Long-term visual, anterior and posterior corneal changes after crosslinking for progressive keratoconus

Abstract

Aim To evaluate the long-term outcomes of corneal cross-linking (CXL) in patients with progressive keratoconus. Method In this retrospective non-comparative study, forty-five eyes of 31 patients with progressive keratoconus were treated with 30 min “epi-off” corneal cross-linking. The visual, refractive, topographic and tomographic outcomes were evaluated preoperatively and at least 10 years after cross-linking. Results Ten years post-corneal cross-linking, the mean anterior maximum keratometry decreased (−2.10 ± 3.25 D, P = 0.0001). Conversely, the posterior maximum keratometry increased (6.38 ± 9.79 D, P = 0.065). Both uncorrected and corrected distance visual acuity improved (LogMAR −0.08 ± 0.30) and (LogMAR −0.05 ± 0.21), respectively (P > 0.05, both). A statistically significant hyperopic shift was observed postoperatively (0.70 ± 1.31 D, P = 0.0009). The anterior topographic cylinder values revealed no change (−0.17 ± 1.31 D, P = 0.3), whereas the mean posterior cylinder values decreased (absolute value increased) significantly compared to baseline from −1.31 ± 0.97 D to −1.82 ± 1.78 D, (P < 0.05). The minimum corneal thickness values decreased significantly (−35.11 ± 48.63 µm, P = 0.0001). Four eyes (8.8%) showed more than 1 D increase in the anterior maximum keratometry. Conclusion This protocol and duration of Epi-off corneal cross-linking was found to be effective in halting keratoconus progression over the follow up period (10 years). Anterior corneal flattening and a hyperopic shift were observed. A statistically significant increase in the posterior corneal cylinder was observed. Although, not reaching statistical significance, the logMAR uncorrected and corrected visual acuity were improved.

Independent-effect comparison of five crosslinking procedures for Progressive Keratoconus based on Keratometry and the ABCD Grading System using Generalized Estimating Equations (GEE)

“…Corneal haze following CXL has been reported in previous studies [ 41 ], but the reasons remain unclear at present. Potential reasons for this phenomenon are as follows: (1) more severe corneal ectasis caused by the fibroblast proliferation, which is more common in pediatric patients than in adults due to a more active proliferation response than adults [ 42 , 43 ]; (2) the haze could be related to slow spontaneous crosslinking reactions triggered by residual riboflavin in the corneal stroma and UV-A rays in natural light [ 44 ] as two patients had a history of sunlight exposure early in the postoperative period; or (3) endothelial toxicity caused by reduced corneal thickness [ 45 ]. To improve the efficacy of CXL and ensure treatment safety, the High-Fluence Accelerated CXL procedure should be applied to pediatric patients with additional caution.…”

Corneal higher-order aberration changes after accelerated cross-linking for keratoconus

“…Another limitation in our study is that eight of the patients had both of their eyes analysed which could be a source of statistical bias. As corneal biomechanical changes continue for longer than one year after corneal cross-linking [ 26 , 27 ], the relatively short follow-up time is another limitation of this study. The power of the study is influenced by several factors, but as a general rule, higher power is obtained by increasing the sample size.…”

Identification of Treatment Protocols for Effective Cross-Linking of the Peripheral Cornea: An Experimental Study

“…The standard fluence applied with CXL (5.4 J/cm 2 ) is effective in stabilizing the central corneal tissue in most cases [ 22 ]. Yet, when performed on the cornea’s periphery, no significant increases in rigidity (Young’s modulus) could be observed with the protocol A21 (5.4 J/cm 2 ) in this trial (Table 1 ).…”

“…Accordingly, there appears to be a benefit to increasing the fluence to 7.2 J/cm 2 with 100% oxygen or to 10 J/cm 2 in order to achieve a significant effect in terms of biomechanical stability when treating the peripheral 9–11 mm of human corneal tissue. Although long-term studies after CXL in keratoconic eyes showed stability of the disease for up to a decade, long-term trails will have to show if this remains true for cases after peripheral CXL and corneal transplantation [ 22 ].…”