The Effects of Epithelium-off Corneal Collagen Cross-linking on Peripheral Corneal Keratometry, Pachymetry as well as Scheimpflug Imaging Calculated Corneal Indices in Keratoconus

Abstract

Purpose: To utilize Scheimpflug imaging to describe corneal changes in keratoconic patients undergoing collagen crosslinking.Study type: Case series. Study design:Retrospective chart review at two sites: Calgary, Alberta and Brandon, Manitoba, Canada. All patients were diagnosed with keratoconus and had undergone corneal collagen crosslinking. All patients had pre-and post-procedure imaging done with Oculus Pentacam.Results: Sixty-one eyes of 48 patients with 6 months followup and 36 eyes of 27 patients with one year follow-up were included. Average age was 27 ± 12 years (15-48 years). Fiftyone males and 10 females were studied. At 1 year follow-up, all Pentacam indices were found to improve: ISV -4.44 ± 18.6 (p = 0.16), IVA -0.07 ± 0.27 (p = 0.12), KI -0.009 ± 0.082 (p = 0.49), CKI -0.012 ± 0.027 (p = 0.01), IHA -3.87 ± 23.3 (p = 0.33) and IDH -0.062 ± 0.308 (p = 0.24). Keratometry measurements were flatter at the pupil centre by 0.87 ± 2.53 D (p = 0.05). K max and K min were flatter by 0.58 ± 1.37 D (p = 0.02) and 0.33 ± 1.70 D (p = 0.25) respectively. Pupil center pachymetry was thinner by 12.9 ± 21.1 µm (p = 0.0006) at 6 months, as were the corneal apex and thinnest local by 12.9 ± 22.3 µm (p = 0.001) and 21.8 ± 54.6 µm (p = 0.05) respectively. However, all central pachymetry readings were not statistically different from baseline at the one year measurements. Peripheral corneal measurements at 6 mm diameter were no different from baseline at 6 months, however, were significantly thicker at the 1 year follow-up. Conclusion:The data, in this study, points to a more uniform cornea post corneal collagen crosslinking. The inferior cornea becomes flatter and superior cornea steeper with less variation when comparing the corneal curvatures. The peripheral cornea becomes thicker at 1 year post-procedure. Collagen crosslinking stabilizes the cornea.

Keratoconus Management: Navigating Patient Options

“…Corneal pachymetry becomes more compact at 6 months, and reverts to pre-CXL levels by 12 months. 13 CXL is contraindicated in patients with <400 µm central corneal thickness as it may damage the endothelium due to toxicity. 14 However, recent studies dispute this notion.…”