Use of spectral domain-optical coherence tomography to visualize photoreceptor abnormalities in cone-rod dystrophy 6.

Objective: The purpose of this study was to describe the spectral domain-optical coherence tomography findings in a patient with cone-rod dystrophy 6.

Methods: This is a case report of a 13-year-old girl who presented with progressive loss of vision. Fundus photography, a fluorescein angiogram, an electroretinogram, autofluorescence imaging, spectral domain-optical coherence tomography, and genetic testing were performed.

Results: The patient's fundi showed mild granularity of the perifoveal retinal pigment epithelium. An electroretinogram showed cone dysfunction and normal rod function. Genetic testing showed a heterozygous CGC>CAC nucleotide substitution at codon 838 of the GUCY2D gene. This results in an amino acid change of Arg838His and provides a molecular diagnosis of cone-rod dystrophy 6. The spectral domain-optical coherence tomography showed abnormalities at the inner segment/outer segment junction and the outer segment layer suggestive of loss or disease of photoreceptor outer segments. Autofluorescence imaging showed a perifoveal ring of hyperfluorescence that correlated with abnormallities on spectral domain-optical coherence tomography.

Conclusions: Spectral domain-optical coherence tomography can show photoreceptor abnormalities that correlate with the perifoveal ring seen with autofluorescence imaging of patients with cone-rod dystrophy 6. Spectral domain-optical coherence tomography has significant potential for understanding and following the natural history of diseases such as cone-rod dystrophy 6.