Potential measurement error from vessel reflex and multiple light paths in dual-wavelength retinal oximetry

IF 3 3区医学 Q1 OPHTHALMOLOGY

Acta Ophthalmologica Pub Date : 2023-10-03 DOI:10.1111/aos.15776

James M. Beach, Benjamin Shoemaker, George J. Eckert, Alon Harris, Brent Siesky, Julia C. Arciero

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Abstract

Purpose

This study aims to characterize the dependence of measured retinal arterial and venous saturation on vessel diameter and central reflex in retinal oximetry, with an ultimate goal of identifying potential causes and suggesting approaches to improve measurement accuracy.

Methods

In 10 subjects, oxygen saturation, vessel diameter and optical density are obtained using Oxymap Analyzer software without diameter correction. Diameter dependence of saturation is characterized using linear regression between measured values of saturation and diameter. Occurrences of negative values of vessel optical densities (ODs) associated with central vessel reflex are acquired from Oxymap Analyzer. A conceptual model is used to calculate the ratio of optical densities (ODRs) according to retinal reflectance properties and single and double-pass light transmission across fixed path lengths. Model-predicted values are compared with measured oximetry values at different vessel diameters.

Results

Venous saturation shows an inverse relationship with vessel diameter (D) across subjects, with a mean slope of −0.180 (SE = 0.022) %/μm (20 < D < 180 μm) and a more rapid saturation increase at small vessel diameters reaching to over 80%. Arterial saturation yields smaller positive and negative slopes in individual subjects, with an average of −0.007 (SE = 0.021) %/μm (20 < D < 200 μm) across all subjects. Measurements where vessel brightness exceeds that of the retinal background result in negative values of optical density, causing an artifactual increase in saturation. Optimization of model reflectance values produces a good fit of the conceptual model to measured ODRs.

Conclusion

Measurement artefacts in retinal oximetry are caused by strong central vessel reflections, and apparent diameter sensitivity may result from single and double-pass transmission in vessels. Improvement in correction for vessel diameter is indicated for arteries however further study is necessary for venous corrections.

Abstract Image

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双波长视网膜血氧计中血管反射和多条光路的潜在测量误差。

目的：本研究旨在描述视网膜血氧计中测量的视网膜动脉和静脉饱和度对血管直径和中枢反射的依赖性，最终目的是确定潜在原因并提出提高测量准确性的方法。方法：应用Oxymap分析仪软件对10名受试者进行血氧饱和度、血管直径和光密度测量，不进行直径校正。饱和度的直径依赖性使用饱和度测量值和直径之间的线性回归来表征。与中心血管反射相关的血管光密度（OD）负值的出现是从Oxymap Analyzer获得的。根据视网膜反射特性以及固定路径长度上的单通和双通光传输，使用概念模型来计算光密度比（ODR）。将模型预测值与不同血管直径下的血氧测定值进行比较。结果：受试者的静脉饱和度与血管直径（D）呈反比，平均斜率为-0.180（SE = 0.022）%/μm（20 结论：视网膜血氧计的测量伪影是由强烈的中心血管反射引起的，而视直径敏感性可能是由血管中的单程和双程透射引起的。动脉的血管直径校正有所改善，但静脉校正需要进一步研究。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Ophthalmologica 医学-眼科学

CiteScore

7.60

自引率

5.90%

发文量

433

审稿时长

6 months

期刊介绍： Acta Ophthalmologica is published on behalf of the Acta Ophthalmologica Scandinavica Foundation and is the official scientific publication of the following societies: The Danish Ophthalmological Society, The Finnish Ophthalmological Society, The Icelandic Ophthalmological Society, The Norwegian Ophthalmological Society and The Swedish Ophthalmological Society, and also the European Association for Vision and Eye Research (EVER). Acta Ophthalmologica publishes clinical and experimental original articles, reviews, editorials, educational photo essays (Diagnosis and Therapy in Ophthalmology), case reports and case series, letters to the editor and doctoral theses.