Progression Analysis With ABCD Grading System Following Corneal Collagen Cross-Linking in Keratoconus

Abstract

To evaluate the ABCD grading system used in follow-up of keratoconus progression after the corneal collagen cross-linking (CXL) treatment in different Kmax groups. Methods: This study included 57 eyes of 43 patients applied with CXL treatment for progressive keratoconus. All the patients were applied with the standard CXL protocol (Dresden). According to the changes in the Kmax value at the end of 12 months postoperatively (0-1D, 1-2D, >2D), the groups were separated as steepening and flattening. Scheimpflug progression parameters, such as ABCD keratoconus grading systems, were evaluated in six different groups. The Paired Samples t-test was used in the evaluation of parameters with normal distribution and the Wilcoxon test for parameters not showing normal distribution. A value of p<0.05 was accepted as statistically significant. Results: Mean age of patients was 18.37±3.86 years (11-28 years). According to the ABCD grading system, 0.19 significant regression was determined in grade A (p=0.014) and 0.24 in grade D (p<0.0001). 0.10 progression was seen in grade B (p=0.089), and 0.11 in grade C (p=0.011). In the mean Kmax value 0.25±0.42, D flattening was seen (p=0.137). Conclusion: The anterior corneal surface grade in ABCD system is correlated with Kmax in different groups. However, the posterior corneal surface parameter is not correlated with Kmax in 1-2 D steepening and >2D flattening groups. Although there is an increase in posterior elevation after CXL, despite excessive Kmax flattening, it would be inaccurate to consider this increase as an indicator of topographic progress.

Short-Term Effect of Conventional Versus Accelerated Corneal Cross-Linking Protocol on Corneal Geography and Stability

“…Saglik et al found a regression in parameter A in the one-year post-standard procedure follow-up, as in the CXL30 group in the present study. Other parameters showed similar trends to the current study [ 39 ]. However, they found a significant positive correlation between the change in Kmax values and parameter A.…”

“…In the literature, only a few studies evaluated the applicability of the ABCD staging system in monitoring the efficacy of the standard procedure. In contrast, only one recently published retrospective study investigated its utility in evaluating accelerated protocols and compared the effectiveness of different protocols regarding the ABCD grading system [ 8 , 39 , 40 , 41 , 42 , 43 ]. Danesh and coauthors showed no significant changes in parameters A and D, while parameters B and C significantly increased one year after conventional CXL [ 8 ].…”

Assessment of the postoperative effect of corneal cross-linking on keratoconus using the ABCD grading system

“…Sağlık et al . [ 21 ] showed significant regression in parameter A 1 year after CXL, which coincides with the results of Bardan,[ 16 ] but differs from the results of the current study. Bardan et al .…”

“…The flattening of Kmax, which was shown in many previous studies, was not noticed in ours, although it should be emphasized that the values of Kmax remained stable over time. [ 16 21 23 ]…”

The ABCD grading system in assessment of corneal cross-linking effect in keratoconus with different cone locations

“…There have been many reports of increased posterior elevation after CXL. 27 , 29 It is suggested that posterior steepening along with anterior flattening may be the cause for the stabilisation of keratometric values after CXL. 29 Other study found no significant changes in posterior elevation after CXL.…”