White Dot Syndromes Series Part 4: Birdshot Chorioretinopathy

Birdshot chorioretinopathy may not be common, but failure to detect and treat the disease may lead to permanent vision loss. In this fourth installment of Optometry Advisor’s White Dot Syndromes Series, Mohammad Rafieetary, OD, details the clinical characteristics, prognostic outcomes, and management strategies associated with this condition. For the previous installment please click here.

Birdshot retinochoroidopathy, also known as birdshot chorioretinopathy (BSCR) or birdshot uveitis, is a bilateral, posterior uveitic disease. This particular white dot syndrome can be identified by the multiple cream- or yellowish-white-colored lesions observed on clinical examination and color fundus photography and confirmed by the presence of HLA-A29 — a human leukocyte antigen (HLA) present in 85 to 95% of individuals with BSCR.¹  

Approximately 1 to 2% of uveitis cases involve BCSR and the condition is more prevalent among women who are middle-aged (mean age, 53 years).² 

Clinical Characteristics

In the subacute phase, patients with BSCR present with complaints of floaters, light flashes, and scotomas and experience poor night and color vision and contrast sensitivity.^3,4 Vision loss is often progressive. Clinical signs include bilateral, oval-shaped, cream-colored lesions at the retinal pigment epithelium (RPE) and choroid (Figure 1).⁵  

Anterior uveitis is not commonly seen, but some degree of vitritis is often present.² Optical coherence tomography (OCT), which shows reduced reflectivity and RPE alterations, can also identify posterior vitreous cells (Figure 2).    

Fluorescein angiography (FA) and indocyanine green (ICG) angiography can reveal diffuse choroiditis and retinal vasculitis. ICG can distinctly show the lesions that resemble a pattern created by small shotgun pellets or birdshot (Figure 3).

Management

Systemic corticosteroids are preferred in acute cases of BSCR.^2,4 However chronic cases may require immunomodulation with agents such as cyclosporine, methotrexate, or azathioprine.^2,4 

Prognosis

Although the scientific community has not reached a consensus on the long-term prognostic outcomes associated with BSCR, research shows that 20% of cases are self-limiting and waxing and waning of the inflammatory response can result in irreversible chorioretinal damage leading to poor visual outcomes.⁵ Potential long-term complications include macular edema, retinal and choroidal neovascularization, epiretinal membrane, and optic atrophy (Figure 4).⁶ 

Case Report

A 53-year-old woman was seen in October of 2020 for evaluation of a choroidal lesion in her left eye. The patient was asymptomatic and in relatively good health. Her visual acuities were 20/20 in each eye and all other findings were unremarkable except for trace nuclear sclerosis cataracts in both eyes and a large amelanotic choroidal nevus in the left eye (Figure 5).

The patient attended a 6-month follow-up visit based on risks associated with the lesion, and all of the findings, including the nevus, remained stable. The patient was asked to follow up with the referring optometrist and return to our clinic in 1 year. The patient returned 16 months later, indicating progressive vision loss for several months which had been attributed to cataract progression. Her best corrected visual acuities were now 20/30 (OD) and 20/40 (OS). While her lens status remained trace nuclear sclerosis, significant changes were noted upon posterior segment examination. Multiple scattered cream-colored choroidal lesions were noted on fundus examination, with OCT scans of both eyes revealing significant outer retinal disease. FA was remarkable for diffuse choroiditis and retinal vasculitis (Figure 6).

The patient was diagnosed with posterior uveitis with suspicion of BSCR due to the clinical presentation. Oral prednisone (40 mg daily) was prescribed, and the patient was sent for a systemic work-up which confirmed a positive HLA-A29 presence. Vision improved to 20/25 (OD) and 20/20 (OS) at a 2-week follow-up visit and there was a remarkable improvement in posterior segment OCT findings. The patient was referred to a rheumatologist for immunomodulatory therapy and continues to be monitored for ocular symptoms (Figure 7). 

BSCR is not a commonly encountered clinical finding and failure to provide early intervention can result in poor visual outcomes. Clinicians who are familiar with the disease’s acute phase presentation and serology can provide a speedy diagnosis and timely management strategies to avoid permanent vision loss in their patients.