Cone Structure in Patients With Usher Syndrome Type III and Mutations in the Clarin 1 Gene

Phenotypic Characteristics Including In Vivo Cone Photoreceptor Mosaic inKCNV2-Related “Cone Dystrophy with Supernormal Rod Electroretinogram”

“…Previous studies have consistently reported reasonable correlation between IS-OS junction disruption and absence of visible cones at the fovea and perifovea in cone dysfunction syndromes 23,24 and a wide range of retinal conditions. 27,50,51 Further, the cone mosaic and density were also markedly abnormal in regions outside the fovea where SD-OCT showed less marked IS-OS disruption; the presence of intact rod photoreceptors in the region is the likely reason for this relative IS-OS preservation. 52 The presence of a generalized cone abnormality in the ERG suggests that regions of nondetectable cones on AOSLO might represent dysfunctional or absent cones rather than cones that are functional but not visible.…”

Relationship Between Foveal Cone Structure and Clinical Measures of Visual Function in Patients With Inherited Retinal Degenerations

“…Although previous studies 34,35,[41][42][43][44][45][46][47][48][49][50][51][52] have used AOSLO to assess cone spacing and density in normal and diseased eyes, none have reported on how foveal cone measures and visual function are correlated. The present study demonstrates a significant correlation between increased AOSLO cone spacing Z-scores and decreased VA at or near the fovea, as well as a significant correlation between Z-scores and foveal sensitivity.…”

“…Although these studies have assessed OCT structure-function correlations over broad ranges of disease severity (range, 20/15-20/1000 VA 29 ), none to date have reported on the relationship for a narrower range of VAs. However, OCT abnormalities have been observed in patients with good acuity and foveal thresholds, 28,[34][35][36] suggesting that structural measures may provide a more sensitive measure of disease than visual function.…”

“…34,35,[41][42][43][44][45][46][47][48][49][50][51][52] Adaptive optics-based studies 41,42 of retinal degeneration showed a significant correlation between macular cone spacing and central visual function, but given the small size and unique anatomy 53 of foveal cones and the resulting difficulties posed on imaging, 54 these studies were unable to assess cone morphology at the foveal center. Within the past few years, advanced systems that have implemented improvements in AO scanning laser ophthalmoscopy (AOSLO) system design 55 and advanced controls 56 have been able to more routinely visualize the foveal cone mosaic.…”

Methods for investigating the local spatial anisotropy and the preferred orientation of cones in adaptive optics retinal images

“…Central to the clinical application of this technology is the ability to quantitatively analyze the photoreceptor mosaic. At present, the majority of studies have focused on the analysis of cone density and spacing of cones (Li & Roorda, 2007; Chui et al , 2008; Li et al , 2010; Dees et al , 2011; Song et al , 2011; Garrioch et al , 2012; Chiu et al , 2013; Lombardo et al , 2013a; Park et al , 2013; Ratnam et al , 2013). These studies demonstrate moderate to high variability within cone density and spacing within the healthy adult population, making it difficult to detect small deviations from normal.…”