The Association between Tear Film Thickness as Measured with OCT and Symptoms and Signs of Dry Eye Disease: A Pooled Analysis of 6 Clinical Trials

Gerhard Garhöfer,René M Werkmeister,Doreen Schmidl,Valentin Aranha Dos Santos,Narine Adzhemian,Hannes Stegmann,Leopold Schmetterer

doi:10.3390/jcm9113791

Abstract

Purpose: To determine the association between tear film thickness (TFT) as measured with ultra-high resolution optical coherence tomography (UHR-OCT) and signs and symptoms of dry eye disease (DED). Methods: A total of 450 eyes from 225 patients with DED from six different randomized clinical trials were included in this pooled analysis. In all subjects, TFT was measured with a custom-built UHR-OCT system. Symptoms of DED were quantified using a standardized Ocular Surface Disease Index (OSD)I questionnaire and clinical signs including tear film break up time (TFBUT) and Schirmer I test were assessed. Associations of the average TFT with OSDI, TFBUT, and Schirmer I test were calculated using a linear regression analysis. Results: The average TFT of the included sample (mean age, 45.0 ± 13.3 years; 65% female) was 4.2 ± 0.5 µm and the OSDI 36.2 ± 10.4. A significant negative correlation was found between TFT and OSDI (r = −0.36 to −0.31; p < 0.001). Tear break up time and Schirmer I test were not correlated with OSDI. Significant albeit weak correlations were found between TFT and TFBUT (r = 0.17 to 0.25; p < 0.01) as well as Schirmer I (r = 0.36 to 0.37; p < 0.001). Subgroup analysis revealed that the correlation was stronger in the subjects with abnormal Schirmer I (<15 mm; r = 0.50 to 0.54; p < 0.001). Conclusions: The present study demonstrates an objective measurement of TFT using a novel OCT approach for DED that correlates with symptoms and signs of DED. Our data are consistent with the idea that TFT represents the aqueous-deficient component of DED.

Highlights

Dry eye disease (DED) is a highly prevalent ocular condition that is characterized by alterations in the homoeostasis of the precorneal tear film and the ocular surface [1,2,3,4]
We recently reported in a small cross-sectional study a correlation between tear film thickness (TFT) and symptoms of DED using the Ocular Surface Disease Index (OSDI) as well signs of DED such as tear film break-up-time (TFBUT) and tear osmolarity [23]
The severity of DED ranged from mild to moderate with an average OSDI of 36.2 ± 10.4

Summary

Introduction

Dry eye disease (DED) is a highly prevalent ocular condition that is characterized by alterations in the homoeostasis of the precorneal tear film and the ocular surface [1,2,3,4]. Direct visualization and quantification of the most important component in DED, namely the tear film, are valuable for both diagnosis and follow up. Given that the total thickness of the human tear film is thin, ranging between 3 and 5 micrometers over the central cornea, quantification of tear film thickness (TFT) and its components requires highly sophisticated technical approaches [11]. These include classical interferometry based methods, by which TFT measurements can be achieved via thickness-dependent fringes, angle-dependent fringes or wavelength-dependent fringes [12,13,14], thermal imaging [15], and others [16]

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