Tóth Márta, Holló Gábor
Department of Ophthalmology Semmelweis University, Budapest.
J Glaucoma. 2006 Feb;15(1):53-9. doi: 10.1097/01.ijg.0000195598.24763.98.
To investigate the potential advantages of an enhanced corneal compensation algorithm (ECC) compared with variable corneal compensation (VCC), in scanning laser polarimetry.
One eye of 15 healthy ametropic subjects was imaged immediately before and 7 days after uncomplicated LASIK surgery. Anterior segment birefringence was assessed at each measurement session. For post-LASIK calculations, either actual post-LASIK corneal retardation (VCC and ECC groups), or the pre-LASIK corneal retardation (VCC* and ECC* groups) was used.
The typical scan score-value was higher for ECC both before and after LASIK (P < 0.01), and it was not influenced by LASIK in either compensation method. Both the axis and the magnitude of corneal birefringence altered after LASIK (P < 0.01). After LASIK, with VCC* all eyes showed uncompensated birefringence, but with ECC* none did. LASIK had no effect on retinal nerve fiber layer measurements in VCC and ECC methods. In VCC* the LASIK-induced retinal nerve fiber layer thickness change was significant (P < 0.01) in the temporal, superior, and nasal quadrants. After LASIK, the number of significantly altered sectors along the TSNIT plot showed no difference when comparing VCC and ECC, VCC and ECC*, or ECC and ECC*. In contrast, significantly more sectors were altered in VCC* than in either VCC or ECC* (P < 0.001).
The new ECC software is more effective than VCC in neutralization of atypical polarization pattern and the uncompensated corneal retardation.
在扫描激光偏振仪中，研究增强型角膜补偿算法（ECC）相较于可变角膜补偿（VCC）的潜在优势。
对15名健康屈光不正受试者的一只眼睛在单纯准分子激光原位角膜磨镶术（LASIK）手术前及术后7天立即进行成像。在每次测量时评估眼前节双折射。对于LASIK术后计算，使用实际的LASIK术后角膜延迟（VCC和ECC组）或LASIK术前角膜延迟（VCC和ECC组）。
LASIK术前和术后ECC的典型扫描分值均较高（P < 0.01），且在两种补偿方法中均不受LASIK影响。LASIK术后角膜双折射的轴和大小均发生改变（P < 0.01）。LASIK术后，采用VCC时所有眼睛均显示未补偿的双折射，但采用ECC时均未出现。LASIK对VCC和ECC方法中的视网膜神经纤维层测量无影响。在VCC中，LASIK诱导的视网膜神经纤维层厚度变化在颞侧、上方和鼻侧象限显著（P < 0.01）。LASIK术后，比较VCC和ECC、VCC和ECC或ECC和ECC时，沿TSNIT图显著改变的扇区数量无差异。相比之下，VCC中显著改变的扇区比VCC或ECC*中更多（P < 0.001）。
新的ECC软件在中和非典型偏振模式和未补偿的角膜延迟方面比VCC更有效。
