Femtosecond Laser LASIK Research Articles

Effect of femtosecond laser and mechanical lamellar LASIK on the stability of corneal flap thickness

Effect of femtosecond laser and mechanical lamellar LASIK on the stability of corneal flap thickness

Comparison of early visual quality between PPCIOL implantation and femtosecond laser LASIK

Comparison of early visual quality between PPCIOL implantation and femtosecond laser LASIK

Comparison on visual quality after ICL implantation and femtosecond laser LASIK in correction of high myopia

Objective To compare the visual quality after implantable collamer lens (ICL) implantation and femtosecond laser in situ keratomileusis(FS-LASIK) in correction of high myopia. Methods The data of 182 eyes of 91 cases who underwent refractive surgery were collected and retrospectively analyzed. The patients were divided into two groups: ICL group, 78 eyes of 39 cases, underwent ICL implantation; LASIK group, 104 eyes of 52 cases, underwent FS-LASIK. The postoperative visual quality between the two groups were compared. Results The difference of safety index at 1, 3 and 6 months postoperatively between the two groups were not statistically significant( P=1.000, 0.373, 0.230). The difference in validity index at 3 and 6 months postoperatively between the two groups were statistically significant (P=0.000, 0.000). The difference in diopter at 3 and 6 months postoperatively between the two groups were statistically significant (P=0.042, 0.002). The increasing amplitude of total high order aberration, spherical aberration and coma aberration at 6 months postoperatively in ICL group were lower than those in LASIK group(P=0.000, 0.000, 0.001). Six months after surgery, the difference of contrast sensitivity were not significant between two groups at 1.5 cpd, 3.0 cpd and 6.0 cpd spatial frequencies under light condition(P=0.576, 0.659, 0.840), however, the difference of contrast sensitivity in ICL group were higher than that in LASIK group at 12.0 cpd and 18.0 cpd (P=0.000, 0.000). Under mesopic condition, the contrast sensitivity in ICL group were higher statistically at all spatial frequencies than in LASIK group(P=0.000, 0.000, 0.000, 0.000, 0.000). Conclusion The postoperative long-term uncorrected visual acuity and diopter are more stable in patients with ICL implantation, and the higher order aberration increase less, and the contrast sensitivity is improved in each spatial frequency. The postoperative visual quality is significantly better than FS-LASIK. ICL implantation is a surgical approach of strong predictive, high safety and good stability to treat high myopia. Key words: Lens, intraocular, phakic, posterior chamber; Collamer lens, implantable; Laser in situ keratomileusis, femtosecond; Myopia, high; Visual quality

Comparison of the Optical Quality between Small Incision Lenticule Extraction and Femtosecond Laser LASIK.

Purpose. To investigate the visual quality after SMILE and Femto-LASIK. Methods. About 123 eyes from 63 patients were enrolled in this study. The parameters were measured preoperatively and 1 week, 1 month, and 3 months postoperatively using Sirius System. Results. The MTF curve increase slightly from low to high frequency at 3 mm and 6 mm pupil diameter after SMILE surgery (P < 0.05) during the follow-up time comparing with the preoperative values. And the SR has a significant increase at various pupil diameters as well (P < 0.05). However, there was little increase for MTF at intermediate to high frequency at 3 mm pupil diameter after Femto-LASIK procedure (P < 0.05). And the SR had only significant increase at 3 mm pupil diameter. Between SMILE and Femto-LASIK, there was no statistic difference both in MTF and SR (P > 0.05) at 3 mm pupil diameter at vertical and horizontal meridian. However, significant difference was found in MTF at low to mediate frequency at 6 mm pupil diameter at vertical meridian at 1 week postoperatively (P < 0.05). Conclusions. Both SMILE and Femto-LASIK show a great improvement in optical quality at small diameter. It was found that SMILE shows better optical quality than Femto-LASIK at larger pupil diameter, which might be good for the night vision.

FS200 femtosecond laser LASIK flap digital analysis parameter evaluation: comparing two different types of patient interface applanation cones

