The Pathways of Light Measured in Fundus Reflectometry

Kraats, Jan van de; Berendschot, Tos T. J. M.; Norren, Dirk van

doi:10.1016/0042-6989(96)00001-6

Cited by 141 publications

(135 citation statements)

References 40 publications

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“…Interestingly, this result is not fully consistent with any of the three leading optical models of the retina described in Section 1 (Introduction), at least for wavelengths in the near infrared. The first model bases the origin of the optical SCE on reflections over the entire axial length of the outer segment due to refractive index modulations induced by the discs [20]. Our findings indicate that only the reflections at or near the two ends of the outer segment contribute meaningfully.…”

Section: Directionality Of the Retinal Layers Measured With Sd-octmentioning

confidence: 70%

“…Two leading views are that the waveguided light originates from (1) reflections across the entire axial length of the outer segment due to refractive index variations induced by the stack of photopigment carrying discs [20] and (2) reflections from the posterior tips of the photoreceptor outer segments (PTOS) and possibly from melanin granules of the RPE [21][22][23]. A third view has been suggested recently in that light reflecting from layers further behind the photoreceptors is also waveguided, especially at longer wavelengths [24].…”

Section: Introductionmentioning

confidence: 99%

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Measuring retinal contributions to the optical Stiles-Crawford effect with optical coherence tomography

Gao¹,

Cense²,

Zhang³

et al. 2008

Opt. Express

119

113

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The directional component of the retinal reflection, i.e., the optical Stiles-Crawford effect (SCE), is well established to result from the waveguiding property of photoreceptors. Considerable uncertainty, however, remains as to which retinal reflections are waveguided and thus contribute. To this end we have developed a retina camera based on spectral-domain optical coherence tomography (SD-OCT) that axially resolves (~5 μm) these reflections and permits a direct investigation of the SCE origin at near infrared wavelengths. Reflections from the photoreceptor inner/outer segments junction (IS/ OS) and near the posterior tip of the outer segments (PTOS) were found highly sensitive to beam entry position in the pupil with a considerable decrease in brightness occurring with an increase in aperture eccentricity. Reflections from the retinal pigment epithelium (RPE) were largely insensitive. The average directionality (ρ oct value) at 2 degree eccentricity across the four subjects for the IS/OS, PTOS, and RPE were 0.120, 0.270, and 0.016 mm −2 , respectively. The directionality for the IS/OS approached typical psychophysical SCE measurements, while that for the PTOS approached conventional optical SCE measurements. Precise measurement of the optical SCE was found to require significant A-scan averaging.

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Section: Directionality Of the Retinal Layers Measured With Sd-octmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Measuring retinal contributions to the optical Stiles-Crawford effect with optical coherence tomography

Gao¹,

Cense²,

Zhang³

et al. 2008

Opt. Express

119

113

View full text Add to dashboard Cite

show abstract

“…Using known spectral characteristics of the different absorbers within the eye (lens, MP, melanin, blood), the densities of the pigments and percent reflectance at the interfaces are optimized to fit the measured data at all wavelengths. 25,26 For a detailed discussion of this analysis see Berendschot et al 27,28 …”

Section: Mp Reflectometermentioning

confidence: 99%

Macular pigment optical density measurements: evaluation of a device using heterochromatic flicker photometry

Kinkelder

Veen

Verbaak

et al. 2010

Eye

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Purpose Accurate assessment of the amount of macular pigment (MPOD) is necessary to investigate the role of carotenoids and their assumed protective functions. High repeatability and reliability are important to monitor patients in studies investigating the influence of diet and supplements on MPOD. We evaluated the Macuscope (Macuvision Europe Ltd., Lapworth, Solihull, UK), a recently introduced device for measuring MPOD using the technique of heterochromatic flicker photometry (HFP). We determined agreement with another HFP device (QuantifEye; MPS 9000 series: Tinsley Precision Instruments Ltd., Croydon, Essex, UK) and a fundus reflectance method. Methods The right eyes of 23 healthy subjects (mean age 33.9±15.1 years) were measured. We determined agreement with QuantifEye and correlation with a fundus reflectance method. Repeatability of QuantifEye was assessed in 20 other healthy subjects (mean age 32.1 ± 7.3 years). Repeatability was also compared with measurements by a fundus reflectance method in 10 subjects. Results We found low agreement between test and retest measurements with Macuscope. The average difference and the limits of agreement were À0.041 ± 0.32. We found high agreement between test and retest measurements of QuantifEye (À0.02±0.18) and the fundus reflectance method (À0.04±0.18). MPOD data obtained by Macuscope and QuantifEye showed poor agreement: À0.017 ± 0.44. For Macuscope and the fundus reflectance method, the correlation coefficient was r ¼ 0.05 (P ¼ 0.83). A significant correlation of r ¼ 0.87 (Po0.001) was found between QuantifEye and the fundus reflectance method. Conclusions Because repeatability of Macuscope measurements was low (ie, wide limits of agreement) and MPOD values correlated poorly with the fundus reflectance method, and agreed poorly with QuantifEye, the tested Macuscope protocol seems less suitable for studying MPOD.

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“…[11][12][13][14][15] The optical techniques are based on the principle that light entering the inner segments of the cones is guided along the outer segment and is absorbed by the photopigment, multiply scattered into the deeper retinal layers, or singly scattered or reflected back along the outer segments, thereby retracing its path. 13,16 This light is then radiated from the inner segments back toward the pupil. Thus, by examining the pupillary distribution of light returning from the retina, it is possible to measure the directionality of the cone photoreceptors.…”

Section: Introductionmentioning

confidence: 99%

Variations in photoreceptor directionality across the central retina

Burns

et al. 1997

J. Opt. Soc. Am. A

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Cones show a differential sensitivity to light coming from different portions of the pupil, typically being most sensitive to light from the center of the pupil. We measured the directional properties of the cones across the central 6 deg of the retina, using an optical imaging technique. We find that the cones in the center of the fovea have the broadest tuning. The width of the angular tuning changes rapidly from 0 deg to 1 deg retinal eccentricity, with cones at 1 deg being much more narrowly tuned than the cones in the center of the fovea. Directional tuning of the cones remains relatively constant from 1 deg to 3 deg retinal eccentricity. Receptoral disarray contributes minimally to the measured directional properties of the foveal cones, and there is no evidence of asymmetry between horizontal and vertical retinal locations. There are only small differences among the five subjects in the change in angular tuning of the cones with retinal location. We find that at the foveal center the directional tuning of the cones is limited by the diameter of the cone apertures.

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The Pathways of Light Measured in Fundus Reflectometry

Cited by 141 publications

References 40 publications

Measuring retinal contributions to the optical Stiles-Crawford effect with optical coherence tomography

Measuring retinal contributions to the optical Stiles-Crawford effect with optical coherence tomography

Macular pigment optical density measurements: evaluation of a device using heterochromatic flicker photometry

Variations in photoreceptor directionality across the central retina

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