Journal of refractive surgery

Re-treatment in LASIK: To Flap Lift or Perform Surface Ablation

Colin Chan, MBBS, FRANZCO; Michael Lawless, MBBS, FRANZCO, FRACS; Gerard Sutton, MBBS, MD, FRANZCO; Chris Hodge, BAppSc, PhD

Journal of Refractive Surgery. 2020;36(1):6-11

PURPOSE:

To review safety and efficacy outcomes following re-treatment for residual refractive errors in eyes with prior laser in situ keratomileusis (LASIK) and determine the most appropriate course of action for patients.

METHODS:

A review of all patients undergoing LASIK enhancement at a single refractive surgery center between 2012 and 2017 was undertaken. Refraction and biomicroscopy results before and after enhancement were collated and analyzed according to the method of enhancement (flap lift or surface ablation).

RESULTS:

A total of 108 eyes were included in the analysis; 58 eyes underwent flap lift and 50 underwent surface ablation retreatment with mean times to enhancement of 22.3 and 53.2 months, respectively. The mean spherical equivalent prior to enhancement was −0.43 ± 0.69 and −1.03 ± 1.01 diopters (D) for the flap lift and surface ablation groups, respectively. The absolute difference from intended refraction was statistically significant (lift 0.16 ± 0.24 versus surface ablation 0.31 ± 0.35 D; P = .01). The difference was more pronounced for eyes with prior hyperopia (P = .041). The incidence of haze following re-treatment was 3.4% in the flap lift group versus 10.0% in the surface ablation group, and 8.6% of the flap lift group had evidence of epithelial ingrowth, with 1 eye requiring washout. There was no correlation between time to enhancement, refraction, and incidence of complications following the enhancement procedure.

CONCLUSIONS:

There has been a trend toward treating residual LASIK refractive error through surface ablation. This review suggests that flap lift may result in a more accurate refractive outcome, albeit with an expected greater risk of epithelial ingrowth.

Impact of Primary Calcification in Segmented Refractive Bifocal Intraocular Lenses on Optical Performance Including Straylight

Timur M. Yildirim, MD; Grzegorz Labuz, PhD; Ramin Khoramnia, MD, PhD; Hyeck-Soo Son, MD; Sonja K. Schickhardt, PhD; Ingo Lieberwirth, PhD; Michael C. Knorz, MD, PhD; Gerd U. Auffarth, MD, PhD

Journal of Refractive Surgery. 2020;36(1):20-27

PURPOSE:

To describe and analyze the impact of calcification on the optical quality of segmented refractive bifocal intraocular lenses (IOLs).

METHODS:

Eight segmented refractive bifocal IOLs made of hydrophilic acrylic were explanted from 8 patients due to opacification (and one opacified IOL that was not explanted) and analyzed in a cross-sectional study with laboratory analysis. Nine cases comprised three IOL models: LS-313 MF30 (5 cases), LS-312 MF30 (3 cases), and LS-313 MF15 (1 case). Material analysis with scanning and transmission electron microscopy confirmed IOL calcification. Measurements of modulation transfer function (MTF) and straylight permitted assessment of the IOL optical quality. Values were compared to a control lens.

RESULTS:

Except for one case of Nd:YAG (neodymium:yttrium-aluminum-garnet) capsulotomy, there was no secondary surgical procedure in the patients’ histories. Eight of nine patients reported deteriorated visual quality, ultimately requiring IOL exchange. Material evaluation revealed fine granules of a calcium phosphate. Despite calcification, all but one lens still showed two distinct foci on the MTF measurements. Straylight values were higher than in a cataractous lens (33.1 deg2/sr) in all cases, with an average value of 170.1 ± 71.5 deg2/sr.

CONCLUSIONS:

Optical quality assessment showed that IOL calcification had a small effect on the MTF of segmented refractive bifocal lenses but a large impact on the straylight levels. Accordingly, in the clinical case, straylight levels were elevated.

Transepithelial Surface Ablation With Mitomycin C for the Treatment of Chronic Central Corneal Scars Following Adenoviral Keratoconjunctivitis

Renan F. Oliveira, MD; Gabriel A. Ferreira, MD, MSc; Vinícius C. Ghanem, MD, PhD; Paulo Elias Corrêa-Dantas, MD, PhD; Ramon C. Ghanem, MD, PhD

Journal of Refractive Surgery. 2020;36(1):55-61

PURPOSE:

To assess visual and refractive outcomes and recurrence rates of subepithelial infiltrates after corneal surface ablation with mitomycin C (MMC) 0.02% for the treatment of chronic corneal scars following epidemic keratoconjunctivitis and to compare these results with a control group receiving only medical treatment.

METHODS:

This was a retrospective case series enrolling patients with central corneal scars following epidemic keratoconjunctivitis. Patients were divided into two groups: (1) control with clinical follow-up and refractive correction with glasses or rigid gas-permeable contact lenses when necessary and (2) transepithelial phototherapeutic keratectomy (PTK) with MMC 0.02%, combined with photorefractive keratectomy (PRK) in selected cases (treatment group). Signs and symptoms, corrected distance visual acuity (CDVA) in logMAR units, manifest and cycloplegic refraction, and depth of the corneal opacities were assessed.

RESULTS:

Thirty-five eyes of 27 patients (11 men [40.7%] and 16 women [59.3%]) were enrolled, with a mean follow-up of 54.4 ± 19.7 and 27.5 ± 22.8 months in the control and treatment groups, respectively. Mean improvement in CDVA was 0.13 ± 0.17 logMAR (P = .007) in the control group and 0.29 ± 0.24 logMAR (P = .001) in the treatment group. Intergroup comparison showed a greater improvement in the treatment group (P = .041). Mean hyperopic shift induced in the treatment group was +0.46 ± 1.20 diopters. The recurrence rate of subepithelial infiltrates was 77.7% in the control group and 11.7% in the treatment group throughout the follow-up (54.4 ± 19.7 and 27.5 ± 22.8 months, respectively).

CONCLUSIONS:

Corneal surface ablation with MMC 0.02% was efficient in treating corneal scars following adenoviral epidemic keratoconjunctivitis, with greater visual improvement in comparison to clinical treatment and a decreased rate of infiltrate recurrence.