联合应用谱域OCT和眼底自发荧光观察激光术后光凝斑视网膜结构的变化

目的探讨应用谱域OCT(SD-OCT)和眼底自发荧光(fundus autofluorescence,FAF)评价激光光凝术后视网膜神经上皮层及色素上皮层结构变化。方法对视网膜激光光凝术后14只眼539个光凝斑进行眼底彩色照相、SD-OCT和FAF检查,部分病例行标准红外线(stand-ard infrared,IR)检查。观察时间为术后1 h、1~2周、1~6个月、6~12个月、1~2.5年和2.5年以上。通过488 nm激发光,500 nm滤光片成像系统采集FAF(Spectralis HRA2+OCT)。结果视网膜激光光凝术后1 h,SD-OCT图像显示神经感觉层组织全层增厚,高反光,提示神经感觉层全层水肿,色素上皮层(RPE)变薄或者正常,光凝斑处自发荧光信号衰减,表现为自发荧光暗点。激光光凝术后2周,SD-OCT图像显示神经上皮层全层向光凝斑中心牵拉,RPE层,变厚提示RPE细胞增生;光凝斑自发荧光信号显著增强。激光光凝术后1~6个月,光凝斑自发荧光信号中心部增强,周边部环形减弱,SD-OCT扫描显示激光斑中心部RPE细胞层增厚,周围环形萎缩。激光光凝术后6~12个月,光凝斑处自发荧光表现为周围环形低荧光区域面积扩大,中心强信号范围缩小,呈孤岛状;SD-OCT扫描显示RPE萎缩面积扩大,光凝斑中心部少量RPE细胞增殖。激光光凝术后1年以上,SD-OCT图像显示光凝斑处RPE萎缩伴神经感觉组织严重受损,激光斑自发荧光变成黑点并扩大。结论应用SD-OCT和FAF可以长期随访光凝斑处视网膜结构变化,补充荧光血管造影技术观察激光光凝治疗效果。二者联合应用为活体内研究激光斑提供新的观察手段。

Combination of Special Domain OCT and Fundus Autofluorescence to Observe Retinal Structural Changes after Conventional Laser Photocoagulation

Objective The spectral domain optical coherence tomography（SD-OCT） can deliver retinal cross-sectional images with high resolution.This may allow to evaluate the extent of damage to the retinal pigment epithelium（RPE） and the neurosensory retina after laser treatment.The fundus autofluorescence（FAF） is derived from the lipofuscin contained by the retinal pigment epithelial cells.The aim of the study is to use SD-OCT and FAF to evaluate these characteristics with clinically visible alterations in outer retina（OR） and RPE after laser treatment.Methods The color fundus photography,SD-OCT,and fundus camera-based AF and partially standard infrared（IR） were performed in 539 conventional retinal laser（CRL） lesions of 14 eyes following retinal photocoagulation at various times after treatment（i.e.1 h,1-2 weeks,1-6 months,6-12 months,1-2.5 and more than 2.5 years）.FAF was excited by 488 nm and detected by a barrier filter at 500 nm（Spectralis HRA2＋OCT,Heidelberg Engineering）.CRL lesions were applied with an ophthalmoscopically slightly grayish-white appearance.The appearance and size of the laser lesions were documented and correlated to the time of treatment.Results All CRL lesions were characterized by high reflectivity in OCT images throughout the full thickness of the neurosensory tissue 1 h after irradiation,suggesting complete neurosensory coagulation.The RPE layer appeared to be regular or thinner immediately after treatment.Identification of the lesions was possible by FAF imaging showing an intensity decay in the irradiated area.Lesions could be identified as hypoautofluorescent spots.Strong contraction through the full thickness of the neurosensory layers was observed within 2 weeks after treatment.A RPE thickening indicating RPE proliferation was observable.Previously decreased autofluorescence in all lesions changed to significantly increased autofluorescence.One to six months after irradiation,the FAF of CRL change into central hyperautofluorescence with surrounding signal was decreasing.In OCT scan,a central RPE thickening and surrounding ring-shaped atrophy was observable.Over the next 6 months,the area of central hyperautofluorescence continued to decrease forming solitary island shape.CRL lesions were characterized by area of RPE atrophy enlarging with less central RPE cells proliferation.One year and later after treatment,CRL lesions were characterized by RPE atrophy combined with significant damage of the neurosensory tissue.lesions again changed to complete dark spots,enlarging later on.Conclusions Spectral domain OCT and fundus autofluorescence can be used clinically to follow the development of laser-induced lesions over time,which will assist invasive fluorescein angiography in many cases to verify therapeutic laser success.The combination of SD-OCT with AF will provide a whole new era for analysis of laser-induced lesions in vivo.