Comparison of DLK incidence after laser in situ keratomileusis associated with two femtosecond lasers: Femto LDV and IntraLase FS60

Refractive Surgery in Myopic Children

In this paper, we summarize the current knowledge on refractive surgery performed in the myopic pediatric population. We describe the main concerns about refractive surgery in myopic children and the indications for refractive surgery in this age group. We present a range of surgical procedures that are being used for the management of unilateral/bilateral myopia in children: corneal refractive surgery (PRK, LASEK, LASIK, FS-LASIK and SMILE) and intraocular refractive surgery (phakic intraocular lens implantation, refractive lens exchange or clear lens extraction), with both their advantages and drawbacks. We also describe the various complications and measures to prevent them.

X-ray generation by fs-laser processing of biological material

The use of ultrashort pulse lasers in medical treatments is increasing and is already an essential tool, particularly in the treatment of eyes, bones and skin. One of the main advantages of laser treatment is that it is fast and minimally invasive. Due to the interaction of ultrashort laser pulses with matter, X-rays can be generated during the laser ablation process. This is important not only for the safety of the patient, but also for the practitioner to ensure that the legally permissible dose is not exceeded. Although our results do not raise safety concerns for existing clinical applications, they might impact future developments at higher peak powers. In order to provide guidance to laser users in the medical field, this paper examines the X-ray emission spectra and dose of several biological materials and describes their dependence on the laser pulse energy.

Refractive Corneal Lenticule Extraction With the CLEAR Femtosecond Laser Application

PURPOSE

The aim of this study was to evaluate a new femtosecond laser application for refractive corneal lenticule extraction with suction control and computerized regulation of centration and alignment (Ziemer CLEAR).

METHODS

This was a retrospective, consecutive, noncomparative case series study. Patients undergoing CLEAR for spherical equivalent (SE) between -3 and -10 D, evaluating SE, defocus equivalent, refractive astigmatism, visual acuity, and centration at 10 months were evaluated in the study.

RESULTS

Fifty-three eyes of 42 patients (mean age 40.4 ± 8.6 years) were included, with preoperative SE -5.99 ± 1.49 D and mean corrected distance visual acuity (CDVA) of 0.05 ± 0.07 logMAR. With no suction losses, an intact lenticule was extracted in all eyes. In 6 eyes, peripheral adhesion was resolved by lenticulerrhexis, and in 1 eye, the incision was opened by a crescent blade. Moderate interface inflammation occurred in 3 eyes. At day 1, in the 42 eyes with uneventful surgery, the mean CDVA was 20/27, whereas in the 11 eyes with extra surgical manipulations, it was 20/36 ( P = 0.04). At 10 months, for the 53 eyes, the mean uncorrected distance visual acuity was 0.05 ± 0.09 logMAR; in 37 eyes (70%), it was 20/25 or better; and the mean CDVA was 0.04 ± 0.06 logMAR. Eight eyes (15%) lost 1 logMAR line. The mean SE was -0.13 ± 0.15 D. The mean defocus equivalent was 0.33 ± 0.32 D, with 46 eyes (87%) ≤0.50 D and 52 eyes (98%) ≤1 D. Refractive astigmatism was ≤0.50 D in 48 eyes (90%). The efficacy index was 1.00, and the safety index was 0.98. The mean decentration from the corneal vertex was 0.28 ± 0.07 mm.

CONCLUSIONS

The application yielded good predictability, efficacy, and safety. Slower visual recovery was observed after extra surgical manipulations.

Post-laser refractive surgery keratitis: A concise narrative review

Laser refractive surgery (LRS) is a specialized surgical discipline within ophthalmology that focuses on vision correction via laser techniques. LRS requires a high rate of accuracy and exactitude to improve the visual outcome and minimize complications, which may lead to delayed visual recovery. Keratitis, either infectious or noninfectious, is a post-LRS complication that requires early diagnosis and proper interventional measures. In this narrative review, we summarize different aspects of keratitis following LRS. This literature review aims to provide a thorough understanding of the causes of post-LRS infectious keratitis and its appropriate management for successful outcomes.

Delayed diffuse lamellar keratitis after small-incision lenticule extraction related to immunoglobulin A nephropathy: A case report

BACKGROUND

Diffuse lamellar keratitis (DLK) is a complication of laser-assisted in situ keratomileusis (LASIK). This condition can also develop after small-incision lenticule extraction (SMILE) with a distinctive appearance. We report the case involving a female patient with delayed onset DLK accompanied by immunoglobulin A (IgA) nephropathy.

