Spectral reflectance of the human eye

Norren, Dirk van; Tiemeijer, L.F.

doi:10.1016/0042-6989(86)90028-3

Cited by 163 publications

(98 citation statements)

References 7 publications

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“…Only a foveal field is used, and MP levels are derived from a model fit that takes into account the absorption and scattering coefficients of all retinal layers traversed in a double-path succession by the light. [16][17][18] A review of the technology can be found in Ref. 19 .…”

Section: Introductionmentioning

confidence: 99%

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

2006

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We have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores ("autofluorescence") as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the bluegreen wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils.

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Section: Introductionmentioning

confidence: 99%

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

2006

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“…Computational simulations are being employed in a variety of fields to assist the study of complex biological systems, [10][11][12] and several computer models [13][14][15][16][17] have been proposed to investigate the processes that control the amount of light that enters the human eye and its interaction with ocular fundus tissues. Recently, we developed the first biophysically based iridal light transport model ͑ILIT͒ to investigate tissue optics phenomena affecting iridal appearance.…”

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confidence: 99%

Qualitative assessment of undetectable melanin distribution in lightly pigmented irides

Baranoski

Lam

2007

J. Biomed. Opt.

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Abstract.A longstanding issue in biomedical research concerns the biophysical factors affecting the color diversity of the human irides and its connection with ocular diseases. Although the pigmentation and morphological characteristics of heavily and moderately pigmented irides have been extensively discussed in the literature, similar studies are scarce for lightly pigmented irides. We present computer experiments indicating that the spectral signature of these specimens may be directly affected by still undetectable melanin distributions in the outermost iridal layers. Our findings represent in silico evidence of this relationship which, in turn, may have implications in the investigation of the higher risk of death from metastatic ocular melanoma verified in individuals with light-colored irides.

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“…6 MP is mainly of dietary origin 4 and is thought to have a protective role by acting as an optical filter to shorter wavelengths and as a consequence of its antioxidant properties. [7][8][9][10][11] Several techniques have been adopted to measure MP in vivo, including Raman detection, 12 scanning laser ophthalmoscope, 13 reflectometry, [14][15][16][17] autofluorescence, 14 colour matching, 18 and heterochromatic flicker photometry using 'Maxwellian' and 'freeview' systems, 19,20 but there are limitations to all these techniques; Raman spectroscopy, scanning laser ophthalmoscopy, reflectometry, and autofluorescence all require complex equipment and have been developed as research tools. The more widespread techniques used in clinical practice to measure MP rely on colour matching or heterochromatic flicker photometry, both of which are dependent on subjective interpretation of an end point by the individual performing the test and this may be difficult in elderly subjects, especially if fixation is poor; there is therefore a need for a simple objective technique that could be applied in a clinical setting.…”

Section: Discussionmentioning

confidence: 99%

Multispectral retinal image analysis: a novel non-invasive tool for retinal imaging

Calcagni

Gibson

Styles

et al. 2011

Eye

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Purpose To develop a non-invasive method for quantification of blood and pigment distributions across the posterior pole of the fundus from multispectral images using a computer-generated reflectance model of the fundus. Methods A computer model was developed to simulate light interaction with the fundus at different wavelengths. The distribution of macular pigment (MP) and retinal haemoglobins in the fundus was obtained by comparing the model predictions with multispectral image data at each pixel. Fundus images were acquired from 16 healthy subjects from various ethnic backgrounds and parametric maps showing the distribution of MP and of retinal haemoglobins throughout the posterior pole were computed. Results The relative distributions of MP and retinal haemoglobins in the subjects were successfully derived from multispectral images acquired at wavelengths 507, 525, 552, 585, 596, and 611 nm, providing certain conditions were met and eye movement between exposures was minimal. Recovery of other fundus pigments was not feasible and further development of the imaging technique and refinement of the software are necessary to understand the full potential of multispectral retinal image analysis. Conclusion The distributions of MP and retinal haemoglobins obtained in this preliminary investigation are in good agreement with published data on normal subjects. The ongoing development of the imaging system should allow for absolute parameter values to be computed. A further study will investigate subjects with known pathologies to determine the effectiveness of the method as a screening and diagnostic tool.

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Spectral reflectance of the human eye

Cited by 163 publications

References 7 publications

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

Qualitative assessment of undetectable melanin distribution in lightly pigmented irides

Multispectral retinal image analysis: a novel non-invasive tool for retinal imaging

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