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Robert Herber, Mathew Francis, Eberhard Spoerl, Lutz E Pillunat, Frederik Raiskup, Abhijit Sinha Roy; Evaluation of biomechanical changes and corneal stiffening after corneal cross-linking in progressive keratoconus: A prospective follow-up study using an air-puff applanation Scheimpflug analyzer. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6824.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze the biomechanical changes and corneal stiffening after accelerated corneal cross-linking (A-CXL) in patients with progressive keratoconus using a dynamic Scheimpflug analyzer (Corvis ST).
Eighty eyes of 80 keratoconic patients were enrolled in this study. 40 eyes with stable keratoconic findings were used as controls. 40 keratoconic eyes have shown progression and were cross-linked with the modified Dresden protocol (9mW/cm2, 10 min). All eyes were examined with the Corvis ST and Pentacam (Oculus, Wetzlar, Germany) after 6 and at least 12 months. Dynamic corneal response (DCR) parameters, topographical and tomographical parameters were analyzed with the linear mixed model using SPSS 25. Taking into account pachymetric changes after cross-linking, parameters were adjusted by corneal thickness.
Mean age, biomechanical intraocular pressure (bIOP), maximal keratometry (Kmax) and thinnest corneal thickness (TCT) did not differ between both groups at baseline (P>0.05). TCT and Kmax remained stable in the control group over 12 months. In the CXL group, TCT decreased significantly after 6 months and recovered to baseline values after 12 months, whereas Kmax decreased by -0.84±3.39 D. In DCR, a significant increase of bIOP was observed in CXL group by +1.47±2.57 mmHg (P=0.001) and +1.71±2.76 mmHg (P<0.001) compared to baseline after 6 and 12 months, respectively. SPA1 adjusted by pachymetry was increased by +7.1±13.1 mmHg/mm (P=0.003) and +9.9±14.7 mmHg/mm (P<0.001) after 6 and 12 months, respectively. In comparison to the control group, bIOP (P>0.05) and SPA1 (P>0.05) remained unchanged over the same period. Other DCR parameters showed no significant changes.
SPA1 and bIOP showed significantly higher values after CXL, whereas the control group remained stable after the same follow-up period. The increase of SPA1 became significant after considering the pachymetric changes after CXL. BIOP, however, is less influenced by main corneal parameters and age. Therefore, bIOP seems to be a valuable parameter to evaluate significant changes in biomechanical properties after CXL.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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