Purpose:
To compare the Haag-Streit OLCR Pachymeter with the Zeiss ACMaster for measuring central corneal thickness (CCT) in high myopia and after myopic LASIK.
Methods:
CCT was measured in 55 eyes of 30 myopic subjects (spherical equivalent refraction from -5.25 to -10.75 diopters, D) and in 37 eyes of 21 patients following LASIK for high myopia (preoperative spherical equivalent refraction between -6.0 and -10.75 D). Measurements were performed using the Haag-Streit OLCR pachymeter and the Zeiss ACMaster. A group refractive index of 1.376 was used for the OLCR, while the default refractive index of 1.3851 was used for the ACMaster. Thickness measurements were compared using paired t-tests, Pearson’s correlation, and Bland-Altman plots.
Results:
In highly myopic subjects the CCT measured 531 ± 28 µm using the OLCR and 533 ± 27 µm using the ACMaster (P < 0.01). The two methods were closely correlated (r = 0.99, P < 0.001) and no systematic variations were identified (figure). In LASIK treated eyes, the average CCT measured 472 ± 24 µm using the OLCR and 475 ± 23 µm using the ACMaster (P<0.01). Measurements were closely correlated (r = 0.99, P<0.001) and without systematic variations (figure).
Conclusions:
CCT measurements in highly myopic subjects and after myopic LASIK were very similar with the Haag-Streit OLCR pachymeter and the Zeiss ACMaster. Thus, using the current group refractive indices, the OLCR and the ACMaster may be used interchangeably for assessment of CCT, also in LASIK treated patients.
Keywords: cornea: clinical science • refractive surgery