Long-Term Clinical Outcomes of Small-Incision Femtosecond Laser-Assisted Intracorneal Concave Lenticule Implantation in Patients with Keratoconus

Abstract

Purpose. The purpose of this study was to evaluate the long-term prognosis of small-incision femtosecond laser-assisted intracorneal concave lenticule implantation (SFII) in correction of human keratoconus. Methods. This was a prospective study for 11 patients who received SFII after being diagnosed as progressive keratoconus based on the Amsler–Krumeich classification system. Clinical assessment was performed for all the patients prior to and postsurgically at different time points for 5 years. These included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), biomechanically corrected intraocular pressure (bIOP), corneal topography, anterior segment optical coherence tomography (AS-OCT), confocal microscopy, and biomechanical assessment with Corvis ST. Results. Comparison of preoperative and 60-month postoperative UDVA and CDVA ( P 60 months = 0.081 and 0.001, respectively), all eyes showed an improvement in CDVA. Corneal topography showed no significant changes in corneal anterior K1, K2, posterior K1, K2, posterior elevation, or corneal densitometry compared with preoperative levels ( P > 0.05 ). Corvis ST showed that central corneal thickness (CCT) and stiffness at applanation 1 (SP-A1) were significantly greater 1 week postsurgically when compared to the baseline ( P < 0.05 ) and remained stable thereafter. The lenticule under the AS-OCT remained transparent throughout the entire postsurgical period. Under confocal microscopy, corneal edema and an increase in cell activation and reflectivity were observed at the lenticule-stromal interface within 1 week postoperatively. These reactions gradually subsided with time within 6 months. Conclusion. SFII is an effective procedure to prevent the progression of keratoconus due to its minimal invasiveness and capability of maintaining a steady biometry of the cornea.

Applications of SMILE-extracted lenticules in ophthalmology

“…The results showed long-term graft stabilization and visual improvement in both groups. Maximum central keratometry reduced after concave lenticule implantation, which was more significant than other studies [57][58] . However, visual improvement was better in the SFII group compared to the PK group.…”

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK: a case series

“…In some previous reports, the implanted lenticules were fabricated from cadaver donor corneas with a laser, and the size, refractive power, and thickness were specifically designed that matched the recipient data. Most of these lenticules are designed to be negative meniscus in shape, which compensates for the central steepening topography of corneal ectasia and keratoconus [12][13][14] . For patients with asymmetric corneal ectasia, the lenticule can be further fabricated into specialized forms, such as dog-nut, ring, or crescent shapes that balance the protrusion at different sites [15][16] .…”

Incisional surface quality of electron-beam irradiated cornea-extracted lenticule for stromal keratophakia: high nJ-energy vs. low nJ-energy femtosecond laser

“…10.3389/fmed.2023.1289528 (10,(39)(40)(41). The interface between the lenticule and host stroma may heal and become unnoticeable given sufficient time (14,39,40,42). The minimally invasive nature of the lenticule reimplantation procedure does not extensively disrupt the ocular surface, ensuring the minimal involvement of ocular surface antigen-presenting cells (43), hence there is minimal effect on stromal remodeling and tissue bio-integration in the long term.…”