Applications of femtosecond lasers in ophthalmic surgery

Purpose: To review recent advancements in applications of the femtosecond (FS) laser in ophthalmology. Design: Literature review and commentary. Results: With the FS laser, it is now possible to produce a more precise flap diameter, hinge and depth of the flap in laser in situ keratomileusis surgery. Recently, the FS laser has been used for both flap creation and refractive correction by lenticule extraction. This laser can also be used for preparing host and donor tissue in different shapes so as to obtain faster recovery and improved postoperative visual acuity. Intracorneal ring segments for keratoconus and post-laser in situ keratomileusis ectasia can be placed using the FS laser. Higher precision of capsulorrhexis and lens softening is also achievable with FS laser-assisted cataract surgery. Conclusion: Innovations focused on improving FS laser technology will continue and will lead to expanded applications of the FS laser in ocular surgery

Comparison of wavefront-optimized ablation and topography-guided contoura ablation with LYRA protocol in LASIK

PURPOSE: To compare the refractive outcomes and aberration data analysis of wavefront-optimized (WFO) ablation and topography-guided Contoura ablation (TGCA) (Contoura on the WaveLight laser; WaveLight GmbH, Erlangen, Germany) in patients who had laser-assisted in situ keratomileusis (LASIK) for myopia or myopic astigmatism. METHODS: In this comparative contralateral eye study, patients who underwent LASIK with TGCA in one eye and with WFO ablation in the fellow eye were analyzed. Aberration measurements and corneal topography were analyzed using the WaveLight Oculyzer II diagnostic device (Alcon Laboratories, Inc., Fort Worth, TX). Total corneal higher order aberrations (HOAs) including vertical and oblique astigmatism (Z2 2, Z2 -2), coma (Z3 1, Z3 -1), trefoil (Z3 3, Z3 -3), spherical aberration, and Q value were analyzed. These measurements were taken preoperatively and 3 months postoperatively. RESULTS: This study comprised 32 patients. There were no significant differences between both procedures according to postoperative uncorrected and corrected distance visual acuity values, refractive errors, and manifest refraction spherical equivalents within ±0.50 diopters (D) of emmetropia (P > .05). The preoperative corneal HOAs and Q values were also similar between the groups (P > .05). At 3 months postoperatively, the vertical and horizontal coma values in the WFO ablation group were statistically significantly higher compared to the TGCA group (P = .013 and .020, respectively). Less stromal tissue was ablated in the TGCA group compared to the WFO ablation group (P < .001). CONCLUSIONS: Although WFO ablation and TGCA protocols had statistically similar visual outcomes, the TGCA protocol was associated with a significantly lower induction in vertical and horizontal coma and smaller amount of tissue ablation compared to WFO ablation. © 2019 Slack Incorporated. All rights reserved

Preliminary Results of Femtosecond Laser Assisted Corneal Ring Segment Implantation for Keratoconus

ABSTRACT Purpose To present refractive, visual and topographic outcomes of femtosecond laser assisted intrastromal ring segments (ISRS) implantation. Settings Bascom Palmer Eye Institute, Miami, FL, USA. Materials and methods Nineteen eyes of 15 patients with keratoconus, clear central corneas, and contact lens intolerance had implantation of a symmetrical 0.45 mm Inta cs segment (Addition Technology Inc, California, USA) using 200 kHz femtosecond laser (WaveLight GmbH, Erlangen, Germany). The outcomes of the procedure were evaluated in terms of uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), average keratometry value (K-value) and spheric equivalent (SE). Results Femtosecond laser assisted ISRS implantation could be performed with ease, while no intra- or postoperative complications were encountered. Mean UCVA improved from 0.95 ± 0.39 to 0.66 ± 0.28 logMAR, mean BSCVA improved from 0.46 ± 0.13 to 0.29 ± 0.21 logMAR, mean spherical equivalent considerably reduced from −7.15 ± 4.57 to −4.38 ± 4.07 and K value reduced from 52.39 ± 5.79 to 49.78 ± 6.84 D at the last follow-up. Conclusion Using a 200 kHz femtosecond laser is a safe procedure providing optimal refractive, visual and topographic outcomes in our preliminary study. How to cite this article Ozulken K, Cabot F, Kankariya VP, Yoo SH. Preliminary Results of Femtosecond Laser Assisted Corneal Ring Segment Implantation for Keratoconus. Int J Kerat Ect Cor Dis 2013;2(2):47-50

In-vivo corneal biomechanical analysis of unilateral keratoconus

AIM: To evaluate and compare corneal biomechanical findings measured by ocular response analyzer, topographic and pachymetric findings in patients with unilateral keratoconus patients and healthy controls. METHODS: This is an observational, case -control study. Patients with keratoconus in one eye and forme fruste keratoconus in the fellow eye were compared with sex and age matched with controls healthy subjects. All subjects were evaluated with rotating scheimpflug imaging system. The receiver -operating -characteristic curves were analyzed to evaluate the sensitivity and specificity of the parameters. RESULTS: Twenty-seven patients with keratoconus in one eye and forme fruste keratoconus in the fellow eye were compared with 40 eyes of 40 normal subjects. Corneal hysteresis (CH) was 8.0 +/- 1.7 mm Hg in keratoconus group, 8.3 +/- 1.6 mm Hg in forme fruste keratoconus group, and 9.8 +/- 1.6 mm Hg in control groups (P=0.54 between keratoconus and forme fruste keratoconus groups, P<0.01 between control group and other groups). Corneal resistance factor (CRF) was 7.1 +/- 2.2 mm Hg in keratoconus group, 7.8 +/- 1.2 mm Hg in forme fruste keratoconus group and 9.9 +/- 1.5 mm Hg in control group (P < 0.001 between control group and other groups). Using receiver-operating-characteristic analysis, the area under curve values of the parameters to distinguish forme fruste keratoconus from control subjects were: CH (0.768), CRF (0.866). Best cut-off points were 9.3 mm Hg and 8.8 mm Hg for CH and CRF respectively. CONCLUSION: Ocular response analyzer parameters (CH and CRF) are found to be significantly lower in forme fruste keratoconus patients compared to normal control subjects