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

Asaf Achiron*, Roy Yavnieli, Hagar Olshaker, Eliya Levinger, Raimo Tuuminen, Eitan Livny, Uri Elbaz, Irit Bahar, Yoav Nahum

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)2665-2671
Number of pages7
JournalInternational Ophthalmology
Volume42
Issue number9
DOIs
StatePublished - Sep 2022

Funding

FundersFunder number
Finnish Ophthalmological Society
Silmäsäätiö

    Keywords

    • Cross-linking
    • D-index
    • Keratoconus
    • Pentacam

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