Purchase this article with an account.
H. Zhuang, J. Xu; A Novel Method for Pachymetry Mapping of Human Precorneal Tear Film Using Pentacam With Fluorescein. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3695.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To report a novel method for pachymetry mapping of human precorneal tear film using Pentacam with fluorescein.
Precorneal tear film is undetected by Pentacam Scheimpflug imaging routinely that measures corneal thickness from corneal epithelium to endothelium. Fluorescein could help visualize tear film under Pentacam rotating Scheimpflug camera through altering the optical property of tear film (Figure 1A, 1B). Corneal pachymetric measurement includes the full thickness of visulized tear film after fluorescein application. Therefore, the differential map of corneal thickness between two measurements (with and without fluorescein) using Pentacam is identified as the pachymetry map of precorneal tear film. Thirty healthy volunteers were recruited for this prospective study. Right eye of each subject was scanned once with Pentacam and rescanned 5 minutes after applying fluorescein. Internal software in Pentacam system could generate pachymetry map of tear film through comparison of two corneal pachymetry map of each eye (Figure 2A, 2B, 2C). Evaluated Tear film thickness (TFT) at corneal apex and in the periphery (Superior, Inferior, Nasal, Temporal with diameter 6mm) respectively.
The mean central TFT was 32.27 ± 3.80 µm, and Superior 34.37 ± 7.33 µm, Inferior 28.83 ± 7.18 µm, Nasal 29.87 ± 6.93 µm, Temporal 32.40 ± 7.44 µm respectively. Inferior tear film was significantly thinner than superior tear film (paired t-test, P =0.0060), and central TFT was intermediate between those two; Nasal tear film tended to be thinner than temporal tear film, although this was not statistically significant (paired t-test, P =0.1331). Additionally, wide individual variability of TFT was found in our study, and the coefficient of variance was even greater towards the periphery.
The novel method feasibly could be used to map the TFT across the entire cornea as a noninvasive, high-resolution and convenient examination. Thus, it provides a valuable means to investigate the spatial distribution of overall precorneal tear film.
This PDF is available to Subscribers Only