The locus of fixation and the foveal cone mosaic

Putnam, Nicole; Hofer, Heidi; Doble, Nathan; Chen, Li; Carroll, Joseph; Williams, David R.

doi:10.1167/5.7.3

Cited by 151 publications

(171 citation statements)

References 39 publications

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“…21 Cone density alone was found to be an insufficient parameter to determine the location of fixation. 22 Similarly, the impact of changes in binocular fixation characteristics due to improvement in vision in one eye in the eyes with bilateral NV-AMD was not accounted for in this study. 23 Further studies on autofluorescence and morphological characteristics of the macula may also provide insight into the determinants of fixation.…”

Section: Discussionmentioning

confidence: 87%

Quality of fixation in eyes with neovascular age-related macular degeneration treated with ranibizumab

Sivaprasad

Pearce

Chong

2011

Eye

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Aims To define factors that determine the location and stability of fixation in patients with neovascular age-related macular degeneration (NV-AMD) treated with intravitreal ranibizumab injections. Methods The location and stability of fixation using microperimetry were determined in 77 eyes treated with ranibizumab for NV-AMD for at least 12 months. All patients were treated with three injections of ranibizumab 0.5 mg, 1 month apart and retreated according to predefined criteria. The fixation parameters were correlated to the visual acuity, and quantitative measures on OCT. Results The location of fixation was predominantly central in 52.6%, poor central fixation in 9.2%, and predominantly eccentric fixation in 38.2%. The fixation was stable in 65%, relatively unstable in 25%, and unstable in 10%. Visual acuity was the only factor that determined the stability and location of fixation. The characteristics of fixation were not related to the macular thickness or volume as measured by OCT. Conclusions Better visual outcome ensures central and stable fixation. Quantitative measures of OCT parameters do not determine fixation. Further studies on morphological features of the macula may provide some insight into the determinants of fixation.

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Section: Discussionmentioning

confidence: 87%

Quality of fixation in eyes with neovascular age-related macular degeneration treated with ranibizumab

Sivaprasad

Pearce

Chong

2011

Eye

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“…To control the retinal location imaged, subjects were instructed to fixate on particular intersections of black radial lines and concentric circles on a white background. Between seven and 30 images were collected for each condition described below, registered with subpixel accuracy (Putnam et al, 2005), and added together. To minimize the deleterious effects of fluctuations in cone reflectivity over time (Pallikaris et al, 2003), the different imaging conditions were interleaved over a period of 1-3 d.…”

Section: Methodsmentioning

confidence: 99%

Organization of the Human Trichromatic Cone Mosaic

Hofer¹,

Carroll²,

Neitz³

et al. 2005

J. Neurosci.

413

311

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Using high-resolution adaptive-optics imaging combined with retinal densitometry, we characterized the arrangement of short-(S), middle-(M), and long-(L) wavelength-sensitive cones in eight human foveal mosaics. As suggested by previous studies, we found males with normal color vision that varied in the ratio of L to M cones (from 1.1:1 to 16.5:1). We also found a protan carrier with an even more extreme L:M ratio (0.37:1). All subjects had nearly identical S-cone densities, indicating independence of the developmental mechanism that governs the relative numerosity of L/M and S cones. L:M cone ratio estimates were correlated highly with those obtained in the same eyes using the flicker photometric electroretinogram (ERG), although the comparison indicates that the signal from each M cone makes a larger contribution to the ERG than each L cone. Although all subjects had highly disordered arrangements of L and M cones, three subjects showed evidence for departures from a strictly random rule for assigning the L and M cone photopigments. In two retinas, these departures corresponded to local clumping of cones of like type. In a third retina, the L:M cone ratio differed significantly at two retinal locations on opposite sides of the fovea. These results suggest that the assignment of L and M pigment, although highly irregular, is not a completely random process. Surprisingly, in the protan carrier, in which X-chromosome inactivation would favor L-or M-cone clumping, there was no evidence of clumping, perhaps as a result of cone migration during foveal development.

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“…Although there was some success in imaging the smallest photoreceptors, the cones at the foveal center and the rods (which are comparable in size and morphology) using flood illuminated adaptive optics ophthalmoscopy, 11,12 these cells remained unresolved in adaptive optics scanning laser ophthalmoscopy (AOSLO) until only recently (Dubra et al, in preparation). Foveal cones are particularly interesting to study because along with the optical quality of the eye, it is these cells that underlie visual acuity.…”

Section: Photoreceptorsmentioning

confidence: 99%

Imaging retinal mosaics in the living eye

Rossi

Chung

Dubra

et al. 2011

Eye

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Adaptive optics imaging of cone photoreceptors has provided unique insight into the structure and function of the human visual system and has become an important tool for both basic scientists and clinicians. Recent advances in adaptive optics retinal imaging instrumentation and methodology have allowed us to expand beyond cone imaging. Multi-wavelength and fluorescence imaging methods with adaptive optics have allowed multiple retinal cell types to be imaged simultaneously. These new methods have recently revealed rod photoreceptors, retinal pigment epithelium (RPE) cells, and the smallest retinal blood vessels. Fluorescence imaging coupled with adaptive optics has been used to examine ganglion cells in living primates. Two-photon imaging combined with adaptive optics can evaluate photoreceptor function non-invasively in the living primate retina.

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The locus of fixation and the foveal cone mosaic

Cited by 151 publications

References 39 publications

Quality of fixation in eyes with neovascular age-related macular degeneration treated with ranibizumab

Quality of fixation in eyes with neovascular age-related macular degeneration treated with ranibizumab

Organization of the Human Trichromatic Cone Mosaic

Imaging retinal mosaics in the living eye

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