Fluorescence lifetime imaging ophthalmoscopy (FLIO) has developed as a new diagnostic tool in ophthalmology. FLIO measurements are taken from 30° retinal fields in two spectral channels (short spectral channel (SSC): 498–560 nm, long spectral channel (LSC): 560–720 nm). Because of the layered structure of the eye, the detected signal is an interaction of the fluorescence decay of the anterior part and of the fundus. By comparing FLIO measurements before and after cataract surgery, the impact of the natural lens was proven, despite the application of a confocal laser scanning (cSLO) technique. The goal of this work was to determine the best algorithmic solution to isolate the sole fundus fluorescence lifetime from the measured signal, suppressing artifacts from the natural lens. Three principles based on a tri-exponential model were investigated: a tailfit, a layer-based approach with a temporally shifted component, and the inclusion of a separately measured fluorescence decay of the natural lens. The mean fluorescence lifetime τ_m,12 is calculated using only the shortest and the intermediate exponential component. τ_m,all is calculated using all three exponential components. The results of tri-exponential tailfit after cataract surgery were considered as a reference, because the implanted artificial lens can be assumed as non-fluorescent. In SSC, the best accordance of τ_m,all of the reference was determined with τ_m,12 of the tailfit before surgery. If high-quality natural lens measurements are available, the correspondence of τ_m,12 is best with τ_m,all of the reference. In LSC, there is a good accordance for all models between τ_m,12 before and after surgery. To study the pure fundus fluorescence decay in eyes with natural lenses, we advise to utilize fluorescence lifetime τ_m,12 of a triple-exponential tailfit, as it corresponds well with the mean fluorescence lifetime τ_m,all of eyes with fluorescence-less artificial intraocular lenses.

中文翻译：

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荧光寿命成像检眼镜（FLIO）中抑制天然镜片伪影的算法比较

荧光寿命成像检眼镜（FLIO）已发展成为一种新的眼科诊断工具。从两个光谱通道（短光谱通道（SSC）：498–560 nm，长光谱通道（LSC）：560–720 nm）的30°视网膜视野中进行FLIO测量。由于眼睛的分层结构，检测到的信号是前部和眼底的荧光衰减的相互作用。通过比较白内障手术前后的FLIO测量，尽管采用了共聚焦激光扫描（cSLO）技术，但仍证明了自然晶状体的影响。这项工作的目的是确定最佳算法解决方案，以从测量信号中分离出唯一的眼底荧光寿命，从而抑制自然晶状体的伪影。研究了基于三指数模型的三个原理：尾部贴合，具有随时间变化的分量的基于层的方法，以及单独测量的自然晶状体的荧光衰减。平均荧光寿命τ仅使用最短和中间指数成分来计算_m，12。τm _，all是使用所有三个指数成分计算的。白内障手术后三指数尾部拟合的结果被认为是参考，因为可以将植入的人工晶状体假定为非荧光性的。在SSC中，最佳参考τm _，所有参考均由手术前的尾部拟合τm _，12确定。如果可获得高质量的自然晶状体测量值_，则所有参考_均应将τm _，12与τm最佳对应。在LSC中，τm _，12之间的所有模型都有很好的一致性手术前后。为了研究天然晶状体眼睛的纯眼底荧光衰减，我们建议使用三指数尾部拟合的荧光寿命τm，₁₂，因为它与平均荧光寿命τm很好地吻合_，所有人工荧光较少的眼睛人工晶状体。