Woman presents with ‘muddy’ spots in vision
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A 39-year-old woman was referred to the New England Eye Center complaining of new-onset intermittent “muddy” spots in her vision. She had no associated vision loss, flashes, floaters or eye pain.
The patient’s ocular history included dry eye syndrome and a right lower eyelid papilloma. Her medical history was notable for polycystic ovarian syndrome treated with metformin. She had no known allergies, and social history was noncontributory.
Examination
On initial exam, best corrected visual acuity was 20/20 in both eyes. IOPs were 12 mm Hg in the right eye and 14 mm Hg in the left eye. Pupils were round, equal and reactive without an afferent pupillary defect. Confrontation visual fields and extraocular motility were full, and the patient was orthophoric in both eyes. Color vision was full in both eyes. Anterior segment exam was within normal limits. Within the anterior vitreous of the right eye, there was 1+ cell and haze. Posterior exam revealed mild disc edema in the right eye with venous sheathing but no signs of vasculitis or other findings (Figure 1).
The decision was made to defer treatment given that the patient was mostly asymptomatic, but she was followed closely thereafter. At a follow-up visit 4 months later, the patient had developed significant vitritis and retinal vasculitis within the left eye, as well as creamy yellow-white ovoid lesions in the choroid, radiating outward from the optic disc in the nasal and inferior peripapillary region (Figure 2).
OCT of the macula showed vitreous cell in both eyes, as well as epiretinal membranes in both eyes (Figure 3). Fluorescein angiography (FA) showed optic nerve head leakage and vasculitis (Figure 4).
What is your diagnosis?
‘Muddy’ spots in vision
This patient’s examination findings are consistent with bilateral posterior uveitis. Posterior uveitis can affect different aspects of the retina or choroid, following the Standardization of Uveitis Nomenclature categories: focal/multifocal/diffuse choroiditis, chorioretinitis, retinochoroiditis, retinitis and neuroretinitis. The differential diagnosis for bilateral posterior uveitis can be further divided into infectious or noninfectious categories. Included in the list of possible infectious conditions that can present with posterior uveitis are tuberculosis, syphilis, toxoplasmosis, herpes simplex virus, varicella-zoster virus, cytomegalovirus and HIV. Noninfectious etiologies include sarcoidosis, punctate inner choroidopathy, birdshot choroidopathy, multifocal choroiditis, lymphoma or retinal pigment epitheliitis (Krill’s disease).
Our differential diagnosis can be narrowed by the features of characteristic discrete yellow choroidal lesions in a peripapillary distribution, findings of vitritis, vasculitis and optic nerve head leakage, as well as the patient’s symptoms of blurry vision. A presumptive diagnosis of birdshot chorioretinopathy was made. The patient underwent workup for other possible infectious and autoimmune etiologies, including tuberculosis, sarcoidosis, syphilis and HIV; all testing returned negative. Ultimately, she tested positive for HLA-A29, which has a sensitivity of 96% and a specificity of 93% when correlating to a diagnosis of birdshot chorioretinopathy.
Discussion
Birdshot chorioretinopathy, also known as birdshot choroiditis, is an uncommon bilateral autoimmune condition localized to the eyes that largely affects white women, especially of northern European descent, 40 years of age and older. It is thought to comprise 6% to 8% of all posterior uveitis cases. The disease was first named in 1980 when Ryan and Maumenee published a case series of 13 patients with a distinct syndrome presenting with a white, painless eye with minimal anterior segment inflammation but with vitritis, retinal vascular leakage and cream-colored choroidal lesions. Since then, additional studies have further characterized this condition.
