Interdevice variability of central corneal thickness measurement

Abstract

PurposeTo evaluate variability of central corneal thickness measurement (CCT) devices using a hitherto unprecedented number of CCT devices.MethodsCCT was measured consecutively in 122 normal corneas of 61 subjects with seven different devices using three distinct measurement technologies: Scheimpflug, Ultrasound, and Optical Coherence Tomography (OCT). Per device deviation from the mean CCT value per eye was used to determine which of the devices performed best, compared to the mean value.ResultsCirrus OCT yielded the lowest deviation. Deviations of the individual devices from the mean CCT of each eye were (OS/OD) 12.8±5.0/14.9±9.4 μm for Topcon noncontact specular microscopy (NCSM), 11.3±5.9/10.6±7.3 μm for Pentacam, 10.7±5.2/10.4±4.8 μm for Spectralis OCT, 6.0±3.9/6.2±4.9 μm for Topcon DRI OCT, 5.1±3.4/5.9±10.3 μm for AngioVue OCT, 4.8±4.1/5.7±4.6 μm for US pachymetry, and 4.2±3.2/5.7±4.6 μm for Cirrus OCT. The maximum differences between US pachymetry and the other devices were very high (up to 120 μm).ConclusionCentral corneal thickness may be under- or overestimated due to high interdevice variations. Measuring CCT with one device only may lead to inappropriate clinical and surgical recommendations. OCT showed superior results.

Investigation of predictability and influence factors of the achieved lenticule thickness in small incision lenticule extraction

“…The results suggest that the Pentacam overestimate in high value and underestimate in low value with respect to the ultrasound pachymetry. Similar results have been recently reported by peter et al [20] (95% LoA: − 2.7 to 31.6).…”

Comparison of corneal thickness measurements using ultrasound pachymetry, noncontact tonopachy, Pentacam HR, and Fourier-domain OCT

“…Other studies have also found that non-contact specular microscopes underestimated CCT compared to USP. [ 16 , 17 ] Taken together, these outcomes imply the importance of scrutinizing corneal thickness measurements using non-contact pachymetric machines. In this study, TP used the Scheimpflug imaging principle to measure corneal thickness.…”

Measurement of corneal thickness using Pentacam HR versus Nidek CEM-530 specular microscopy

“…We compared the Oculus Pentacam HR and the Nidek CEM-530 SM because these two devices do not require corneal contact and because both the Pentacam 11 , 15 , 18 – 22 and Nidek 23 , 24 have been singularly compared with other devices. Among these comparisons, only a few have involved a Scheimpflug camera versus SM devices 15 , 18 – 20 and only one has involved a Scheimpflug camera versus the Nidek CEM-530.…”

“…Similarly, Maloca et al. 20 compared the Oculus Pentacam version 1.19r11 with the noncontact SP-1P specular microscope, version 1.21 (Topcon Corporation) and found that the latter produced thinner central CT measurements.…”

“…We compared the Oculus Pentacam HR and the Nidek CEM-530 SM because these two devices do not require corneal contact and because both the Pentacam 11,15,[18][19][20][21][22] and Nidek 23,24 have been singularly compared with other devices. Among these comparisons, only a few have involved a Scheimpflug camera versus SM devices 15,[18][19][20] and only one has involved a Scheimpflug camera versus the Nidek CEM-530. 25 We did not make a comparison with UP because it requires contact, may be uncomfortable for patients, and may damage the corneal epithelium with potential corneal infection; additionally, the measurement reproducibility depends on the examiner's expertise in placing the probe.…”