RESUMEN
Femtosecond laser (FSL) applications in corneal surgery have increased since its inception. Corneal surgery has undergone a tremendous transformation thanks to the introduction of FSL technology. This laser makes precise, three-dimensional incisions while causing minimal damage to surrounding tissue. This review updates and summarizes current and upcoming FSL applications in corneal surgery, current commercially available FSL, and its respective applications. Refractive surgery applications include laser in-situ keratomileusis flaps, refractive corneal lenticule extraction such as small incision lenticule extraction, astigmatic keratotomy, intracorneal ring segments tunnels for keratoconus including corneal allogenic intrastromal ring segments, and presbyopia treatments with intrastromal pockets for corneal inlays and intrastromal incisions (INTRACOR). Keratoplasty applications include penetrating keratoplasty trephination; superficial and deep anterior lamellar keratoplasty trephination, lamellar dissection, and tunnel creation; posterior lamellar keratoplasty donor and recipient preparation; Bowman layer transplantation donor, and recipient preparation; and stromal keratophakia. Other applications include conjunctival graft preparation in pterygium surgery, and keratopigmentation (corneal tattooing). FSL is a surgical instrument widely used in corneal surgery because it improves reproducibility and safety in many procedures.
RESUMEN
We report the first case of refractive corneal lenticule extraction with the femtosecond laser application CLEAR as retreatment technique after previous laser vision correction. A 42-year-old woman, operated by bilateral photorefractive keratectomy (PRK) 19 years previously, with moderate dry eye, came for post-PRK regression and underwent correction of a residual myopia of -3 -0.5 × 159° D in the left eye by CLEAR. Surgery was uneventful, with a regular laser pattern and a normal dissection of the lenticule. At day 1, uncorrected visual acuity was 20/25; at 3 months, it was 20/20, with a refraction of +0.25 × 115° D. The cornea and interface were regular and transparent; no dry eye symptoms occurred. At 3 months, on optical coherence tomography, the treatment was well centered, the surgical interface was centrally regular, whereas the anterior profile of the stromal surface was slightly corrugated, compensated by a smooth epithelial surface. The present case demonstrates that myopia after PRK can be achieved by CLEAR; an irregular stromal surface may occur, not affecting the visual result in virtue of epithelial remodeling.
RESUMEN
Background Researches showed that femtosecond laser corneal small incision lenticule extraction (SMILE) was used in the correction of myopia and myopic astigmatism due to its fast recovery,good shortterm efficacy and few complications.However,few research focused on its long-term efficacy.Objective Thisstudy was to evaluate the effectiveness,safety,predictability,stability and complications of SMILE.Methods A serial cases-observational study was carried out under the approval of Ethic Committee of Henan Eye Institute and informed consent of patients.Sixty-seven eyes of 34 patients with myopia and myopic astigmatism were included in Henan Eye Institute from January to June 2013.All the patients received SMILE and followed-up for 2-year duration.The uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),automatic optometry,intraocular pressure and corneal topography were examined before surgery and 1 day,1 week,1 month,3 months,1 year and 2 years after surgery and calculated the spherical equivalent (SE).The long-term efficacy of SMILE included effective index (preoperative BCVA/postoperative UCVA),safety index (postoperative BCVA/ preoperative BCVA),predictability (linear regression analysis between actual SE and attempted SE) and refractive stability (SE changes at postoperative time points).Results The preoperative BCVA was ≥ 20/20 in 60 eyes with the percentage of 89.55％.UCVA≥ 20/20 were found in 61 eyes and 60 eyes in postoperative 3 months and 2 years respectively (91.04％ and 89.55％).The effective index was 1.038±0.182 and 1.029±0.231 in postoperative 3 months and 2 years respectively,showing an insignificant difference between them (t =0.400,P ＞ 0.05).Compared with the preoperative BCVA,8.96％ (6/67) and 10.45％ (7/67) eyes lost 1 line at 3 months and 2 years after surgery,respectively.The safety indexes were 1.141±0.193 and 1.312±0.242 at 3 months and 2 years after surgery,with no significant difference between them (t =0.414,P＞0.05).A linear correlation was found between actual SE and attempted SE both at postoperative 3 months and 2 years,with the linear regression equations of Y=0.897 1X-0.440 8 (R2 =0.914 2,P＜0.05) and Y =0.893 7X-0.382 3 (R2 =0.915 7,P＜0.05),respectively.The SE was (0.013±0.578),(-0.033±0.489),(-0.106±0.508),(-0.103±0.375),(-0.154±0.518) and (-0.147±0.366)D 1 day,1 week,1 month,3 months,1 year and 2 years after surgery,respectively,and there were no significant difference among different time points (F =0.185,P =0.176).Eighteen in the 67 eyes occurred opaque bubble layer after surgery.Diffuse lamellar keratitis appeared in 6 eyes and punctate keratitis was in 2 eyes.These complications were cured 1 month after administration of drugs.Conclusions SMILE is good in effectiveness,safety,predictability and refreactive stability and has fewer complications during 2-year following-up.