Viscoelastic properties of the human tear film

Recchioni, Alberto; Mocciardini, Emanuele; Ponzini, Erika; Tavazzi, Silvia

doi:10.1016/j.exer.2022.109083

Cited by 17 publications

(15 citation statements)

References 103 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, tear fluid moisturizes the corneal surface and prevents it from drying out at rest. In contrast, the application of stress, manifested as blinking, makes tear fluid more elastic rather than viscous, preventing tears from being removed from the surface of the cornea [ 3 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

Rheological Considerations of Pharmaceutical Formulations: Focus on Viscoelasticity

Budai,

Fülöpné Pápay

et al. 2023

Gels

View full text Add to dashboard Cite

Controlling rheological properties offers the opportunity to gain insight into the physical characteristics, structure, stability and drug release rate of formulations. To better understand the physical properties of hydrogels, not only rotational but also oscillatory experiments should be performed. Viscoelastic properties, including elastic and viscous properties, are measured using oscillatory rheology. The gel strength and elasticity of hydrogels are of great importance for pharmaceutical development as the application of viscoelastic preparations has considerably expanded in recent decades. Viscosupplementation, ophthalmic surgery and tissue engineering are just a few examples from the wide range of possible applications of viscoelastic hydrogels. Hyaluronic acid, alginate, gellan gum, pectin and chitosan are remarkable representatives of gelling agents that attract great attention applied in biomedical fields. This review provides a brief summary of rheological properties, highlighting the viscoelasticity of hydrogels with great potential in biomedicine.

show abstract

Section: Introductionmentioning

confidence: 99%

Rheological Considerations of Pharmaceutical Formulations: Focus on Viscoelasticity

Budai,

Fülöpné Pápay

et al. 2023

Gels

View full text Add to dashboard Cite

show abstract

“…35 Contact lens wear may induce viscosity alterations, causing higher shear stress at high sliding velocity. 36 In addition, CL wear reduces film thickness by splitting it, resulting in the contact between sliding surfaces. This would cause the system to fall back into the boundary regime even at high speed.…”

Section: Shear Stressmentioning

confidence: 99%

“…35 At relatively high sliding velocities (hydrodynamic regime), the two sliding surfaces (lid wipers and cornea) are separated by the tear film and the viscosity of tears governs the sliding resistance. [35][36][37] At lower speed (boundary regime), the sliding surfaces are in close contact within the limits of their surface roughness, 4,38 and the coefficient of friction (CoF) is represented by the ratio between shear force and normal applied force. The hydrodynamic phase is dominant in the tribology of the bare healthy eye in normal conditions.…”

Section: Shear Stressmentioning

confidence: 99%

Physical Properties and Interaction With the Ocular Surface of Water-Gradient Contact Lenses

Ponzini

Recchioni²,

Cheloni³

et al. 2023

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

Self Cite

View full text Add to dashboard Cite

Since the introduction of silicone hydrogel contact lenses, many silicone-hydrogel materials have been produced, including water-gradient contact lenses with a silicone hydrogel core and a thin hydrogel outer layer (e.g., delefilcon A, verofilcon A, and lehfilcon A). Their properties have been investigated in various studies assessing both the chemical-physical characteristics and the comfort, but the overall picture is not always consistent. In this study, water-gradient technology is reviewed by looking at basic physical properties both in vitro and in vivo and at the interaction with the human ocular surface. Surface and bulk dehydration, surface wetting and dewetting, shear stress, interaction with tear components and with other environmental compounds, and comfort are discussed.

show abstract

“…The fast-closing part of the blink cycle is needed to fluidize the tear film because it shows non-Newtonian viscosity i.e., the higher the shear force the less viscous the tears ( Pult et al, 2015b ; Arshinoff et al, 2021 ; Recchioni et al, 2022 ). Blinking also cleans the ocular surface by removing tears via the tear menisci into the puncta, lacrimal canaliculi and lacrimal sac ( McDonald and Brubaker, 1971 ).…”

Section: Tear Film Dynamics and Effects Of Microgravitymentioning

confidence: 99%

Dry eye disease in astronauts: a narrative review

Ax,

Ganse,

Fries

et al. 2023

Front. Physiol.

View full text Add to dashboard Cite

Long-duration spaceflight can have adverse effects on human health. One of the most common ocular conditions experienced by astronauts is dry eye disease (DED). Symptoms of DED include feelings of eye irritation, eye strain, foreign body sensation and blurred vision. Over 30% of International Space Station expedition crew members reported irritation and foreign body sensation. We reviewed the current literature on the prevalence and mechanisms of DED in astronauts and its potential implications for long-duration spaceflight, including the influence of environmental factors, such as microgravity and fluid shift on tear film physiology in space. DED has negative effects on astronaut performance, which is why there is a need for further research into the pathophysiology and countermeasures. As an in-flight countermeasure, neurostimulation seems to be among the most promising options.

show abstract

Viscoelastic properties of the human tear film

Cited by 17 publications

References 103 publications

Rheological Considerations of Pharmaceutical Formulations: Focus on Viscoelasticity

Rheological Considerations of Pharmaceutical Formulations: Focus on Viscoelasticity

Physical Properties and Interaction With the Ocular Surface of Water-Gradient Contact Lenses

Dry eye disease in astronauts: a narrative review

Contact Info

Product

Resources

About