Eyeworld

22 | EYEWORLD | MARCH 2021 Contact Le: nhon.le@bcm.edu Weikert: mweikert@bcm.edu The authors demonstrated that low-ener- gy femtosecond laser, single-use instruments, powderless gloves, and the avoidance of corneal markings can result in a low incidence of DLK. However, given the noncomparative nature of the study, the effect each factor had in reducing the incidence of DLK is unknown. Identifying the contribution of each factor on the rate of DLK is important in enabling providers to iden- tify and adopt practice patterns with the most benefit to patient outcomes. Further, a compar- ison of the authors' DLK rates prior to and after their adoption of low-energy femtosecond laser LASIK would better elucidate the effect that their technique had in reducing the risk of DLK. Future prospective, randomized controlled trials may help adjudicate the effects low-energy fem- tosecond laser settings and sterile techniques to reduce interface contamination each have on the incidence of DLK. ASCRS NEWS Diffuse lamellar keratitis after LASIK with low-energy femtosecond laser Antonio Leccisotti, MD, PhD, Stefania Fields, AO, MSc J Cataract Refract Surg. 2021;47(2):233–237. n Purpose: To evaluate the incidence, evolution and prognosis of diffuse lamellar keratitis (DLK) in a large series of laser-assisted in situ keratomileusis (LASIK) with low-energy femtosecond laser. n Setting: Private practice, Siena, Italy n Design: Retrospective, consecutive, non-comparative case series study. n 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). n 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: treated with topical steroids, they had no visual consequences. Three patients had bilateral grade 3–4 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 LASIK for hyperopic shift in one eye. In all the 5 eyes developing grade 4 DLK, corneal thickness decreased until the first month, then partially recovered; mean final tissue loss at 1–2 years was 35 µm. Compensatory epithelial thickening was observed. n Conclusion: DLK after low-energy femtosecond LASIK is rare; severe DLK (stages 3 and 4) was only found in 6 eyes (0.016%). Flap lifting and irrigation may 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 LASIK. continued from page 21 Analysis While previous studies involving femtosecond LASIK showed DLK incidence rates as high as 37.5% with higher energy settings, Leccisotti and Fields demonstrated that low-energy femto- second settings in combination with techniques to reduce interface contaminants resulted in a low incidence of DLK (0.63% of eyes). 7 Their study reported that all patients with grade 1 and 2 DLK recovered without sequelae. Epithe- lial changes throughout the course of grade 4 DLK were previously not well described in the literature. Leccisotti and Fields illustrated that thinning and opacification of the cornea in pa- tients with grade 4 DLK peaked at 1 month post- operatively and slowly recovered within 2 years, although no patients attained a full-thickness recovery. In the single patient who underwent flap lift and irrigation for bilateral grade 3 DLK, treatment was unable to prevent progression to grade 4 DLK. Further, this manuscript presented the first published case, known to Leccisotti and Fields, of repeat femtosecond LASIK for hyper- opic shift in a patient with grade 4 DLK, who ultimately had a satisfactory outcome after the retreatment. References (cont.) 10. Fogla R, et al. Diffuse lamellar keratitis: are meibomian secre- tions responsible? J Cataract Refract Surg. 2001;27:493–495. 11. Kaufman SC, et al. Interface inflammation after laser in situ keratomileusis. Sands of the Sahara syndrome. J Cataract Refract Surg. 1998;24:1589–1593. 12. Cosar CB, et al. The efficacy of hourly prophylactic steroids in diffuse lamellar keratitis epidemic. Ophthalmologica. 2004;218:318–322. 13. Moilanen JA, et al. Keratocyte activation and inflammation in diffuse lamellar keratitis after formation of an epithelial defect. J Cataract Refract Surg. 2004;30:341–349. 14. Choe CH, et al. Incidence of diffuse lamellar keratitis after LASIK with 15 KHz, 30 KHz and 60 KHz femtosecond laser flap creation. J Cataract Refract Surg. 2010;36:1912–1918. 15. Linebarger EJ, et al. Diffuse lamellar keratitis: diagnosis and management. J Cataract Refract Surg. 2000;26:1072–1077.

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