Influence of bacterial burden on meibomian gland dysfunction and ocular surface disease

Purpose: Bacterial burden on the eyelid margin and within meibomian glands was evaluated for influence on specific ocular surface disease (OSD) markers across the meibomian gland dysfunction (MGD) spectrum. Methods: In this prospective, observational, single-center study, 40 patients were divided into 4 equal groups of 10 that encompassed increasingly worse MGD/OSD categories. All patients answered the standard Ocular Surface Disease Index questionnaire, and underwent tear osmolarity testing (TOT), Schirmer 1, matrix metalloproteinase 9 (MMP-9) testing, meibography, and lissamine green staining. Cultures of eyelid margins and meibomian gland secretions were directly plated on blood, chocolate, and Sabouraud agar; smears were sent for gram and Papinicolau evaluation. Results: Mean patient age was 55.25 +/- 17.22 years; there were 10 males and 30 females. TOT and MMP-9 testing were similar across groups. Culture positivity was 62.5% for right eyes, 70% for left eyes, and was not statistically different across groups (for both eyelid margin and meibomian glands). The majority of cultures were positive for coagulase-negative staphylococcus (CNS). Conclusion: This study is in concordance with others, citing the predominance of CNS within the biofilm of both "normal" and clinically significant MGD/OSD patients. Our study exemplifies that symptoms of OSD do not necessarily correlate with degree of clinical exam findings, nor culture positivity. These results argue that bacterial burden should be reconsidered as a direct risk factor and treatment target for MGD/OSD patients.