Optical coherence tomography for monitoring the process of Candida endophthalmitis

An 82-year-old man, who had been managed by intravenous hyperalimentation after surgery for hepatocellular carcinoma, was referred because of bilateral blurring of vision. He was diagnosed to have endogenous Candida endophthalmitis based on candidemia and ophthalmoscopic findings. Although treated with intravenous micafungin, his general condition deteriorated gradually and he died 35 days after diagnosis. In his left eye, ophthalmoscopy revealed several chorioretinal lesions, one quarter to one half disc diameter in size, scattered in the posterior pole. We focused on a juxtafoveal opalescent one (Fig. 1A). At the first visit, a horizontal optical coherence tomography (OCT) scan captured a dome-shaped protrusion of the highly reflective line corresponding to the retinal pigment epithelium (RPE) (Fig. 1B). Ten days later the lesion had flattened and turned yellowish in colour, similar to the other lesions (Fig. 1C), and OCT imaged a highly reflective mass beneath the damaged retina (Fig. 1D) – similar to the previous histopathological studies (Fig. 1E) by Griffin et al. (1973). Thirty days later, the lesion had shrunk and partially protruded into the vitreous cavity (Fig. 1F). OCT showed that the highly reflective lesion infiltrated the sensory retina and partially penetrated through the vitreoretinal interface (Fig. 1G). The OCT findings of this lesion are quite similar to the histopathological manifestations (Fig. 1H) reported by Griffin et al. (1973). At the first visit, an opalescent juxtafoveal lesion (A) is imaged with optical coherence tomography (OCT) as a dome-shaped protrusion of the highly reflective line (B). Ten days later, the lesion has turned yellowish (C) and OCT depicts a highly reflective mass beneath the damaged retina (D), similar to a previously reported histopathological image (E), which shows destruction of Bruch’s membrane and retinal pigment epithelium (RPE) and subretinal invasion. Thirty days later, the lesion had shrunk and partially protruded into the vitreous cavity (F), as also shown by OCT (G), similar to the previous histopathological report (H). A smaller lesion (I) was imaged by OCT as a highly reflective mass protruding from the inner retinal layers into the vitreous cavity (J). Note the preserved outer retinal layers, similar to the previous histopathological images (K). Arrows in (A), (C), (F) and (I) indicate the OCT scanning direction. (E) and (H) reprinted from Griffin et al. (1973) with permission from Archives of Ophthalmology; (K) reprinted from Kawanishi et al. (1987) with permission from Folia Ophthalmologica Japonica. In the right eye, there was a smaller lesion adjacent to the fovea (Fig. 1I). At the first visit, OCT demonstrated a highly reflective mass protruding from the inner retinal layers into the vitreous cavity. It was not accompanied by distortion of the outer retinal layers beneath the lesion (Fig. 1J). During follow-up, the ophthalmoscopic and OCT findings of this lesion were stable. The OCT findings of this lesion are similar to the histopathological manifestations (Fig. 1K) reported by Kawanishi et al. (1987). Endogenous fungal endophthalmitis is well known as one of the sight-threatening infectious eye diseases (Smith et al. 2007), and the most common causative microorganism is the Candida species (Ness et al. 2007). Two different pathways have been proposed for the intraocular dissemination of Candida: via the short posterior ciliary artery route (Griffin et al. 1973) and via the central retinal artery route (Kawanishi et al. 1987). In our patient imaged with OCT, the lesion in the left eye arose from the sub-RPE level and eventually penetrated into the vitreous cavity, destroying all retinal layers. On the other hand, the lesion in the right eye stayed within the inner sensory retina. The striking similarity between the former histopathological investigations and the OCT images highlights the credibility and usefulness of OCT in localizing the depth of chorioretinal lesion in non-invasive fashion. Localization of the fungal lesion on retinal transverse sections can be valuable, especially when considering vitrectomy and when estimating risk for subsequent chorioretinal neovascularization (Jampol et al. 1996). OCT also captured a novel finding that had not been reported histopathologically. The opalescent lesion in the left eye seen at the patient’s first visit was imaged as a dome-shaped protrusion of the RPE. This stage (protrusion of the RPE) seems to conflict with the assumption that a fungal lesion penetrates the RPE easily, because histopathological investigations have suggested swift invasion of the RPE. It is possible that, with timely usage of antifungal drugs, the RPE may provide a temporal sheet-like barrier against the development of a full-thickness retinal lesion. OCT, which is superior in observing changes over time in a retinal lesion, can provide detailed information about fungal endophthalmitis that was formerly obtained only by histopathological investigation. The real-time analysis of chorioretinal lesions is likely to be useful in clinical decision making when managing C. endophthalmitis and could offer new insights into the disease.