The increase in branched-chain fatty acids may reflect greater quantities of wax and cholesterol esters and triglycerides in meibomian gland excreta. Since wax and cholesterol esters are the main lipids of meibum, these differences may have physical consequences for tear-film lipid-layer fluidity and stability. Meibomian fatty acid composition and particularly the increase in branched chains could be a marker for meibomian gland dysfunction.

This study showed better tear film stability after minocycline treatment and a biological effect on meibomian fatty acid composition in MGD patients. Minocycline was more effective than lid hygiene alone. Both interventions partly corrected fatty acid composition abnormalities. Among the fatty acids, isoC20 could be a biological marker of MGD.

The increase in BCFAs in the tears of blepharitis patients does not consistently participate in the conjunctival cell changes throughout the course of the disease. Instead, it is likely an adaptive response of the ocular surface to the lack of tears, possibly increasing meibum fluidity, thus enhancing lacrimal film stability.

Aims: To evaluate conjunctival expression of trefoil factor family (TFF)1, MUC5AC and human leucocyte antigen (HLA)-DR in patients with glaucoma treated with topical drugs, and to determine whether these parameters can predict the outcome of glaucoma surgery. Methods: 77 conjunctival impression cytology specimens were collected from 77 patients with glaucoma (66 receiving drops with preservative and 11 treated with preservative-free drops) and 43 controls. TFF1, MUC5AC and HLA-DR expression was analysed using flow cytometry. Trabeculectomy was performed in 56 patients; success was defined as an intraocular pressure (IOP) (15 mm Hg without any IOP-lowering drug at 6 months. Results: The expression of TFF1, MUC5AC and HLA-DR was significantly higher in patients than in controls (p = 0.01, 0.05 and 0.004, respectively). A higher expression of MUC5AC was found in patients treated with preserved drops than in those receiving unpreserved drops (p = 0.04). A higher MUC5AC expression and a lower HLA-DR expression was observed in successful glaucoma surgeries than in failures. Conclusions: TFF1 and MUC5AC secretions are probably a response to mild ocular surface changes caused by long-term use of topical treatment. Their increased expression could be a predicting factor of further successful glaucoma surgery.

ABSTRACT:Purpose: To determine whether tear osmolarity contributes to the assessment of the ocular surface in soft contact lens (CL) wearers. Methods: Prospective, case-control series in 44 CL wearers (28 tolerant and 16 intolerant) and 34 healthy subjects. Every patient underwent a thorough ophthalmic examination with a tear osmolarity test (TearLab System), conjunctival impression cytology and meibomian lipid sampling. Symptoms, break-up time (BUT), tear osmolarity, conjunctival expression of HLA-DR and meibomian fatty acid composition were evaluated. Results: Tear osmolarity did not differ between controls and CL wearers (p = 0.23). Flow cytometry results expressed in antibody-binding capacity (ABC) units and percentage of positive cells revealed a significant difference between the intolerant CL wearer group and the control group (p < 0.0001). Comparisons between tolerant and intolerant CL wearers showed only a significant difference for mean fluorescence levels expressed in ABC units (p < 0.0001). The BUT was significantly shorter in intolerant and tolerant CL wearers subjects than in healthy subjects (p < 0.0001), whereas there was no significant difference in meibomian fatty acid composition (p = 0.99) between the two groups. Conclusion: Contact lens wear is responsible for ocular surface alterations whose patterns are very similar to those reported in early dry-eye syndrome. However, tear osmolarity was not modified in these selected CL wearers. The yield of tear osmolarity with TearLabÔ in assessing ocular surface disorders in CL wearers deserves further investigation.