White-To-White Corneal Diameter And Effect On Parameters Assessed By Pentacam And Corvis St In Chinese Eyes With Myopia
Published 2023 - 41st Congress of the ESCRS
Reference: PP12.15 | Type: Free paper | DOI: 10.82333/2pnw-hw28
Authors: Li Lim* 1 , Elizabeth Wen Ling Lim 2 , Hla Myint Htoon 3 , Peng Yi Tan 1
1Singapore National Eye Centre,Singapore,Singapore, 2Ministry of Health Holdings,Singapore,Singapore, 3Singapore Eye Research Institute,Singapore,Singapore
Purpose
To study the effect of corneal white-to-white diameter on parameters assessed by Pentacam Scheimpflug cornea tomography and Corvis ST corneal visualization Scheimpflug technology in Chinese Eyes with myopia
Setting
This is a retrospective cross-sectional study performed at Singapore National Eye Centre.
Methods
197 eyes of 197 Chinese myopic patients (low, moderate and high myopes included: spherical equivalent range: -11.00D to -1.25D) who were assessed for refractive surgery using Pentacam and Corvis ST machines were included. Patients were divided into groups based on corneal diameter: Group A <12mm and Group B ³ 12mm. Variables such as age, gender, spherical equivalent, Pentacam variables and Corvis ST variables were collected. The data was statistically analysed with unpaired t tests for continuous variables and chi-square analysis for categorical variables to determine if any statistically significant difference in the means between the 2 groups was present.
Results
Group A had 115 patients and Group B had 82 patients. There was no statistically significant difference in age, gender or spherical equivalence in both groups. For Pentacam data, Group A had significantly higher Belin/Ambrosio Enhanced Ectasia Display (BAD-D) scores (0.98 [Group A], 0.67 [Group B]), pachymetric progression average, steeper K1 (front), K2 (front), Km (front), Kmax (front), whereas Group B had larger anterior champer depth and Maximum Ambrosio relational thickness (ARTmax) (444.43 [Group A], 471.98 [Group B]). For Corvis ST data, Group A had a significantly higher corneal biomechanical index (CBI) while Group B had a higher Ambrosio relational thickness to the horizontal profile (ARTh) (462.04 [Group A], 514.72 [Group B]).
Conclusions
Corneal diameter has an influence on both Pentacam and Corvis ST parameters, with smaller corneal diameters having a higher BAD-D and a lower ARTmax and ARTh. As refractive surgery evaluation relies heavily on these biomechanical indices, taking corneal diameter into account would improve both sensitivity and specificity in pre-refractive surgery screening for ectasia/keratoconus.