[Phenocopies of hereditary retinal degenerations]

Phenocopies of retinal degenerations mimic the clinical signs of inherited retinal dystrophies. The purpose of this study is to discuss the difficulties of differential diagnosis.

Four patients were examined ophthalmologically and by standard electroretinography (ERG).

(a) A 19-year-old woman presented with progressive visual loss, bone spicules, concentric narrowing of visual fields and extinguished ERG responses. At 3 years of age, she had developed a retinopathy induced by an infection with measles. (b) A 27-year-old man had bilateral visual loss, night blindness, pigmentary retinal changes, marked attenuation of visual fields and a reduced ERG. All signs of syphilitic retinopathy were regressive under antibiotic therapy. (c) A 59-year-old man showed a visual loss in the left eye, bilateral photophobia, color vision disturbances and a ring scotoma. Cone responses were nonrecordable in the ERG. A birdshot chorioretinopathy was suggested by ophthalmoscopic appearance and HLA typing. (d) A 40-year-old woman presented with paravenous pigmented retinochoroidal atrophy associated with Behcet disease.

Systemic viral or bacterial inflammation as well as autoimmune disorders may present as phenocopies of hereditary retinal degenerations. A faulty diagnosis may have serious consequences, because necessary therapy may be withheld. Moreover, the misdiagnosis of a hereditary retinal degeneration may have severe effects on the psychic and social status of the patient.