Photorefractive intrastromal corneal crosslinking for treatment of myopic refractive error: Findings from 12-month prospective study using an epithelium-off protocol

Elling, Matthias; Kersten-Gomez, Inga; Dick, H. Burkhard

doi:10.1016/j.jcrs.2018.01.022

Cited by 22 publications

(26 citation statements)

References 13 publications

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“…In 2014, Kanellopoulos presented a series of 4 cases with myopia treated with an epi-on protocol in room air (Kanellopoulos 2014). In 2018, Elling et al presented 12-month results similar to ours with PiXL treatment of myopia in room air, but with an epi-off protocol (Elling et al 2018). These results were also stable from 6 to 12 months, in accordance with our present findings.…”

Section: Discussionsupporting

confidence: 88%

“…presented 12‐month results similar to ours with PiXL treatment of myopia in room air, but with an epi‐off protocol (Elling et al. ). These results were also stable from 6 to 12 months, in accordance with our present findings.…”

Section: Discussionsupporting

confidence: 81%

“…However, these decisions were necessary and we still feel that our present findings, together with what has previously been published in this field (Kanellopoulos ; Elling et al. ; El Hout et al. ), are interesting enough to justify further studies on PiXL treatment for low‐grade myopia.…”

Section: Discussionmentioning

confidence: 67%

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A prospective evaluation of photorefractive intrastromal cross‐linking for the treatment of low‐grade myopia

Fredriksson

Näslund

Behndig

2019

Acta Ophthalmologica

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Purpose To evaluate photorefractive intrastromal cross‐linking (PiXL) treatment for low‐grade myopia, comparing three treatment protocols. Methods Healthy individuals, 25.6 ± 3.6 years of age, with low‐grade myopia underwent epi‐on PiXL with either: 4‐mm zone treated in high oxygen environment (4 mm‐HIGH; n = 15), 4‐mm/room air (4‐mm LOW; n = 6), or 6‐mm/high oxygen (6‐mm HIGH; n = 6). Efficacy was determined by change in uncorrected visual acuity (UCVA), manifest refractive spherical equivalent (MRSE) and corneal curvature (Kmean) over a 12‐month follow‐up. Safety was determined by best spectacle corrected visual acuity (BSCVA), corneal endothelial cell loss and registration of side‐effects. Results Twenty‐seven subjects were included. Due to insufficient effect with the 4‐mm LOW treatment and an unacceptable degree of initial light sensitivity/ocular irritation in the 6‐mm HIGH group, the inclusions to these treatments were stopped after inclusion of 6 patients in each group. The 4‐mm HIGH treatment showed a significantly larger improvement in UCVA (−0.45 ± 0.27 LogMAR) and MRSE (+0.99 ± 0.44 D) at 1, 6 and 12 months compared with the 4‐mm LOW treatment (p < 0.05). At 12 months posttreatment, endothelial cell count and BSCVA were unaltered. More initial side‐effects were noted with the 6‐mm HIGH treatment, compared with the 4‐mm HIGH treatment (p < 0.05). Conclusion Epi‐on PiXL may become a safe and effective non‐ablative treatment for low‐grade myopia. The effect is augmented by high oxygen environment and remains stable for 12 months. The initial ocular irritation is acceptable with a 4‐mm treatment zone. The present results justify further clinical studies on PiXL, including refinements of the technique and long‐term results.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 81%

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A prospective evaluation of photorefractive intrastromal cross‐linking for the treatment of low‐grade myopia

Fredriksson

Näslund

Behndig

2019

Acta Ophthalmologica

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“…New human endothelial UV safety thresholds need to be evaluated in order to determine a more solid guideline for thin corneas with a pachymetry of less than 400 lm. 35 In particular with respect to customized 36 and refractive CXL, 37 using substantially higher energy parameters, which are currently entering the clinical routine.…”

Section: Endothelial Riboflavin Concentrations During CXLmentioning

confidence: 99%

Riboflavin Concentrations at the Endothelium During Corneal Cross-Linking in Humans

