Agreement between Placido topography and Scheimpflug tomography for corneal astigmatism assessment

DELRIVO MARIANELLA; RUISEÑOR VÁZQUEZ PABLO; GALLETTI JONATÁN; GARIBOTTO MARTÍN; FUENTES BONTHOUX FERNANDO; PFÖRTNER TOMÁS; GALLETTI JEREMÍAS GASTÓN

JOURNAL OF REFRACTIVE SURGERY - (Print)

SLACK INC

Año: 2013

1081-597X

Purpose: To evaluate inter-device agreement between Placido topography (iTrace, Tracey Technologies, Houston, TX, USA) and Scheimpflug tomography (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany) for measuring corneal power and cylinder and axis of astigmatism. Methods: Observational case series of 54 eyes from 54 subjects with no ocular disease. Main outcome measures were corneal power, cylinder power and axis of astigmatism and their agreement was assessed by Bland-Altman analysis. Results: For corneal power and corneal cylinder, 95% limits of agreement (LoA) were considered good (-0.38 to 0.45 D and -0.49 to 0.27 D, respectively). In contrast, the 95% LoA for corneal astigmatism axis exceeded the clinically relevant margins (-14.8 to 13.5): 28 eyes (52%) had a >5º difference, 10 eyes (19%) had a >10º difference and 4 eyes (7%) exhibited a >20º difference between instruments. This absolute difference was significantly correlated with average corneal cylinder (Spearman?s r = -0.379, p = 0.005) but not with average corneal power. In eyes with corneal astigmatism ≥ 2 D, the 95% LoA for axis were -8.7 to 6.7º, whereas in those with corneal astigmatism < 1D, the 95% LoA for axis were -19.1 to 16.6 º. Conclusion: Placido topography and Pentacam show good agreement for corneal power and cylinder, but not for corneal astigmatism axis. Only in eyes with corneal astigmatism ≥ 2 D these instruments could be used interchangeably.