Purpose To compare the repeatability of central corneal thickness (CCT) measurements taken with a new hand-held pachymeter (Occuity PM1 Pachymeter) and to assess its agreement with ultrasound biometry and two commercially available optical biometers in participants with normal eyes.

Methods Three consecutive CCT measurements of the right eye of 105 participants with normal corneas were acquired by the PM1 pachymeter, Lenstar LS900 and Oculus Pentacam HR in a random order. This was followed by three measurements with a hand-held ultrasound pachymeter (UP) (Pachmate-2). Repeatability and the repeatability limit were calculated with each device and Bland-Altman limits of agreement (LoA) were determined for the PM1 pachymeter compared to the other devices.

Results The mean CCT (±SD) was 551.04±33.43 μm, 558.62±31.46 μm, 549.41±31.00 μm, and 539.73±29.50 μm for the PM1 pachymeter, UP, Lenstar and Pentacam, respectively. The repeatability limits (expressed as the within subject SD for repeat measurements) were 14.02, 13.68, 4.99 and 9.90 μm respectively. The closest agreement was between the PM1 and Lenstar (mean difference = 1.63 μm with LoA 10.72 μm below and 13.97 μm above the readings obtained with the Lenstar. The PM1 underestimated CCT compared to UP (mean difference = 7.58 μm, LoA 24.63 μm below and 9.47 μm above UP. The agreement was lowest between the PM1 and Pentacam (mean difference= -11.30 μm, LoA between 4.29 μm and 26.89 μm).

Conclusions The PM1 pachymeter shows excellent precision for CCT measurements across a range of corneal thicknesses in normal eyes and provides a safe and easy to use alternative to ultrasound pachymetry.

Key points

Measurement of central corneal thickness (CCT) is an important clinical measurement in the diagnosis and management of glaucoma and certain corneal dystrophies, it also provides useful information prior to refractive surgery

The Occuity PM1 pachymeter is a new hand-held non-contact perimeter that uses confocal technology to measure CCT. The device showed excellent precision for CCT measurements across a range of corneal thicknesses in normal eyes

The PM1 pachymeter provides a safe and easy to use alternative to ultrasound pachymetry that could facilitate an increased uptake of pachymetry in routine optometric practice

The authors have declared no competing interest.

The work ws supported by Occuity Ltd

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study conformed to the tenets of the Declaration of Helsinki and was approved by the School of Health and Psychological Sciences Research and Ethics Committee (REC reference: ETH2021-1765)

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Data availability statement: Data available on request Funding statement: The work was supported by Occuity Ltd

Conflict of interest disclosure: The authors have no proprietary interest in any of the materials mentioned in this article.

Ethics approval statement: The study conformed to the tenets of the Declaration of Helsinki and was approved by the School of Health and Psychological Sciences Research and Ethics Committee (REC reference: ETH2021-1765)

Patient consent statement: Written informed consent was obtained from all participants

All data produced in the present study are available upon reasonable request to the authors