ACUTE ZONAL OCCULT OUTER RETINOPATHY

1. AZOOR
DR SHRUTI LADDHA

2. Acute Zonal Occult Outer Retinopathy (AZOOR)
• Young women
• Photopsia(fireworks, blinking lights, movement of microbes under a microscope,
the TV screen being off signal, flashes of light, heat waves coming off the road,
and other visual phenomenon-movement associated with all these
phenomenons)
• Acute onset visual field loss
• Minimal or no funduscopic changes
• Sometimes inflammation of vitreous –if large visual field is affected.
• Electroretinographic abnormalities affecting one or both eyes.

3. • Some patients - antecedent viral-like illness.
• The symptoms and the visual field loss generally stabilized within four to six
months and in a small percentage of cases improved.
• The fellow eye was involved soon after or even years later.
• A late recurrence in the same eye occurred occasionally.

4. A 26-year-old highly myopic male with sudden onset of large blind spot including the center and temporal field
with photopsia in OD of one day duration. Best corrected visual acuity 6/12 OD and 6/6 OS. Normal fundi OU

5. FFA and ICGA
• At early stage-usually normal when fundus is also normal
• If the receptor cell death occurs, pigmentary change at the level of the RPE
ensues
• RPE migration to the inner retina results in bone spicule appearance, akin to
retinitis pigmentosa late in the course of the disease.
• FFA done at this time would show-transmission defects corresponding to the area
of pigment epithelial changes
• ICGA- hypofluroscence corresponding to zone of RPE changes

6. Late fundus changes showing pigment epithelial migration
into the inner retina

8. Fundus autofluorescence (FAF) image reveals normal autofluorescence in the area outside the demarcation line (zone 1), speckled
hyperautofluorescence within the AZOOR lesion (zone 2), and hypoautofluorescence corresponding to the development of choroidal
atrophy (zone 3)
ICGA outside the AZOOR lesion is normal (zone 1). Inside the AZOOR line, the subacute area shows minimal late extrachoroidal leakage
(zone 2). Hypocyanescence is observed together with the absence of leakage of the ICG molecule into the choroid corresponding to
choriocapillaris atrophy (zone 3)
SD-OCT is normal outside the AZOOR line (zone 1). Inside the AZOOR line, multifocal material is present in the subretinal space
resembling subretinal drusenoid deposits (zone 2). Photoreceptor, retinal pigment epithelium and choroidal atrophy is evident in the
more advanced or long-standing area of the lesion (zone 3).

9. ERG
• Depend on degree of receptor involvement
VISUAL FIELDS
• 90%-enlarged blind spot

10. PATHOGENESIS
• Viral or other infectious agent in the photoreceptors.
• Preclinical stage-cell to cell spread of the virus occurs with retention of normal
function of the photoreceptors.
• “Acute symptomatic phase”- the infected cell dysfunction is triggered by the host
immune response.
• 90% of eyes with AZOOR have visual field defects that include one or both blind
spots and the peripheral isopters, suggests that the ora serrata and optic disk
margin are possible sites for invasion of a virus into the receptor cells
• Few patients-many months or years later - delayed visual field loss may occur as a
result of resetting of the cells’ apoptotic clock during the initial acute phase of
AZOOR.

11. • Some patients-immune response results in early receptor cell death,
development of a variable degree of inflammation including vitreous cells,
perivascular exudation, and occasionally optic disc oedema.
• These inflammatory signs typically develop within several weeks following the
onset of AZOOR, appear to be proportional to the size of the affected retinal
zones, and probably result from an inflammatory response to the dead retinal
receptor cells.

12. • Weeks or months later, narrowing of the retinal vessels, particularly the retinal
arteries, perivascular sheathing and reactive changes in the RPE occur.
• The loss of interaction of the microvilli of the RPE with the photoreceptors causes
migration of the RPE into the inner retina to line up along the blood vessel wall
giving the typical bone-spicule appearance

13. TREATMENT
• No treatment
• Presumed viral etiology-antiviral drugs are given
• Along with steroids