Ocular surface assessment in soft contact lens wearers; the contribution of tear osmolarity among other tests

Abstract

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.

Tear film osmolarity and dry eye disease: a review of the literature

“…The literature is divided over whether or not contact lens wear increases 2 , 22 , 23 or has no effect on tear osmolarity. 10 , 24 , 25 Where osmolarity was measured in some of these studies, 10 , 24 there was an appropriate delay between contact lens removal and osmolarity measurement. The differences in reported results are likely a function of the wearer’s ability to maintain homeostasis of their tear film, overcoming the drying effect of contact lenses.…”

“…Certain commonly encountered external factors such as contact lens wear may or may not increase tear osmolarity, depending on the individual response. 2 , 24 The impact of environmental factors, such as temperature, humidity, and airflow on tear osmolarity appears unclear, as is the effect of sex hormones; these factors would benefit from further investigation. 20 , 21 , 25 , 36 , 37 The effect of ocular surgery on tear osmolarity may be partially dependent on the patient’s age, the type of surgery performed, and the ability of the eye to recover.…”

TFOS DEWS II Tear Film Report

“…In cross-sectional studies there are no statistically significant differences in tear film osmolarity between contact lens wearers and non-lens wearers [131,585]. The concentration of phospholipase A2 levels in tears has been associated with an increased concentration of malondialdehyde, which is also a by-product of phospholipid degradation and shorter TBUT over a contact lens [586].…”

Tear film evaluation and management in soft contact lens wear: a systematic approach

“…Management of pre‐existing tear film dysfunction should be undertaken prior to the commencement of contact lens wear. Beyond the adaptation period, soft contact lens wear does not appear to significantly alter tear osmolarity levels …”