Association of Retinal Pigment Epithelium Reflectivity on Optical Coherence Tomography with Recurrence of Vogt-Koyanagi-Harada Disease: A Retrospective Observational Study

Abstract

Purpose: Despite the necessity of optical coherence tomography (OCT) for diagnosis and longitudinal monitoring in patients with Vogt-Koyanagi-Harada (VKH) disease, no studies have identified useful OCT markers for predicting recurrence in these patients. Although the precise reason for this remains unclear, one possibility is that infiltration of inflammatory cells into the choroid attenuates the OCT signal, making it difficult to precisely assess the structure of the choroid. Therefore, this study aimed to investigate changes in retinal pigment epithelium (RPE) reflectivity immediately above the choroid in eyes with acute VKH disease, as well as the association between RPE reflectivity and VKH disease recurrence.

Patients and methods: This single-centered retrospective observational study included 20 treatment-naïve patients with acute VKH disease presenting with serous retinal detachment (SRD) in the posterior pole at the initial visit between October 2015 and January 2020, as well as 15 healthy control eyes. All patients were followed up for at least 6 months and received treatment with intravenous methylprednisolone followed by oral administration of prednisolone. Swept-source OCT images through the fovea were used to measure central retinal thickness, central choroidal thickness, and RPE reflectivity.

Results: During an observation period of 37.2 ± 30.8 months, recurrence of inflammation was observed in 11 patients (55.0%). Initial visual acuity was worse in patients who developed recurrence than in those who did not (P=0.024). On initial OCT images, RPE reflectivity differed significantly between patients with and without recurrence (1.75 ± 0.42 vs 1.35 ± 0.20; P=0.018), while there were no significant differences in other chorioretinal parameters, such as central retinal thickness and choroidal thickness.

Conclusion: RPE reflectivity on OCT images may be useful for predicting the recurrence of inflammation in patients with VKH disease.

Keywords: Vogt-Koyanagi-Harada disease; inflammation recurrence; optical coherence tomography; retinal pigment epithelium.

Figure 1

Evaluation of the reflectivity of RPE. (a) The vertical swept-source OCT B-scan images with a width of 12 mm and a depth of 2.6 mm through the center of the fovea were obtained. (b) RPE was defined as the point with the highest reflectivity in the depth direction of the RPE layer by using a plot profile. (c) Ten points of the RPE were randomly selected and their reflectivity was measured and averaged. The averaged reflectivity of the vitreous body and retinal nerve fiber layer (RNFL) as the standard in each image was measured, and we defined the level in the vitreous as 0 and in RNFL as 1 after measuring each averaged reflectivity.

Figure 2

RPE reflectivity on OCT in patients with acute Vogt–Koyanagi–Harada (VKH) disease. (a, c, e, and g) Representative patient with VKH disease (62 years old, female) who did not experience recurrence during follow-up. (a) At the initial visit, visual acuity (VA) was 20/40, central choroidal thickness (CCT) was 848 µm, and RPE reflectivity was 1.12. (c) The reflectivity on the swept-source (SS) OCT image at the initial visit was adjusted as 0 for the vitreous body and 1 for the retinal nerve fiber layer (RNFL). (e) One month after the initiation of steroid therapy, VA was 20/13. Choroidal thickening was still present; however, serous retinal detachment (SRD) had disappeared, and the RPE had straightened. (g) After 6 months of steroid therapy, VA was 20/13, and no recurrence was observed. (b, d, f, and h) Representative patient (76 years old, female) who experienced a recurrence of VKH disease during follow-up. (b) At the initial visit, VA was 20/17, CCT was 1051 µm, and RPE reflectivity was 1.47. (d) The reflectivity on the SS-OCT image at the initial visit was adjusted as 0 for the vitreous body and 1 for RNFL. (f) One month after the initiation of steroid therapy, VA was 20/13. The choroidal thickening was still present; however, SRD had disappeared, and the RPE had straightened. (g) After 6 months of steroid therapy, VA was 20/13, and SRD was not observed. However, choroidal thickening was present, and cross-sections of the choroid vessels were obscured, indicative of recurrence.

Figure 3

Scatter plot of the RPE reflectivity on OCT, receiver operating characteristic (ROC) curve, and cut-off values. (a) Scatter plot of the RPE reflectivity on OCT at the initial visit. In eyes with future recurrence of inflammation, higher RPE reflectivity was observed than in eyes without the recurrence (P=0.018). In the majority of eyes with high RPE reflectivity, the recurrence of inflammation was observed. (b) The ROC curve is shown for the RPE reflectivity on OCT at the initial visit as the independent variable, and whether the recurrence of inflammation was observed or not within 6 months from the initial visit as the dependent variable. The area under the curve was 0.7980. The point of the Youden index was at a difference in VDI of 1.4700, at which point, the sensitivity was 72.73% and the specificity was 88.89%.