Topography-guided corneal surface laser ablation combined with simultaneous accelerated corneal collagen cross-linking for treatment of keratoconus

Yu Zhang,Yueguo Chen

doi:10.1186/s12886-021-02042-x

Abstract

Backgroundto study the outcomes of topography-guided customized excimer laser subepithelial ablation combined with accelerated CXL for progressive keratoconus.MethodsThirty-one eyes of 30 patients with progressive keratoconus were included in this prospective study. Topography-guided excimer laser ablation without refractive correction was performed. Simultaneous accelerated collagen cross-linking with ultraviolet light of 30 mW/cm2 for 4 min was followed. Uncorrected distance visual acuity (UCVA), manifest refraction, corrected distance visual acuity (CDVA), tomograghy were examined at postoperative 1, 6, and 12 months.ResultsUDVA improved slightly after surgery (P > 0.05). BSCDVA improved significantly from 0.32 ± 0.20 logMAR to 0.15 ± 0.14 logMAR at postoperative 12 months (P < 0.05). During 12-month follow-ups, there were no significant differences in manifest refraction and corneal keratometry except for maximal keratometry value of the anterior surface (Kapex), which decreased significantly from 57.23 ± 5.09D to 53.13 ± 4.47D (P < 0.05). Even though the thinnest corneal thickness decreased from 465 ± 24 μm to 414 ± 35 μm (P < 0.05), curvature asymmetry index front (SIf), keratoconus vertex front (KVf) and Baiocchi Calossi Versaci index front (BCVf) decreased significantly till postoperative 12 months (P < 0.05). Corneal higher-order aberrations and coma also decreased significantly till 12 months after surgery (P < 0.05).ConclusionsTopography-guided surface ablation without refractive correction combined with simultaneous accelerated collagen cross-linking provided good stability in refraction and corneal curvature, and also showed significant improvement in BSCDVA, corneal regularity and corneal optical quality.

Highlights

Keratoconus is a progressive ectatic corneal disorder that results in corneal stroma impairment and biomechanical weakening
We examined the evolution of the visual, refractive and tomographic changes during 1-year follow-up after simultaneous topography-guided photorefractive keratectomy (TG-PRK) without refractive correction followed by accelerated Corneal collagen cross-linking (CXL) in patients with progressive keratoconus
There was no significant difference in uncorrected distance visual acuity (UDVA) between preoperative and postoperative time points (P > 0.05)

Summary

Introduction

Keratoconus is a progressive ectatic corneal disorder that results in corneal stroma impairment and biomechanical weakening. Corneal collagen cross-linking (CXL) is an effective treatment to halt the progression of keratoconus [1]. The classic Dresden CXL uses ultraviolet light of 3mW/cm illumination and a single treatment process needs 60 min to reach a total energy of 5.4 J/cm2 [2]. Several accelerated protocols have been reported to provide comparable results to the classic Dresden CXL [3, 4]. Accelerated CXL has been proven to halt the progression of keratoconus in the majority of pediatric patients [5]. Despite reports of well prevention for keratoconus progression and slight improvements of keratometry following CXL, the benefits in terms of improvement in UDVA or CDVA are negligible [6, 7]. Some attempts have been made to prevent the progression of keratoconus, and improve visual quality in keratoconus patients

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