Progressive Outer Retinal Necrosis in Immunocompetent Patients: Optic Nerve Involvement and an Unproven Viral Pathway

Design and population: Observational consecutive case series of five immunocompetent patients (seven affected eyes) with progressive outer retinal necrosis (PORN), evaluated at Zhongshan Ophthalmic Center between October 2020 and March 2022. Ocular-fluid quantitative PCR identified herpes simplex virus (HSV) or varicella-zoster virus (VZV) in every affected eye; cytomegalovirus testing was negative.

Principal findings: All seven eyes showed optic nerve edema on MRI and OCT evidence of sensory retinal necrosis with relative sparing of retinal pigment epithelium (RPE) and choroid. Retinal hemorrhage and perfusion abnormalities accompanied rapid disease progression. Five eyes ended with no light perception; the two eyes of one patient retained 20/200 and 20/32 vision, respectively. The authors propose an optic nerve/retinal nerve fiber route of viral spread from the lateral geniculate nucleus (LGN), but this mechanism was not directly demonstrated.

PORN is a rapidly destructive alphaherpesvirus-associated necrotizing retinitis classically described in severely immunocompromised patients. The investigators ask whether PORN can occur in immunocompetent hosts, whether optic nerve and inner retinal involvement is a consistent feature, and whether its anatomic pattern supports a distinct pathway of viral dissemination from that proposed for acute retinal necrosis (ARN).

Despite its name, “outer retinal” necrosis may be anatomically misleading: the authors observed changes involving the entire neurosensory retina rather than only photoreceptor outer segments.

Five consecutive immunocompetent patients underwent ocular examination, BCVA measurement, fundus photography, spectral-domain OCT and fluorescein angiography where feasible. Aqueous or vitreous fluid was analyzed by qPCR for HSV, VZV and CMV. All patients underwent optic nerve/brain MRI; visual evoked potentials were obtained in selected patients with adequate visual function. The analysis is descriptive and has no control group, prospective diagnostic-accuracy testing, or direct viral tracking.

Two patients had prior viral encephalitis. The reported patient age range was 18–55 years. The article’s narrative describes one male and four female patients, while its Table 1 labels a second patient as male; this discrepancy is not resolved in the source and should not be silently reconciled.

Every affected eye was positive for an alphaherpesvirus: HSV in three patients and VZV in two. All were CMV-negative. The seven affected eyes included two patients with bilateral disease and three with unilateral disease. Presentation included abrupt visual loss, variable pain on eye movement and mild initial anterior-segment inflammation that could subsequently progress. Unilateral cases showed a relative afferent pupillary defect.

Two patients with unilateral involvement had histories of viral encephalitis and temporal-lobe/hippocampal abnormalities on MRI. These observations are compatible with neurological involvement but do not establish the LGN as the reservoir or origin of the retinal infection.

• Fundus: rapidly advancing yellow-white retinal opacity/necrosis, beginning near the horizontal raphe or peripheral retina and sometimes leaving an arcuate island of relatively spared retina.
• OCT: marked neurosensory retinal hyperreflectivity and thickening consistent with extensive retinal injury, sometimes accompanied by exudative macular or retinal detachment; the RPE and choroid appeared relatively spared in the imaged lesions.
• Fluorescein angiography: vascular nonperfusion/interrupted retinal blood flow and hemorrhage tracking along larger retinal vessels, interpreted by the authors as vascular wall injury. One eye could not undergo FFA because of fluorescein allergy.
• MRI: optic nerve edema in all seven affected eyes, an important association in this small series.

Imaging demonstrates anatomic injury, but does not independently prove viral transport through retinal nerve fibers or direct viral lysis of vascular cells.

The disease was visually devastating in most affected eyes: five of seven ended with no light perception. In the fifth patient, the initially affected left eye ended at 20/200, whereas the fellow right eye developed disease during hospitalization and recovered to 20/32 after prompt antiviral management. The authors describe combinations of systemic antivirals, intravitreal antivirals and, in selected eyes, pars plana vitrectomy with silicone oil tamponade.

Interpretive caution: The better outcome in the later-treated fellow eye is a single uncontrolled observation, not proof that any particular combination, timing, or dose is superior. The article contains unusual dose/unit reporting in its treatment table; it should not be used as a standalone dosing protocol.

According to the authors’ proposed framework, PORN can have very rapid visual decline, early optic nerve findings/RAPD, early macular involvement, relatively mild initial inflammation, arcuate spread along retinal nerve fiber bundles and predominant neurosensory retinal injury with RPE/choroidal sparing. Classic ARN is described as more peripheral in onset, with prominent early inflammation, circumferential lesion expansion and inflammatory involvement of additional ocular layers.

These are hypothesis-generating clinical distinctions, not validated sensitivity/specificity criteria. PORN and ARN presentations can overlap; immune competence does not exclude PORN, and neither an optic nerve MRI finding nor a particular OCT pattern alone establishes the diagnosis.

The authors hypothesize that HSV/VZV may reactivate in the lateral geniculate nucleus, travel through the optic tract/chiasm/optic nerve, then follow retinal ganglion cell axons to their terminals, causing neurosensory retinal necrosis. The proposal is motivated by optic nerve edema, arcuate retinal patterns, RPE/choroidal sparing and the neurotropic behavior of alphaherpesviruses. Their contrasting model for ARN invokes trigeminal/ciliary nerve pathways.

Evidence boundary: No LGN viral sampling, optic nerve tissue analysis, ocular histopathology, serial viral localization or viral tracing was performed in these patients. The observations cannot establish where latency occurred, the direction of viral movement or whether axonal propagation is the dominant pathogenic route. The authors themselves call for animal viral-tracking studies.

Suspected necrotizing herpetic retinitis is an ophthalmic emergency requiring urgent retina/uveitis assessment, ocular-fluid PCR where appropriate and timely systemic antiviral management. In a rapidly progressive case with optic nerve dysfunction, early neurosensory retinal necrosis and RPE/choroidal sparing, consider PORN even in an immunocompetent patient. Evaluate the fellow eye closely because bilateral involvement occurred in two of five patients.

The authors favor early intensive antiviral treatment and caution against early systemic corticosteroid monotherapy. However, their suggestions about a preferred systemic drug combination, duration of intravitreal therapy and stopping criteria are expert hypotheses from a small uncontrolled series, not comparative evidence or established guidelines. Treatment selection and dosing require specialist judgment and current protocols.

• Very small sample: five patients and seven eyes, all from one referral center, limit representativeness and precision.
• No comparator: differences from ARN were not tested against a matched ARN cohort; proposed diagnostic criteria remain unvalidated.
• Mechanistic inference: MRI and OCT findings do not directly establish LGN latency or optic-nerve-mediated viral transport.
• Selection and timing: referral delays, prior diagnoses and heterogeneous treatments may substantially influence final vision.
• Incomplete imaging: one eye lacked FFA; supplementary images were not independently available in the extracted main article.
• Reporting inconsistencies: the text/table differ in sex designation for case 2; treatment-dose reporting should be checked against the primary publication before clinical reuse.
• Outcome attribution: the better-treated fellow eye provides no controlled estimate of antiviral efficacy.

This small case series broadens the clinical spectrum of PORN to include immunocompetent patients and highlights concurrent optic nerve edema, severe neurosensory retinal necrosis and potentially characteristic vascular and arcuate imaging patterns. Its proposed LGN-to-optic-nerve route is a provocative unverified pathogenic hypothesis. The actionable message is prompt recognition, urgent virologic evaluation and treatment, not adoption of an unvalidated mechanistic or drug-regimen algorithm.