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Theo Günter Seiler, Isaak Fischinger, Gerald Schmidinger, Theo G Günter Seiler; Intrastromal application of riboflavin for corneal crosslinking. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3702.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate feasibility, efficiency and safety of intrastromal application of riboflavin for corneal crosslinking by means of a femtosecond laser created intrastromal channel system.
In stripes of 36 porcine corneas stress-/strain measurements were performed (UStrech, Cellscale, Waterloo, Canada) in a 16 % dextran bath (Dextran T-500). A 5 mm wide stripe was excised of the cornea parallel to the vertical axis through the center and the stress was measured continuously until a strain of 12%. The 36 eyes were subdivided into 4 groups. (1) 9 eyes with an intrastromal channel system created with a femtosecond laser and an injection of 0.5 % riboflavin solution. (2) 9 eyes with an intrastromal channel system created with a femtosecond laser and an injection of BSS (3) 9 eyes treated by the Dresden protocol (epithelial removal) and (4) 9 untreated eyes. The channel system consisted of 2 concentric rings with 2 radial connections (Fig. 1) in a depth of 300 µm. The dissected area was less than 10 % of the total area of the cornea. All eyes were irradiated by UVA light (λ= 365 nm) by a UVX2000 lamp (IROC Innocross, Zurich, Switzerland) with a total energy of 5.4 J/cm2. UVA transmission experiments were performed at 5 untreated porcine corneas, 5 corneas treated by the Dresden protocol and 5 corneas with intrastromal application of 0.5% riboflavin by means the channel system. At 5, 10, 20 and 30 min UVA transmission was measured.
At a strain of 10% the increase in stiffness after intrastromal application of riboflavin was 64% compared to untreated corneas. Eyes treated by the Dresden protocol achieved an increase in stiffness of 81% compared to untreated corneas There is no significant difference in stress/strain measurement results between untreated corneas and corneas with an intrastromal channel system (without riboflavin). UVA transmission at t=30 min was 58 ± 3 % in untreated corneas, 8 ± 1.5% in corneas treated by the Dresden protocol, and 2 ± 0.5% in corneas with intrastromal application of riboflavin.
Intrastromal application of riboflavin into a channel system represents an alternative epi-on procedure. The protective effect on the endothelium of riboflavin is better than that of the Dresden protocol.
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