# Tear meniscus height comparison between AS-OCT and Oculus Keratograph® K5M

## TL;DR

This study compares two devices for measuring tear meniscus height and finds they agree well, even with contact lens wear.

## Contribution

The study demonstrates the interchangeability of AS-OCT and Oculus K5M for tear meniscus height measurements in clinical settings.

## Key findings

- AS-OCT and Oculus K5M showed good agreement in measuring tear meniscus height.
- Contact lens wear slightly reduced tear meniscus height but returned to baseline after adaptation.
- Bland-Altman analysis confirmed clinically acceptable agreement between the two devices.

## Abstract

To evaluate the agreement between Spectral-Domain Optical Coherence Tomography (AS-OCT) and Oculus Keratograph® 5M in measuring tear meniscus height (TMH) and to assess the impact of contact lens wear on these measurements. Materials and methods: TMH was measured in 54 healthy eyes using AS-OCT (3D OCT-1 Maestro, Topcon, Tokyo, Japan) and Oculus Keratograph® 5M (OCULUS Optikgeräte, Wetzlar, Germany), with and without contact lens wear. Bland-Altman analysis was used to assess agreement between the two devices. Delefilcon A, water-gradient, daily disposable contact lenses were used, and measurements were carried out after a 20-minute adaptation period.

The means of TMH without the contact lenses were 0.21 ± 0.06 mm and 0.20 ± 0.05 mm obtained from AS-OCT and Oculus K5M, respectively, and these measurements were not statistically significant (t (53) = 0.99, p = 0.33). No significant differences were observed in TMH compared to contact lenses (t (53) = 1.52, p = 0.13). Agreement between measurements obtained by both the instruments was assessed using Bland-Altman analysis. The limits of agreement were within clinically acceptable ranges (0.10 mm - 0.15 mm), with no evidence of significant bias (t = -0.32, r = 0.22). The results obtained with contact lenses were also not statistically significant (t (53) = 1.52, p < 0.05).

The present study compared tear meniscus height (TMH) measurements obtained from AS-OCT and Oculus K5M in subjects with and without contact lens wear. Both instruments showed good agreement, with AS-OCT consistently measuring slightly higher TMH values than Oculus K5M. The mean TMH values were similar to those of previous studies, indicating normal tear film in the subjects. Contact lens wear was found to reduce TMH slightly, but it returned to baseline after a short adaptation period. The Bland-Altman analysis confirmed good agreement between the two instruments, with most data points falling within the limits of agreement. These findings suggest that AS-OCT and Oculus K5M can be reliable tools for measuring TMH and can be used interchangeably for clinical practice.

AS-OCT and Oculus Keratograph® 5M showed comparable results in measuring TMH, suggesting potential interchangeability in clinical practice. Further validation in broader clinical settings and diverse subject groups may be warranted.