Fluorescein-free detection of focal leak in a patient with acute central serous chorioretinopathy

Abstract

Fundus fluorescein angiography (FFA) is considered the gold standard for identifying focal leaks in central serous chorioretinopathy (CSCR). However, there are situations where FFA cannot be performed, and alternative noninvasive investigations are required to pinpoint area of focal leaks. We present a case of a 36-year-old female patient with bilateral steroid induced acute CSCR with three distinct fluorescein-free signs converging in the same area indicating presence of focal leak.

Introduction

Central serous chorioretinopathy (CSCR) causes central blurring of vision or scotomas in 20–45 years old males and is characterized by neurosensory retinal detachment at the macula with associated serous pigment epithelial detachments (PEDs).[1] CSCR usually resolves spontaneously but warrants focal laser in chronic cases or certain acute CSCR situations. Fundus fluorescein angiography (FFA) is the gold standard method of identify focal leaks for planning focal laser if there is no resolution of CSCR over a period. However, FFA is an invasive investigation and may not be suitable for all patients. There have been reports of FA-free noninvasive signs on fundoscopy, fundus photography, optical coherence tomography (OCT), OCT angiography (OCTA), and fundus autofluorescence (FAF) that can help identify leaks for which focal laser can be done. In this case report, we describe a 36-year-old woman with steroid induced bilateral CSCR with characteristic FA-free retinal signs.

Case Report

A 36-year-old woman presented with complaints of scotoma in the left eye (OS) for the past 2 days. Four weeks ago, she was diagnosed with leukocytoclastic vasculitis of her lower limbs and was started on oral steroids 20 mg/day. Unaided visual acuity was 6/6, N6 in both eyes (OU). Anterior segment examination of OU was normal. Fundus examination of the right eye (OD) showed serous PEDs temporal to the macula and superonasal to the fovea with associated minimal subretinal fluid [Figure 1a]. Fundus examination of OS showed a large pocket of subretinal fluid adjacent to the fovea temporally and extending inferiorly with subretinal fibrin [Figure 1b]. FAF showed hyperautofluorescent areas corresponding to the subretinal fluid in OU. OCT showed normal foveal contour in the OD with subretinal fluid and small PEDs superior to the fovea with dipping of the neurosensory retina over the PED. OCT of OS showed a normal foveal contour with a serous PED and subretinal fluid temporal to the fovea and dipping of the neurosensory retina over it [Figure 2a]. Hyperreflective subretinal material suggestive of fibrin was also noted. In view of steroid-induced bilateral CSCR, the patient was advised to consult her rheumatologist for reduction in oral steroid dosage. A month later, patient was on 7.5 mg oral steroids. In OD, there was resolution of the minimal amount of subretinal fluid superonasal to the fovea. In OS, a significant reduction in subretinal fluid was noted with subretinal fibrin deposition temporal to the fovea. OCT through the temporal part of the macula showed a retinal pigment epithelium (RPE) defect with a hyporeflective space in connection to it in-between the hyperreflective subretinal fibrin [Figure 2b]. Corresponding FAF showed a hypoautofluroscent spot in the same area [Figure 3]. As the subretinal fluid was not involving the fovea and not interfering with vision, the patient was observed further with tapering of steroids. Three months later, she was noted to have complete resolution of subretinal fluid in OS.

Figure 1.

(a) Color fundus photo of the right eye showing pigment epithelial detachments superonasal and temporal to the fovea (yellow dotted circles), (b) Color fundus photo of the left eye showing a large pocket of subretinal fluid temporal to the fovea (yellow dotted circle)

Figure 2.

(a) Optical coherence tomography of the left eye at first visit showing subretinal fluid temporal to the fovea and the retinal dipping sign (block arrow), (b) Optical coherence tomography of the left eye at the follow-up visit showing decrease in subretinal fluid and the vacuole sign (star) at the same location as the retinal dipping sign

Figure 3.

Fundus autofluorescence of the left eye showing a hypoautofluorescent spot (yellow arrow) in the same location

Discussion

FFA is the gold standard for identifying focal leaks in CSCR, but in cases where FFA is avoided such as kidney disease patients and pregnancy, there is a need for alternative noninvasive methods of identification of focal leaks. In our patient, OU showed an OCT sign called “retinal dipping sign” on initial presentation. The “retinal dipping sign in CSCR” is defined as dipping of the outer neurosensory retina in an inverted triangular pattern and protruding over the PED. It is seen in eyes with subretinal fibrin, and the area of sagging can depict location of focal leaks.[2,3] On follow-up, the same location showed an area of hyporeflective clearing between the hyperreflective fibrin and above an RPE defect. This is known as the “vacuole sign.” The “vacuole sign” in CSCR was described by Rajesh et al. and refers to a hyporeflective space/vacuole adjacent to RPE defect and is a sign of constant fluid egress.[4] The vacuole is said to depict the site of active flow of clear fluid within the fibrin and corresponds to RPE leaks on FFA.[4] In our patient, the location of retinal dipping sign in the first visit corresponded to the vacuole sign on follow-up. This location is a possible area of focal leak in this patient. Maltsev et al. showed that in eyes with CSCR, PEDs and photoreceptor outer segment thinning coincided with leakage points.[5] PEDs have been recognized as leakage sites in various studies. Kim et al.[3] and Mohanty and Mahapatra[6] noted that the “retinal dipping sign” corresponded to the leakage site, which was seen in our case. Subretinal fibrin is said to be around the leakage site. “Vacuole sign”[4] is one of the latest findings on OCT which corresponds to area of leakage which was also seen in our case.[5] OCTA has shown thinner choriocapillaris vessel density at leakage sites.[7] Mohanty and Mahapatra identified a discrete hypopigmented spot (HPS) on fundoscopy in 76% of the eyes which coincided with leaks on FFA.[6] HPS is said to occur due to RPE loss at the leakage site or fibrin egress into the subretinal space secondary to RPE defects at leakage sites.[3] However, the absence of HPS does not imply there is no leak and an FFA is required in such cases for confirmation. In FAF, a hypoautofluoresecent spot is said to correspond to leaks as seen in 93% of the cases by Wang et al.[8] which was also seen in the same location in our patient.

Although our patient did not require focal laser as the subretinal fluid resolved with observation, the two signs on OCT and hypoautofluorescent spot on FAF could have located the area of focal leak without FFA if there was need for laser. The limitation of this case report is lack of FFA confirmation of the focal leak. The strength of this case report is the use of three FA-free noninvasive signs to detect possible area of focal leak. In our patient, despite not conducting FFA for confirmation, the convergence of three noninvasive signs in the same location strongly suggested the presence of a focal leak and could have been used to perform focal laser, if required. In conclusion, a combination of these FA-free noninvasive signs can serve as a useful alternative to detect areas of focal leaks in CSCR in patients who are not candidates for FFA.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.