TOBACCO EFFECTS ON OCULAR SURFACE, MEIBOMIAN GLANDS AND CORNEAL EPITHELIUM AND THE BENEFITS OF TREATMENT WITH A LIPID BASED LUBRICANT

To evaluate the ocular surface in chronic smokers and to assess the clinical benefit of treatment with preservative-free sodium hyaluronate versus semi-fluorinated alkane perfluorohexyloctane based topical lubricants on ocular surface parameters, meibomian gland functional and morphological characteristics and CET measurements.

Department of Ophthalmology, Hospital Garcia de Orta E.P.E

This prospective study enrolled healthy non-smokers and chronic smokers. Patients were divided in 2 groups: Control group and Smokers group. Subjects of the Smokers were instructed to apply one eyedrop of Hyabak on one eye (Sodium Hyaluronate (SH) based topical lubricant subgroup) and one eyedrop of Evotears on the other eye (Semi-fluorinated Alkane (SFA) based topical lubricant subgroup) 4 times daily for 2 months. Subjects underwent a series of clinical assessments: OSDI questionnaire, symptoms score questionnaire, CET, lipid layer thickness (LLT), meibography, lid margin assessment, Tear film break-up time test (TBUT), Tear film break-up pattern (TBUP), CFS score and Schirmer test I. Measurements were compared at baseline and after the 2-month treatment with artificial tears.

This study enrolled 120 eyes. Forty-two eyes of 42 patients were included in the Control group, with a mean age of 40.03±6.78 years, and 78 eyes of 39 patients were included in the Smokers group, 39 in the SH subgroup and 39 in the SFA subgroup, with a mean age of 49.50±2.74 years. 

At baseline, 100% of eyes in Smokers group had a clinical diagnosis of DED and none of the eyes of the Control group had dry eye (p<0.001). Symptoms score, lid margin abnormalities score and Meibo-score were higher in the Smokers subgroups than in the Control group (p<0.05). LLT and CET measurements in the superior and temporal superior mid-peripheral and perilimbal corneal octans were lower in the Smokers group in comparison to controls (p<0.05).

After the 2-month treatment period, prevalence of DED decreased in Smokers group (100 vs 12.82%, p<0.001 in SH group and 100 vs 10.26%, p<0.001 in SFA group). Whereas in the SHA group there was an improvement in DED symptoms and in all homeostatic biomarkers, only dry eye symptoms improved in the SH group. LLT measurement was lower in the SH group than in the SFA group (SH group vs SFA group: 39.05±5.65 vs 49.56±4.33nm, p=0.03). No differences were found in the remaining meibomian gland evaluation and CET measurements between SH and SFA subgroups after treatment (p>0.05). 

Our results confirm that smoking may be associated with dry eye, MGD and corneal epithelial thinning. Although there was an improvement in subjective symptoms of DED, tear film stability and LLT, the two latter only after treatment with the SFA based lubricant, impairment of meibomian gland morphology and corneal epithelial thinning did not seem to be totally reversible with neither type of artificial tear treatment, at least on the short-term.