Two-year outcome of Fs-LASIK combined accelerated corneal cross-linking for moderate and high myopia

Objective To evaluate the safety, effectiveness and predictability of femtosecond laser assisted excimer laser in-situ keratomileusis combined with accelerated cross-linking (Fs-LASIK Xtra) in moderate and high myopia with thin cornea. Methods A retrospective case-control study was carried out after the whole clinical data of 2 years' follow-up from the patients undergoing Fs-LASIK Xtra or single Fs-LASIK in our hospital during March 2016 and March 2017 were collected. Forty-four patients (88 eyes) undergoing Fs-LASIK Xtra surgeries were included in the study group, and 50 patients (100 eyes) Fs-LASIK surgeries in the control group. Changes in uncorrected distance visual acuity (UCVA), correction of best distant vision (BCVA), equivalent spherical mirror (SEQ), corneal curvature, intraocular pressure, endothelium, depth of demarcation line in anterior segmental optical coherence tomography (OCT), and the incidences of postoperative complications, such as interlaminar inflammation reaction and corneal haze in 1 week, and 1, 3, 12 and 24 months after surgery were measured and observed. Results The pre-operative BCVA and post-operative UCVA at 3, 12 and 24 months were all significant improved (P < 0.05). The pre-operative corneal curvature and SEQ were also greatly decreased in 3, 12 and 24 months after surgery. The SEQ reached the predicted value in both groups in 24 months, but there was no obvious difference between them (P>0.05). The distribution of positive SEQ was notably higher, while that of negative SEQ was lower in the study group when compared to the control group (P < 0.05). Significant differences in the percentages of regression and overcorrection at 24 months were seen between the 2 groups (P < 0.05), with the study group having higher percentage of overcorrection, but lower the percentage of regression than the control group. In the study group, the depth of demarcation line of 32 eyes was 224.57±62.01 μm. Six eyes (6.8%) with grade 0.5 haze and 2 eyes (2.3%) with grade 1 haze occurred in 1 to 3 months after surgery, the symptoms were disappeared after topical steroid treatment which had no negative influence in the final visual acuity. Conclusion Fs-LASIK Xtra can treat moderate and high myopia with thin cornea with good safety, effectiveness and predictability. Sufficient glucocorticosteroid eye drop should be used regularly to prevent post-operative inflammation reaction and haze.