Evaluation of ocular surface parameters in dogs with and without meibomian gland dysfunction

Abstract

Background: Interest in meibomian gland dysfunction (MGD) is growing in veterinary medicine. However, research on MGD in dogs is lacking. The aims of this study were to compare the interferometry grades, tear meniscus height (TMH) and non-invasive tear break-up time (NIBUT) grades between dogs with and without MGD. Methods: Routine ophthalmic examination, interferometry, NIBUT assessment, TMH measurement and meibography were performed. Age and Schirmer tear test-1 (STT-1) results were compared between the control and MGD groups using Student's t-test. Interferometry grades, NIBUT grades and TMH were compared between the two groups using Mann-Whitney U-test. Results: There was no significant difference in age between the two groups (p = 0.279). STT-1 (p = 0.024), interferometry (p = 0.004) and NIBUT grades (p = 0.012) were significantly lower in the MGD group than in the control group. No significant difference in TMH values (p = 0.587) was observed between the two groups. While the control group included 18 and seven eyes in meiboscore 0 and 1, in MGD group, 12, eight, five and three eyes were included in meiboscore 0, 1, 2 and 3, respectively. Conclusions: Low interferometry and NIBUT grades were associated with MGD, suggesting decreased meibum and disrupted tear film quality. TMH did not differ between the two groups. Meibography could aid in the diagnosis of MGD in severe cases, although it could not detect early MGD in the dogs in this study.

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

“…In fact, meibomian gland dysfunction represents a major cause of DED in humans 82 . First described in dogs using polarized light microscopy over 30 years ago, 47,83 newer diagnostic tools have stimulated renewed interest and allowed recent investigations to gain a deeper understanding of MGD in canine patients 49–52,84,85 . Non‐contact infrared meibography revealed several morphological anomalies associated with the meibomian glands of dogs including cystic dilatation, shortening, atrophy, and gland dropout 50,52,84,85 .…”

“…82 First described in dogs using polarized light microscopy over 30 years ago, 47,83 newer diagnostic tools have stimulated renewed interest and allowed recent investigations to gain a deeper understanding of MGD in canine patients. [49][50][51][52]84,85 Noncontact infrared meibography revealed several morphological anomalies associated with the meibomian glands of dogs including cystic dilatation, shortening, atrophy, and gland dropout. 50,52,84,85 Such changes were observed in ≥70% of dogs diagnosed with ocular surface disease, 52,85 as well as a dog diagnosed with sebaceous adenitis.…”

A review of diagnostic tests for qualitative and quantitative tear film deficiency in dogs

“…The use of meibography has been critical in identifying meibomian gland abnormalities in dogs, with recent studies observing several morphological anomalies associated with the canine meibomian glands including dilatation, shortening, atrophy, or dropout 86,87,92–95 . Such changes, confirmed on histopathology of selected cases, 92,94 were more common in dogs with KCS (albeit also noted in eyes without aqueous deficiency) 93 and were more pronounced with advanced age 92,95 …”

“…Most NIBUT techniques involve the observation of distorted line(s) or breakup spot on the specular reflection of an illuminated interferometric fringe pattern from the tear film, and provide results that are generally higher than standard TFBUT in humans 26,79 . In dogs, NIBUT results are correlated with tear meniscus height and are significantly shorter in canine patients with meibomian gland dysfunction, suggesting decreased meibum and disrupted tear film quality 86,87 …”

“…Kim et al used the Pult's grading scale described in humans: grade 0 (0% meibomian glands loss), grade 1 (≤25% loss), grade 2 (26%–50% loss), grade 3 (51%–75% loss), and grade 4 (>75% loss) 86,96 . Jeong et al used Arita's grading scale also described in humans: grade 0 (no loss), grade 1(<1/3 of the total area of meibomian glands loss), grade 2 (1/3 to less than 2/3 loss), and grade 3 (≥2/3 loss) 87,97 . In contrast, Viñas et al diagnosed meibomian gland dysfunction when more than 50% of the meibomian glands demonstrated abnormal features (shortening, dropout, or atrophy), and/or more than 75% of terminal duct obstruction was observed in the eyelid 95 …”