Purpose:
At the convalescent stage of Vogt-Koyanagi-Harada (VKH) disease, a sunset glow appearance of the fundi is observed. The detail choroidal architecture, especially at the choroidal level, is not clearly understood so far. We observed the deep choroid in VKH disease in vivo by using high-penetration optical coherence tomography (HP-OCT).
Methods:
Ten eyes of 5 patients with sunset fundi due to VKH disease and 82 healthy eyes as a control were observed with prototype HP-OCT using 1060 nm wavelength light source (Axial resolution 11 microns, and scan speed 50,000 A-scans/sec). It allows us to observe the deep choroid and even sclera, better than commercially available OCT using 840 nm wavelength light source. Choroidal morphological changes as well as choroidal thickness, defined as a distance between retinal pigment epithelium hyperreflective line and scleral surface, were compared to age-matched normal healthy controls.
Results:
Loss of the choriocapillaris and small vessels were prominent in VKH disease. Hyperreflective dots, presumed to be melanocytes, were also lost. The choroid seemed to be more uniformly solid structure with multiple pores just like Emmental Cheese unlike normal meshwork appearance (Figure). The average foveal retinal thickness in VKH disease was similar to control (215 µm vs. 219 µm, P = 0.75). However, the mean subfoveal choroidal thickness was significantly thinned in VKH disease (202 µm vs. 379 µm, P < 0.0001). There was no significant correlation between age, duration of the disease, visual acuity, retinal thickness and choroidal thickness.
Conclusions:
Significant choroidal vascular/structural changes underlies in sunset glow fundi of VKH disease. HP-OCT is useful to observe these deep choroidal pathologies in uveitis.
Keywords: choroid • melanocytes • uvea