To evaluate the safety and efficacy of a novel LASIK flap patient interface (PI) cone with our reported digital analysis and compare for potential differences with the standard metal and glass PI in flap parameters when used with the Alcon/WaveLight FS200 femtosecond laser. Thirty-six consecutive LASIK patients (72 eyes) subjected to a bilateral femtosecond assisted LASIK procedure with the novel clear cone PI FS200 1505 were examined for flap diameter and flap thickness over the entire flap area via digital analysis performed on intraoperation image (flap diameter) and anterior-segment optical coherence tomography image (flap thickness). This group was compared with an age- and procedure-matched group B from our practice, in which the standard metal and glass PI was employed. Horizontal flap diameter for group A (clear cone) was 7.87 mm ± 0.02 mm (range 7.89-7.84 mm) for 8.00 mm programmed, whereas for group B (metal and glass cone) was 7.85 mm ± 0.04 mm (range 7.93-7.80 mm). Likewise, along the vertical line, flap diameter for group A was 7.84 mm ± 0.02 mm (range 7.85-7.80 mm) and for group B was 7.83 mm ± 0.03 mm (range 7.87-7.80 mm). Central flap thickness for group A was 113.29 μm (±1.19 μm) for 110 μm planned, 122.1 μm (±2.10 μm) for 120 μm planned, and 133.50 μm (±0.71 μm) for 130 μm planned. Group B central flap thickness was, accordingly, 112.8 μm (±1.25 μm), 122.4 μm (±2.15 μm), and 132.50 μm (±0.90 μm). The data evaluated (paired group comparisons) between group A and group B did not show statistically significant differences. This study indicates that two PIs in use with the FS200 femtosecond laser are safe and have highly reproducible and accurate flap parameter results, such as achieved diameter and flap thickness. The paired group comparisons between the two PIs' respective data do not show statistically significant differences.

Femtosecond laser in laser in situ keratomileusis

Flap creation is a critical step in laser in situ keratomileusis (LASIK). Efforts to improve the safety and predictability of the lamellar incision have fostered the development of femtosecond lasers. Several advantages of the femtosecond laser over mechanical microkeratomes have been reported in LASIK surgery. In this article, we review common considerations in management and complications of this step in femtosecond laser-LASIK and concentrate primarily on the IntraLase laser because most published studies relate to this instrument.

Differences in the corneal biomechanical effects of surface ablation compared with laser in situ keratomileusis using a microkeratome or femtosecond laser

To compare the effects of different flap creation techniques on the biomechanical properties of the cornea in patients having myopic laser refractive surgery. UCLA Laser Refractive Center of the Jules Stein Eye Institute, Los Angeles, California, USA. In this retrospective case series, eyes that had myopic laser refractive surgery were categorized according to the type of flap creation: mechanical microkeratome (MK) LASIK (n=32), femtosecond laser (FSL) LASIK (n=32), or no flap creation (PRK) (n=33). The preoperative central corneal thickness, intraoperative flap thickness, and planned ablation depth (AD),and the preoperative and postoperative manifest refraction spherical equivalent, corneal hysteresis (CH), and corneal resistance factor (CRF) were recorded. The mean change in CH (DeltaCH) was 2.2 mm Hg, 1.9 mm Hg, and 2.3 mm Hg in the MK, FSL, and PRK groups, respectively. There were no significant differences in AD, DeltaCH, or DeltaCRF between the 3 groups. The correlation between AD and DeltaCH was significant in all 3 groups. The correlation was strongest in the FSL group (r=0.82, P<.0001) and weaker in the PRK group (r=0.47, P= .006) and MK group (r=0.46, P= .008). The biomechanical measures of CH and CRF decreased similarly after PRK and LASIK using laser or mechanical flap creation. However, LASIK using femtosecond laser flap creation caused a significantly more predictable change in corneal biomechanics, which correlated strongly with AD, than the change with PRK and LASIK with microkeratome flap creation.

Comparison of Clinical Result of LASIK using between Femtosecond Laser and Microkeratome for Correction of Myopia

Purpose: To compare results between in femtosecond laser and microkeratome LASIK correction of myopia Methods: We retrospectively analyzed the result of 94 eyes of 47 patients in the femtosecond group (F) and 103 eyes of 52 patients in the microkeratome group (M). All patients had undergone LASIK using either a femtosecond laser or a microkeratome for making of flap. Patients were divided into groups I (6D≤) and II (≥6D) according to preoperative myopia. Each patient was followed up for over 6 months with measurements of uncorrected visual acuity and manifest refraction at 1 week and 1, 3, and 6 months after operation. Complications during and after the operation were reviewed retrospectively in two groups 6month after the operation. Results: In groups F-I, F-II, M-I, and M-II, postoperative 6-month uncorrected visual acuity was 0.98±0.08, 0.96±0.09, 0.97±0.03, 0.98±0.09. At the 6-month follow-up, there were no significant differences between the two groups in uncorrected visual acuity and mean spherical equivalent. Corneal opacity was found in 3 eyes in group M and complication related with flap was found 1 eye in group F and 4 eyes in group M. Conclusions: During a 6-month follow up, LASIK using either a femtosecond laser or a microkeratome has an similar effect in uncorrected visual acuity and mean spherical equivalent. Thus LASIK for using femtosecond laser can be used as an alternative procedure to correct myopia.