Lipid layer thickness decrease due to meibomian gland dysfunction leads to tear film instability and reflex tear secretion.

PURPOSE: To determine the clinical effects of ocular surface and Meibomian gland parameters on tear film stability among individuals with Meibomian gland dysfunction (MGD), those with aqueous deficient dry eye (ADDE), individuals with both conditions and normal controls. METHODS: Patients were divided into four groups: normal controls, patients with ADDE, patients with MGD, and patients who fulfilled diagnostic criteria for ADDE and MGD (Mixed Group). Data for ocular symptom score, lid margin abnormality, ocular staining, tear break-up time, meiboscore, and lipid layer thickness (LLT) measured by a Lipiview interferometer, Schirmer test, and MGD severity score were collected. RESULTS: A total of 109 patients (109 eyes) were evaluated. In patients with MGD, LLT was significantly lower than the ADDE patients. However, the Schirmer test value was the highest in the MGD group. The LLT negatively correlated with meiboscore and MGD severity score in the MGD group. Significant correlation between Schirmer test value and meiboscore was definite in the MGD group. CONCLUSIONS: Tear fluid secretion is more increased and lipid layer thickness is more decreased in MGD patients than in ADDE patients. Decreased lipid layer thickness caused by MGD-related tear film instability may stimulate reflex tear secretion. The obstructive MGD is more prevalent than hypersecretary MGD.Key messagesThe tear film stability is affected by Mebomian gland dysfunction (MGD). The measurement of the tear film parameters including lipid layer thickness suggests that the obstructive MGD is more prevalent than hypersecretary MGD and the aqueous layer compensates the decreased lipid layer caused by MGD.

The effect of bevacizumab on corneal neovascularization in rabbits.

PURPOSE: To determine the efficacy of topical application and subconjunctival injection of bevacizumab in the treatment of corneal neovascularization. METHODS: Corneal neovascularization was induced with a silk suture of the corneal stroma in 12 rabbits (24 eyes). One week after suturing, four rabbits were treated with topical bevacizumab at 5 mg/mL (group A) and another four rabbits were treated with topical bevacizumab 10 mg/mL (group B) in the right eyes twice a day for two weeks. A subconjunctival injection of bevacizumab 1.25 mg/mL was done in the right eyes of four rabbits (group C). All of the left eyes (12 eyes) were used as controls. The area of corneal neovascularization was measured after one and two weeks, and the concentration of vascular endothelial growth factor (VEGF) in corneal tissue was measured after two weeks. RESULTS: The neovascularized area was smaller in all treated groups than in the control group (p<0.001). Upon analysis of the neovascularized area, there was no significant difference between groups A and B. However, the mean neovascularized area of group B was significantly smaller than that of group C after two weeks of treatment (p=0.043). The histologic examination revealed fewer new corneal vessels in all treated groups than the control group. The concentration of VEGF was significantly lower in all treated groups compared to the control group (p<0.01), but no difference was shown between treated groups. CONCLUSIONS: Topical and subconjunctival bevacizumab application may be useful in the treatment of corneal neovascularization and further study is necessary.