Estimation of melanin content in iris of human eye

Koblova, Ekaterina V.; Bashkatov, Alexey N.; Genina, Elina A.; Tuchin, Valery V.; Bakutkin, Valery V.

doi:10.1117/12.593651

Cited by 18 publications

(9 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Controversially, while having comparable cone white-light responses, photopic red-light evoked responses of larger amplitudes in albino compared to pigmented rats. Melanin, the iris pigment of pigmented animals has a peak absorption in the low wavelength range (335 nm) and basically does not absorb long wavelength light above 700 nm [33]. Thus, iris pigmentation only filters out a negligible portion of red light, which may not explain our findings.…”

Section: Differences Of Red Light On Retinal Responses Between Brown mentioning

confidence: 65%

Challenging a Myth and Misconception: Red-Light Vision in Rats

Niklaus

Albertini

Schnitzer

et al. 2020

Animals

View full text Add to dashboard Cite

Simple Summary: Light substantially influences animal physiology and behavior. Thus, it is a prerequisite to house laboratory animals under optimal light conditions. Different species possess different sets of photoreceptors, resulting in differential perception of the visible-light spectrum. While humans are trichromats with red-, green-and blue-sensitive cones, rats and mice are dichromats possessing ultraviolet-and green-sensitive cones. This led to the common assumption that red light is invisible to rodents and therefore red lights are commonly used in husbandry and experiments to observe animals during their dark phase. The retinal sensitivity of rats to red light though has never been assessed under scotopic conditions (dark-adapted) even though this mimics the setting red observation lights are being used. We examined the sensitivity to far-red light of the dark-and light-adapted rat retina. Our study demonstrates that the rat retina responds to far-red light under both conditions with great sensitivity, indicating that rats are not red-light blind. This should be taken into consideration when using red light to keep the effects of light on the retina and physiology to a minimum and will improve animal well-being and lead to better quality data by decreasing the variable light.Abstract: Due to the lack of L-cones in the rodent retina, it is generally assumed that red light is invisible to rodents. Thus, red lights and red filter foils are widely used in rodent husbandry and experimentation allowing researchers to observe animals in an environment that is thought to appear dark to the animals. To better understand red-light vision in rodents, we assessed retinal sensitivity of pigmented and albino rats to far-red light by electroretinogram. We examined the sensitivity to red light not only on the light-but also dark-adapted retina, as red observation lights in husbandry are used during the dark phase of the light cycle. Intriguingly, both rods and cones of pigmented as well as albino rats show a retinal response to red light, with a high sensitivity of the dark-adapted retina and large electroretinogram responses in the mesopic range. Our results challenge the misconception of rodents being red-light blind. Researchers and housing facilities should rethink the use of red observation lights at night.Animals 2020, 10, 422 2 of 14 impact of light on organisms, it is essential to ensure optimal illumination in laboratory animal facilities to maximize animal well-being.Vision is rendered in the retina. Photoreceptors convert the physical light stimulus into an electrical stimulus, which, via retinal interneurons, is further transmitted to the brain. Rats and mice are the most frequently used laboratory mammals, hence understanding exact species-and strain-specific differences in visual processing, including the range of spectral sensitivity, is key not only for ophthalmic studies but also to ensure appropriate environmental lighting conditions for husbandry. Rats and mice, being nocturnal animals, possess a rod...

show abstract

Section: Differences Of Red Light On Retinal Responses Between Brown mentioning

confidence: 65%

Challenging a Myth and Misconception: Red-Light Vision in Rats

Niklaus

Albertini

Schnitzer

et al. 2020

Animals

View full text Add to dashboard Cite

show abstract

“…Melanin concentration in the choroid, similar to the RPE, has many different reported values. Because the iris and the choroid are both the same layer in the eye, we used a melanin concentration of 26 mg/cm 3 as reported by Koblova et al 57 The absorption and scattering coefficients of blood were calculated from data published by Bosschaart et al 49 The assignment of scattering angles is achieved in the Monte Carlo through a Henyey Greenstein phase function, 58 and this has been shown to provide an effective phase function for blood with physiological haematocrit in the visible range. 59 The index of refraction for all layers was kept at 1.37.…”

Section: Eye Modelmentioning

confidence: 99%

A Monte Carlo Analysis of Error Associated With Two-Wavelength Algorithms for Retinal Oximetry

Rodriguez

Pfefer

Wang

et al. 2016

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

show abstract

“…At least two types of iridal melanin have been identified; eumelanin, a dark-brown pigment and phenomelanin, a reddish-yellowish pigment. [4][5][6][7][8][9][10] The innermost layer of the iris pigment epithelium is dark in all irises and basically contains eumelanin. 1,7,11 However, the structure and mixtures of both melanins in the iris stroma vary with iris color.…”

Section: Introductionmentioning

confidence: 99%

Hyperspectral optical imaging of human iris in vivo: characteristics of reflectance spectra

et al. 2011

View full text Add to dashboard Cite

We report a hyperspectral imaging system to measure the reflectance spectra of real human irises with high spatial resolution. A set of ocular prosthesis was used as the control condition. Reflectance data were decorrelated by the principal-component analysis. The main conclusion is that spectral complexity of the human iris is considerable: between 9 and 11 principal components are necessary to account for 99% of the cumulative variance in human irises. Correcting image misalignments associated with spontaneous ocular movements did not influence this result. The data also suggests a correlation between the first principal component and different levels of melanin present in the irises. It was also found that although the spectral characteristics of the first five principal components were not affected by the radial and angular position of the selected iridal areas, they affect the higher-order ones, suggesting a possible influence of the iris texture. The results show that hyperspectral imaging in the iris, together with adequate spectroscopic analyses provide more information than conventional colorimetric methods, making hyperspectral imaging suitable for the characterization of melanin and the noninvasive diagnosis of ocular diseases and iris color.

show abstract

Estimation of melanin content in iris of human eye

Cited by 18 publications

References 19 publications

Challenging a Myth and Misconception: Red-Light Vision in Rats

Challenging a Myth and Misconception: Red-Light Vision in Rats

A Monte Carlo Analysis of Error Associated With Two-Wavelength Algorithms for Retinal Oximetry

Hyperspectral optical imaging of human iris in vivo: characteristics of reflectance spectra

Contact Info

Product

Resources

About