Reflectance and curvature of the inner limiting membrane at the foveola

Gorrand, Jean-Marie; Delori, François C.

doi:10.1364/josaa.16.001229

Cited by 35 publications

(23 citation statements)

References 25 publications

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“…Several studies have suggested that there may be age-related change in foveal architecture, and that could be relevant to the changes in photopigment OD distribution that we have observed (Elsner et al, 1998;Gorrand & Delori, 1999). Alpern (1979) suggested that perhaps "cone outer segments may be growing longer as subjects grow older" (p. 99).…”

Section: Photopigment Od and Normal Agingmentioning

confidence: 55%

Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea

et al. 2004

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Photopigment optical density (OD) of middle-(M) and long-(L) wavelength-sensitive cones was determined to evaluate the hypothesis that reductions in the amount of photopigment are responsible for age-dependent sensitivity losses of the human cone pathways. Flicker thresholds were measured at the peak and tail of the photoreceptor's absorption spectrum as a function of the intensity of a bleaching background. Photopigment OD was measured at 0 (fovea), 2, 4, and 8 deg in the temporal retina by use of a 0.3-deg-diameter test spot. Seventy-two genetically characterized dichromats were studied so that the L-and M-cones could be analyzed separately. Subjects included 28 protanopes with M-but no L-cones and 44 deuteranopes with L-but no M-cones (all male, age range 12-29 and 55-83 years). Previous methods have not provided estimates of photopigment OD for separate cone classes in the foveola. In this study, it was found that foveolar cones are remarkably efficient, absorbing 78% of the available photons (OD ϭ 0.65). Photopigment OD decreased exponentially with retinal eccentricity independently of age and cone type. Paradoxically, the OD of perifoveal cones increased significantly with age. Over the 70-year age range of our participants, the perifoveal M-and L-cones showed a 14% increase in capacity to absorb photons despite a 30% decrease in visual sensitivity over the same period.

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Section: Photopigment Od and Normal Agingmentioning

confidence: 55%

Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea

et al. 2004

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“…A more parallel alignment of the photoreceptor axons with respect to the imaging light would result in a reduction of phase retardation along that axis. A reduction in the lateral displacement of these central photoreceptor axons would cause an age-associated shallowing of the foveal pit, as demonstrated with reflectivity maps of the foveal depression (Gorrand & Delori, 1999). Changes of this nature would also be expected to cause a decrease in the centerpoint macular thickness, also consistent with recent findings of macular thinning with age (Song et al, 2010), although changes with age in macular thickness are inconsistent among laboratories.…”

Section: Discussionmentioning

confidence: 99%

Foveal phase retardation changes associated with normal aging

et al. 2011

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This study quantified normal age-related changes to the photoreceptor axons in the central macula using the birefringent properties of the Henle fiber layer. A scanning laser polarimeter was used to acquire 15 × 15 deg macular images in 120 clinically normal subjects, ranging in age from the third decade to the eighth. Raw image data of the macular cross were used to compute phase retardation maps associated with Henle fiber layer. Annular regions of interest ranging from 0.25 to 3 deg eccentricity and centered on the fovea were used to generate intensity profiles from the phase retardation data, which were then analyzed using sine curve fitting and Fast Fourier Transform (FFT). The amplitude of a 2f sine curve was used as a measure of macular phase retardation magnitude. For FFT analysis, the 2f amplitude, as well as the 4f, were normalized by the remaining FFT components. The amplitude component of the 2f curve fit and the normalized 2f FFT component decreased as a function of age, while the eccentricity of the maximum value for the normalized 2f FFT component increased. The phase retardation changes in the central macula indicate structural alterations in the cone photoreceptor axons near the fovea as a function of age. These changes result in either fewer cone photoreceptors in the central macula, or a change in the orientation of their axons. This large sample size demonstrates systematic changes to the central cone photoreceptor morphology using scanning laser polarimetry.

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“…Although the reflection at the ILM is specular and therefore directional, it does illuminate the pupil quasi-uniformly and can therefore be treated as nondirectional because it emanates from an image of the source located very close to the retina. 22 Next, the only directional reflection takes place at the cone outer segments. A further nondirectional reflection occurs at the retinal pigment epithelium.…”

Section: Overviewmentioning

confidence: 99%

Directional and nondirectional spectral reflection from the human fovea

Kraats

Norren

2008

J. Biomed. Opt.

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A model of the directional and nondirectional reflection spectrum of the human fovea is developed, incorporating reflectors, absorbers, and a wavelength-dependent optical Stiles-Crawford effect (OSCE). Data from 102 healthy subjects between 18 and 75 years obtained with the fundus reflection analyzer (FRA), an imaging spectrograph that measures the directional reflection profile of the human fovea in the pupil plane from 400 to 950 nm, were analyzed. Subgroups of young (<40 years) and old (>50 years) observers were defined. Mean results of the young group defined a template for directionality versus wavelength. For the whole group, mean reflection at 550 nm from the cones was 2.12%, from the retinal pigment epithelium 0.56%, and from the choroid 7.92%. Lens density, cone disc reflection, and blood layer thickness showed significant trends versus age. The model for the first time simultaneously describes the spectra of the directional and nondirectional reflection of the human fovea. Rayleigh scatter losses of the media and in preretinal layers were assumed zero in the nondirectional pathway. Mean density of the macular pigment of a subgroup (53 subjects, 19 to 75 years) correlated significantly with independent data from reflectance and autoflourescence images obtained by scanning laser ophthalmoscope (SLO) and data from flicker photometry.

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Reflectance and curvature of the inner limiting membrane at the foveola

Cited by 35 publications

References 25 publications

Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea

Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea

Foveal phase retardation changes associated with normal aging

Directional and nondirectional spectral reflection from the human fovea

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