A Model for Tear Film Thinning With Osmolarity and Fluorescein

Braun, Richard; Gewecke, Nicholas; Begley, Carolyn G.; King‐Smith, P. Ewen; Siddique, Javed

doi:10.1167/iovs.13-12773

Cited by 42 publications

(69 citation statements)

References 52 publications

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“…Indirect evidence from sensations recorded during TBU and with hyperosmolar drops indicates that tear film osmolarity could reach 800–900 mOsM within areas of TBU or thinning. Recent mathematical modeling also predicts spikes in osmolarity within TBU (Braun, 2012; Braun et al, 2014; Peng et al, 2014; Zubkov et al, 2012). The theories we describe here will supply quantitative estimates for the osmolarity in locations that cannot be measured at the time of writing, in situations like TBU which may have very localized and high values of osmolarity.…”

Section: Interblinkmentioning

confidence: 99%

“…The FL images can be further processed to calculate the thickness when the FL concentration is in the quenching regime (Braun et al, 2014; Nichols et al, 2012). Effectively, when the concentration is above the critical FL concentration f cr , the thickness is, to a good approximation, proportional to the square root of the intensity.…”

Section: Interblinkmentioning

confidence: 99%

“…However, tear film osmolarity is difficult to measure directly over the ocular surface and is currently estimated by sampling tears from the lower meniscus (Bron et al, 2014; Lemp et al, 2011). Mathematical modeling of changes in tear film fluorescence within areas of tear film instability has provided a method to estimate tear film hyperosmolarity within the same regions over the ocular surface (Braun et al, 2014). In this paper, we add to previous results from mathematical models of TBU (Peng et al, 2014) and we present new results for osmolarity all over the exposed ocular surface.…”

Section: Introductionmentioning

confidence: 99%

“…However, conditions within areas of TBU and predisposing factors in the tear film have been difficult to measure experimentally, although theoretical mechanisms for TBU have been proposed (Fatt, 1991; Holly, 1973; Sharma and Ruckenstein, 1985). Recent experimental evidence, combined with mathematical modeling, points to an unequal distribution or composition of lipids and evaporation as driving mechanisms for TBU and thinning (Braun et al, 2014; King-Smith et al, 2013a, 2009a, 2008). …”

Section: Introductionmentioning

confidence: 99%

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Dynamics and function of the tear film in relation to the blink cycle

Braun

King‐Smith

Begley

et al. 2015

Progress in Retinal and Eye Research

118

163

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Great strides have recently been made in quantitative measurements of tear film thickness and thinning, mathematical modeling thereof and linking these to sensory perception. This paper summarizes recent progress in these areas and reports on new results. The complete blink cycle is used as a framework that attempts to unify the results that are currently available. Understanding of tear film dynamics is aided by combining information from different imaging methods, including fluorescence, retroillumination and a new high-speed stroboscopic imaging system developed for studying the tear film during the blink cycle. During the downstroke of the blink, lipid is compressed as a thick layer just under the upper lid which is often released as a narrow thick band of lipid at the beginning of the upstroke. “Rippling” of the tear film/air interface due to motion of the tear film over the corneal surface, somewhat like the flow of water in a shallow stream over a rocky streambed, was observed during lid motion and treated theoretically here. New mathematical predictions of tear film osmolarity over the exposed ocular surface and in tear breakup are presented; the latter is closely linked to new in vivo observations. Models include the effects of evaporation, osmotic flow through the cornea and conjunctiva, quenching of fluorescence, tangential flow of aqueous tears and diffusion of tear solutes and fluorescein. These and other combinations of experiment and theory increase our understanding of the fluid dynamics of the tear film and its potential impact on the ocular surface.

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Section: Interblinkmentioning

confidence: 99%

Section: Interblinkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dynamics and function of the tear film in relation to the blink cycle

Braun

King‐Smith

Begley

et al. 2015

Progress in Retinal and Eye Research

118

163

View full text Add to dashboard Cite

show abstract

“…The lipid layer prevents evaporation of aqueous tears and subsequent drying. This causes increased tear osmolarity which in turn can lead to ocular surface inflammation and damage 5. Over-the-counter (OTC) artificial tear supplementation is commonly used for the relief of dry eye symptoms.…”

Section: Introductionmentioning

confidence: 99%

Tear lipid layer thickness with eye drops in meibomian gland dysfunction

Fogt¹,

Kowalski²,

King‐Smith³

et al. 2016

OPTH

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PurposeThe aim of this study was to evaluate the efficacy of a lipid containing emollient eye drop, Soothe XP, which was reformulated in 2014 with a more stable preservative and buffer system, compared to a control, non-emollient, eye drop (Systane Ultra) in improving lipid layer thickness (LLT) in subjects with dry eye due to meibomian gland dysfunction (MGD).Patients and methodsThis prospective single-center, open-label, cross-over, examiner masked-study enrolled subjects aged 30–75 years with lipid-deficient dry eye and a clinical diagnosis of MGD as determined by a slit lamp examination, an evaluation of meibomian gland drop out with meibography, and a standard patient evaluation of eye dryness questionnaire of >5. Eligibility was then determined by a LLT of <75 nm at baseline and the inability to increase LLT ≥15 nm with three blinks, as determined by interferometric methods. Subjects were randomized to receive a single emollient or non-emollient eye drop at Visit 1 and were crossed over for the alternate treatment at Visit 2. At each visit, LLT was measured prior to and 15 minutes following the instillation of the assigned eye drop. The primary endpoint was the change in LLT from baseline.ResultsSubjects (n=40) were enrolled and 35 completed the two study arms. Mean (±SD) patient age was 55.7 years (10.9) and 69% were female. Mean (±SD) LLT at baseline was 49.5 nm (9.2). Instillation of Soothe XP resulted in an increase in LLT to 77.5 nm (29.3) 15 minutes following drop instillation, which is an increase of 28.0 nm (27.4) (P<0.001). In contrast, LLT 15 minutes after the instillation of Systane Ultra was 50.8 nm (14.1), which was not statistically significant when compared to the baseline LLT.ConclusionIn this study of subjects with MGD, the emollient, or lipid containing eye drop, increased the LLT of tears when measured 15 minutes after instilling a single eye drop.

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