Corneal epithelial opacity in dysfunctional tear syndrome

Abstract

Purpose: To compare the appearance of the superficial corneal epithelium in patients with dysfunctional tear syndrome (DTS) and that of an asymptomatic control group using laser scanning confocal microscopy and to determine the correlations between confocal microscopic findings and clinical severity parameters.

Design: Prospective case-control study.

Methods: Thirty-one patients with newly diagnosed DTS and 21 asymptomatic control subjects were evaluated for this study. Subjects with DTS were classified into 4 levels of clinical severity (DTS 1 through 4) based on the Delphi dry eye panel report criteria. The Heidelberg Retina Tomograph 2 Rostock Cornea Module (Heidelberg Engineering GmbH, Heidelberg, Germany) laser scanning confocal microscope was used to image the superficial corneal epithelium. Areas of single or multiple opaque superficial epithelial cells were measured as a percentage of the 400 x 400-microm(2) field area in 4 randomly selected confocal images from each eye. Spearman correlations between the confocal findings and severity of symptoms, visual acuity, and ocular surface signs were calculated.

Results: The mean area of opaque superficial corneal epithelial cells was significantly greater in DTS patients than in normal subjects (P < .0001). Significant differences were observed between the DTS severity groups and the control group (P < .001), except for the DTS 1 group. The area of opaque cells significantly increased with level of clinical severity. The confocal findings showed significant correlation with clinical severity parameters, including blurred vision symptoms (r = 0.86; P = .0001), best-corrected visual acuity (Spearman r = 0.4; P = .03), conjunctival lissamine green staining scores (Spearman r = 0.4; P = .026), corneal fluorescein staining scores (Spearman r = 0.5; P = .002), and videokeratoscopic surface regularity index (Spearman r = 0.5; P = .02).

Conclusions: Morphologic changes in the superficial corneal epithelium of DTS patients detected by laser scanning confocal microscopy correlates with blurred vision symptoms and objective severity parameters. Objective confocal image analysis of the superficial corneal epithelium may prove useful for classifying DTS severity and for monitoring the efficacy of therapies.

Figure 1

Corneal epithelial opacity in dysfunctional tear syndrome and Asymptomatic Controls. The total area of opaque cells in the superficial epithelium, were outlined and measured in square microns using the Image J analysis software.

Figure 2

(Left) Corneal epithelial opacity in superficial corneal epithelium of a 46 year old asymptomatic control female.(Right) corneal epithelial opacity in superficial corneal epithelium of a 44 year old female patient with level 3 dysfunctional tear syndrome.

Figure 3

Severity of blurred vision symptoms versus area of corneal epithelial opacity in dysfunctional tear syndrome. Correlation between area of opaque superficial corneal epithelial cells in μm² and severity of blurred vision symptoms measured by ocular surface disease questionnaire

Figure 4

Best corrected visual acuity (BCVA) versus area of corneal epithelial opacity in dysfunctional tear syndrome. Correlation between area of opaque superficial corneal epithelial cells in μm² and BCVA (logmar units)

Figure 5

Conjunctival staining score versus corneal epithelial opacity in dysfunctional tear syndrome. Correlation between area of opaque superficial corneal epithelial cells in μm² and the severity of conjunctival lissamine green staining

Figure 6

Corneal staining score versus corneal epithelial opacity in dysfunctional tear syndrome. Correlation between area of opaque superficial corneal epithelial cells in μm² and the severity of corneal fluorescein staining

Figure 7

Videokeratoscopic surface regularity index (SRI) versus corneal epithelial opacity in dysfunctional tear syndrome. Correlation between area of opaque superficial corneal epithelial cells in μm² and SRI.