[Imaging features of posterior polymorphous corneal dystrophy observed by in vivo confocal microscopy].

Objective: To identify and analyze imaging features of posterior polymorphous corneal dystrophy (PPCD) by in vivo confocal microscopy (IVCM). Methods: This retrospective case series enrolled 27 eyes of 18 patients (including 10 males and 8 females) who were diagnosed with PPCD at the Department of Ophthalmology in Peking University Third Hospital between January 2013 and December 2019. The mean age was (23.61±14.81) years. There were 9 monocular and 9 binocular cases. All patients were examined by slit-lamp biomicroscopy and IVCM. The visual acuity, the mean endothelial cell density, and the images of IVCM were analyzed in all cases. Results: The mean best-corrected visual acuity was 0.76±0.33, and the mean endothelial cell density was (1 723.6±698.3) cells/mm2. The IVCM images of type 1 PPCD (vesicular lesions) showed hyperreflective, placoid or homocentric lesions at the level of the Descemet's membrane, hyporeflective, oval or round lesions at the level of the Descemet's membrane, and hyporeflective, crater-like lesions at the level of the endothelial cell layer. The IVCM images of type 2 PPCD (band lesions) displayed hyperreflective, band lesions and a fibrous strand structure at the level of the Descemet's membrane, hyporeflective, vesicular lesions at the level of the Descemet's membrane, and hyporeflective, trough-and ridge-like lesions at the level of the endothelial cell layer. The IVCM images of type 3 PPCD (geographic placoid opacities) showed loss of the hexagonal features of endothelial cells and epithelial-like cell transformation. Conclusions: PPCD primarily affects the endothelium and Descemet's membrane. IVCM could highlight the special characteristics of PPCD including hyperreflective lesions at the level of the Descemet's membrane, hyporeflective lesions at the level of the endothelial cell layer, and epithelial-like cell transformation of endothelial cells. IVCM is an invaluable tool for clinical diagnosis and dynamic monitoring of PPCD.目的： 探讨后部多形性角膜营养不良（PPCD）在共聚焦显微镜下的影像学特征。 方法： 回顾性病例系列研究。收集2013年1月至2019年12月期间在北京大学第三医院眼科诊断为PPCD的18例（27只眼）患者资料，其中男性10例，女性8例。年龄（23.61±14.81）岁。单眼和双眼发病的患者各9例。所有患者均行裂隙灯显微镜和共聚焦显微镜检查，分析视力、角膜内皮细胞密度及不同分型PPCD在共聚焦显微镜下的影像学特征。 结果： 患眼最佳矫正视力为0.76±0.33，角膜内皮细胞密度为（1 723.6±698.3）个/mm2。1型PPCD的主要共聚焦显微镜下影像学表现：Descemet膜可见鳞片状或同心圆状高反光区及圆形或椭圆形低反光暗区，角膜内皮层可见“弹坑状”或“火山口状”暗区；2型PPCD主要表现：Descemet膜条带状、片状高反光，可伴纤维条索样改变以及囊泡状低反光暗区，角膜内皮层可见脊状结构和沟槽状暗区；3型PPCD表现：角膜内皮细胞失去正常六边形的形态，呈上皮细胞样化生。 结论： PPCD主要累及Descemet膜和角膜内皮层，使用共聚焦显微镜可观察到Descemet膜高反光增厚、角膜内皮层暗区及角膜内皮细胞的上皮样化生等独特的影像学特征，是临床诊断及动态监测PPCD的重要方法。.