Pachymetric measurements with a new Scheimpflug photography-based system: intraobserver repeatability and agreement with optical coherence tomography pachymetry.
OBJECTIVE
To evaluate the intraobserver repeatability of pachymetric measurements obtained with a new Scheimpflug photography-based system and the agreement of the measurements with those obtained by optical coherence tomography (OCT).


METHODS
Vissum Corporation, Alicante, Spain.


METHODS
Evaluation of diagnostic technology.


METHODS
Corneal thickness was measured at different locations (center; 2.5 mm and 4.0 mm nasal, temporal, superior, and inferior) in 18 eyes of 18 patients with no ocular pathology or previous surgery with a Scheimpflug photography-based system (Sirius). Three consecutive measurements at each location were obtained with the system to evaluate intraobserver repeatability. Afterward, pachymetric measurements were obtained at the same locations with an OCT system (Visante) to evaluate the agreement between techniques using the Bland-Altman method.


RESULTS
The intraclass correlation coefficient of repeated measures ranged from 0.990 to 0.997. The coefficient of variation was lower than 1% and the standard deviations of the repeated measurements (S(w)) were below 6 μm at all corneal locations. Statistically significant differences were found between the coefficient of variation and S(w) values of the repeated measurements corresponding to the 2.5 mm and 4.0 mm locations (P ≤ .037). The agreement with OCT pachymetric measurements was poor, with ranges of agreement larger than 20 μm at all corneal locations. Statistically significant differences were found between standard deviations of the differences between the 2 devices at the 2.5 mm and 4.0 mm locations (P ≤ .017).


CONCLUSIONS
Scheimpflug photography-based technology provided repeatable pachymetric measurements that were not equivalent to those obtained with OCT.
Vissum Corporation-Instituto Oftalmológico de Alicante, Universidad de Alicante, Alicante, Spain.
Myriam
M
Milla
David P
DP
Piñero
Francisco
F
Amparo
Jorge L
JL
Alió
D000328:Adult; D003315:Cornea / Q000033:anatomy & histology*; D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D010781:Photography; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence; D055815:Young Adult