[source]
pmid = PMID:30095615
title = A novel CRX frameshift mutation causing cone-rod dystrophy in a Chinese family: A case report
[diagnosis]
disease_id = OMIM:120970
disease_label =	Cone-rod retinal dystrophy-2
[text]
The proband (Fig.1,1, IV:5), a 19-year-old man, first presented 10 years ago with binocular vision loss, photophobia, and impaired vision in the dark without any obvious cause. The uncorrected visual acuity of each eye was 0.5 and no significant improvement was observed with spectacles. Since then, the proband's visual acuity has decreased progressively. Over the past 4 years, binocular vision has decreased significantly and the night blindness has become severe. The ocular examination results showed that uncorrected visual acuity was 0.15 (right eye) and 0.1 (left eye), with no improvement observed with correction. We found no abnormality in the anterior segment. Fundus examination showed a clear optic disc border, slightly light color, a thinning artery, mid-peripheral diffuse retinal pigment epithelium (RPE) atrophy, gold foil-like reflection, and geographic pigment epithelium atrophy foci in each macular area (Fig. ​(Fig.2A).2A). FFA showed delayed retinal arterial filling, diffuse transmitted fluorescence, and irregularly geographic hypofluorescence in the macular area (Fig. ​(Fig.2B).2B). OCT revealed a thinning retinal nerve epithelium layer in the binocular macular area, a significantly thinning outer nuclear layer of the fovea centralis, and an absent fovea centralis, with the structure of the inner segment/outer segment (IS/OS) layer being difficult to distinguish (Fig. 2C). Visual field examination revealed quadrant defects in the binocular nasal field (Fig. ​(Fig.3A).3A). F-ERG showed the binocular rod cell response amplitude and maximum response amplitude were both decreased, and both the cone cell reaction and 30Hz scintillation reaction indicated the absence of an effective waveform (Fig. 3B).
Ophthalmic examination results of the proband. A: Fundus images showed retinal pigment epithelium atrophy and gold foil-like reflection in the macular area. Blue arrow: geographic atrophy foci. B: Fluorescein fundus angiography showed diffuse transmitted fluorescence and geographic hypofluorescence in the macular area (orange arrow). C: Optical coherence tomography showed an absent fovea centralis and an undefined IS/OS layer (green arrow). OD: right eye, OS: left eye.
Further ophthalmic examination results of the proband. A: Visual field examination showed quadrant defects in the binocular nasal field. B: Full field electroretinography showed the binocular rod cell response amplitude and maximum response amplitude were both decreased, and both the cone cell reaction and 30Hz scintillation reaction indicated the absence of an effective waveform. OD: right eye, OS: left eye.