherence tomography (EDI-OCT).

Methods: A retrospective comparative study was performed at two academic institutions. Forty eyes with CSC, their fellow eyes, and 40 eyes of age-matched controls were studied. Subfoveal cross sectional EDI-OCT images were recorded, and the hypo reflective and hyperreflective areas of the inner and outer choroid in the EDI-OCT images were separately measured. The images were analyzed by a binarization method to determine the sizes of the hyporeflective and hyperreflective areas.

Results: In the inner choroid, the hyperreflective area was significantly larger in the CSC eyes (35,640±10,229 μm2) than the fellow eyes (22,908±8,522 μm2) and the control eyes (20,630±8,128 μm2; P<0.01 vs control for both, Wilcoxon signed-rank test). In the outer choroid, the hyporeflective area was significantly larger in the CSC eyes (446,549±121,214 μm2) than the control eyes (235,680±97,352 μm2, P<0.01). The average ratio of the hyporeflective area to the total choroidal area was smaller in the CSC eyes (67.0%) than the fellow eyes (76.5%) and the control eyes (76.7%) in the inner choroid (P<0.01, both). However, the ratio was larger in the CSC eyes (75.2%) and fellow eyes (71.7%) than in the control eyes (64.7%) in the outer choroid (P<0.01, both).

Conclusions: The larger hyperreflective area in the inner choroid is related to the inflammation and edema of the stroma of the choroid in the acute stage of CSC. The larger hyporeflective areas in the outer choroid is due to a dilatation of the vascular lumens of the larger blood vessels. These are the essential characteristics of eyes with CSC regardless of the onset.

Fig 1. Spectral domain optical coherence tomographic (SD-OCT) images of an eye with central serous chorioretinopathy, of the normal fellow eyes, and normal control eyes.

SD-OCT images of a control eye (A, D and G), an eye with central serous chorioretinopathy (CSC; B, E, and H), and the fellow eyes of a patient with unilateral CSC (C, F, and I) are shown. The original OCT images (A-C), binarized images (D-F), and the images in which the hyporeflective areas are outlined in color are shown (G-I). Yellow dashed lines indicate the segmentation lines between the inner and outer choroid (middle row). The area outlined in dark yellow represents the hyporeflective area in the inner choroid and the one in dark red represents the hyporeflective area in the outer choroid.

Fig 2. Scatterplots of choroidal areas of control eyes, CSC eyes, and fellow eyes.

The total choroidal area, hyporeflective area, and hyperreflective area in the three types of eyes are shown as a function of the location in the choroid. (A) whole choroid, (B) inner choroid, and (C) outer choroid. *; P <0.01, Bonferroni’s correction by Wilcoxon signed-rank test.

Fig 3. The ratio of hyporeflective and hyperreflective areas in the choroid.

The total choroidal area (left), the inner choroidal area (center), and the outer choroidal area (right) are shown. The ratio of hyporeflective areas was significantly larger in CSC eyes in the total choroid or CSC fellow eyes. But it was significantly smaller in CSC eyes than fellow eyes or control eyes. *; P<0.01, Wilcoxon signed-rank test; CTRL, control eyes.

Fig 4. Scatterplots of CSC index as a function of the total choroidal area for each type of eyes.

Scatterplot of the eyes for the total choroidal area (X-axis) and CSC index (Y-axis) is shown. In controls, the choroidal area was distributed at a lower range than CSC eyes, and the CSC index was distributed at a lower range than CSC eyes (A, B). CSC-fellow eyes were between these two groups from either point (C).