Cytopathology of Vitreous Specimens in Acute Retinal Necrosis

To report the cytopathology of vitreous biopsy samples in patients with acute retinal necrosis (ARN) who underwent pars plana vitrectomy (PPV). We also describe two patients with unique clinical courses, cytopathologic findings, and immune response.

A retrospective review of patients with ARN who developed retinal detachment (RD) and underwent PPV from 22011 to 2019 at the Emory Eye Center was performed to assess cytopathology findings of vitreous biopsy samples. Patient demographics and laboratory testing including aqueous humor PCR for viral pathogens were recorded. Additional clinical details abstracted included intravitreal injections, surgical procedures, and vitreous cytopathological reports including immunohistochemistry findings.

Fourteen eyes of 12 patients with RD were reviewed. Ten eyes showed HSV DNA (71%) and 4 demonstrated VZV DNA (29%). All eyes received intravitreal antivirals (i.e. ganciclovir or foscarnet) with a median of 8.5 intravitreal injections per eye. Diagnoses prompting PPV included tractional RD in 14 eyes (100%), rhegmatogenous RD in 8 eyes (57%), vitreous hemorrhage in 4 eyes (29%) and vitreous opacity in 4 (29%). Ophthalmic pathology reports showed lymphocyte populations in 10 eyes (71%) with a CD3 + T-cell predominance in two patients where immunohistochemistry of CD3+ and CD20+ for T- and B-cell populations was performed. Observed immune cell populations included macrophages or histiocytes (11 eyes, 79%) and polymorphonuclear cells in 4 eyes (29%). Initial median VA was 2.5 (IQR 2.0-3.0) and improved to 2.0 (IQR 1.48-3.00, p = .48) at 6-months and 1.8 (IQR 1.2-3.0, p = .45) at 12 months follow-up.

Our cohort of ARN patients undergoing PPV show a spectrum of immunologic findings with the majority demonstrating a lymphocytic response. Histiocytes, macrophages, and PMNs were also observed. Cytopathologic and immunologic studies suggest that both innate and adaptive immunity are responsible for the clinical disease findings observed in ARN. The variability of the response to treatment in patients with ARN may reflect patient-to-patient differences in their antigen-specific immune response. Understanding the immunologic response associated with ARN may provide valuable information regarding the dosing and timing of treatment.