[Topography-guided transepithelial corneal collagen cross-linking by sequential ultraviolet A irradiation in different diameters for progressive keratoconus in adults].

Objective: To compare the efficacy and safety of a novel customized topography-guided transepithelial corneal collagen cross-linking (TG-CXL) procedure by sequential ultraviolet A irradiation in different diameters and conventional transepithelial corneal collagen cross-linking (TE-CXL) in adult patients with progressive keratoconus. Methods: A prospective cohort study was conducted. Adult patients diagnosed with progressive keratoconus in the Affiliated Xiamen Eye Center of Xiamen University were continuously recruited and randomly assigned to receive the TG-CXL or TE-CXL procedure from March 2020 to March 2021. Patients in the TE-CXL group were irradiated in the central 9-mm zone of the cornea (total energy, 7.2 J/cm2; irradiance, 45 mW/cm2), while patients in the TG-CXL group were first irradiated with the protocol used in the TE-CXL group, and further irradiated in the central 6-mm zone (total energy, 3.6 J/cm2; irradiance, 9 mW/cm2). The subjective symptom of pain and corneal fluorescein sodium staining were scored within postoperative 3 days. Slit lamp examination, measurements of uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), corneal topography, anterior segment optical coherence tomography, in vivo corneal confocal microscopy, corneal endothelial cell count, and non-contact tonometry were performed before surgery and at 3, 6, and 12 months after surgery. Results: A total of 66 patients were enrolled (mean age, 23.0±3.3 years old), with 33 patients (33 eyes) in each group. No statistically significant differences were found in age, gender, and maximum keratometry (Kmax) between the two groups (P>0.05). On day 1 after surgery, the average pain score of the TG-CXL group (2.21±0.45) was significantly higher than that of the TE-CXL group (1.32±0.33) (P<0.05). The pain was rapidly alleviated in both groups on days 2 and 3. On days 1 and 2, the corneal fluorescein sodium staining scores in the TG-CXL group (4.15±0.83 and 2.21±0.60, respectively) were significantly higher than those in the TE-CXL group (1.76±0.56 and 0.85±0.51, respectively, P<0.001), while there was no significant difference between the two groups at day3 (P=0.184). The UCVA and BCVA of the TG-CXL group at 3, 6, and 12 months after surgery were significantly improved when compared with the baseline. At 3, 6, and 12 months, the BCVA (LogMAR) of the TG-CXL group (0.21±0.15, 0.22±0.16, and 0.22±0.16, respectively) were significantly improved when compared with those of the TE-CXL group(0.32±0.15, 0.34±0.15, and 0.36±0.16, respectively, P<0.01). However, there was no significant difference in UCVA between groups at any time point after surgery (P>0.05). The spherical and cylindrical power values of the TG-CXL group were improved when compared with the baseline (P<0.05). However, no significant difference in spherical power values was found between the two groups at any time point after surgery (P>0.05). Meanwhile, there were significant differences in cylindrical power values between the two groups at 6 and 12 months after surgery (P<0.05). The Kmax in the TG-CXL group was improved at all of the time points after surgery when compared with the baseline (P<0.001), while no significant difference in Kmax was found at any time point after surgery in the TE-CXL group when compared with the baseline (P>0.05). At 6 and 12 months after surgery, the Kmax values in the TG-CXL