Comparing Pentacam HR variation Indices in different Normal Corneal Thickness

Leila Ghiasian1 *

  1. Eye Research Center, The Five Senses institute, Rassoul Akram Hospital, Iran university of medical Science, Tehran, Iran

Abstract: To compare Pentacam ectasia detection indices in normal eyes with different corneal thicknesses.

Methods: In a prospective study, 218 normal eyes of 109 patients were recruited consecutively who referred to a tertiary university-based hospital for refractive surgery from October 2015 to April 2019. Corneal keratometries 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, Pentacam, Oculus, Germany). Included were classified as thin (56 eyes), average (105 eyes) and thick (57 eyes) corneas with thinnest point thickness ≤496µm, 497-590µm and ≥591µm respectively. The specificities of all parameters were calculated based on routine cut-off values.

Results: The age, refractive error, keratometry values, corneal elevations, and anterior surface indices were not different among three groups (P-values>0.05). All PPIs (minimum, average and maximum) of thick corneas were significantly lower than average and thin corneas (P-values<0.001). ART-max increased by thickening of the cornea (P<0.001). BAD-D score and normalized indices related to pachymetric parameters decreased by increasing the corneal thickness (P-values<0.001). The specificities of all indices were increasing by increasing the corneal thickness. More than 90% of thick cornea were classified as normal PPI-max, ART-max and BAD-D while nearly less than 50% of thin corneas were normal.

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