Pentacam Scheimpflug Tomography Findings in Chinese Patients With Different Corneal Diameters

To investigate the Pentacam (Oculus Optikgeräte) Scheimpflug tomography findings in Chinese patients with different corneal diameters.

This prospective cross-sectional study included candidates for correction of myopia with normal tomography (ABCD keratoconus grading system, stage 0). The participants were grouped according to their horizontal corneal diameters. Pentacam ectasia detection indices were compared between different corneal diameter-based groups.

A total of 643 eyes were included (corneal diameter ⩽ 11 mm, n = 206; 11 to 12 mm, n = 219; ⩾ 12 mm, n = 218). The corneal powers and the thinnest pachymetry were negatively correlated with corneal diameter (linear regression analysis, P < .001). However, the corneal astigmatism was positively correlated with corneal diameter (R² = 0.03, P < .001). Both the front (FE) and back (BE) elevations were negatively correlated with corneal diameter (FE: R² = 0.027, P < .001; BE: R² = 0.274, P < .001). The three pachymetric progression indices (PPI) (minimum, maximum, and average) were negatively correlated with corneal diameter (PPImin: R² = 0.164, P < .001; PPImax: R² = 0.06, P < .001; PPIavg: R² = 0.158, P < .001). The maximum Ambrósio's relational thickness (ARTmax) also was positively correlated with corneal diameter (R² = 0.031, P < .001). Five normalized indices were negatively correlated with corneal diameter (deviation of normality of the front elevation [Df]: R² = 0.122, P < .001; deviation of normality of the back elevation [Db]: R² = 0.47, P < .001; deviation of normality of pachymetric progression [Dp]: R² = 0.159, P < .001; deviation of normality of relational thickness [Da]: R² = .031, P < .001; Belin/Ambrósio Enhanced Ectasia display: R² = 0.32, P < .001) and Dt was positively correlated with corneal diameter (R² = 0.015, P = .002). Additionally, it was noted that corneal diameter had the greatest influence on Db, Belin/Ambrósio Enhanced Ectasia display (BAD-D), and BE.

Corneal diameter has an influence on the BAD parameters, especially Db, BAD-D, and BE, and therefore should be incorporated as an additional variable in BAD analysis. The analytical dimensions should be individualized for eyes with individual corneal diameter. [J Refract Surg. 2020;36(10):688-695.].