Clinical findings and diagnostics of cone dystrophy

Background: Cone dystrophies present with highly variable clinical findings and often limited retinal changes, which may lead to misdiagnosis. The purpose of the present review of the clinical presentation and diagnosis of cone dystrophies is to provide guidelines for improved patient care.

Methods: A literature search and evaluation of the clinical findings were carried out in 450 patients with cone dystrophy examined between 1986 and 2008.

Results: Characteristic signs are loss of visual acuity, photophobia and central scotoma. The diagnosis of cone dystrophy is determined by a full-field electroretinogram (ERG). Fundus and near-infrared autofluorescence as well as optical coherence tomography allow detection of retinal structural abnormalities even when findings from ophthalmoscopy are normal.

Conclusions: The diagnosis of cone dystrophy is difficult due to unspecific subjective symptoms and absence of characteristic ophthalmoscopic findings. The differential diagnosis of unexplained visual loss should include cone dystrophy and requires either a full-field or multifocal ERG.