Continuing Education

Sep
2006

Winter Wonder(?) Land

A 46-year-old white female presented complaining of blurred vision O.U., trouble seeing at night and an increase in floaters for the past two years. She also noted that colors did not appear as vivid as they once did.

Best-corrected acuity was 20/25 O.D. and 20/30 O.S. Confrontation fields were full to careful finger counting O.U. Pupils were equally round and reactive with no afferent pupillary defect. The anterior segment exam was unremarkable.

A dilated fundus exam showed significant vitritis O.U. Both optic nerves had moderate-sized cups with good rim coloration and perfusion. The arteries and veins appeared attenuated. There appeared to be a mild epiretinal membrane in each macula, but visualization of the details was difficult due to the vitritis. Indirect ophthalmoscopy revealed numerous depigmented lesions that were easily visible in the posterior pole and throughout the peripheral retina, as shown. 
 
Posterior pole and midperiphery O.U. Note the hazy media, attenuated vessels and hypopigmented spots.

Take the Retina Quiz

1. At what level in the retina are the depigmented lesions located?
a. Choroid.
b. RPE.
c. Sensory retina.
d. Both sensory retina and RPE.

2. What additional test may help confirm the diagnosis?
a. Fluorescein angiography.
b. HLA-A29 (human leukocyte antigens-A29).
c. Angiotension converting enzyme (ACE).
d. HLA-B9.

3. What is this patient’s likely diagnosis?
a. Multifocal choroiditis.
b. Panuveitis.
c. Serpiginous choroiditis.
d. Birdshot retinochoroidopathy.

4. What is the most common complication from this disease?
a. Cystoid macular edema.
b. Retinal detachment.
c. Retinitis pigmentosa.
d. Cataract.

5. What is the best treatment option for this patient?
a. Corticosteroids.
b. Observation.
c. Immunosuppressive agents.
d. Both A and C.

For answers, click here.

Discussion
The findings in this patient represent birdshot retinochoroidopathy. Investigators first recognized this unusual presentation in the fundus in 1975. The widespread nature of the lesions was reminiscent of the dispersion pattern of BBs—or birdshot—from an exploded shotgun shell; hence, the descriptive term.1

Clinicians also have used the term “vitiliginous chorioretinitis” to describe this condition. That’s because the patches of hypopigmented spots in the fundus appear and develop in a manner similar to those that occur on the skin of patients with vitiligo.2

Birdshot retinochoroidopathy typically occurs in women ages 50-70. Blurred vision, increased floaters and photopsia often accompany it. As the disease progresses, patients develop night blindness and loss of color vision.

Patients with birdshot retinochoroidopathy usually have a significant vitritis, which explains the floaters, and multifocal patches of depigmented or hypopigmented lesions that may be creamy yellow or orange in color. The ill-defined patches are typically round or oval shaped. Some appear elongated in a pattern that radiates toward the peripheral fundus.

The striking feature of these lesions is a lack of chorioretinal scarring or hyperpigmentation at the margins that often appears in other inflammatory conditions. Also, there does not appear to be thinning within the RPE or choroid in the areas of depigmentation.

The diagnosis of birdshot retinochoroidopathy is usually based on the clinical presentation, though there is a strong association with the HLA-A29 antigen. More than 95% of patients with birdshot retinochoroidopathy have a positive HLA-A29, suggesting an autoimmune mechanism and a genetic predisposition.3

Advances in subtyping of HLA-A29 have shown an exclusive linkage to HLA-A29.2. Patients with a positive HLA-A29.1 may have the creamy-colored lesions, but they may have resistance to intraocular inflammation.3,4

Birdshot retinochoroidopathy is chronic and progresses slowly, with remissions and exacerbations. Patients typically lose vision from the cystoid macular edema (CME) that often results from chronic inflammation. The emphasis of treatment is to quiet the inflammation.

Corticosteroids have been the mainstay of treatment, but with limited success. Patients may report improved vision as the CME disappears, but the number and extent of lesions do not decrease. Immunosuppressive agents such as cyclosporine and cytotoxic drugs have been used when corticosteroids alone cannot control the inflammation.

We followed this patient for more than 10 years. She experienced recurrent bouts of inflammation that occasionally led to the development of CME; this responded well to oral prednisone. Unfortunately, we were unable to taper her off the prednisone, as the CME would recur. On her last visit, her acuity was 20/40 O.U., and she had developed a mild cataract O.U., most likely from chronic steroid use and chronic inflammation.

1. Ryan SJ, Rao NR. Birdshot Retinochoroidopathy. In: Ryan SJ. Schachat AP, Murphy RP, editors. Retina, vol. II–Medical Retina. 3rd ed. St. Louis: Mosby-Year Book, 2000:1702-8.
2. Gass JMD. Stereoscopic Atlas of Macular Disease: Diagnosis and Treatment. 4th ed. St. Louis: Mosby-Year Book, 1997:710-3.
3. LeHoang P, Ozdemir N, Benhamou, A, et al. HLA-A 29.2 subtype associated with birdshot retinochoroidopathy. Am J Ophthalmol 1992 Jan 15;113(1):33-5.
4. Tabary T, Prochnicka-Chalufour A, Cornillet P, et al. HLA-A29 subtypes and “birdshot” choroido-retinopathy susceptibility: a possible “resistance motif” in the HLA-A29.1 molecule. C R Acad Sci III. 1991;313(13):599-605.

 

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