目的：了解表面切削手术前后角膜透明性变化，初步建立角膜光密度与角膜上皮下雾状混浊(Haze)对应的数据库。方法：收集我院行表面切削手术的病人74人146眼。患者手术前、术后3个月行裂隙灯角膜透明性检查和眼前节分析仪(Pentacam，0表示角膜完全透光，100表示角膜混浊不透光)测量角膜光密度。使用SPSS13.0软件对数据进行统计，术前、术后3个月角膜光密度进行Wilcoxon秩和检验；根据裂隙灯下角膜透明性将术后数据分成透明角膜组和Haze组与术前分别对比。术后角膜光密度与裂隙灯下Haze分级进行等级资料Spearman相关分析；按照裂隙灯分级将不同程度Haze与角膜光密度对应，初步建立术后Haze的角膜光密度数据库。结果：术后3个月时，透明角膜(0级Haze)80眼、I级Haze49眼、II级Haze 13眼、III级Haze2 眼、IV级Haze2眼。术前最大 角膜光密度平均值为19.7±2.47，术后3个月时最大角膜光密度平均值为30.3±7.2，术后角膜光密度比术前升高(Z=?7.404，P<0.001)；另外术后Haze组和术后透明角膜组光密度分别为38.2±15.2和21.2±3.51，与术前比两者差异也有统计学意义(Z=?4.783，P<0.001；Z=?5.195，P<0.001)。术后角膜光密度与Haze呈正相关(r=0.819，P<0.001)。各级Haze组对应角膜光密度参考值为I级Haze：29.4±2.58；II级Haze 43.2±5.68；III级Haze：59.5±0.92；IV级Haze: 89.5±14.9。结论：Haze的出现使光密度增加，影响角膜的透明性。手术后裂隙灯观察下的透明角膜光密度较术前高，可能与术后角膜的炎症反应或胶原纤维排列变化有关，需要进一步研究明确。表面切削手术前后角膜的透明性除了传统的裂隙灯检查外，也可以用角膜光密度来评价。用角膜光密度来评价角膜的透明性比单纯的裂隙灯检查更容易发现细微的异常。
Objective: To measure corneal transparency before and after the surface ablation and establish a preliminary database of corneal density and haze. Methods: Seventy-four patients (146 eyes) who underwent surface ablation were measured with the slit lamp and the densitometry program of the Pentacam Scheimpflug imaging system (0=no clouding, 100=tissue completely opaque). The corneal density before and after operation were analyzed with the Wilcoxon’s Matched Pairs Test of the SPSS 13.0. Eyes of 3 months after operation were categorized as postoperative clear corneas and postoperative with haze. According to the slit lamp, different degrees of haze were correlated with corneal density to establish a preliminary corneal density database.Results: At 3 months after operation, there were 80 eyes with clear cornea (grade 0 haze) and 66 eyes with haze which contained 49 eyes with grade I haze, 13 eyes with grade II haze, 2 eyes with grade III haze and 2 eyes with grade IV haze. Maximum density of preoperative corneas was 19.7±2.47, and it was increased to 30.3±7.2 postoperation (Z=?7.404, P<0.001). Maximum density of postoperative clear corneal (21.2±3.51) and postoperative with haze (38.2±15.2) were both higher than preoperation (Z=?5.195, P=0.004 and Z=?4.783, P<0.001). And the haze correlated corneal density was grade I haze 29.4±2.58; grade II Haze 43.2±5.68; grade III haze 59.5±0.92; grade IV haze 89.5±14.9. Conclusion: Corneal density will increase with haze. Maximum density of postoperative clear corneal was higher than preoperation which may be influenced by the postoperative corneal inflammation or the rearrange of collagen ,and it need the further research. Besides the slit lamp, we can use the corneal density to measure the corneal transparency after surface ablation. The densitometry program of the Pentacam can provide a useful objective measure of postoperative and other mild corneal haze.
目的：研究准分子激光原位角膜磨镶术(laser in situkeratomileusis，LASIK)前后角膜滞后量(corneal hysteresis，CH)和角膜阻力因子(corneal resistance factor，CRF)变化量，对其相关因素进行多元线性回归分析。方法：前瞻性研究。纳入行LASIK手术的近视眼及近视散光患者70眼(38例)，术前与术后6个月各项参数分别由眼反应分析仪(ocular response analyzer，ORA)、非接触眼压仪、超声角膜测厚仪及Pentacam眼前节分析仪测量。分析LASIK手术前后△CH，△CRF与术前、手术设计等参数的相关性，并对相关参数进行多元线性回归分析。结果：手术前后CH分别为(10.05±1.36)，(8.15±0.90) mmHg(1 mmHg=0.133 kPa)，CRF分别为(9.91±1.38)，(6.92±0.88) mmHg，差异均有统计学意义(P<0.01)；△CH与△CRF分别为(1.90±1.15)，(2.99±1.23) mmHg。△CH与术前CH，CRF，眼压(intraocular pressure，IOP)，预计切削深度(ablative depth，AD)以及AD/CCT呈正相关；△CRF与术前CH，CRF，IOP，AD，AD/CCT，术前等值球镜(spherical equivalent，SE)以及预计基质床厚度(residual stromal bed’s thickness，RSBT)有相关性。采用多元线性回归对LASIK手术前后△CH，△CRF与术前、手术设计等各相关参数进行分析，回归方程为：△CH=?6.182+0.658CH术前+8.421AD/CCT (R2=0.639，P<0.01)，△CRF=?0.007+0.725CRF术前?0.014RSBT (R2=0.689，P<0.01)。结论：LASIK术前后CH与预计AD和角膜厚度比值密切相关，CRF变化量与预计角膜RSBT密切相关，在设计手术时应慎重考虑预计AD与预计RSBT。
Objective: To discuss the change of corneal hysteresis and corneal resistance factor before and after laser in situkeratomileusis (LASIK), and to analyze their related factors by multivariate linear regression. Methods: In this prospective study, 70 eyes (38 patients) with myopia and myopic astigmatism undergoing LASIK were included. Related factors were measured preoperatively and at 6 months postoperatively by ocular response analyzer, noncontact tonometer (NCT), ultrasonic pachymeter, and Pentacam system. TTe correlation was analyzed between △CH, △CRF and preoperative and operative design’s parameters, and correlative factors analyze. △CH and △CRF were analyzed by the multiple linear regression. Results: CH before and after LASIK were (10.05±1.36) and (8.15±0.90) mmHg, and CRF before and affer LASIK were (9.91±1.38) and (6.92±0.88) mmHg. TTere was signiffcant difference between preoperative and postoperative CH and CRF (P<0.01). △CH and △CRF were (1.90±1.15) and (2.99±1.23) mmHg. Preoperative CH, CRF, intraocular pressure (IOP), ablative depth (AD) and AD/CCT were positive correlated with △CH. Preoperative CH, CRF, IOP, AD, AD/CCT, preoperative spherical equivalent (SE) and predicted residual stromal bed’s thickness (RSBT) were correlated with △CRF. TTe regression equation of △CH and △CRF and influencing factors were △CH =?6.182 + 0.658CHpreoperative + 8.421AD/CCT (R2 =0.639, P<0.01), △CRF =?0.007 + 0.725CRFpreoperative ? 0.014RSBT (R2 =0.689, P<0.01). Conclusion: The change of CH before and after LASIK is correlative with AD/CCT. The change of CRF before and after LASIK is correlative with predicted residual stromal bed’s thickness. Ablative depth and predicted residual stromal bed’s thickness should be considered carefully during the surgical design.