CASE SUMMARY

A 22-year-old woman was referred to our department for DLK and a decline in vision 1 mo after undergoing SMILE. The initial examination showed grade 2 DLK in the flap involving the central visual axis of the right eye. She was immediately administered with a large dose of a topical steroid for 30 d. However, the treatment was ineffective. Her vision deteriorated from 10/20 to 6/20, and DLK gradually worsened from grade 2 to 4. Eventually, interface washout was performed, after which her vision improved. DLK completely disappeared 2 mo after washout. Six months after SMILE, the patient was diagnosed with IgA nephropathy due to a 4-year history of interstitial hematuria.

CONCLUSION

DLK is a typical complication of LASIK but can also develop after SMILE. Topical steroid therapy was ineffective in our patient, and interface washout was required. IgA nephropathy could be one of the factors contributing to the development of delayed DLK after SMILE.

Myopic LASIK Outcomes: Comparison of Three Different Femtosecond Lasers and a Mechanical Microkeratome Using the Same Excimer Laser

INTRODUCTION

To compare the influence of one microkeratome and three femtosecond lasers on myopic laser in situ keratomileusis (LASIK) outcomes.

METHODS

Retrospective, observational cohort study. We compared 134 eyes treated with the IntraLase 60 kHz, 112 eyes treated with the Femto LDV Z6, 206 eyes treated with the FS200, and 98 eyes treated with the Hansatome zero compression microkeratome. All eyes were operated on using the same surgical protocol with the same excimer laser (Wavelight Allegretto) and were allocated to refraction-matched groups.

RESULTS

One day and one week postoperatively, uncorrected distance visual acuity was significantly lower in the FS200 group compared to others (P = 0.0001). This difference disappeared at the 1- and 3-month postoperative visits. Significant differences were found among groups in terms of safety index (P = 0.0001), residual sphere (P = 0.0001), and residual cylinder (P = 0.02) at the 3-month postoperative visit. No significant differences were found in corrected distance visual acuity or efficacy index.

CONCLUSION

According to our results, a slight delay in visual restoration after FS200 LASIK surgery might be expected. This delay was statistically significant at 1 day and 1 week postoperatively, but there were no differences from the 1-month visit onwards. Additionally, significant differences were found among devices in terms of safety index and the refractive results, which were found not to be clinically relevant.

Flap Thickness and the Risk of Complications in Mechanical Microkeratome and Femtosecond Laser In Situ Keratomileusis: A Literature Review and Statistical Analysis

INTRODUCTION

A recent Cochrane review found no difference in visual acuity outcomes between femtosecond-assisted laser in situ keratomileusis (LASIK) and LASIK using mechanical microkeratomes (MMKs). This study compares the flap thickness and risk of complications related to flap creation using femtosecond lasers and MMKs.

METHODS

PubMed and the Web of Science are used to search the medical literature. An extensive search is performed to identify the flap thickness and complications of LASIK as reported up to 15 July 2021. The following keywords are used in various combinations: Corneal flap, femtosecond laser, laser in situ keratomileusis, laser-assisted in situ keratomileusis, LASIK, mechanical microkeratome.

RESULTS

After removing duplicates and irrelevant studies, 122 articles were included for review. Pooled differences for intended vs. postoperative flap thickness using MMKs and femtosecond laser were -4.07 μm (95% CI: -19.55, 3.24 μm) in studies on the MMK and 5.43 μm (95% CI: 2.30, 7.84 μm; p < 0.001), respectively. After removing the studies evaluating outcomes of the old generation Hansatome MMKs (which had a significantly greater variation of flap thickness), the pooled difference for newer MMKs was 4.97 μm (95% CI: 0.35, 9.58 μm; p < 0.001), but the results still favored the femtosecond laser. Uncommon and mild complications unique for the femtosecond LASIK are epithelial gas breakthrough, opaque bubble layer, transient light sensitivity syndrome, and rainbow glare. A single study reported a very low, but stastically different risk of postoperative flap slippage (0.033% for MMK LASIK, and 0.003% for femtosecond LASIK, respectively).

CONCLUSION

In both manual microkeratome and femtosecond LASIK, intra- and postoperative complications were uncommon. The evidence of the superiority of one technique in terms of complications over another cannot be indisputably stated.