Seiler

Batista

Frueh

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To determine the riboflavin concentration in the posterior corneal stroma, Descemet's membrane, and endothelium prior to UV irradiation in corneal cross-linking (CXL) in humans. METHODS.Five human deepithelialized cadaver corneas were mounted into artificial anterior chambers. After the establishment of stable physiological hydration, two-photon imaging with a certified multiphoton tomograph was used to determine fluorescence intensity and second harmonic generation signals from collagen throughout each cornea by optical sectioning, with a step size of 2.5 lm. Afterward, 0.1% riboflavin solution was applied to the anterior corneal surface, similar to the standard CXL protocol. To determine the absolute riboflavin concentration immediately before UV irradiation, corneas were measured by two-photon imaging just at the end of the riboflavin imbibition and after riboflavin saturation. RESULTS.The topical application of 0.1% riboflavin results in a riboflavin concentration that decreases to 0.035% in the posterior stroma. Inside Descemet's membrane and endothelium, the concentration drops further to only approximately 0.015% at the endothelial level. Local riboflavin distribution indicates a predominantly paracellular passive diffusion of riboflavin into the anterior chamber.CONCLUSION. The experimentally determined riboflavin concentration of 0.015% at the endothelium shows a substantial discrepancy of a factor of 1.7 to the previously theoretically calculated 0.025%. A lower riboflavin concentration at the endothelium may enable higher radiant exposures and further improve the efficacy of CXL.

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“…One of the confounding factor is the potential effect on corneal flattening solely by CXL itself, since previous studies have reported mild corneal flattening and myopia reduction in keratoconus patients after CXL treatment using the current protocol 5,27,28 , though most of which was observed in steeper cornea 29 . Elling et al 30 have performed CXL alone in myopic patients with normal corneas and observed the mean keratometry changed from 42.64 D at baseline to 42.11 D at 1 month post-op. However, the energy they used was 2-3 times higher than that in our study (10-15 J/cm 2 vs. 5.4 J/cm 2 ).…”

Section: Discussionmentioning

confidence: 99%

Effects of corneal crosslinking on corneal shape stabilization after orthokeratology

Liao

Lin

Keel

et al. 2020

Sci Rep

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Orthokeratology (Ortho-K) works to reshape cornea and is the only non-surgical way to enable vision without corrective aids. However, its effect is only temporary, and successful stabilization requires ongoing Ortho-K wear to maintain the reshaping effect. Corneal crosslinking (CXL) is a commonlyused technique in clinical practice to stabilize corneal shape in keratoconic eyes. However, whether or not CXL can stabilize corneal shape after Ortho-K in normal cornea has not been reported. Therefore, this proof-of-concept study using 2 rhesus monkeys aimed to determine the efficacy of the combined procedure. One monkey wore Ortho-K bilaterally for 24 hours, and the other from 6 pm to 8 am for 7 days. The left eyes of both monkeys underwent CXL after Ortho-K while the contralateral eye served as control. Results showed a gradual regression of corneal shape in all eyes with or without CXL. However, eyes underwent CXL regressed more slowly than the control eyes. The control eyes and the CXL treatment eye in the 7-day Ortho-K monkey regressed completely at last, while the CXL treatment eye in the 24 h Ortho-K monkey maintained a corneal flattening of −1.48 D 27 days after procedure. These findings suggest CXL can slow the regression of Ortho-K for a short duration, but cannot sustain its effect according to the current protocol.

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Photorefractive intrastromal corneal crosslinking for treatment of myopic refractive error: Findings from 12-month prospective study using an epithelium-off protocol

Abstract: Photorefractive intrastromal CXL was a safe and efficacious treatment of refractive error in patients with low myopia.

Cited by 22 publications

References 13 publications

A prospective evaluation of photorefractive intrastromal cross‐linking for the treatment of low‐grade myopia

A prospective evaluation of photorefractive intrastromal cross‐linking for the treatment of low‐grade myopia

Riboflavin Concentrations at the Endothelium During Corneal Cross-Linking in Humans

Effects of corneal crosslinking on corneal shape stabilization after orthokeratology

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