Posterior Scleritis With Secondary Uveal Effusion Unmasking Peripapillary Pachychoroid Syndrome

Technical Summary: Posterior Scleritis With Secondary Uveal Effusion Unmasking Peripapillary Pachychoroid Syndrome

Problem Statement
Posterior scleritis is a rare inflammatory condition (<10% of scleritis cases) that presents significant diagnostic challenges due to its clinical overlap with other entities such as Vogt–Koyanagi–Harada disease, sympathetic ophthalmia, and choroidal metastasis. A specific diagnostic and therapeutic dilemma arises when posterior scleritis coexists with disorders of the pachychoroid spectrum, particularly peripapillary pachychoroid syndrome (PPS). While corticosteroids are the standard treatment for posterior scleritis, they are known to exacerbate pachychoroid spectrum disorders. The paper addresses the difficulty in distinguishing inflammatory exudation from pachychoroid-driven fluid and the risk of iatrogenic worsening of the latter when treating the former.

Methodology
The authors present a case report of a 71-year-old male patient presenting with decreased visual acuity (20/100) and periocular pain in the right eye (OD). The diagnostic workup was multimodal, including:

• Clinical Examination: Best-corrected visual acuity (BCVA), slit-lamp, and dilated fundus examination.
• Imaging: Spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF), fluorescein angiography (FA), indocyanine green angiography (ICGA), B-scan ultrasonography, and contrast-enhanced orbital magnetic resonance imaging (MRI).
• Laboratory Testing: Interferon-γ release assay, HLA-B27, and chest X-ray.
• Treatment Protocol: The patient received high-dose intravenous methylprednisolone (500mg for 3 days) followed by an oral taper. Systemic immunosuppression with subcutaneous methotrexate was introduced as a steroid-sparing agent.

Key Results

• Initial Presentation: The right eye exhibited optic nerve edema, macular serous detachment, and four-quadrant choroidal detachments. The left eye (OS) was asymptomatic but showed choroidal folds. MRI confirmed posterior scleral enhancement and choroidal detachments. FA showed mottled hyperfluorescence without vasculitis, and ICGA ruled out choriocapillaritis or stromal granulomas.
• Response to Steroids: Following intravenous corticosteroids, the patient experienced symptomatic improvement, and BCVA in the right eye improved to 20/32. Serous retinal detachment and choroidal detachments resolved.
• Emergence of PPS: Three weeks later, despite the resolution of subretinal fluid, the patient developed new bilateral peripapillary intraretinal fluid (IRF) and schisis. Retrospective analysis revealed the patient had short axial lengths (hyperopic anatomy), pre-existing choroidal folds, and a chronic peripapillary pigment epithelial detachment (PED).
• Final Outcome: Recognizing the underlying PPS, the medical team cautiously de-escalated corticosteroids while maintaining methotrexate. This led to the resolution of the bilateral peripapillary fluid. Final BCVA was 20/25 (OD) and 20/20 (OS).

Key Contributions

1. Coexistence of Pathologies: The paper documents a rare case where posterior scleritis with secondary uveal effusion coexisted with peripapillary pachychoroid syndrome (PPS).
2. Mechanistic Insight: The authors propose a pathophysiological model where short, hyperopic eyes (pachychoroid phenotype) have inherent scleral thickening that reduces transscleral fluid egress. In the setting of posterior scleritis, active inflammation further increases choroidal vascular permeability and exacerbates outflow obstruction, leading to extensive choroidal detachments.
3. Temporal Dynamics of Steroid Effect: The case illustrates the temporal sequence of corticosteroid-induced pachychoroid worsening. While the inflammatory component responded immediately, the pachychoroid component (manifesting as peripapillary IRF) emerged in the third week, attributed to corticosteroid-induced transcriptional changes that increase choroidal vascular permeability and impair the retinal pigment epithelium barrier.
4. Diagnostic Differentiation: The study highlights the utility of multimodal imaging (specifically MRI and ICGA) in distinguishing posterior scleritis from granulomatous choroiditis and other infiltrative diseases.

Significance and Claims
The paper claims that posterior scleritis may coexist with PPS, and that the standard treatment for scleritis (corticosteroids) may paradoxically worsen the underlying pachychoroid condition. The authors emphasize that the appearance of peripapillary IRF during corticosteroid therapy, particularly in hyperopic eyes with pre-existing pachychoroid features, should prompt a reconsideration of the underlying mechanism.

The significance of this case lies in its therapeutic implication: early recognition of this coexistence is critical to shifting management from escalating immunosuppression toward a steroid-sparing strategy (e.g., methotrexate). This approach aims to control the inflammatory disease while mitigating iatrogenic worsening of the pachychoroid spectrum disorder, ultimately preserving visual acuity. The authors conclude that multimodal imaging is essential for prompt diagnosis and for distinguishing inflammatory exudation from pachychoroid-driven fluid, which have distinct therapeutic requirements.