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Editor,—HLA-B27 positivity occurs in 40%–50% of patients with anterior uveitis.1 ,2 HLA-B27 associated anterior uveitis is typically non-granulomatous, recurrent, and unilateral or alternatingly bilateral. The most frequent systemic disease associations in HLA-B27 positive patients with anterior uveitis include ankylosing spondylitis, Reiter's syndrome, inflammatory bowel disease, and psoriatic arthritis.1 ,2 Ocular complications are more common in HLA-B27 positive patients with anterior uveitis compared with HLA-B27 negative patients,2 and include cataract formation, pupillary synechiae, secondary glaucoma, and cystoid macular oedema.1 ,2 Although severe vitreous inflammation and optic disc oedema can be seen in 15%–20% of patients with HLA-B27 associated anterior uveitis, ischaemic optic neuropathy is rare.3-6 We describe a patient who developed anterior ischaemic optic neuropathy in the setting of known HLA-B27 associated recurrent, anterior uveitis and ankylosing spondylitis.
A 29 year old white man with a 10 year history of recurrent, alternating, anterior uveitis, HLA-B27 positivity, and radiographically documented sacroiliitis presented with a 2 week history of decreased vision in his right eye. His first episode of anterior uveitis occurred in his right eye 10 years before presentation. Two subsequent episodes involved the right eye 6 years and again 6 months before presentation. Each episode was controlled with topical prednisolone acetate 1%. His most recent episode was associated with mildly decreased vision, mild photophobia, and partial loss of his lower visual field on the right but no significant ocular pain or pain with eye movement. Examination revealed a best corrected visual acuity of 20/40 on the right and 20/20 on the left. Colour vision was slightly decreased on the right, measured as a slow 19/20 using pseudo-isochromatic plates. Anterior segment examination disclosed an afferent pupillary defect and a mild anterior uveitis. Posterior segment examination on the right revealed no vitreous inflammation but did show moderately severe optic disc oedema with a surrounding Paton's ring, as well as inferior capillary telangiectasis and superior capillary closure on the optic disc (Fig1A). Fluorescein angiography confirmed superior capillary closure on the optic disc (Fig 1B), and revealed late leakage from the telangiectatic disc vessels (Fig 1C). Humphrey visual field testing disclosed an inferior altitudinal defect corresponding with the area of superior optic disc pallor. The patient was treated with topical prednisolone acetate, 1%, and was given a sub-Tenon's injection of triamcinolone acetonide 40 mg. A magnetic resonance scan of the brain and orbits failed to show enhancement of the optic nerve or evidence of central demyelination. Serological tests including a normal complete blood cell count, a negative serum anti- Bartonella henselae IgG, a negative serum anti-Toxoplasma gondii IgG, and a negative enzyme linked immune assay for Borrelia burgdorferi. A chest x ray was unremarkable. On follow up examination, vision improved to 20/30 on the right and the optic disc oedema resolved but the afferent pupillary defect, superior optic disc pallor, and inferior altitudinal defect (Fig 1D) remained.
Although optic disc oedema may be observed in 15%–20% of HLA-B27 associated uveitis,2 it usually occurs in the setting of moderate to severe vitreous inflammation, and rarely results from an ischaemic optic neuropathy. The absence of vitreous inflammation and the presence of an afferent pupillary defect, decreased colour vision, and the subsequent development of disc pallor accompanied by a persistent altitudinal field defect in our patient suggest, however, that an ischaemic optic neuropathy can occur in the setting of HLA-B27 associated uveitis. This notion is supported by previous descriptions of optic neuropathy in patients with HLA-B27 associated uveitis, both in the absence of systemic involvement,2 and in patients with anterior uveitis in the setting of systemic disease.3-6
This work was supported in part by a career development award to Dr E T Cunningham Jr from Research to Prevent Blindness, Inc, New York, USA.