Central corneal thickness measurements using Orbscan II, Visante, ultrasound, and Pentacam pachymetry after laser in situ keratomileusis for myopia

Abstract

Pentacam and Visante measurements of corneal thickness 6 months after LASIK were significantly less than those obtained using Orbscan and US pachymetry, although all 4 measurement methods showed a high correlation with each other.

Assessment of central corneal thickness in normal, keratoconus, and post-laser in situ keratomileusis eyes using Scheimpflug imaging, spectral domain optical coherence tomography, and ultrasound pachymetry

“…There is also the risk for corneal epithelial damage and transmission of infections. 3 In addition, measurements can vary as a result of probe misalignment or decentering and the probe may not be perpendicularly aligned or may be inaccurately positioned because of a lack of fixation and gaze control. Other disadvantages include the estimation of the thickness of a single point with each contact and changes in the speed of sound in corneal tissues with different degrees of hydration.…”

Comparison of central corneal thickness measurements by Orbscan II and Pentacam after corneal refractive surgery

“…[14][15][16][17] To the best of our knowledge, only one comparison of the measurements of postoperative CCT by these two devices has been published. 18 Although reports show that scanning-slit corneal topography/pachymetry underestimates CCT in eyes after excimer laser keratorefractive surgery, [14][15][16][17] the accuracy of CCT measurements using the rotating Scheimpfl ug camera is still unclear. Since biomechanical stability of the cornea after excimer laser surgery depends on residual corneal thickness, postoperative pachymetry is very important, especially in candidates for enhancement surgery.…”

Agreement of non-contact pachymetry after LASIK: comparison of combined scanning-slit/Placido disc topography and specular microscopy

“…Finally, ultrasonic pachymetry was not performed in the study eyes, thus precluding direct comparison of both non-contact methods with the gold standard in order to find out which of the two is closer to the 'true' value. However, such a comparison has already been extensively reported, 2,3,5,10,27,31,36,37 and has been included in the discussion of our results with those of previously published studies.…”

“…Thus, although the devices were calibrated appropriately, an acoustic factor was changed 10 or a subtraction method applied, 36 one cannot reliably replace the other. A tendency and a systematic bias also were described when each scanning-slit and specular pachymetry, respectively, were previously compared with ultrasonic pachymetry in patients who underwent LASIK.…”