Accutome PachPen handheld ultrasonic pachymeter: intraobserver repeatability and interobserver reproducibility by personnel of different training grades.

To assess the intra-observer repeatability and inter-observer reproducibility of central corneal thickness (CCT) measurements of PachPen (Accutome, Inc., Pennsylvania, USA), a hand-held, portable ultrasonic pachymeter when used by an ophthalmic nurse compared to an ophthalmologist. Ophthalmology Clinic, University of Malaya Medical Center In this prospective study, CCT was measured in 184 eyes of 92 healthy subjects, first by a corneal surgeon experienced in ultrasound pachymetry (Observer 1) followed by an ophthalmic nurse new to the procedure (Observer 2). Nine measurements were obtained from each eye by each observer, independently. Measurements were compared between the observers. Coefficients of repeatability and reproducibility were calculated. The Bland-Altman plot was used to assess agreement between observers. Mean age of the study population was 54.3 ± 15.2 years old and consisted of 43.5% male. Mean CCT as measured by Observers 1 and 2 were 528.3 ± 32.9 and 530.7 ± 33.3 µm, respectively. Observer 1 showed higher repeatability of measurements compared to that of Observer 2 (coefficient of repeatability 3.46 vs. 5.55%). The measurements by both observers showed high correlation (0.96) and good agreement (mean difference -2.4 µm; 95% limits of agreement -21.4, 16.7 µm). Coefficient of reproducibility of measurements between observers was 5.08%. Accutome PachPen hand-held ultrasound pachymeters gives excellent intra-observer repeatability and inter-observer reproducibility by personnel of different training grades.

Central corneal thickness measurements with different imaging devices and ultrasound pachymetry.

PURPOSE: The aim of this study was to compare 4 methods of central corneal thickness (CCT) measurements in terms of their agreement, repeatability, and measurement time. METHODS: CCT was measured in 184 eyes of 92 healthy subjects by the same examiner. The methods used were as follows: noncontact specular microscopy (SM; Topcon SP-3000P; Topcon Corporation, Tokyo, Japan), Pentacam rotating Scheimpflug photography system (Oculus Inc, Wetzlar, Germany), optical low-coherence reflectometry (OLCR; LenStar LS900; Haag-Streit AG, Koeniz, Switzerland), and ultrasound pachymetry (UP; PachPen; Accutome Inc, Malvern, PA). The duration for each examination was measured by an independent observer. RESULTS: The mean age (±SD) of the subjects was 54.3 (± 15.3) years. The mean CCTs (± SD) for SM, Pentacam, OLCR, and UP were 507.8 (± 30.2), 538.4 (± 31.7), 531.8 (± 31.4), and 528.3 (± 32.9) µm, respectively. The Bland-Altman plots showed closest agreement for OLCR-UP, followed by OLCR-Pentacam and Pentacam-UP. SM had the poorest agreement with the other methods. CCTs measured by SM were on average 20 to 30 µm thinner than those of the other methods. The coefficient of repeatability for SM, Pentacam, OLCR, and UP were 3.14%, 4.23%, 1.51%, and 3.46%, respectively. The mean measurement times (± SD) were 13.5 (± 5.7), 45.7 (± 12.3), 18.5 (± 7.1), and 5.6 (± 1.0) seconds, respectively. CONCLUSIONS: CCT measurements between OLCR-UP and OLCR-Pentacam are comparable and can be used interchangeably in clinical practice. However, SM underestimates CCT compared with the other methods, whereas Pentacam was found to be the least repeatable and took the longest time.