Five-Year Incidence, Management, and Visual Outcomes of Diffuse Lamellar Keratitis after Femtosecond-Assisted LASIK

Femtosecond (FS) lasers initially had a higher incidence of diffuse lamellar keratitis (DLK) compared with microkeratome flap creation. It has been theorized that higher-frequency lower-energy (HFLE) FS lasers would reduce the incidence of DLK. Our study sought to evaluate the incidence of newer HFLE FS lasers with pulse frequencies above 60 kHz. It was a retrospective case-control study evaluating the incidence of DLK following flap creation with one of three FS lasers (AMO iFs, WaveLight FS200, Zeiss VisuMax). Uncomplicated LASIK cases were included as the control group (14,348 eyes) and cases of DLK were recorded in the study group (637 eyes). Of the 637 cases of DLK, 76 developed stage II, 25 progressed to stage III, and only three developed stage IV DLK. The overall incidence rate of DLK was 4.3%; it has fallen with the invention of newer HFLE FS lasers and is approaching the DLK incidence rates of DLK with microkeratome.

Diffuse lamellar keratitis after LASIK with low-energy femtosecond laser

PURPOSE

To evaluate the incidence, evolution, and prognosis of diffuse lamellar keratitis (DLK) in a large series of laser in situ keratomileusis (LASIK) with low-energy femtosecond laser.

SETTING

Private practice, Siena, Italy.

DESIGN

Retrospective, consecutive, noncomparative case series study.

METHODS

Single-use instruments, powder-free gloves, and no corneal marking were used. Flap was created by a low-energy femtosecond laser (Ziemer Z2 and Z4).

RESULTS

A total of 37 315 eyes of 19 602 patients were reviewed. DLK was observed in 236 eyes (0.63%) of 149 patients (0.76%). Grade 1 DLK was observed in 231 eyes of 142 patients, grade 2 in 1 eye: when treated with topical steroids, they had no visual consequences. Three patients had bilateral grade 3 to 4 DLK: one of them, with bilateral grade 3, despite flap lifting and irrigation worsened to stage 4 (central stroma thinning and flattening), partially recovered in 2 years, and underwent repeat femtosecond laser-assisted LASIK for hyperopic shift in 1 eye. In all the 5 eyes that developed grade 4 DLK, corneal thickness decreased until the first month and then partially recovered; mean final tissue loss at 1 to 2 years was 35 µm. Compensatory epithelial thickening was observed.

CONCLUSIONS

DLK after low-energy femtosecond laser-assisted LASIK is rare; severe DLK (stages 3 and 4) was found in only 6 eyes (0.016%). Flap lifting and irrigation might not prevent progression. Spontaneous reformation of stromal tissue and epithelial thickening improve visual acuity in the long term; residual hyperopic shift can be corrected by repeat femtosecond laser-assisted LASIK.

Incidence and Outcomes of Sterile Multifocal Inflammatory Keratitis and Diffuse Lamellar Keratitis After SMILE

PURPOSE

To report the incidence outcomes of sterile multifocal inflammatory keratitis and diffuse lamellar keratitis (DLK) after small incision lenticule extraction (SMILE) in a large population.

METHODS

This was a retrospective review of a population of 4,000 consecutive eyes treated by SMILE at the London Vision Clinic using the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). The inclusion criterion was to have presented with inflammatory keratitis after SMILE. In some cases after SMILE, the inflammatory keratitis presented as sterile multifocal interface keratitis uncharacteristic of classic DLK. The incidence was measured and categorized as primary or secondary by presenting appearance, grade, and time to presentation. Patients were observed for 1 year after surgery and standard outcomes analysis was performed.

RESULTS

Of the 4,000 eye population, there were 18 cases (0.45%) of DLK grade 1 or 2. All cases were managed and resolved with topical steroid therapy. Of these, 12 cases (67%) were of classic appearance and 6 cases (33%) presented as sterile multifocal inflammatory keratitis. DLK was primary in nature in 11 cases (61%) and secondary in 7 cases (39%). Postoperative uncorrected distance visual acuity was 20/20 or better in 93% of eyes. No patients lost any lines of corrected distance visual acuity and there was no change in contrast sensitivity.

CONCLUSIONS

DLK occurred after SMILE with an incidence of 0.45% in this population. Topical steroid therapy resolved the DLK in all cases with no sequelae and no adverse effect on refractive or visual outcome at 1 year postoperatively. A unique type of DLK presentation can occur after SMILE, characterized by multiple focal sterile inflammatory spots. Management is the same as for classic DLK, but with a lower threshold for performing an interface washout. [J Refract Surg. 2018;34(11):751-759.].

