Femtosecond-assisted intrastromal corneal cross-linking for early and moderate keratoconus


Collagen cross-linking by UVA light augmented by riboflavin was proposed to improve the biomechanical properties of keratoconic corneas.1 As an alternative to the standard technique (riboflavin saturation of stroma through denuded corneal surface, followed by UVA irradiation2, 3, 4) we developed a femtosecond-assisted intrastromal pocket for riboflavin induction.

Case report

Twelve eyes of 9 patients (mean age 29.75±9.3 years) with early progressive keratoconus (K-readings>48D, skewed steepest radial axis >22°, superior–inferior difference on the 5 mm circle >2.5D, inferior–superior difference >1.5 D, minimum corneal thickness >380 μm) were included. Progression was confirmed by K-reading increase of ≥1 D, or thickness decrease ≥5 μm in two consecutive Orbscan corneal tomographies.

A 6-mm-diameter doughnut-shaped intrastromal pocket was created at 200 μm depth by the Technolas Femtec 520 (Technolas Perfect Vision GmbH, Munich, Germany), leaving a 3 mm clear central optical zone (Figure 1, 1). Two 0.5 × 0.5 mm entry channels 180° apart were created, for riboflavin infusion and depressurization; a tapered Intacs spatula hook was used to bluntly dissect the pocket (Figure 1, 2). In all, 0.3 ml of 0.1% riboflavin in 20% dextran solution was introduced into the pocket using Intacs stromal channel irrigation cannula, until the entire pocket was coloured bright yellow (Figure 1, 3). Cornea was irradiated with UVA 365–375 nm light (3 mW/cm2 irradiance) for 30 min. Total fluency at the corneal plane was 5.4 J/cm2.

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Source: Pubmed