Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China.
BMC Ophthalmol. 2022 Jul 11;22(1):300. doi: 10.1186/s12886-022-02524-6.
Opaque bubble layer (OBL), which generates from photo-disruptive procedures on the cornea, has been a common phenomenon during femtosecond laser-assisted refractive surgeries and it would potentially impact eye tracking and flap lifting. And we have observed that an updated flap-making pattern could form less OBL clinically than the traditional pattern, which needed further approval. Thus, the purpose of this study is to prove our observation and investigate the possible risk factors related to the occurrence and type of OBL in laser in situ keratomileusis (LASIK) flaps using the Visumax laser system.
This prospective study included 167 eyes of 86 patients (mean age: 27.5 ± 6.1 years) undergoing bilateral femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia/myopic astigmatism by the same surgeon from April 2020 to August 2020. Preoperative data on refraction, central corneal thickness (CCT), and keratometry as well as intraoperative data were included for analysis. A new flap-making pattern creating an offset between flap-cut and side-cut was adopted to compare with the traditional pattern. The operation video of flap formation was analyzed to identify the existence and type of OBL. The area covered by OBL and the ratio of OBL to flap were calculated using Image J software.
Among 167 eyes, 54 eyes (32.3%) developed OBLs, consisting of 31 as hard OBL coexisting with soft OBL, and 23 as soft OBL alone. The OBL incidence was significantly reduced in eyes with the new flap-making pattern compared with the traditional pattern (13.8% vs. 52.5%, P < 0.001). Hard OBLs had larger area ratios than soft OBLs (14.3 ± 8.3% vs. 1.1 ± 1.8%, P < 0.001). Univariate analyses revealed that eyes with more myopia, thicker CCT, and traditional flap-making patterns were more likely to develop OBLs. Multivariate analysis further confirmed that more myopia, thicker CCT, and traditional flap-making pattern were risk factors for OBLs. A Larger corneal diameter was associated with a higher incidence of hard OBL when applying the traditional flap-making process.
More myopia, thicker CCT, and larger corneal diameter were risk factors for OBL development during flap creation, whereas a flap-making pattern with an offset between flap-cut and side-cut could reduce the incidence of OBL.
在飞秒激光辅助屈光手术中，角膜上的光致破裂程序会产生不透明泡层（OBL），这是一种常见现象，可能会影响眼跟踪和瓣掀起。我们观察到，与传统模式相比，更新的瓣制作模式在临床上形成的 OBL 更少，这需要进一步证实。因此，本研究的目的是证明我们的观察结果，并调查与使用 Visumax 激光系统的 LASIK 瓣相关的 OBL 发生和类型的可能危险因素。
本前瞻性研究纳入了 2020 年 4 月至 2020 年 8 月由同一位外科医生为 86 例（平均年龄：27.5±6.1 岁）双眼近视/近视散光患者行飞秒激光辅助 LASIK（FS-LASIK）的 167 只眼。分析了术前屈光度、中央角膜厚度（CCT）、角膜曲率以及术中数据。采用一种新的瓣制作模式，在瓣切割和侧切割之间形成偏移，与传统模式进行比较。通过分析瓣形成的手术视频来识别 OBL 的存在和类型。使用 Image J 软件计算 OBL 覆盖的面积和 OBL 与瓣的比值。
在 167 只眼中，54 只眼（32.3%）出现 OBL，其中 31 只眼为硬 OBL 合并软 OBL，23 只眼为单纯软 OBL。与传统模式相比，新瓣制作模式的 OBL 发生率明显降低（13.8%比 52.5%，P<0.001）。硬 OBL 的面积比软 OBL 大（14.3±8.3%比 1.1±1.8%，P<0.001）。单因素分析显示，近视度数较高、CCT 较厚、采用传统瓣制作模式的眼更容易发生 OBL。多因素分析进一步证实，近视度数较高、CCT 较厚、采用传统瓣制作模式是 OBL 的危险因素。当采用传统瓣制作过程时，较大的角膜直径与硬 OBL 的发生率较高相关。
在瓣制作过程中，近视度数较高、CCT 较厚、角膜直径较大是 OBL 发生的危险因素，而瓣切割和侧切割之间形成偏移的瓣制作模式可以降低 OBL 的发生率。
