Evaluation of the Cornea of Dogs With Dry Eye Disease Using Spectral Domain Optical Coherence Tomography.

PURPOSE: To evaluate the central corneal thickness (CCT) and corneal epithelial thickness (CET) in dogs affected by dry eye disease (DED) using optical coherence tomography (OCT).

METHODS

Sixty-three canine eyes were allocated into two groups: healthy dogs, without clinical signs of dry eye disease (DED) and Schirmer tear test-1 (STT-1) values ≥ 15 mm/min (n = 29 eyes), and DED-affected dogs, exhibiting clinical signs of DED and STT-1 values < 15 mm/min (n = 34 eyes). The OCT software automatically generated a 17-section corneal pachymetry map within a 6-mm diameter. The thickness of the corneal epithelium was measured manually. Only scans with a quality score of 27 or greater and proven to be free of motion artifacts were accepted for data collection. The Mann-Whitney U test and Spearman's correlation were used to analyze the data.

RESULTS

When comparing the CET of healthy dogs with dogs DED-affected, a median of 73.0 μm (interquartile range [IQR] = 9.0) and 105.0 μm (IQR = 71.0) were obtained, respectively, demonstrating a statistically significant difference (p < 0.0001). A moderate negative correlation was observed between STT-1 and CET (r = -0.581). A moderate-to-strong inverse association was observed between tear film breakup time (TFBUT) and CET (r = -0.66). Dogs with DED exhibited epithelial thickening accompanied by a marked reduction or loss of hyperreflective epithelial interfaces, as well as increased hyperreflectivity within the epithelial layer.

CONCLUSION

DED-affected dogs exhibited a pronounced increase in CET. Both STT-1 and TFBUT values were directly associated with CET in DED-affected dogs.