Diagnosis, Clinical Trend, and Treatment of Diffuse Lamellar Keratitis after Femtosecond Laser-Assisted in situ Keratomileusis: A Case Report

We report a severe case of diffuse lamellar keratitis (DLK) following femtosecond laser-assisted in situ keratomileusis (femto-LASIK). A 25-year-old man was submitted to 150 kHz iFS® IntraLase-assisted LASIK in both eyes for compound myopic astigmatism. The day after surgery, clinical examination showed a diffuse whitish granular cell reaction particularly in the right eye. High-dose dexamethasone eyedrops with topical antibiotic and artificial tears were prescribed. Five days after surgery, a central corneal opacity with convergent striae was detected at biomicroscopy. The suspicion of DLK was confirmed. Additional therapy based on hyperosmolar ophthalmological solution, oral doxycycline, and topical 10% sodium citrate was prescribed. Treatment was continued and tapered for over 3 months. Improvement in corneal transparency were obtained 2 weeks after the systemic therapy had been started. Uncorrected visual acuity improved from 20/32 to 20/20 at 1-year follow-up. DLK represents an infrequent complication after femto-LASIK. It should resolve without sequelae if promptly diagnosed and treated, without necessity of corneal flap lifting.

Comparison of self-reported quality of vision outcomes after myopic LASIK with two femtosecond lasers: a prospective, eye-to-eye study

Purpose

To compare self-reported quality of vision (QoV) outcomes after myopic LASIK (laser-assisted in situ keratomileusis) with two femtosecond lasers.

Design

Prospective, randomized, eye-to-eye study.

Methods

Consecutive myopic patients were treated with wavefront-guided LASIK bilaterally. Eyes were randomized according to ocular dominance. The flap of one eye was made with the IntraLase FS 60 kHz femtosecond laser with a conventional 70° side-cut, and the flap of the fellow eye was made with the IntraLase iFS 150 kHz femtosecond laser with an inverted 130° side-cut. Patients completed the validated, Rasch-tested, linear-scaled 30-item QoV questionnaire preoperatively and at Months 1, 3, 6, and 12.

Results

The study enrolled 120 fellow eyes in 60 patients. None of the measured QoV parameters exhibited statistically significant differences between the groups preoperatively or at any postoperative time point.

Conclusion

Creating LASIK flaps with an inverted side-cut using a 150 kHz femtosecond laser and with a conventional 70° side-cut using a 60 kHz femtosecond laser resulted in no significant differences in self-reported QoV assessed by the QoV questionnaire.

Comparison of performances of femtosecond laser and microkeratome for thin-flap laser in situ keratomileusis

OBJECTIVE

To compare the clinical outcomes of femtosecond laser (FS) and microkeratome (MK) for thin-flap in situ keratomileusis (LASIK).

MATERIALS AND METHODS

Data from patients with moderate to high myopia (spherical equivalent, >-4 diopters [D]) who underwent thin-flap LASIK using FS (199 eyes/110 patients) and MK (157 eyes/86 patients) were analyzed in this retrospective study. Preoperative and postoperative data were recorded from day 1 and months 1 and 3, postoperatively. Visual and refractive outcomes were compared for efficacy, safety, predictability, stability, and the efficacy and safety indices.

RESULTS

Three months postoperatively, more eyes in the FS group had an uncorrected distance visual acuity (UCVA) of 20/40 or better compared to MK group (relative risk [RR] 1.01, 95% confidence interval [CI], 0.97-1.05, P = 0.58); significantly more eyes in FS group had an UCVA of 20/20 or better (RR, 1.26, 95%CI, 1.08-1.48, P = 0.003). Intraoperative bleeding occurred in 5% and 36.7%, respectively, of FS and MK groups. There were no significant differences in the refractive predictability within spherical equivalents of 0.5 D (FS, 72%; MK, 63%) and 1.0 D (FS, 90%; MK, 86%). Both groups showed good stability 3 months, postoperatively. The efficacy index in FS group was 113.4%; that in MK group was 102.5% at 3 months postoperatively (P < 0.05). The safety indices for FS and MK groups at 3 months postoperatively were 116.4% and 108.2%, respectively (P < 0.05).

CONCLUSIONS

Both methods of thin-flap created LASIK were effective, safe, predicable, and stable. FS group had significant improvements in efficacy and safety, confirmed by the efficacy and safety indices, compared to MK group. Lasers Surg. Med. 48:596-601, 2016. © 2016 Wiley Periodicals, Inc.