Assessment of Corneal Epithelial Thickness in Dry Eye Patients

Abstract

Purpose To investigate the features of corneal epithelial thickness topography with Fourier-domain optical coherence tomography (OCT) in dry eye patients. Methods In this cross-sectional study, 100 symptomatic dry eye patients and 35 normal subjects were enrolled. All participants answered the ocular surface disease index questionnaire and were subjected to OCT, corneal fluorescein staining, tear breakup time, Schirmer 1 test without anesthetic (S1t), and meibomian morphology. Several epithelium statistics for each eye, including central, superior, inferior, minimum, maximum, minimum – maximum, and map standard deviation, were averaged. Correlations of epithelial thickness with the symptoms of dry eye were calculated. Results The mean (±SD) central, superior, and inferior corneal epithelial thickness was 53.57 (±3.31) μm, 52.00 (±3.39) μm, and 53.03 (±3.67) μm in normal eyes and 52.71 (±2.83) μm, 50.58 (±3.44) μm, and 52.53 (±3.36) μm in dry eyes, respectively. The superior corneal epithelium was thinner in dry eye patients compared with normal subjects (p=0.037),whereas central and inferior epithelium were not statistically different. In the dry eye group, patients with higher severity grades had thinner superior (p = 0.017) and minimum (p < 0.001) epithelial thickness, more wide range (p = 0.032), and greater deviation (p = 0.003). The average central epithelial thickness had no correlation with tear breakup time, S1t, or the severity of meibomian glands, whereas average superior epithelial thickness positively correlated with S1t (r = 0.238, p = 0.017). Conclusions Fourier-domain OCT demonstrated that the thickness map of the dry eye corneal epithelium was thinner than normal eyes in the superior region. In more severe dry eye disease patients, the superior and minimum epithelium was much thinner, with a greater range of map standard deviation.

Age-related differences in corneal epithelial thickness measurements with anterior segment optical coherence tomography

“…It is also interesting that the minimum CET value tends to thin with age, while the maximum CET value does not change with age. The decrease in the minimal CET value and the increased topographic variability have been associated with various pathologic conditions, such as keratoconus [5,31] and dry eye [7,8]. Although patients with these pathologic conditions were excluded from our study, the findings obtained here may have some clinical association with aging.…”

“…Corneal epithelial thickness (CET) has recently drawn increasing attention because it not only plays an active role in determining total corneal power but also manifests structural or functional changes under various conditions, such as keratoconus, contact lens use, dry eye, and limbal stem cell deficiency [1][2][3][4][5][6][7][8][9]. The recent availability of corneal epithelial imaging by optical coherence tomography (OCT) presents a practical tool for clinical in vivo epithelial mapping, with good repeatability in normal and post-LASIK eyes [2,5,10].…”

Correlation of Sex and Myopia With Corneal Epithelial and Stromal Thicknesses

“…11 The distribution of the tear film thickness has been shown to be the reverse of the epithelial thickness profiles because the tear film compensated for the irregularities of the epithelial surface. 29,30 Therefore, a small amount of detail in the CET profiles may be lost by including the tear film in the measurement. 9 The observed epithelial thickness difference may be underestimated in this regard.…”

Advances in dry eye imaging: the present and beyond

“…OCT allows non-contact assessment of a larger corneal epithelial surface, extending up to 6×6 mm. Results of epithelial measurements for DED using OCT however have been contrasting, with reports of augmented epithelial thickness in early-stage subclinical DED,88 while another study demonstrated no difference in the central corneal epithelium but a thinner superior corneal epithelium in DED 89. However, the observed difference of corneal epithelium between DED and healthy subjects is small and approaches the 5 µm maximal resolution limit of most anterior segment OCT devices.…”