Symptoms of birdshot uveitis include blurry vision, which can be mild and intermittent at first. Patients may also notice flickering or flashing lights, nyctalopia, floaters or even changes in their color vision. It is common for the anterior segment to be uninvolved or only minimally involved. A dilated fundus examination is crucial for diagnosis, as it typically shows multifocal, ovoid, cream- or yellow-colored lesions confined to the choroid or retinal pigment epithelial layer spanning nasally in a radial distribution. FA may show lesions with initial hypofluorescence followed by late staining that can be subtle. Retinal vasculitis, macular edema and optic nerve head leakage can also be seen on FA. Indocyanine green angiography may show lesions as well-circumscribed, hypocyanescent spots. When differentiating between birdshot uveitis and other posterior uveitides, laboratory workup should include a complete blood count, complete metabolic panel, HLA-A29 test, syphilis serology, ACE, lysozyme, QuantiFERON gold assay and a chest X-ray.
Unlike other forms of uveitis, treatment of birdshot uveitis tends to involve rapid initiation of steroid-sparing immunomodulatory therapy, as research has shown that early involvement of systemic therapy can increase the chance of long-term visual function preservation. Steroid treatment can be used as a bridge until a patient begins treatment with immunomodulatory therapy such as infliximab, adalimumab, mycophenolate mofetil, methotrexate or cyclosporine A. For those patients who defer or are intolerant to systemic treatment, longer-acting steroid-eluting injections and implants including dexamethasone intravitreal implants, suprachoroidal triamcinolone acetonide injections or fluocinolone implants are another option. With any local therapy, patients may experience higher rates of cataract progression and/or increased IOP and should be counseled accordingly. Despite these side effects, these steroid treatments are often useful if a patient experiences breakthrough uveitic macular edema.
In birdshot chorioretinopathy, it is especially important to carefully assess the patient’s symptoms to determine whether there is active disease because the clinical exam and imaging do not always capture the nuance of active disease. Although there is still no true consensus regarding management guidelines, the current recommendation is for these patients to be monitored closely with full-field ERGs and automated 30-2 visual field testing. Some studies have also shown OCT with enhanced depth imaging to be a useful tool to capture foci of active disease. Given the vague symptomatology and rarity of birdshot choroiditis, patients often experience a delay in diagnosis. Therefore, it is crucial to keep this vision-threatening disease entity on the differential diagnosis when seeing any patient with evidence of posterior uveitis.
Clinical course
The patient was initially treated with sub-Tenon triamcinolone acetonide injections in both eyes until she was transitioned to more definitive systemic therapy with methotrexate. While on full-dose methotrexate, she experienced a flare of her symptoms indicating inadequately controlled disease, so an oral steroid taper was added. She continued to worsen and was then transitioned to adalimumab every 2 weeks with resulting quiescence. However, she began to develop oral ulcers as a side effect from the methotrexate, which was then switched to mycophenolate mofetil. She has since remained stable, barring a flare during the COVID-19 pandemic when she missed a dose of adalimumab. The patient remains with best corrected vision of 20/20 in both eyes with no evidence of activity or progression on FA, visual field testing or ERG.
- References:
- Böni C, et al. Invest Ophthalmol Vis Sci. 2016;doi:10.1167/iovs.15-18832.
- Brady CJ, et al. Cochrane Database Syst Rev. 2016;doi:10.1002/14651858.CD010469.pub2.
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- Minos E, et al. Orphanet J Rare Dis. 2016;doi:10.1186/s13023-016-0429-8.
- Ryan SJ, et al. Am J Ophthalmol. 1980;doi:10.1016/0002-9394(80)90226-3.
- Shah KH, et al. Surv Ophthalmol. 2005;doi:10.1016/j.survophthal.2005.08.004.
- Sudharshan S, et al. Indian J Ophthalmol. 2010;doi:10.4103/0301-4738.58470.
- 2021-2022 Basic and Clinical Science Course, Section 09: Uveitis and Ocular Inflammation. https://ebooks.aao.org/reader/index.html. Accessed Oct. 10, 2023.
- For more information:
- Edited by Jonathan T. Caranfa, MD, PharmD, and Angell Shi, MD, of New England Eye Center, Tufts University School of Medicine. They can be reached at jcaranfa@tuftsmedicalcenter.org and ashi@tuftsmedicalcenter.org.
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