Assessment of the Tomographic Values in Keratoconic Eyes After Collagen Crosslinking Procedure

Abstract

Goal:This study aimed to investigate the differences in values of K1 and K2 readings, the central corneal thickness (PAH) before the collagen crosslinking procedure (CXL) and 3, 6, 12 months later.Methods:64 eyes were evaluated in retrospective cross sectional study. The corneal biomechanical parameters were taken with WaveLight Allegro Oculyzer produced by Alcon before the CXL, 3,6, 12 months after the procedure. The curvature of K1 reading and K2 reading were taken and the central corneal thickness were considered due to the time after CXL.Results:The value of K1 reading before the treatment was 48.8 diopters (D) (46.65-50.50) and was statistically significant lower comparing to the value of K1 3 months after the collagen CXL procedure 46.30 D (43.57-49.45) (p=0.0006), K1 reading one year post collagen CXL procedure was 47.20 D (44.35-50.07) (p=0.002). The value of K2 reading before the collagen CXL procedure was 52.65 D (47.55-54.72), 3 months after the procedure was 51.4 (45.05-54.0), 6 months later 48.55 D (47.20-50.62), 12 months later 51.30 D (47.22-54.77). There is statistically significant lower value of K2 reading 6 months after the treatment comparing to the values 3 months postoperatively (p=0.014). However there is significantly lower values of K2 reading 12 months postoperatively comparing to preoperative period (p=0.006). The value of central corneal thickness preoperative was 431.0 microns (398.0-446.25), 3 months after collagen CXL procedure was 373.50 microns (363.25-430.75), 6 months later 435.0 microns (360.0-464.75), 12 months after the CXL procedure was 429.50 microns (357.75-496.25). There is statistically significant lower values of central corneal thickness 3 months after collagen CXL treatment comparing to the central corneal thickness preoperative (p<0.005). There is statistically significant lower values of pachymetry 12 months after the CXL procedure comparing to the values 6 months later (p=0.036) and those preoperativelly (p=0.032). There is no statistically significant difference in the values of central corneal thickness in the period from 3 and 6 months postoperatively.Conclusion:After riboflavin-UVA CXL in eyes with keratokonus there was significant decrease in central corneal thickness 3 and 6 months after the procedure and the thickness is almost the same 12 months. However, K2 (Kmax) reading is significantly changed 3 and 6 months later and is followed by changing of K1 reading.

Predictive Factors of the Standard Cross-linking Outcomes in Adult Keratoconus: One-Year Follow-Up

“…It is assumed that the changes in corneal thickness with the time is a sign of the disease progression of KC [ 24 ]. After CXL, corneal pachymetry becomes regularly thinner, so limiting corneal thickness role to document the early disease progression [ 25 ]. Therefore, it is hard to conclude the post-CXL thinning either due to the disease progression or CXL impacts.…”

Assessing progression of keratoconus: novel tomographic determinants

“…Visual acuity methods are very variable, as many practitioners have seen how unpredictable these subjective measurements can be in a keratoconic patient [ 36 ]. Corneal thickness measurements are typically altered (thinned) after crosslinking, thus limiting its value to document progression as well [ 41 ] (Table 1 ).…”

Assessing Progression of Keratoconus and Cross-linking Efficacy: The Belin ABCD Progression Display

“…Visual acuity methods are very variable 36 and corneal thickness measurements are typically altered (thinned) after cross-linking, limiting its value to document treatment efficacy as well. 41 It has been suggested that tomographic-derived pachymetry may be a more valuable method to document ectatic disease and follow progression. 32,42 Furthermore, changes in posterior corneal curvature [32][33][34] and corneal asymmetry have been shown to be additional methods of detecting early disease progression.…”