Summary of Retinal and Uveal Disorders in Ophthalmology

Retinal and Uveal Disorders in Ophthalmology Explained

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Introduction

Acute Retinal Necrosis (ARN) is a rapidly progressive, vision-threatening necrotizing retinitis caused by herpes-family viruses. Prompt recognition and aggressive antiviral therapy are essential to limit retinal destruction, control intraocular inflammation, and reduce complications. This material focuses on antiviral treatment and practical management steps for ARN in a clinical setting.

Definition: Acute Retinal Necrosis (ARN) is a fulminant, circumferential necrotizing retinitis associated with occlusive periarteritis and vitritis, most commonly caused by varicella-zoster virus (VZV) and herpes simplex virus (HSV).

Etiology and epidemiologic clues

  • Common causes: VZV, HSV-1, HSV-2 (HSV causes ARN more often in patients younger than 25 years).
  • History to elicit: recent zoster or varicella infection, systemic herpetic disease, unilateral red painful eye, prior herpes exposures.
  • Laboratory support: PCR on aqueous or vitreous fluid can detect viral DNA and guide therapy.

Pathophysiology (digestible steps)

  1. Viral reactivation in the retina leads to focal retinitis.
  2. Rapid circumferential extension of necrosis across the retina.
  3. Occlusive periarteritis (arteriolar vasculitis) leads to retinal ischemia and hemorrhage.
  4. Intense vitritis and anterior uveitis (keratic precipitates, possible raised IOP) produce the "angry" red eye and hazy view.
  5. Secondary complications (e.g., rhegmatogenous retinal detachment) may follow from full-thickness retinal necrosis.

Clinical features relevant to management

  • Unilateral, acute, red painful eye with decreased vision.
  • Anterior segment: keratic precipitates (KPs), possible scleritis, elevated IOP.
  • Posterior segment: dense vitritis, multifocal necrotizing retinitis, periarteritis with vessel sheathing, retinal hemorrhages.
  • Fundus exam: circumferential spread; wide-field (BIO) exam is critical to assess peripheral necrosis.

Note: In bilateral disease the acronym BARN (bilateral ARN) is used.

Diagnostic steps prior to/while initiating therapy

  1. Rapid clinical diagnosis based on exam (do not delay treatment).
  2. Obtain anterior chamber paracentesis or vitreous tap for PCR (send to uveitis/retina lab).
  3. Baseline labs as indicated (renal function if using IV antivirals, HIV status if immunosuppression suspected).
  4. Wide-field binocular indirect ophthalmoscopy (BIO) with dilation is important to visualize the peripheral retina; use high plus lenses or scleral depression/gonio if needed for detailed peripheral evaluation.

Antiviral treatment — principles

  • Start systemic antiviral therapy immediately when ARN is suspected; wait for PCR confirmation only to tailor or confirm diagnosis, not to start therapy.
  • Severe/fulminant cases: inpatient IV antiviral therapy is recommended.
  • Transition to high-dose oral antiviral therapy for a prolonged course to reduce recurrence and contralateral involvement.

Recommended antiviral regimens

  1. First-line (severe/fulminant; inpatient):
    • Acyclovir IV: initial dosage of 15 mg/kg three times daily for 10 days (adjust for renal function), then transition to oral.
  2. Oral step-down and maintenance:
    • Oral acyclovir 800 mg five times daily for at least 6 weeks, with gradual tapering over months (many regimens extend to 3–6 months depending on response and specialist advice).
  3. Alternatives for acyclovir-resistant or intolerant cases, or when better oral bioavailability is preferred:
    • Valacyclovir (prodrug of acyclovir with higher oral bioavailability) — dosing per specialist guidance.
    • Famciclovir — oral alternative.
    • Ganciclovir (oral or IV) — used if HSV/VZV co-infection suspected or resistance concerns.
    • Foscarnet — reserved for resistant strains or immunocompromised patients; often given IV.
  4. Intraocular antiviral injections (intravitreal ganciclovir, foscarnet) can be used adjunctively for severe focal disease or poor systemic penetr
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ARN Antiviral Management

