Abstract
PurposeTo assess clinical results of the 9 mW/5.4 J/cm2 accelerated crosslinking (ACXL) in the treatment of progressive keratoconus (KC) over a span of 5 years.MethodsThe prospective open non-randomized interventional study (Siena Eye-Cross Study 2) included 156 eyes of 112 patients with early progressive KC undergoing the Epi-Off 9 mW/5.4 J/cm2 ACXL at the Siena Crosslinking Centre, Italy. The mean age was 18.05 ± 5.6 years. The 20-min treatments were performed using the New KXL I (Avedro, Waltham, USA), 10 min of 0.1% HPMC Riboflavin soaking (VibeX Rapid, Avedro, Waltham, USA) and 10 min of continuous-light UV-A irradiation. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), Kmax, coma, minimum corneal thickness (MCT), surface asymmetry index (SAI), endothelial cell count (ECC) were measured, and corneal OCT performed.ResultsUDVA and CDVA improved significantly at the 3rd (P = 0.028), Δ + 0.17 Snellen lines and 6th postoperative month, respectively (P < 0.001), Δ + 0.23 Snellen lines. Kmax improved at the 6th postoperative month (P = 0.03), Δ − 1.49 diopters from the baseline value. Also, coma aberration value improved significantly (P = 0.004). A mild temporary haze was recorded in 14.77% of patients without affecting visual acuity and without persistent complications. Corneal OCT revealed a mean demarcation line depth at 332.6 ± 33.6 μm.ConclusionThe 5-year results of Epi-Off 9 mW/5.4 J/cm2 ACXL demonstrated statistically significant improvements in UCVA and CDVA, corneal curvature and corneal higher-order aberrations which confers a long-term stability for progressive ectasia. Based on the results of the Siena Eye-Cross Study 2, the 9 mW/5.4 J/cm2 ACXL is a candidate to be the natural evolution of Epi-Off CXL treatment for the management of early progressive corneal ectasia, and thus optimize clinic workflow.
Highlights
IntroductionConventional riboflavin UV-A induced corneal crosslinking (CXL) with epithelium removal (Epi-Off) [1, 2] represents a cost-effective treatment [3] with documented long-term efficacy in stabilizing progressive keratoconus [4, 5] and secondary ectasia [6, 7] in randomized clinical trials [8] and open non-randomized studies both in young adult [9] and pediatric populations [10], which reduce the need of corneal transplants for keratoconus by 25% [11] to 50% [12].The standard energy dose of 5.4 J/cm delivered in 30 min at 3 mW/cm UV-A irradiance after 30 min of isotonic 0.1% Riboflavin-Dextran 20% stromal soaking (the Dresden protocol) [13], was approved in the United States by the Food and Drug Administration (U.S FDA) in April 2016 [14], and requires a long treatment time of 1 h [15]
We report the long-term (5-years) clinical results of the 9 mW/5.4 J/cm2 ACXL protocol named “Dresden Accelerated Protocol” in a large cohort of patients performed in Italy at the Siena Crosslinking Centre named “Siena Eye-Cross Study 2”
Dataset and study design The prospective long-term open non-randomized, noncomparative interventional Siena Eye-Cross Study 2 was approved by the institutional review board (IRB) of the Siena Crosslinking Center following the tenets of the Declaration of Helsinki and included 156 eyes of 112 patients who underwent an Epi-Off 9 mW/5.4 J/cm2 ACXL procedure for progressive KC and completed the 5-year follow-up
Summary
Conventional riboflavin UV-A induced corneal crosslinking (CXL) with epithelium removal (Epi-Off) [1, 2] represents a cost-effective treatment [3] with documented long-term efficacy in stabilizing progressive keratoconus [4, 5] and secondary ectasia [6, 7] in randomized clinical trials [8] and open non-randomized studies both in young adult [9] and pediatric populations [10], which reduce the need of corneal transplants for keratoconus by 25% [11] to 50% [12].The standard energy dose of 5.4 J/cm delivered in 30 min at 3 mW/cm UV-A irradiance after 30 min of isotonic 0.1% Riboflavin-Dextran 20% stromal soaking (the Dresden protocol) [13], was approved in the United States by the Food and Drug Administration (U.S FDA) in April 2016 [14], and requires a long treatment time of 1 h [15]. Conventional riboflavin UV-A induced corneal crosslinking (CXL) with epithelium removal (Epi-Off) [1, 2] represents a cost-effective treatment [3] with documented long-term efficacy in stabilizing progressive keratoconus [4, 5] and secondary ectasia [6, 7] in randomized clinical trials [8] and open non-randomized studies both in young adult [9] and pediatric populations [10], which reduce the need of corneal transplants for keratoconus by 25% [11] to 50% [12]. Richoz et al [32] demonstrated that the Bunsen-Roscoes’ law does not apply in full for ACXL because the biomechanical effect of CXL decreases significantly when using high-UV irradiance with short irradiation times due to the reduced stromal oxygen diffusion capacity which may be a limiting factor that reduces overall treatment efficiency. Clinical studies [33,34,35] demonstrated that the 9 mW/5.4 J/ cm ACXL gained comparable visual outcomes with conventional 3 mW/cm Dresden protocol with keratoconus stabilization [36, 37]
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