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Niklas Pircher, Andreas Gschliesser, Ruth Donner, Jan Lammer, Gerald Schmidinger; Correlation between central stromal demarcation line depth and flattening of the cornea after corneal cross-linking comparing two different treatment protocols. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2920.
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© ARVO (1962-2015); The Authors (2016-present)
A corneal stromal demarcation line (DL) induced by corneal cross-linking (CXL) has lately been suggested as a possible surrogate parameter for the flattening effect and success of the CXL-procedure. Aim of this study was to investigate the correlation between depth of the DL in the center of the cornea 1 month (mo) and reduction in maximal keratometry values (Kmax) 12mo after CXL treatment as well as comparing the effect in two different treatment protocols.
Treatment-naive subjects with keratoconus were treated either following the Standard Dresden Protocol (SDP, 30 minutes (min) Riboflavin + 20% Dextran [Peschke D] soaking, 30min irradiation UVX-1000, 3mW/cm2) or an Accelerated CXL Protocol (ACP, 10min HPMC [Vibex Rapid] soaking, 10min irradiation UVX-2000, 9mW/cm2). Depth of the DL was measured using Visante anterior segment OCT (Carl Zeiss Meditec Inc.) imaging 1mo post-operatively (OP). Kmax (preOP) and change in Kmax (preOP - 12mo postOP) were assessed using corneal topoghrapy (Pentacam HR tomography, Oculus GmBH).
91 eyes were included in this retrospective study. 60 eyes were treated according to the SDP and 31 eyes following the ACP. PreOP mean±SD Kmax was 57.26±6.97 D in the SDP group, and 56.82±6.36 D in the ACP group (p=0.10). A DL at 1mo postOP was observed in all eyes of both groups. Stromal depth was 326.57±76.64 µm in the SDP group, and 168.74±73.15 µm in the ACP group (p<0.001). Mean change in Kmax was -1.17±0.79 D after 12mo in the SDP group and -0.85±0.44 D in the ACP group. Change in Kmax was significant in the SDP group (p<0.001), but not in the ACP group (p=0.75). No statistically significant correlation between stromal depth of the DL after 1mo and change in Kmax after 12mo was found in either of the groups (Pearson r: -0.09 and -0.02 respectively).
Different CXL treatment protocols seem to induce different depths of the stromal demarcation line. Even though eyes that were treated following the Standard Dresden Protocol showed a deeper DL and a significant change in Kmax at 12mo, the interpretation of the stromal depth of the DL as a surrogate parameter for the effect of the procedure may be doubted, since a statistically significant association between DL depth and Kmax reduction after 12 months was not found in either of the groups.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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