In Vitro Multispectral Diffuse Reflectance Measurements of the Porcine Fundus

Salyer, David; Twietmeyer, Karen; Beaudry, Neil A.; Basavanthappa, S.; Park, Robert I.; Chipman, Russell A.

doi:10.1167/iovs.04-1020

Cited by 4 publications

(5 citation statements)

References 10 publications

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“…32 They are inexpensive, readily available, and provide a good model of the human eye. 33 They are also useful for preliminary testing before performing live swine or human eye studies with their requirements for a team of doctors, technicians, and associated costs.…”

Section: Testing the Rox-3 On An Enucleated Swine Eyementioning

confidence: 99%

Retinal oximeter for the blue-green oximetry technique

et al. 2011

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Abstract. Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO 2 ) via the retinal vessels but requires a calibrated accuracy of ± 3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the bluegreen oximetry (BGO) technique can provide accuracy within ± 3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO 2 measurements of ∼1 and ∼65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of ± 2% SO 2 . The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Testing the Rox-3 On An Enucleated Swine Eyementioning

confidence: 99%

Retinal oximeter for the blue-green oximetry technique

et al. 2011

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“…This inconsistency suggested that the combined effect of the cornea and fundus scattering only represent an equivalent model. Although the integral reflectance of the porcine fundus exhibited the Lambertian characteristic 37 and the Lambertian assumption has been adopted in previous studies, [38][39][40] the internal scattering from the multilayer fundus to the retina and directly absorbed at the fovea photoreceptors was not considered. Due to the lack of the experimental data on the angular distribution of internal fundus scattering, the Lambertian characteristic was used in the present model.…”

Section: Discussionmentioning

confidence: 99%

“…36 However, when the integral reflectance was considered, in vitro measurements of the porcine fundus 37 showed that the fundus behaved generally as a Lambertian reflector within 20% deviations. Also, previous studies had adopted the Lambertian assumption to either report the integral fundus reflectance 38,39 or to validate the fundus reflection model.…”

Section: Retina Fundusmentioning

confidence: 99%

Development of a human eye model incorporated with intraocular scattering for visual performance assessment

et al. 2012

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Abstract. A biometry-based human eye model was developed by using the empirical anatomic and optical data of ocular parameters. The gradient refractive index of the crystalline lens was modeled by concentric conicoid isoindical surfaces and was adaptive to accommodation and age. The chromatic dispersion of ocular media was described by Cauchy equations. The intraocular scattering model was composed of volumetric Mie scattering in the cornea and the crystalline lens, and a diffusive-surface model at the retina fundus. The retina was regarded as a Lambertian surface and was assigned its corresponding reflectance at each wavelength. The optical performance of the eye model was evaluated in CodeV and ASAP and presented by the modulation transfer functions at single and multiple wavelengths. The chromatic optical powers obtained from this model resembled that of the average physiological eyes. The scattering property was assessed by means of glare veiling luminance and compared with the CIE general disability glare equation. By replacing the transparent lens with a cataractous lens, the disability glare curve of cataracts was generated to compare with the normal disability glare curve. This model has high potential for investigating visual performance in ordinary lighting and display conditions and under the influence of glare sources.

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“…The latter were probably not included in the evaluation, since nothing is written about them in these publications. To avoid this problem Sayler et al (2005) illuminated ex-vivo porcine eyes from the inside of the eye by inserting an illumination fiber in the vitreous of the eye [13] . With this set-up, an increase in reflectance of the inner eyewall with increasing wavelength was presented, too.…”

Section: Introductionmentioning

confidence: 99%