Klíčové pojmy: ARN is a fulminant herpetic necrotizing retinitis requiring urgent antiviral therapy, Start systemic antiviral therapy immediately; do not wait for PCR confirmation, Severe ARN: admit and give IV acyclovir 15 mg/kg three times daily (adjust for renal function), After IV therapy, transition to oral acyclovir 800 mg five times daily for at least 6 weeks with gradual taper, HSV is more common cause of ARN in patients younger than 25 years; VZV often in older patients, Obtain aqueous or vitreous PCR early to identify causative virus and guide therapy, Start systemic corticosteroids only after antiviral therapy is established (commonly 48–72 hours), Consider intravitreal antiviral injections (ganciclovir or foscarnet) for severe focal disease or poor systemic response, Monitor renal function during IV antivirals and adjust dosing, Frequent dilated fundus exams during convalescence; co-manage with retina specialist, Consider prophylactic laserpexy in selected eyes to reduce risk of retinal complications, Treat ocular hypertension and anterior inflammation concurrently as needed

## Introduction Acute Retinal Necrosis (ARN) is a rapidly progressive, vision-threatening necrotizing retinitis caused by herpes-family viruses. Prompt recognition and aggressive antiviral therapy are essential to limit retinal destruction, control intraocular inflammation, and reduce complications. This material focuses on antiviral treatment and practical management steps for ARN in a clinical setting. > Definition: Acute Retinal Necrosis (ARN) is a fulminant, circumferential necrotizing retinitis associated with occlusive periarteritis and vitritis, most commonly caused by varicella-zoster virus (VZV) and herpes simplex virus (HSV). ## Etiology and epidemiologic clues - Common causes: **VZV**, **HSV-1**, **HSV-2** (HSV causes ARN more often in patients younger than 25 years). - History to elicit: recent zoster or varicella infection, systemic herpetic disease, unilateral red painful eye, prior herpes exposures. - Laboratory support: PCR on aqueous or vitreous fluid can detect viral DNA and guide therapy. ## Pathophysiology (digestible steps) 1. Viral reactivation in the retina leads to focal retinitis. 2. Rapid circumferential extension of necrosis across the retina. 3. Occlusive periarteritis (arteriolar vasculitis) leads to retinal ischemia and hemorrhage. 4. Intense vitritis and anterior uveitis (keratic precipitates, possible raised IOP) produce the "angry" red eye and hazy view. 5. Secondary complications (e.g., rhegmatogenous retinal detachment) may follow from full-thickness retinal necrosis. ## Clinical features relevant to management - Unilateral, acute, red painful eye with decreased vision. - Anterior segment: keratic precipitates (KPs), possible scleritis, elevated IOP. - Posterior segment: dense vitritis, multifocal necrotizing retinitis, periarteritis with vessel sheathing, retinal hemorrhages. - Fundus exam: circumferential spread; wide-field (BIO) exam is critical to assess peripheral necrosis. > Note: In bilateral disease the acronym BARN (bilateral ARN) is used. ## Diagnostic steps prior to/while initiating therapy 1. Rapid clinical diagnosis based on exam (do not delay treatment). 2. Obtain anterior chamber paracentesis or vitreous tap for PCR (send to uveitis/retina lab). 3. Baseline labs as indicated (renal function if using IV antivirals, HIV status if immunosuppression suspected). 4. Wide-field binocular indirect ophthalmoscopy (BIO) with dilation is important to visualize the peripheral retina; use high plus lenses or scleral depression/gonio if needed for detailed peripheral evaluation. ## Antiviral treatment — principles - Start systemic antiviral therapy immediately when ARN is suspected; wait for PCR confirmation only to tailor or confirm diagnosis, not to start therapy. - Severe/fulminant cases: inpatient IV antiviral therapy is recommended. - Transition to high-dose oral antiviral therapy for a prolonged course to reduce recurrence and contralateral involvement. ## Recommended antiviral regimens 1. First-line (severe/fulminant; inpatient): - **Acyclovir IV**: initial dosage of 15 mg/kg three times daily for 10 days (adjust for renal function), then transition to oral. 2. Oral step-down and maintenance: - **Oral acyclovir** 800 mg five times daily for at least 6 weeks, with gradual tapering over months (many regimens extend to 3–6 months depending on response and specialist advice). 3. Alternatives for acyclovir-resistant or intolerant cases, or when better oral bioavailability is preferred: - **Valacyclovir** (prodrug of acyclovir with higher oral bioavailability) — dosing per specialist guidance. - **Famciclovir** — oral alternative. - **Ganciclovir** (oral or IV) — used if HSV/VZV co-infection suspected or resistance concerns. - **Foscarnet** — reserved for resistant strains or immunocompromised patients; often given IV. 4. Intraocular antiviral injections (intravitreal ganciclovir, foscarnet) can be used adjunctively for severe focal disease or poor systemic penetr