Combined reflectance spectroscopy and stochastic modeling approach for noninvasive hemoglobin determination via palpebral conjunctiva

Abstract

A combination of stochastic photon propagation model in a multilayered human eyelid tissue and reflectance spectroscopy was used to study palpebral conjunctiva spectral reflectance for hemoglobin (Hgb) determination. The developed model is the first biologically relevant model of eyelid tissue, which was shown to provide very good approximation to the measured spectra. Tissue optical parameters were defined using previous histological and microscopy studies of a human eyelid. After calibration of the model parameters the responses of reflectance spectra to Hgb level and blood oxygenation variations were calculated. The stimulated reflectance spectra in adults with normal and low Hgb levels agreed well with experimental data for Hgb concentrations from 8.1 to 16.7 g/dL. The extracted Hgb levels were compared with in vitro Hgb measurements. The root mean square error of cross‐validation was 1.64 g/dL. The method was shown to provide 86% sensitivity estimates for clinically diagnosed anemia cases. A combination of the model with spectroscopy measurements provides a new tool for noninvasive study of human conjunctiva to aid in diagnosing blood disorders such as anemia.

Parkinson’s disease-associated melanin steal

“…Both melanin and dopamine fluctuations have been documented. 1 , 4 , 20 – 25 The inverse association between the increasing daily L-dopa dosing value with the magnitude of dopamine fluctuations in the competitive inhibition state has also been documented. 1 , 4 Not documented until now are the interactions of L-tyrosine, L-dopa, and dopaquinone, with regard to the previously documented dopamine variances.…”

“…30 Melanin fluctuations have been documented in vivo and in vitro. 20 – 22 The hypothesis is that if decreasing tyrosine hydroxylase activity and increasing tyrosinase activity is more effective in the synthesis of dopaquinone than dopamine, then this leaves melanin synthesis and fluctuations in a more primary position, while the melanin-induced fluctuations of L-tyrosine and L-dopa are reflected as dopamine fluctuations on laboratory assay.…”

Semantic Segmentation of Conjunctiva Region for Non-Invasive Anemia Detection Applications

“…As reported by earlier works, a pale conjunctiva is considered an accurate sign of anemia [42][43][44]. Hence, it is considered as a Region of Interest (ROI), and typically manual cropping is performed on eye images to extract its color features, while automatic segmentation tried for this application using image processing techniques still needs some improvement.…”

Evaluation of Non-Invasive Measurement of Haemoglobin using PPG in Clinically Ill Pediatric Patients

“…SpHb monitoring has gained enormous attention as a point of care testing that facilitates to monitor haemoglobin concentration in a continuous, accurate, and non-invasive fashion. Various technologies and methods are employed by researches all over the globe to develop a system/device for SpHb monitoring [5][6][7][8][9][10][11][12][13]. Among the various methods, research on SpHb monitoring using Photoplethysmograph (PPG) is huge [14][15][16][17][18].…”