
Acute retinal necrosis (ARN) is a rare but potentially blinding retinal condition. The main etiology for ARN is varicella-zoster virus or herpes simplex virus infection [1], and panuveitis with obstructive vasculitis and rapidly progressing peripheral necrotizing retinitis are classically seen in ARN cases [2]. While most ARN cases occur in immunocompetent individuals, immunocompromised patients are also susceptible [3]. Previously, choroidal involvement at the posterior pole—visualized by optical coherence tomography and indocyanine green angiography (ICGA)—has been reported in ARN cases, leading to poor visual prognoses[4-6]. Herein, we report an atypical case of ARN with primary choroidal involvement, with a pattern of inflammation distinctive from the retinal necrosis, along with relatively early development of rhegmatogenous retinal detachment (RRD). This study was approved by the Institutional Review Board of Chungbuk University Hospital (2024-06-005) and adhered to the tenets of the Declaration of Helsinki.
A 67-year-old immunocompetent, healthy woman presented with a chief complaint of blurred vision in the right eye for 5 days. The best-corrected visual acuity of the right and left eyes was 0.32 (20/63) and 1.0 (20/20), respectively, and the intraocular pressure was 12 mmHg in both eyes. Slit-lamp examination revealed 2+ cells in the anterior chamber and 1+ cells in the anterior vitreous cavity of the right eye. Moreover, fundus examination of the right eye revealed multiple yellowish retinal infiltrations in the inferotemporal, inferonasal, and superotemporal peripheral quadrants, along with perivascular sheathing/hemorrhage in the inferotemporal quadrant (Fig. 1). Examination of the left eye was unremarkable.
Notably, optical coherence tomography revealed some vitreous opacity but intact ellipsoid zone integrity. Fluorescein angiography (FA) showed early hyperfluorescence with diffuse late-phase leakage, especially in the inferotemporal quadrant, corresponding to retinitis. Furthermore, it revealed a blockage of the retinal vessels in the inferotemporal quadrant, indicating retinal obstructive vasculopathy. Interestingly, ICGA revealed multiple hypofluorescence signals from the early to late phases, focused in the inferotemporal quadrant, which did not correlate with retinal infiltration or hemorrhage upon fundus photography or FA, indicative of primary choroidal inflammation. Serology was negative for human immunodeficiency virus, interferon gamma release assay, Toxoplasma, Toxocara, and anti-nuclear antibody. Therefore, based on the clinical presentation, ARN was diagnosed, and the patient was treated with intravenous acyclovir (13 mg/kg) 3 times a day.
After 3 days of treatment, polymerase chain reaction analysis of the anterior chamber fluid revealed a positive result for varicella-zoster virus, confirming the diagnosis of ARN. Fundus examination revealed exacerbation of necrotic infiltration of the inferotemporal quadrant and ghost vessels at the 360-degree periphery. Moreover, the best-corrected visual acuity dropped to 0.05 (20/400) with the development of macular edema. Therefore, oral prednisolone (0.5 mg/kg) was started to reduce inflammation and ischemic optic neuropathy.
After 1 week of treatment, infiltrations in the superotemporal and inferonasal quadrants subsided, while those in the inferotemporal quadrant persisted. Treatment was switched from intravenous acyclovir to oral acyclovir (800 mg) 5 times a day. Tapering of oral acyclovir and prednisolone was initiated during the outpatient clinic visits. The remaining infiltrations decreased gradually with treatment adherence. As the retinal necrotizing infiltration subsided, choroidal inflammation became visible, with fundus photography showing yellowish subretinal deposits in the same region of focus as the hypofluorescent dots observed upon ICGA (Fig. 2).
After 4 weeks of treatment, the retinal infiltrations nearly resolved; however, RRD developed from the inferior aspect. Therefore, pars planar vitrectomy with an encircling buckle and silicone oil injection were performed. Intraoperative findings showed multiple necrotic retinal holes at the inferior periphery, along with choroidal infiltration in the same region as the focus of hypofluorescence upon the previous ICGA. Interestingly, the area of focus of choroidal inflammation remained attached, whereas other regions of the retina were detached (Fig. 3). The detached retina was reattached during surgery.
