Combined Flapless Refractive Lenticule Extraction and Intrastromal CXL in Mild Keratoconus: Refractive and Biomechanical Outcomes
Purpose
To report visual, refractive, topographic and biomechanical outcomes of simultaneous small incision lenticule extraction [SMILE] and intrastromal crosslinking in eyes with abnormal topography and forme fruste keratoconus.
Methods
Prospective case series of 59 eyes of 33 patients. Inclusion criteria were topographic diagnosis of forme fruste KC, stable refraction and topographic findings for at least 1 year, BCVA>0.7, central corneal thickness >460u, patient age >21 years, follow up at 1 day, 1 week,1,3,6,9,12 months. Study parameters were UCVA, BCVA, manifest refraction, topographic, clinical evaluation, IOP and biomechanical stability of the cornea are assessed. SMILE was performed using Visumax 500(Carl Ziss meditec) all cases had a 100u cap and 300u residual stromal bed followed by intra-pocket injection of isotonic riboflavin 3 times with a 5 minute interval then 5 min 18 mw/cm2 UV cross-linking. Bio-mechanical stability was assessed using the Corvis ST Oculaus, measuring and correlating IOP and deformation amplitude.
Results
Mean patient age was 29.4+/-5.63(22-35). Mean preoperative UCVA 0.13+/-0.08 and 0.82+/-0.13 postoperative. Mean preoperative refraction was -3.97±1.87 D sphere(range -6.0 to -1.25) and -2.85 D cylinder (range -0.75 to -4.25), mean postoperative SER was -0.14±0.73 D (range -1.25 to +1.5)mean astigmatism was -0.18 ± 0.45 D. 72% within +/- 0.5 and 89% within +/- 1.0 D. 3 eyes lost 1 line of BCVA, 1 eyes lost 2 lines and 1 eye due to haze. All patients presented intrastromal haze that improved during the follow-up. Mean deformation amplitude was 1.38 mm ±0.29 pre-op. to 1.19 mm ±0.29 postop while pre- and postoperative IOP showed no significance.
Conclusion
Combined SMILE and crosslinking might be a safe predictable and stable treatment option in patients where conventional laser refractive surgery is contraindicated. Further follow-up and larger samples are needed.