Tear lipocalin, lysozyme and lactoferrin concentrations in postmenopausal women

Among the most frequently encountered pathologies examined by the ophthalmologist is dry eye syndrome (DE), which can be discovered particularly in the elderly. The initial diagnosis of DE is of high importance, but also challenging. This is because the biochemical changes in the tear film often develop before any detectable signs.

In this study, the possible relationship between ocular symptomatology, tear volume and tear break-up time (TBUT) and lipocalin, lactoferrin and lysozyme concentrations in the tear film were explored in a group of symptomatic dry-eyed postmenopausal (PM) women compared to age-matched controls.

Sixty-six healthy PM females with ages of at least 50 years were grouped in two homogeneous lots (by age, post-menopause, co-morbidities) of 33 females each, one lot presenting mild or moderate dry eye syndrome (DE) and one asymptomatic non-dry eye (NDE), based on their feedback to the Ocular Surface Disease Index (OSDI) questionnaire and noninvasive TBUT and Schirmer test results. Tears were collected via capillary tubes and an eye wash method. Tear lysozyme, lactoferrin and lipocalin concentrations were determined via electrophoresis.

OSDI responses revealed 3 mild DE, 30 moderate DE and 33 NDE. The OSDI total score and sub scores for the DE group were significantly greater than for the NDE group (p < 0.001). The mild and moderate DE group exhibited significantly shorter TBUTs compared to NDE (p < 0.001). No difference in tear lysozyme or lipocalin concentrations was found between DE and NDE groups, irrespective of the tear collection method, but a significant difference was found in lactoferrin concentration (p<0.001). No significant correlations were found between symptoms or signs of DE compared to either lipocalin, lysozyme or lactoferrin concentrations.

In a PM population, lipocalin and lysozyme are invariable, irrespective of the presence and severity of DE symptoms. However, lactoferrin shows a significant decrease. This is a comprehensive study of lipocalin, lactoferrin and lysozyme in dry-eyed PM women and our results suggested that lactoferrin could be used as a biomarker of DE in postmenopausal women.

PM = postmenopausal; DE = dry eye disease; NDE = non-dry eye; ELISA = Enzyme-linked immunosorbent assay.