Transepithelial corneal crosslinking in treatment of progressive keratoconus: 12 months’ clinical results

Abstract

Objective:The purpose of this study was to evaluate the safety and efficacy of transepithelial corneal collagen cross linking (TE-CXL) with modified riboflavin and accelerated UVA irradiance in thin corneas with pachymetry less than 400 microns at thinnest point, untreatable by epithelium off corneal collagen cross linking (CXL) in adult Pakistani population with progressive keratoconus.Methods:This quasi experimental study included twenty six eyes of 26 patients with progressive keratoconus who underwent accelerated transepithelial CXL in Armed forced institute of ophthalmology with 12 months follow up. Modified riboflavin, ParaCel ((riboflavin 0.25%, Benzalkonium chloride, EDTA, Trometamol, hydroxypropyl methylcellulose) and vibeX Xtra (riboflavin 0.25%) (Avedro, USA)) were applied to cornea in two stages. Uncorrected and Corrected Distant Visual Acuities (UDVA, CDVA), spherical equivalent (SE), astigmatism, pachymetry at thinnest point (Pachy thin), apex keratometry (Kmax), simulated and steep keratometry (Sim K, steep K) were measured at baseline and at 3, 6 and 12 months post operatively. The cornea was then exposed to accelerated UVA irradiance of 9mW/cm2 for 10 min (total dose 30 mW/cm2).Results:The mean age of the patient was 24.54±5.16 years. UDVA, CDVA, SE, astigmatism significantly improved at all postoperative test points (p=0.000, 0.004, 0.000, 0.004 respectively). Kmax and pachy thin were significantly reduced over baseline at 1 year (p=0.000, 0.004 respectively). Topographic indices Sim K and steep K did not show significant changes. No intra or post-operative complications were reported.Conclusion:Transepithelial accelerated CXL with modified riboflavin is a safe and effective procedure which halt disease progression in thin corneas with progressive keratoconus.

<p>Transepithelial Accelerated Corneal Collagen Cross-Linking: Two-Year Results</p>

“…There is a growing evidence of the efficacy and safety of combining the trans-epithelial and accelerated protocols. 15,[22][23][24][25][26][27][28][29] In the present study, we evaluated the efficacy of TE-ACXL with a specific accelerated protocol (6 mW/cm 2 of UVA for 15 minutes); there is scarce published evidence. 21,23 Madeira et al had recently concluded that both TE-ACXL (6 mWcm 2 for 15 minutes) and C-CXL were similarly effective.…”

<p>Transepithelial accelerated versus conventional corneal collagen crosslinking in patients with keratoconus: a comparative study</p>

“…Other studies have also demonstrated that transepithelial and accelerated crosslinking protocols may be as effective as conventional protocols;19,22,29–31 however, only a limited amount of studies have evaluated the efficacy of the TE-ACXL protocol 24,25. Until this moment, only few studies conducted in adults evaluated the efficacy of TE-ACXL; however, the protocol used was different.…”

“…Until this moment, only few studies conducted in adults evaluated the efficacy of TE-ACXL; however, the protocol used was different. In one study, the cornea was exposed to UVA irradiance of 9 mW/cm 2 for 10 minutes,25 whilst in an other, an irradiance of 45 mW/cm 2 for a total dose of 7.2 J was used 24. The first study enrolled 26 eyes with progressive keratoconus, with a mean age of 24.54±5.16 years and a significant improvement in BCVA and Kmax after 12 months of follow-up 25.…”

“…This protocol allows to overcome some limitations of conventional protocol, making it a more appealing and promising treatment option. However, medical literature on safety and efficacy of transepithelial accelerated corneal collagen crosslinking (TE-ACXL) remains scarce 24,25. Considering its advantages more studies to evaluate the role of this protocol in keratoconus treatment are needed.…”

Enhanced Transepithelial Riboflavin Delivery Using Femtosecond Laser-Machined Epithelial Microchannels

“…14,18 The development of transepithelial UVA CXL is a highly active area of research, with many different methods being tested both in the laboratory and clinically. Common methods used to avoid debridement of the epithelium include the addition of chemicals such as benzalkonium chloride (BAK) to weaken epithelial tight junctions, 2,[19][20][21][22][23] the addition of vitamin E or C, 24,25 or using iontophoresis during Rf application. [26][27][28][29] Whatever the method of Rf application, however, transepithelial UVA CXL has yet to reproduce the results of traditional UVA CXL.…”