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. 2022 Sep;42(9):2665-2671.
doi: 10.1007/s10792-022-02255-z. Epub 2022 Apr 5.

Validation of the multi-metric D-index change in the assessment of keratoconus progression

Asaf Achiron  1   2 , Roy Yavnieli  3   4 , Hagar Olshaker  4   5 , Eliya Levinger  4   5 , Raimo Tuuminen  6   7 , Eitan Livny  3   4 , Uri Elbaz  3   4 , Irit Bahar  3   4 , Yoav Nahum  3   4
Affiliations

Validation of the multi-metric D-index change in the assessment of keratoconus progression

Asaf Achiron et al. Int Ophthalmol. 2022 Sep.

Abstract

Purpose: To validate the effectiveness of the multi-metric D-index by Pentacam in detecting keratoconus (KC) progression.

Materials and methods: This was a retrospective study of KC patients at the Rabin Medical Center, Petah Tikva, Israel, during 2016-2018 with at least two corneal tomography examinations six months apart. Agreement between clinical diagnosis of progression (1.5D increase in mean keratometric value, 1D increase in Kmax, a 5% decrease in central corneal thickness (CCT), worsening of visual acuity by more than one line, or deterioration of manifest corneal astigmatism > 1.5D) and the D-index was evaluated. Receiver operating characteristic (ROC) analysis was used to find the D-index's optimal cutoff value to show progression.

Results: We included KC eyes in the stable group (N = 7) and the progression group (N = 54). Patient demographics and tomographic parameters at baseline were similar between the groups. The D-index change was significantly higher in the progression group than in the stable group (median + 1 and 0.0, respectively, p = 0.024). Based on the ROC analysis, the optimal D-index cutoff change within at least six months was 0.32 (59.3% sensitivity and 100% specificity (area under the curve [AUC] = 0.771, Youden = 0.592). Subjects with a D-index change above this value had a 21.1-fold increase in odds for corneal ectasia progression requiring CXL (OR: 21.1, 95%CI 1.17-398.8, p = 0.038).

Conclusion: The multi-metric D-index can serve as a clinically feasible parameter to detect KC progression and guide patients' referral for further interventions.

Keywords: Cross-linking; D-index; Keratoconus; Pentacam.

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References

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