This document summarizes acute retinal necrosis (ARN), a rare viral infection of the retina. It begins by describing the initial 1971 case report and clinical features of ARN, which include anterior uveitis, vitritis, and characteristic retinal lesions. The document then discusses the epidemiology, diagnostic criteria, etiology as herpes virus, and treatment with antivirals like acyclovir. It also briefly mentions a more severe variant, progressive outer retinal necrosis (PORN), which mostly affects immunocompromised patients and has a poor prognosis.

1. Bipin Bista
Resident
Ophthalmology
National medical College
& Teaching Hospital

2. Introduction
 Initially described in 1971
in a report by Urayama &
coleagues as an Intraocular
Inflammation, retinal
vascular sheathing & large
white confluent retinal
infiltrates.
 Kirisiwa’s Uveitis
 Developed
Rhegmatogenous RD.
 Suspected as a new disease
d/t mutations in the virus
or changes in host
susceptibilty.

3. Epidemilogy
 Initially was found in Japan, but now it has been
throughout the world.
 Was earlier reported in young adults and older
patients but now it has been found in children as well.
 Described both in immunocompromised &
immunosuppressant.

4. Clinical Features
 May affect one or both eyes,
mostly begins as a unilateral
disease.
 In 1/3rd of the cases, second
eye becomes infected within
1-6 weeks. Reported to occur
upto 20 years.
 H/o : Pain, redness, floaters &
blurred vision.
 Anterior Uveitis :
with/without KPs ; Plasmoid
aqueous.
 Floaters and diminished
vision : Vitritis.

5. Clinical Features
 Earliest retinal lesions are
small, patchy, white-yellow
areas that tend to enlarge
which increases in number
and coalesce over time.
 Usually start in mid-
periphery, occur in
posterior pole.
 Resolves after a week and
makes a ‘Swiss-Cheese
Pattern’.
 Retinal vasculitis and
hemorrhage esp. in Venous
Occlusive Diseases

6. Clinical Features
 Optic Neuropathy and Disc Oedema is the commonest
finding. Rule out RAPD & Severe Visual Loss
 Optic Nerve Sheath Fenestration.
 Severity : No. of Clock Hours involved in Initial retinal
involvement.
 Despite replication control, cellular infiltration into the
vitreous and the formation of vitreal membranes
composed of RPE & fibroblast, develop to tearing &
detachment of an already thinned retina.

7. Criteria for ARN (Executive Committee
of American Uveitis Society); 1994
1. One or more foci of retinal necrosis with discrete
borders in the peripheral retina.
2. Rapid progression of disease if antiviral therapy not
given.
3. Circumferential spread of disease.
4. Evidence of Occlusive Vasculopathy with Arteriolar
involvement.
5. A prominent inflammatory reaction in the vitreous
and Anterior Chamber.

8. Etiology
 Initially was thought to be Autoimmune.
 In 1982, Culbertson & colleagues described the first
occurrence of an enucleated eye in a patient with ARN
where Herpes Virus was noted on Electron Microscopy.
 Histology : Prominent retinal arteritis & marked retinal
necrosis with abrupt demarcation between normal &
necrotic Retina.

9.  Predominance of T-lymphocyte in vitreous & B-lymphocyte
in retina.
 PCR : Caution while interpreting.
 Association between ARN & HLA-DQW7 & Phenotype
BW62, DR4.
 Fas and Fas ligand expression were absent in a retinal
biopsy.
 Apoptosis was noted.
 Involvement of inflammatory cytokines.

10. Therapy
 Benefit from Acyclovir.
 500 mg/m2 every 8 hours Intravenously 10-14 Days, then
800 mg 5 times a day for 6 weeks .
 Goal : Hasten the revolution of disease in infected eye &
prevent contralateral spread.
 Corticosteroid such as prednisolone 0.5-1.0 mg/kg after the
patient has received 1-2 days of IV acyclovir.
 Valaciclovir or Famciclovir is also efficient drug.
 Laser Photocoagulation.
 Surgery : Difficult to repair & proliferative
Vitreoretinopathy is common.
 Vitrectomy, fluid-gas exchange & endolaser treatment.

11. Progressive Outer Retinal Necrosis
 Mostly described in immunocompromised patients.
 Poor : Prognosis.
 Second most common ocular manifestation in AIDS.

12. Diagnosis
 A variant of necrotizing herpetic retinopathy in
immuno-compromised patients.
 1st described by Forster & colleagues (1990)
 Early patchy choroidal lesion & deep retinal lesions
which progressed relentlessly until patients were left
with atrophic and necrotic retinas & pale Optic Nerve.
 Usually asymptomatic.
 Multifocal, deep choroidal lesion present in periphery.

13. Therapy
 Combination of inductions given but not much success.
 Acyclovir 10mg/kg 8 hourly for 2 weeks.
 Complication : 70 % RD.

14. Reference:
- Nussenblatt and whitecup 4th edition
- Myron yanoff 4th edition