group were significantly lower than the TE-CXL group (P<0.05). No significant differences were found in flat keratomety, steep keratometry, the minimal thickness of the cornea, endothelial cell density, and intraocular pressure between the two groups at any time point after surgery (P>0.05). Within one month after surgery, optical coherence tomography revealed the increased density in the anterior stroma in both groups. In most patients in the TG-CXL group, a demarcation line was visible in the central and para-central corneal stroma, representing a clear and continuous, high-signal arc-shaped linear structure, which was deeper in the central cornea than the para-central cornea. In contrast, a demarcation line, fuzzy and focally discontinuous, was visible only in a few patients in the TE-CXL group, with an almost uniform depth in the central and the para-central cornea. Confocal microscopy demonstrated an apparent mesh-like cross-linked collagen structure in the superficial and intermediate corneal stroma at all time points after surgery in the TG-CXL group, with thickening stromal collagen fibers and an increased number of interconnections. In contrast, the mesh-like structure and number of interconnections in the superficial corneal stroma were significantly reduced at 12 months after surgery in the TE-CXL group, with no cross-linking structure in the intermediate corneal stroma at any time point after surgery. No serious complications such as corneal infection, sterile corneal ulcer, and persistent epithelial defect were observed in both groups during the follow-up of 12 months. Conclusions: The TG-CXL procedure by sequential irradiation in two different diameters with ultraviolet A light was effective and safe in the management of progressive keratoconus in adults, achieving significant refractive improvement. This might be a good technical alternative for refractive corneal cross-linking surgery.目的： 探讨使用两种不同直径紫外光斑序贯照射的基于角膜地形图的个性化跨上皮角膜胶原交联术（TG-CXL）治疗成人完成期进展性圆锥角膜的早期疗效及其安全性，并与常规跨上皮角膜胶原交联术（TE-CXL）相比较。 方法： 前瞻性队列研究。连续募集2020年3月至2021年3月间在厦门大学附属厦门眼科中心确诊为完成期进展期圆锥角膜并拟住院接受角膜胶原交联术治疗的患者，采用随机数字表法将患者随机分入TG-CXL组和TE-CXL组并行相应手术。其中，TE-CXL组以角膜中央为中心点采用直径9 mm紫外光斑照射（总能量7.2 J/cm2，辐照度45 mW/cm2）；TG-CXL组在以TE-CXL组同样参数完成基础照射后，再以圆锥锥顶为中心点加用直径6 mm紫外光斑照射（总能量3.6 J/cm2，辐照度9 mW/cm2）。在术前和术后3、6及12个月时进行症状及角膜荧光素染色评分、裂隙灯检查、裸眼与最佳矫正视力、角膜地形图、前节相干光层析成像术（AS-OCT）、活体角膜共聚焦显微镜及角膜内皮细胞计数等检查。 结果： 共纳入患者66例，两组各33例（33只眼），年龄（23.0±3.3）岁，两组在年龄、性别以及Kmax方面的差异均无统计学意义（P>0.05）。TG-CXL组患者术后第1天时疼痛评分为（2.21±0.45）分，高于TE-CXL组的（1.32±0.33）分（P<0.05），之后两组症状均迅速减轻。术后1和2 d时，TG-CXL组角膜荧光素染色分值（4.15±0.83，2.21±0.60）均高于TE-CXL组（1.76±0.56，0.85±0.51，P<0.001），但术后3 d时两组评分差异无统计学意义（P>0.05）。TG-CXL组术后3、6和12个月时的裸眼视力和最佳矫正视力均较术前改善。TG-CXL组在术后3、6和12个月时最佳矫正视力分别为0.21±0.15、0.22±0.16和0.22±0.16，均优于TE-CXL组（0.32±0.15、0.34±0.15和0.36±0.16），差异均有统计学意义（P<0.05）；但裸眼视力在各时间点的组间差异均无统计学意义（P>0.05）。TG-CXL组的球镜和柱镜度数均较术前改善（P<0.05），但在术后各时间点两组球镜度数之间的差异均无统计学意义（P>0.05），在术后6个月和12个月时两组柱镜度数差异有统计学意义（P<0.05）。TG-CXL组Kmax在术后各时间点均较术前改善（P<0.001），但TE-CXL组术后各时间点与术前相比差异均无统计学意义（P>0.05）；术后6和12个月时，TG-CXL的Kmax分别为（56.12±3.77）和（55.98±3.79）D，TE-CXL组则为（57.59±4.45）和（57.74±4.45）D，两组间差异有统计学意义（P<0.05）。术后各时间点K1、K2、角膜最薄点厚度、内皮细胞密度以及非接触眼压的两组间差异均无统计学意义（P>0.05）。术后1个月内，AS-OCT均可见两组浅层基质密度增高。其中，TG-CXL组绝大部分患者在中央及旁中央角膜浅中层基质可见“分界线”，呈连续的界限清晰的高信号弧形线状结构，中央区分界线较深而中周部较浅；而TE-CXL组仅少部分患者可见分界线，结构模糊且局部不连续，中央区与中周部角膜的分界线深度基本一致。共聚焦显微镜下，TG-CXL组术后所有时间点的角膜浅层和中层基质均存在明显的网格状交联结构，基质细胞纤维直径显著增粗，纤维间连接紧密且数量增加；TE-CXL组在术后12个月时浅层基质的交联结构已较前明显减少，且在中层基质无交联征象。随访期间两组患者均未见角膜感染、角膜溃疡、持续性上皮缺损等严重并发症。 结论： 根据角膜地形图特点进行大小光斑序贯照射的个性化角膜胶原交联术对成人圆锥角膜具有明显的屈光改善效应，且安全性良好。联合应用两种不同直径的紫外光斑进行角膜胶原交联是当前国内开展屈光性交联的良好技术选择。.