Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114, USA.
Invest Ophthalmol Vis Sci. 2011 Dec 9;52(13):9379-90. doi: 10.1167/iovs.11-8319.
To evaluate the feasibility and reliability of a standardized approach for quantitative measurements of fundus autofluorescence (AF) in images obtained with a confocal scanning laser ophthalmoscope (cSLO).
AF images (30°) were acquired in 34 normal subjects (age range, 20-55 years) with two different cSLOs (488-nm excitation) equipped with an internal fluorescent reference to account for variable laser power and detector sensitivity. The gray levels (GLs) of each image were calibrated to the reference, the zero GL, and the magnification, to give quantified autofluorescence (qAF). Images from subjects and fixed patterns were used to test detector linearity with respect to fluorescence intensity, the stability of qAF with change in detector gain, field uniformity, effect of refractive error, and repeatability.
qAF was independent of detector gain and laser power over clinically relevant ranges, provided that detector gain was adjusted to maintain exposures within the linear detection range (GL < 175). Field uniformity was better than 5% in a central 20°-diameter circle but decreased more peripherally. The theoretical inverse square magnification correction was experimentally verified. Photoreceptor bleaching for at least 20 seconds was performed. Repeatability (95% confidence interval) for same day and different-day retests of qAF was ±6% to ±14%. Agreement (95% confidence interval) between the two instruments was <11%.
Quantitative AF imaging appears feasible. It may enhance understanding of retinal degeneration, serve as a diagnostic aid and as a sensitive marker of disease progression, and provide a tool to monitor the effects of therapeutic interventions.
评估使用共焦激光扫描检眼镜（cSLO）获得的眼底自发荧光（AF）图像进行定量测量的标准化方法的可行性和可靠性。
使用两台配备内部荧光参考的不同 cSLO（488nm 激发）对 34 名正常受试者（年龄范围 20-55 岁）进行了 30°的 AF 图像采集。对每个图像的灰度（GL）进行校准，使其与参考值、零 GL 和放大倍数相对应，以给出定量自发荧光（qAF）。使用受试者和固定图案的图像来测试探测器相对于荧光强度的线性度、探测器增益变化时 qAF 的稳定性、场均匀性、屈光误差的影响以及重复性。
qAF 与探测器增益和激光功率在临床相关范围内无关，只要调整探测器增益以保持在线性检测范围内（GL<175）。在直径为 20°的中央圆圈内，场均匀性优于 5%，但在外周则降低。理论上的倒数平方放大修正得到了实验验证。至少进行 20 秒的光感受器漂白。qAF 的同一天和不同天重复测试的重复性（95%置信区间）为±6%至±14%。两台仪器之间的一致性（95%置信区间）<11%。
定量 AF 成像似乎是可行的。它可能增强对视网膜变性的理解，作为诊断辅助手段和疾病进展的敏感标志物，并提供监测治疗干预效果的工具。
