## 4 Discussion
In addition, no correlations were observed for TMH between both devices, and the Passing-Bablok analyses showed dots with a disperse distribution without any apparent relationship. Thus, these findings revealed a poor agreement for TMH measurements between the E300 and VX120+. To our knowledge, there are not previous studies investigating the TMH agreement between either the E300 or the VX120+ and another device. However, previous authors have reported limitedconcordance in TMH outcomes measured with other advanced technologies in healthy eyes. Particularly, [PERSON] et al. [23] and [PERSON] et al. [24] found poor agreement between optical coherence tomography (OCT) and Keratography. Similarly, the TMH measures reported by [PERSON] et al. [25] demonstrated a poor agreement even between two OCT devices with Swept-Source and Fourier-Domain Optical technologies, respectively. Therefore, the TMH measurement has been repeatedly reported not to be interchangeable between different devices in the scientific literature. Despite that, the TMH could be less influenced by the differences previously described for the NIBUT measurements, the topographer cone size and, consequently, the distance device-eye could increase the variability in TMH between devices. Additionally, the quality of the images (dependent on the capture image device incorporated) and the tool used for TMH estimation (dependent on the incorporated software) were specific to each instrument. Furthermore, the greatest difference in the TMH measurement between E300 and VX120+ is the light reflection used to visualize the tear meniscus: whereas the E300 provides a reflection along the tear meniscus border, the VX120+ captures a punctual circle reflex representative of the whole meniscus height. Although the influence of each factor is unknown, the combination of all of them might be the consequence of the limited agreement found. The main limitation of the present study could be the modest sample size. However, the numerous significant results obtained support that the power reached in this work has been high enough; the only exception was the lack of significance between NIBUT and 50%NIBUT obtained with the E300 and VX120+, respectively, in right eyes. Nonetheless, the difference found follows the same tendency as left and both eyes (higher median for the NIBUT measured with E300). Thus, enlarging the sample size would not provide different valuable results. In addition, the fact that a single measurement was performed by each instrument could be considered as a limitation. Nonetheless, our methodology was established once the repeatability of both devices for dry eye parameters was previously demonstrated [7, 8]. In conclusion, the Medmont E300 and Visionix VX120+ measurements of NIBUT and TMH are not interchangeable. Therefore, clinicians should consider the intrinsic peculiarities of both devices and the resulting interpretations of each parameter in order to better adapt it to the clinical practice for DED diagnosis. In addition, future clinical investigations are recommended for establishing normal and pathological values and the cut-off of NIBUT and TMH for both instruments. Conceptualization, E.M.-P. and D.P.P. ; methodology, E.M.-P. and A.M.-M.; investigation, E.M.-P. and A.M.-M.; resources, D.P.P. ; writing--original draft preparation, E.M.-P.; writing--review and editing, D.P.P. and A.M.-M.; supervision, D.P.P. ; project administration, D.P.P. ; funding acquisition, D.P.P. All authors have read and agreed to the published version of the manuscript. The author [PERSON] has been supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramon y Cajal, RYC-2016-20471. This research received no external funding. [PERSON] has been supported by European Union-NextGenerationEU. The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of the University of Alicante (protocol code UA-2022-01-20_2 and 3 February 2022) for studies involving humans.