Late traumatic flap dislocation seven years after femtosecond laser-assisted in situ keratomileusis

Late-onset traumatic corneal flap dislocation and secondary epithelial ingrowth 24 years after LASIK

Purpose

To analyze the diagnostic process, treatment, and post-operative outcomes of a unique case involving a late-onset (24 years post) traumatic corneal flap displacement after Laser-assisted in situ keratomileusis (LASIK) surgery due to a plant-related trauma. with an emphasis on the accompanying extensive epithelial ingrowth beneath the flap.

Observations

A 59-year-old male patient experienced corneal flap displacement 24 years post-LASIK due to a minor plant-related trauma. This case was complicated by extensive epithelial ingrowth beneath the flap, which was initially misdiagnosed with fungal keratitis. Upon identification of the actual cause, corneal flap repair surgery was performed, leading to partial vision recovery.

Conclusions and importance

This case signifies the potential for LASIK flap displacement even decades post-surgery due to minor traumas and highlights the need for vigilance in diagnosing associated complications like epithelial ingrowth. It indicates the importance of ophthalmologists and clinicians being vigilant for such complications and necessitates their familiarity with basic management techniques or quick referral to a corneal refractive surgery specialist. This report of a 24-year interval between LASIK and traumatic flap displacement with epithelial ingrowth is one of the longest known. The case also demonstrates that patients with late flap displacement can regain significant visual acuity with timely and appropriate management.

[Complications of femto-LASIK and features of cavitation injuries]

Modern approach to refractive laser surgery features three main types of lamellar surgery. Two of them are types of open laser keratomileusis (LASIK and femtosecond laser-assisted LASIK), and the third - closed (SMILE). All of these techniques allow achieving good clinical outcomes but differ in possible complications. This article reviews the complications of femto-LASIK and specifically the post-operative cavitation injuries, describes the mechanism of their occurrence, variants of their course, and presents the prevention measures.

Flap-making patterns and corneal characteristics influence opaque bubble layer occurrence in femtosecond laser-assisted laser in situ keratomileusis

Background

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.

Methods

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.

Results

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.

Conclusion

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.