One month postoperatively, the retina was reattached with a silicone oil tamponade; however, optic atrophy developed, and the best-corrected visual acuity was 0.05 (20/400). Follow-up FA and ICGA revealed extensive window defects in the necrotic retina. However, numerous previously observed hypofluorescence signals indicative of choroidal inflammation were no longer present (Fig. 4).
ARN is an infectious retinitis that presents as peripheral retinal necrosis and progressive occlusive vasculitis [2]. Apart from peripheral retinitis, optic disc edema, scleritis, and inflammatory orbitopathy can also be associated with ARN involvement [1,7,8]. Moreover, a previous study using immunocytologic staining revealed deposits of immune complexes containing viral antigens in the retinal vessel walls, choroidal stroma, and extraocular muscles [9]. In the present case, both retinitis and primary choroidopathy were accompanied by ARN, which was clearly visualized by ICGA.
Previous reports have highlighted the occurrence of choroidal involvement in ARN [4-6,10]. For example, Singh et al. [5] identified choroidal involvement in ARN through ICGA, demonstrating hypofluorescent lesions that indicated choroidal inflammation. Additionally, Takei et al. [10] described choroidal vascular filling delays and localized dye leakage on ICGA, emphasizing the importance of detecting choroidal vascular lesions in ARN patients. Moreover, previous histopathological studies have demonstrated choroidal plasma cell infiltration in ARN patients, further supporting the notion that choroidal tissues are directly affected by the inflammatory processes in ARN [11]. Using optical coherence tomography, recent case reports have illustrated choroidal involvement with diffuse thickening and disruption of the choroidal architecture in patients with ARN or viral retinitis [4,6]. These observations highlight the importance of comprehensive imaging techniques in diagnosing and managing ARN as choroidal involvement could indicate a more severe disease course and necessitate the application of aggressive treatment strategies.
To our knowledge, the present case report is the first to demonstrate both primary retinitis and primary choroiditis in ARN, as confirmed angiographically. Previous studies have reported choriocapillaris and choroidal ischemia in severe cases of ARN; however, these were typically identified as secondary changes due to primary retinitis, with hypofluorescence on ICGA observed in the same areas as retinal infiltration [4-6,10]. In contrast, our findings showed choroidal involvement as a distinct and separate manifestation of retinal lesions. This distinction suggests that, in ARN, rather than secondary choroiditis resulting from retinitis, inflammation can directly infiltrate the choroid and spread peripherally.
Dark dots/areas can be observed when posterior inflammation and choroidopathy occur. The mechanisms for this are considered to be blockage of fluorescence by inflammatory infiltrates and deficient choriocapillary/choroidal perfusion [12]. Previously, Bissig et al. [13] reported hypofluorescence upon ICGA in the region of retinal infiltration, suggesting retinal and choroidal hypoperfusion in ARN. As fundus photography and FA did not show retinal infiltrates, possibly blocking ICGA fluorescence from the choroid, the dark dots/areas in the present case were considered a visualization of choroidal infiltration or hypoperfusion.
The clinical implications of choroidal involvement in ARN are important. Choroidal inflammation suggests a more severe and extensive inflammatory process, potentially leading to worse clinical outcomes and necessitating more aggressive treatment. In addition, choroidal involvement in ARN has previously been associated with an increased risk of complications such as RRD. Typically, RRD in patients with ARN develops within 3-6 months of the diagnosis [14]; however, in this case, retinal detachment occurred unusually early, within 4 weeks of treatment initiation. This rapid progression might be attributed to choroidal inflammation, as indicated by the multiple hypofluorescent areas observed upon ICGA. These findings imply that choroidal involvement could accelerate retinal damage and contribute to an earlier RRD onset.
Although the exact mechanism behind the early development of RRD in choroid-involved ARN cannot be fully elucidated with this single case report, several potential explanations can be proposed. First, severe inflammation could accelerate retinal ischemia and necrosis, facilitating vitreoretinal traction and leading to RRD. The incidence of RRD in ARN is typically higher in immunocompetent patients compared to those with immune dysfunction, in cases of varicella zoster infection compared to herpes simplex virus, and in eyes involving multiple quadrants compared to those involving a single quadrant [14]. These conditions are all associated with a greater degree of inflammation. Second, exudation from choroiditis may contribute to RRD development. Exudative retinal detachment can occur in ARN, and subretinal exudation from choroiditis may gravitate inferiorly, aiding in the formation of breaks in the necrotic retina and ultimately leading to RRD. In the present case, RRD began inferiorly, with several breaks located in the necrotic retina in the inferior region. Finally, persistent choroidal inflammation may weaken retinal adhesion. Due to recruitment of inflammatory cells in the choroidal and choriocapillary areas, adhesion between the retinal pigment epithelium and photoreceptors can be compromised, making the retina more vulnerable to detachment. This is consistent with previous reports demonstrating that inflammation in these layers disrupts the structural integrity of the retina [11].
