Comparing Pentacam HR Screening Indices in Different Normal Corneal Thicknesses among Refractive Surgery Candidates

Leila Ghiasian; Parya Abdolalizadeh; Ali Hadavandkhani; Acieh Eshaghi; Yasaman Hadi; Fatemeh Nadjafi-Semnani

doi:10.4103/joco.joco_249_21

Comparing Pentacam HR Screening Indices in Different Normal Corneal Thicknesses among Refractive Surgery Candidates

J Curr Ophthalmol. 2022 Jul 26;34(2):200-207. doi: 10.4103/joco.joco_249_21. eCollection 2022 Apr-Jun.

Authors

Leila Ghiasian¹, Parya Abdolalizadeh¹, Ali Hadavandkhani¹, Acieh Eshaghi², Yasaman Hadi¹, Fatemeh Nadjafi-Semnani¹

Affiliations

¹ Eye Research Center, The Five Senses Institute, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
² Department of Ophthalmology, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Abstract

Purpose: To compare Pentacam indices in normal eyes with different corneal thicknesses.

Methods: It is a retrospective observational study. Ninety-six normal eyes of 96 patients who were referred for refractive surgery in a tertiary university-based hospital from October 2015 to April 2019 were recruited consecutively. Corneal keratometry as well as Pentacam's software Belin-Ambrósio Enhanced Ectasia Display (BAD) parameters including pachymetry progression indices (PPIs), maximum Ambrosio's relational thickness (ART-max), corneal elevations, normalized deviations, BAD total deviation value (BAD-D), and anterior surface indices were measured by Pentacam HR (Type 70900). The included were classified as thin (26 eyes), average (45 eyes), and thick (25 eyes) corneas with the thinnest point thickness of ≤496 μm, 497-595 μm, and ≥596 μm, respectively. The specificities of all parameters were calculated based on routine cut-off values.

Results: The refraction, keratometry, and elevations were not different (P > 0.05). All PPIs (minimum, average, and maximum) of thick corneas were significantly lower than average and thin corneas (P < 0.001). ART-max increased by thickening of the cornea (P < 0.001). BAD-D score and normalized indices of pachymetric parameters decreased with the increase of thickness (P < 0.001), while specificities of all indices increased with corneal thickening. More than 96% of thick corneas were classified as normal PPI-max (24/25), ART-max (25/25), and BAD-D (25/25), while nearly <54% of thin corneas (14/26 for PPI-max, 9/26 for ART-max, and 12/26 for BAD-D) were normal.

Conclusions: The pachymetry-related indices and BAD-D were different among normal corneas with various thicknesses. The specificities of PPIs, ART-max, and BAD-D of thin corneas were lower than in thick corneas.

Keywords: Ambrosio's relational thickness; Corneal thickness; Pachymetry progression; Pentacam; Thin cornea.