West Coast Retina
Case of the Month
45 year old man with blurred vision, floaters and nyctalopia
Figures 1: Color fundus photographs of the right and left eye. Note the media haze due to vitreous cells. Pale yellow-white oval lesions are scattered around the posterior pole
A 45-year-old man presented with a two month history of decreasing vision, floaters, and nyctalopia affecting both eyes. Past medical history was non-contributory. Best corrected visual acuity was 20/25 in each eye and intraocular pressures were within normal limits bilaterally. Examination of the anterior segment revealed 1+ cell and flare in the anterior chamber. Posterior segment examination demonstrated 2+ diffuse vitreous inflammation, mild disc edema, dilated retinal veins, and several yellow-white choroidal lesions in the mid- and far-periphery of each eye. (Figure 1) Bilateral leakage from the optic disc and retinal vessels was evident on fluorescein angiography. (Figure 2)
Figures 2: Late phase fluorescein angiogram of the right and left eye. Note the fluorescein staining of the nerve and the pale lesions. CME is present in both eyes.
What is your Diagnosis?
The most likely diagnoses for this patient included birdshot chorioretinopathy, syphilis, and sarcoidosis. Laboratory evaluations including serum FTA-ABS and RPR titers; serum ACE and lysozyme levels, and chest x-ray were normal. Also, antibody testing for HLA-A29 expression was negative.
Because clinical suspicion of birdshot chorioretinopathy remained high, testing for HLA-A29 expression was repeated using a PCR-based method. This test revealed the presence of the HLA-A29 antigen, strongly suggesting the diagnosis of birdshot chorioretinopathy.
Birdshot chorioretinopathy typically occurs in healthy patients in the 5th to 7th decade of life.1 Common symptoms include photopsia, nyctalopia, and dyschromatopsia. Findings on examination include vitritis as well as multiple bilateral and symmetrical cream colored lesions posterior to equator at the level of the choroid. Cystoid macular edema and retinal atrophy can, if untreated, result in decreased vision. Fluorescein angiography often reveals delay in the appearance of dye in the retinal arterioles as well as profuse vascular leakage associated with an increase in retinal circulation time.
The link between birdshot chorioretinopathy and HLA-A29 antigen expression has been firmly established.2,3 Reliable HLA-A29 subtyping is therefore vital in patients suspected of having birdshot chorioretinopathy.
The present report describes a patient with birdshot chorioretinopathy in whom initial antibody-based testing for HLA-A29 antigen expression was negative and in whom subsequent testing using a PCR-based technique was positive. Similar results have been reported for other HLA antigens.4-6 PCR-based testing should be considered when antibody-based testing for the HLA-A29 antigen is unexpectedly negative.7
Take Home Points
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