Schmitz-Valckenberg Steffen, Jorzik Jork, Unnebrink Kristina, Holz Frank G
Department of Ophthalmology, University of Heidelberg, Germany.
Graefes Arch Clin Exp Ophthalmol. 2002 Feb;240(2):73-8. doi: 10.1007/s00417-001-0413-3.
Fundus autofluorescence (AF) imaging using confocal scanning laser ophthalmoscopy (cSLO) has been shown to be superior to fundus photography or angiography for delineating areas of geographic atrophy (GA) in retinal pigment epithelium (RPE) and for recording variation over time. We have evaluated a method for automated computerized detection and quantitation of RPE atrophy.
AF images in vivo were recorded with a confocal scanning laser ophthalmoscope (exc. 488 nm, em. >500 nm; Heidelberg Retina Angiograph). The intensity of AF in atrophic areas was markedly decreased. Two independent readers analysed these areas in 24 right eyes manually by outlining GA areas using a mouse-driven arrow (method A) and automatically by image analysis software (Global Lab Image/2) after subjective adjustment of thresholding (method B). Agreement between observers and between methods A and B was assessed by the Bland-Altman design for method-comparison studies.
Larger areas were measured using method A than B by both readers (agreement A/B: reader 1 mean difference 1.04 mm, 95% CI [0.66,1.42]; reader 2 mean difference 0.62 mm, 95% CI [0.43,0.81]). The agreement between the readers was mean difference 0.39 mm (95% CI [0.02,0.76]) for A and mean difference -0.03 mm (95% CI [-0.23,0.18]) for B. Features making the delineation of borders of GA difficult included large choroidal vessels with autofluorescent properties in the GA area and media opacities.
Fundus AF cSLO imaging provides a reliable means to delineate areas of GA. The automated image analysis allows more accurate detection and quantitative documentation of atrophic areas than manual outlining. This method will be useful in longitudinal natural history studies and for monitoring effects of future therapeutic interventions to slow down GA progression in patients with advanced atrophic ARMD and other retinal diseases associated with outer retinal atrophy.
使用共焦扫描激光眼底镜（cSLO）进行的眼底自发荧光（AF）成像已被证明在描绘视网膜色素上皮（RPE）中地图样萎缩（GA）区域以及记录随时间的变化方面优于眼底照相或血管造影。我们评估了一种自动计算机检测和定量RPE萎缩的方法。
使用共焦扫描激光眼底镜（激发波长488nm，发射波长>500nm；海德堡视网膜血管造影仪）记录体内AF图像。萎缩区域的AF强度明显降低。两名独立的阅片者通过使用鼠标驱动箭头手动勾勒GA区域（方法A）以及在主观调整阈值后通过图像分析软件（Global Lab Image/2）自动分析（方法B），对24只右眼的这些区域进行分析。观察者之间以及方法A和B之间的一致性通过用于方法比较研究的Bland-Altman设计进行评估。
两位阅片者使用方法A测量的面积均大于方法B（A/B一致性：阅片者1平均差异1.04mm，95%可信区间[0.66,1.42]；阅片者2平均差异0.62mm，95%可信区间[0.43,0.81]）。阅片者之间的一致性为方法A平均差异0.39mm（95%可信区间[0.02,0.76]），方法B平均差异-0.03mm（95%可信区间[-0.23,0.18]）。使GA边界勾勒困难的特征包括GA区域具有自发荧光特性的大脉络膜血管和介质混浊。
眼底AF cSLO成像为描绘GA区域提供了一种可靠的方法。与手动勾勒相比，自动图像分析能够更准确地检测萎缩区域并进行定量记录。该方法将有助于纵向自然史研究以及监测未来治疗干预措施对延缓晚期萎缩性年龄相关性黄斑变性（ARMD）和其他与外层视网膜萎缩相关的视网膜疾病患者GA进展的效果。
