Late-onset cone dystrophy, AMD share common traits

Late-onset cone dystrophy has some features in common with age-related macular degeneration, according to a small study. This similarity should be considered in the differential diagnosis of elderly patients with progressive visual loss but without drusen, the study authors said.

Markus Ladewig, MD, and colleagues at Benjamin Franklin University Clinic in Berlin compared ophthalmologic and electroretinographic examinations of 11 patients with late-onset cone dystrophy to those of 20 patients with age-related macular degeneration (AMD) and 23 age-related control subjects.

No differences existed between the late-onset cone dystrophy and AMD patients in severity of visual acuity loss, color vision deficiencies or central visual field defects. Both groups showed signs of posterior pole alterations. None of the late-onset cone dystrophy patients had any signs of drusen, and six displayed temporal optic disc pallor. The electroretinogram showed the major functional difference, with a severe reduction of cone-mediated responses and a moderate reduction of rod-mediated responses in those patients with late-onset cone dystrophy.

The study is published in the November issue of Archives of Ophthalmology.