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Systemic supplemental oxygen therapy during accelerated corneal cross-linking for progressive keratoconus; a randomized clinical trial.

PURPOSE
To investigate the potential additive effect of systemic supplemental oxygen administered during accelerated corneal crosslinking (CXL) for progressive keratoconus (KCN).


SETTING
Department of ophthalmology at an academic center DESIGN:: Randomized Clinical Trial METHODS:: This study includes eyes with progressive KCN ranodmized to three different CXL protocols. The first group (OA-CXL) included 19 eyes that underwent an accelerated CXL protocol (9 mW/ cm2 for 10 minutes) while receiving systemic oxygen at a rate of 5 liters/minute for 10 minutes. The second group consisted of 14 eyes undergoing the same accelerated CXL protocol without supplemental oxygen therapy (A-CXL). The third group (C-CXL) was comprised of 14 eyes undergoing conventional CXL according to the Dresden protocol. All subjects were followed for at least six months. Visual acuity, keratometry and corneal biomechanical parameters including corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively and 6 months postoperatively.


RESULTS
Reduction in K max was significantly greater in the OA-CXL (P=0.01). At baseline, mean K max was 54.31 ± 3.64 D in the OA-CXL group, 54.66 ± 4.99 D in the A-CXL group and 56.03 ± 5.28 D in the C-CXL group (P=0.58), which reached 53.58 ± 3.24, 54.59 ± 4.65 and 55.87 ± 4.73 D at six months in the three study groups, respectively (P= 0.115). Mean CRF was increased significantly only in the OA-CXL group from a baseline value of 6.32 ± 2.12 to 7.38 ± 1.88 mmHg at 6 months (P=0.009) CONCLUSION:: This study suggests superior efficacy of an accelerated CXL protocol coupled with systemic oxygen supplementation as compared to the accelerated CXL protocol and the conventional protocolin eyes with progressive KCN. . In addition to greater reduction in K max as the primary outcome, improvement in corneal biomechanics was also observed at 6 months.