In the present case, although the eye showed near-total retinal detachment, the area of focus of choroidal inflammation remained attached during surgery. Previous studies have reported subretinal fibrosis followed by Vogt–Koyanagi–Harada syndrome, which is a primary choroidal inflammatory disorder [15]. Histological examination revealed subretinal fibrosis with underlying choroidal infiltration of mononuclear cells, indicating that cytokines, immunoglobulins, and inflammatory mediators produced by the infiltrating cells interact with retinal pigment epithelial cells, Müller cells, and choroidal fibrocytes to form fibrotic tissue as a reparative response to the inciting inflammation [15]. This suggests that ongoing choroidal inflammation may act as a temporary protective factor against retinal detachment. However, the presence of choroidal inflammation in ARN may also serve as a biomarker for the severity of intraocular inflammation, potentially indicating a poor prognosis [4-6]. In this case report, it is plausible that the extensive inflammation led to the formation of multiple retinal breaks in the affected retina, which resulted in early RRD development. To clarify the definitive role of choroidal inflammation in the timing or occurrence of RRD in ARN, further studies with larger case series are necessary.
Intravenous and oral antiviral agents are the standard treatment of ARN, presenting their effectiveness in regression of retinitis, visual outcome, and fellow eye involvement [2]. Recently, intravitreal antiviral injections, such as foscarnet, have been found to be beneficial when combined with conventional systemic antiviral therapy, reducing the risk of severe vision loss and the incidence of RRD [16]. Intravitreal antiviral injections can be considered for eyes with ARN involving choroidal inflammation due to the severe grade of inflammation. However, extreme caution is necessary as the procedure itself may act as a risk factor for retinal tear and RRD development.
Anti-inflammatory treatment is essential when choroidal involvement is present. Kawali et al. [4] recently reported successful management of chronic macular edema with topical interferon-2b therapy in a patient with choroid-involved ARN. Systemic corticosteroids may also be beneficial for reducing inflammation. Adjunctive oral corticosteroids, initiated 24 to 48 hours after starting antiviral treatment, can help reduce cystoid macular edema or ischemic optic neuropathy [17]. The combination of corticosteroids with antiviral treatment has been shown to effectively decrease vitritis and retinitis in various reports, without increasing the risk of RRD [18]. However, careful monitoring is required for any aggravation or rapid progression of retinitis when corticosteroid treatment is added. Prophylactic pars planar vitrectomy can be suggested to eliminate the inflammatory mediators in the vitreous body [14].
The use of a prophylactic laser for retinal detachment in patients with ARN is controversial, with several authors recommending laser treatment [19] and others taking a contrary approach [8]. In a recent meta-analysis, patients with mild vitritis and a clear border of the necrotic retina were suitable for prophylactic laser treatment; however, the laser could not achieve lower retinal detachment [14]. Considering that the laser should be used at the healthy uninvolved retina to strengthen chorioretinal adhesion, adopting ICGA in patients with ARN is useful because it can visualize the region of inflammation with hypofluorescence. It is particularly useful when the overlying retina is uninvolved or minimally involved because it can easily be neglected even if this area has choroidal involvement.
In conclusion, this novel case showed primary choroidal involvement in ARN inflammation, as proven by ICGA. The patient developed RRD relatively early, demonstrating focal adhesion of choroidal inflammation, possibly due to subretinal fibrosis formation. Therefore, monitoring choroidal involvement in patients with ARN might provide useful information regarding disease severity and the development of retinal detachment.
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2024-00340391).
The authors declare no conflicts of interest relevant to this article.
Conception (E.J.S.); Design (K.L., E.J.S.); Data acquisition (K.L.); Analysis (E.J.S.); Interpretation (K.T.K., K.L.); Writing (K.L., E.J.S.); Review (K.T.K.); Final approval of the article (All authors)
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