Abstract
Purpose: :
To assess whether a corneal pocket can be created safely under a previous LASIK flap as a prelude to implantation of a small aperture corneal inlay for treatment of presbyopia in patients with prior LASIK distance vision correction.
Methods: :
Inclusion criteria were: adults aged 45-60 years with 20/20 or better uncorrected distance visual acuity (UCDVA) in the untreated eye, UCDVA of 20/50 or better with uncorrected near visual acuity of J4 or worse in the treatment eye, spherical equivalent between -0.75 and 0 with ≤ 0.75 D cylinder, and prior flap thickness ≤ 160 µ with corneal thickness > 480 µ and normal corneal topography. Contraindications include: previous eye surgery other than LASIK or PRK, dry eye, uncontrolled blepharitis, lens opacities, retinal problems, autoimmune diseases, corneal dystrophy or degeneration, and corneal pathologies. Pockets were created in the non-dominant eye with a femtosecond laser. Pockets 6.5 mm wide opened temporally and were positioned to leave 250 µ of residual posterior stroma. Measures included corneal thickness via ultrasound pachymetry (Sonogage, Inc) and Fourier domain optical coherence tomography (FD-OCT, Optovue, Inc) and flap thickness using FD-OCT.
Results: :
The pocket procedure was performed on 7 patients, 5 male/2 female. Mean central corneal thickness showed good agreement between pachymetry (524.7 ± 33.2 µ) and FD-OCT (526.6 ± 17.3 µ). During the original LASIK procedure, flap thickness was targeted for 90 µ for one patient and 160 µ for the remaining 6 patients (mean 150 µ). The FD-OCT measured mean LASIK flap thickness before the pocket procedure was138.4 µ. This exemplifies the importance of accurate corneal measures before attempting the pocket procedure in post-LASIK patients. Mean distance between flap and pocket was 138.1 µ. All corneas were clear 1 day postop. At 1 month postop there were no complications or adverse events. FD OCT showed a mean of 256 µ for Corneal Inlay depth achievement (attempted 250 µ). Cornea or flap structure showed no damage either.
Conclusions: :
To date, the creation of a pocket flap beneath a LASIK flap has shown clear corneas since 1 day postop and no safety issues were observed clinically and at FD OCT. Such a procedure may allow the use of a small aperture corneal inlay to treat presbyopia in patients with previous LASIK to improve Near UCVA.
Keywords: refractive surgery: other technologies • laser • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)