Assessment of corneal and limbal epithelial thickness by spectral‐domain optical coherence tomography in brachycephalic and non‐brachycephalic dogs

Abstract

Objective To investigate the variance in corneal epithelial thickness (CET) and limbal epithelial thickness (LET) according to the age and skull type by using spectral‐domain optical coherence tomography (SD‐OCT) in normal dogs. Animals and procedures This study used an eye each from 46 dogs (24 brachycephalic and 22 non‐brachycephalic dogs) assessed to have clear corneas. Each dog was classified according to age into groups 1 (0–5 years), 2 (6–10 years), and 3 (>11 years). OCT imaging was performed on the central cornea for CET and perpendicular to the quadrant of the limbus for LET. The average of the maximum LET (maxLET) value was measured in four eye quadrants. Results Corneal epithelial thickness was not significantly different according to age in brachycephalic and non‐brachycephalic dogs. Visualization of the limbal invagination was better when the maxLET was thick. Nasal and temporal maxLETs were significantly thicker than superior and inferior maxLETs in non‐brachycephalic dogs. In brachycephalic dogs, there was a significant decrease in nasal maxLET with age (rs = −0.489, p = .015). Significant differences between brachycephalic and non‐brachycephalic dogs were observed in nasal maxLET (p = .024) and temporal maxLET (p = .011). Conclusions Invagination was better visualized in the nasal and temporal limbal quadrants of non‐brachycephalic dogs compared with brachycephalic dogs, and the maxLETs of the regions were thicker than those of the brachycephalic dogs. CET and LET measurements using SD‐OCT can help in clinical assessment and research on ocular surface diseases in dogs.

The pandemic of ocular surface disease in brachycephalic dogs: The brachycephalic ocular syndrome

“…A study by Jeong et al showed that the limbal epithelial thickness was lower nasally and temporally in brachycephalic dogs compared with non‐brachycephalic dogs 36 . The nasal and temporal regions of the limbus might be more vulnerable to damage because of reduced eyelid coverage when compared to superior and inferior regions, and this might be particularly pronounced in brachycephalic dogs with excessively large palpebral fissure and poor corneal protection.…”

“…34,35 2.1.5 | Limbal epithelium A study by Jeong et al showed that the limbal epithelial thickness was lower nasally and temporally in brachycephalic dogs compared with non-brachycephalic dogs. 36 The nasal and temporal regions of the limbus might be more vulnerable to damage because of reduced eyelid coverage when compared to superior and inferior regions, and this might be particularly pronounced in brachycephalic dogs with excessively large palpebral fissure and poor corneal protection. Limbal epithelial thinning has been associated with various pathological conditions in humans, such as contact lens wear and limbal stem cell deficiency, 37 although its clinical significance in canine patients is unknown and requires further investigation.…”

Comparative evaluation of corneal and limbal epithelial thickness in brachycephalic dogs with and without corneal diseases using spectral domain optical coherence tomography

“…The specific OCT test methods followed were described in a previous study 19 . The central corneal OCT images were captured using the pachymetry mode to include the central corneal reflex toward the axial cornea.…”

“…The specific OCT test methods followed were described in a previous study. 19 The central corneal OCT images were captured using the pachymetry mode to include the central corneal reflex toward the axial cornea. CET was defined as the average value of epithelial thickness 1 mm away from the center of the cornea on the horizontal meridian B-scan (Figure 1).…”