Spectral domain optical coherence tomography in the diagnosis and monitoring of dengue maculopathy.

Introduction

A 23-year-old female presented with sudden onset of diminution of vision in the right eye (RE) associated with a central blurring of vision. She had been diagnosed to have dengue fever based on a NS1 Antigen Test 10 days before.[1] Her corrected distance visual acuity (CDVA) in the RE was 20/200 and the left eye (LE) was 20/20. Fundus evaluation revealed a yellow orange lesion at the fovea in the RE and a normal fundus in the LE [Fig. 1]. Fundus fluorescein angiogram showed early hyperfluorescence at the fovea, which persisted in the late phase with mild perifoveal capillary leakage in the RE [Fig. 2]. The RE macular (9 mm radial) spectral domain optical coherence tomography (SD OCT) scan suggested a normal contoured foveal dip with normal inner retinal layers [Fig. 3]. In the outer retina, there was a focal discontinuity of the inner segment-outer segment layer (IS-OS) or ellipsoid zone (EZ) subfoveally, with an irregular and elevated hyper reflective lesion extending from the broken EZ into and filling the outer nuclear layer (ONL) through a disrupted external limiting membrane (ELM). The foveal tent was absent and there was disruption of the outer segment retinal pigment epithelium (OS RPE) layer or the cone outer segment tips (COST) layer due to the central lesion. The RPE was relatively unaffected and appeared to be uniform throughout the scan.[2] A diagnosis of Dengue Foveolitis was made. The patient was started on treatment with oral steroids. Two weeks later the SD OCT scan through the foveal center showed resolution of the lesion [Fig. 4]. There was a focal, linear hyper reflective residual lesion (red arrow) in the outer nuclear layer just underlying the outer plexiform layer. The ELM was now more linear but still remained discontinuous under the subfovea but continuous on either side of this disruption. The EZ appeared to have regained continuity except in the subfoveal region. The foveal tent still remained absent and the RPE was normal as before. The CDVA had improved to 20/60 and funduscopy showed resolution of the foveal lesion. At 12 weeks after treatment, the SD OCT scan showed further resolution of the lesion [Fig. 5]. The ONL was now free of the lesion. The ELM was continuous throughout the scan. The EZ had now gained continuity and the foveal tent had re-appeared. The OS RPE or COST layer underlying the foveal tent could be appreciated in the temporal section of the scan (red arrow) and appeared deficient in the nasal section of the scan corresponding to the papillo-macular bundle. The CDVA had improved to 20/20.

Figure 1

Right eye fundus shows a yellow orange lesion at the fovea (black arrow) with a normal left eye fundus

Figure 2

Fluorescein angiography shows hyperfluorescence in the right fovea, left eye is normal

Figure 3

The hyper reflective lesion extending from the ellipsoid zone into the outer nuclear layer with disruption of the external limiting membrane and an absent foveal tent

Figure 4

Two weeks after treatment, there is partial resolution of the lesion, with remnants persisting in the outer nuclear layer (red arrow) and with incomplete recovery of the ellipsoid zone and the external limiting membrane

Figure 5

Twelve weeks after treatment, there is a near total recovery of the ellipsoid zone and external limiting membrane, no lesion in the outer nuclear layer and partial recovery of the outer segment retinal pigment epithelium layer (red arrow) in the temporal segment of the scan

Discussion

Ocular manifestations of dengue fever are uncommon and include subconjunctival, vitreous and retinal hemorrhages, posterior uveitis, optic neuritis and maculopathies such as foveolitis, edema and hemorrhage.[3] The three patterns of maculopathy that have been described on OCT are foveolitis, diffuse retinal thickening and cystoid macular edema.[4] Foveolitis secondary to dengue fever has been described as a yellow orange lesion at the fovea with disruption of the outer neurosensory retina on OCT.[2] On fluorescein angiography, it is seen as a circumscribed hyperfluorescent staining in late phase.[4] An immune mechanism has been postulated for ocular involvement and treatment options range from observation to immunosuppression with topical, periocular, oral, intravenous steroids and immunoglobulins.[2] Prognosis is variable,[34] with patients usually regaining good vision but scotomata may persist.[45]

Our case demonstrates how SD OCT can be used to determine the exact location of the lesion with respect to individual retinal layers, and be used to monitor improvement both structurally and visually. It is possible that good morphological ‘recovery’ portends with better visual recovery as in our case, and this may have significant prognostic implications in patients with treated dengue foveolitis.