A 52-year-old woman presents with 8 months of floaters, blurred vision, and difficulty with night driving. She has no pain or redness. She is otherwise healthy with no joint disease, no rashes, and no neurological symptoms. Vision is 6/12 in both eyes.
Examination Findings
Both eyes: quiet anterior segments, vitritis, and multiple small cream-coloured ovoid lesions scattered in the posterior pole and mid-periphery — the ‘birdshot’ spots — with mild disc hyperaemia. No snowbanking, no granulomatous keratic precipitates. The lesions are bilateral and symmetric.
Investigations
HLA-A29 testing — present in the great majority of cases and the strongest disease association in uveitis; it supports but does not alone make the diagnosis. Fluorescein angiography shows leakage and staining; indocyanine green angiography reveals many more hypofluorescent choroidal lesions than are visible clinically. Electroretinogram tracks retinal function over time. Baseline workup excludes sarcoid, TB, and syphilis.
Questions to Think About
- Why is HLA-A29 so useful here, and what are its limits?
- Why does this disease need long-term immunomodulation rather than just steroids?
- What monitoring tracks the disease beyond visual acuity?
Diagnosis
Birdshot chorioretinopathy, bilateral.
Reasoning
The diagnosis is birdshot chorioretinopathy — a chronic bilateral posterior uveitis of middle age, strongly associated with HLA-A29 (the strongest HLA association in all of uveitis). HLA-A29 supports the diagnosis powerfully but is not sufficient alone: the clinical pattern of bilateral cream ovoid lesions with vitritis makes the disease, and mimics must still be excluded. The natural history is chronic and relapsing with insidious retinal dysfunction — night blindness and visual field loss that visual acuity underestimates — which is why treatment is long-term immunomodulation (steroid-sparing agents per the uveitis specialist) rather than repeated steroid courses; chronic steroids at the doses needed would guarantee cataract, glaucoma, and systemic harm. Monitoring goes beyond the Snellen chart: visual fields, ERG (especially the 30-Hz flicker implicit time), and angiography track the smouldering retinal damage that acuity misses. The patient needs counselling about the chronic course, the need for sustained therapy, and the reassuring fact that with modern immunomodulation most patients keep useful vision.
Differential Diagnosis
- Birdshot chorioretinopathy — fits: bilateral cream ovoid lesions with vitritis in a middle-aged woman, HLA-A29-associated.
- Sarcoidosis — considered: also bilateral with vitritis, but the birdshot spots and HLA-A29 point away.
- Multifocal choroiditis — ruled out: that affects young myopic women with punched-out scars and CNV, a different demographic and lesion.
- VKH disease — ruled out: no prodrome, no exudative detachments, older patient.
- White-dot syndromes (MEWDS/APMPPE) — ruled out: those are acute and self-limited, not this chronic bilateral disease.
Management
Confirm the pattern with HLA-A29, angiography (including ICG), and exclusion of mimics. Long-term steroid-sparing immunomodulation per uveitis specialist — not chronic high-dose steroids. Monitor with visual fields, ERG, and angiography, not acuity alone. Counsel about the chronic relapsing course and the good long-term outlook with sustained treatment.
Key Learning Points
- Birdshot is bilateral cream ovoid lesions with vitritis in middle age, with the strongest HLA association in uveitis (HLA-A29).
- It is chronic and relapsing — long-term immunomodulation, not repeated steroids, is the strategy.
- Monitor fields and ERG, not just acuity: retinal dysfunction outpaces Snellen loss.
Red Flags
- Night blindness and field loss with ‘good’ acuity — the disease acuity misses
- Chronic steroids without a sparing plan — cataract and glaucoma are certain
- Unilateral disease — birdshot is bilateral; reconsider
- Missing HLA-A29-negative birdshot — rare, but the clinical pattern can still diagnose
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.