Hydrodynamics of a Soft Contact Lens During Sliding Motion

Tear film thickness and pressure distribution under a tilting soft contact lens with peripheral slopes during the early stage of a blink are calculated for various flexibility and aspect ratios. The system is modeled as a slider bearing with the lens behaving as a deformable surface sliding over a rigid eye. The tear is considered to be a linearly viscous (Newtonian) fluid. The velocity profile at the edges and the junctions of the slopes are also calculated for a typical soft contact lens. Back flow at the edges is predicted. It is shown that the tilting of the lens has a major affect on the tendency of the pressure distribution. Also important is the lens’ flexibility for it influences both the film thickness and pressure distribution noticeably. [S0742-4787(00)01002-X]

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Investigation of Lubrication Characteristics for a Soft Contact Lens

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.823.105 ◽

2019 ◽

Vol 823 ◽

pp. 105-109

Author(s):

Hung Jung Tsai ◽

Jeng Haur Horng ◽

Chung Ming Tan

Keyword(s):

Contact Lens ◽

Contact Lenses ◽

Hydrodynamic Lubrication ◽

Tear Film ◽

Hydrodynamic Pressure ◽

Slider Bearing ◽

Soft Contact ◽

Soft Contact Lens ◽

Lubrication Characteristics

It is popular to wear the contact lens nowadays. Also, the output value of the contact lens is estimated more than 4 billion NT dollar every year. Because the phenomena of the contact lenses are very complicated, the relevant mechanisms are not well understood. Thus, the security of contact lens needs to be further investigated. In the lubricated mechanism of the contact lens, there is a layer of tear between the contact lens and cornea. The contact lens’ behavior is akin to that of a slider bearing. The lens represents the slider, the eye plays the role of the stationary pad, and the tear film is the lubricant. Hence, hydrodynamics and contact mechanisms of a contact lens are quite a fascinating subject that is relevant to the science of tribology. In the paper, the lubrication mechanisms include the partial hydrodynamic lubrication (contact lens roughness), contact mechanics and Newtonian fluid mechanics have been established. The parameters of roughness, flow factor, tear film geometry, and hydrodynamic pressure distribution are discussed. The developed technology increases the safety of contact lens.

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A NEW MODEL FOR THE SUCTION PRESSURE UNDER A CONTACT LENS

Journal of Biological System ◽

10.1142/s021833901440004x ◽

2014 ◽

Vol 22 (02) ◽

pp. 235-248 ◽

Cited By ~ 5

Author(s):

KARA L. MAKI ◽

DAVID S. ROSS

Keyword(s):

Mathematical Model ◽

Pressure Distribution ◽

Elastic Properties ◽

Contact Lens ◽

Tear Film ◽

Elastic Equilibrium ◽

Suction Pressure ◽

Soft Contact ◽

New Approach ◽

Soft Contact Lens

We present a new approach to compute the suction pressure under a soft contact lens. When a soft contact lens is placed on an eye, it is subjected to forces from the tear film in which it is immersed and from the blinking eyelid. In response, the lens bends and stretches. The equilibration of these forces generates a suction pressure that keeps the lens on the cornea. In this paper, we develop a mathematical model of the elastic equilibrium of a soft contact lens that allows us to predict the suction pressure distribution under such a lens. We explore the influence of the shape of the lens and its elastic properties on the suction pressure.

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