Investigation of Lubrication Characteristics for a Soft Contact Lens

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.

Download Full-text

Effect of Soft Contact Lens Wear on Tear Film Break up Time

Pakistan Journal of Ophthalmology ◽

10.36351/pjo.v36i2.1028 ◽

2020 ◽

Vol 36 (2) ◽

Author(s):

Syeda Rushda Zaidi ◽

Mohammad Ali A Sadiq ◽

Shua Azam ◽

Uzma Sattar ◽

Samia Iqbal ◽

...

Keyword(s):

Contact Lens ◽

Contact Lenses ◽

Tear Film ◽

Soft Contact ◽

Contact Lens Wear ◽

Soft Contact Lens ◽

History Of ◽

Break Up ◽

Medical University ◽

Lens Wear

Purpose: To see the effect of soft contact lens wears on tear breakup time. Study Design: Descriptive Observational study. Place and Duration of Study: College of Ophthalmology and Allied Vision Sciences, King Edward Medical University, Mayo Hospital, Lahore. From January to March 2016. Material and Methods: Students of King Edward Medical University Lahore wearing soft contact lens for more than 3 months with no known ocular pathology were selected by non-probability convenient sampling technique. Subjects with history of using any eye drops, history of oral drugs, which could cause dry eye and individuals any ocular disease, were excluded from the study. Tear film BUT was tested by using Fluorescein sodium dye and examinig under cobalt blue filter of slit lamp.SPSS version 20 is used to analyze the data. Results: There were 30 participants with mean age of 24.5 ± 5 years. All were females. Sixty percent were wearing corrective lenses, and 40% were wearing cosmetic lenses. Out of 30 patients wearing contact lenses, only 6.67% had marginal tear film BUT and none of the patients has shown dry eyes. Individuals using contact lenses for 9 – 12 years had decreased BUT as compared to subjects using lenses for 3 – 6 months. 33.33% of extended lens wearers had reduced BUT as compared to disposable and daily wearers of contact lenses. Discomfort with contact lenses was observed in only 4 patients. Conclusion: As the duration of contact lens wear increases, the tear film break up time decreases. Individuals using extended wear contact lenses are more prone to develop decreased TFBUT.

Download Full-text

Soft-contact-lenses-induced complications

Vojnosanitetski pregled ◽

10.2298/vsp0801015s ◽

2008 ◽

Vol 65 (1) ◽

pp. 15-20 ◽

Cited By ~ 2

Author(s):

Gordana Suvajac

Keyword(s):

Contact Lens ◽

Vision Loss ◽

Contact Lenses ◽

Tear Film ◽

Video Camera ◽

Conjunctival Hyperemia ◽

Soft Contact ◽

Soft Contact Lenses ◽

Soft Contact Lens ◽

Number Of Patients

Background/Aim. Soft contact lenses occupy significant place in ophthalmology, both in the correction of refraction anomalies and in the treatment of many eye diseases. The number of patients that wear soft contact lenses for the purpose of correcting ametropia is constantly increasing. Due to the increasing number of wearers, the percentage of complications that can lead to serious eye damage and serious vision loss is also increasing. The aim of this study was to point out the most common complications related to soft contact lens use. Methods. In the period from 1995?2004 this prospective study included 510 patients wearing soft contact lenses for correcting ametropia. None of the patients wore contact lenses before and none suffered from any system or local diseases that could affected the development of eventual complications. The study took seven years with the patients who wore conventional lenses and three years with those who wore replacement contact lenses. All the necessary ophthalmologic examinations were done (visual acuity, refractokeratometry, the quantity of tear film, biomicroscopic examination of anterior eye segment). All the complications were filmed by video camera. Results. Of all the patients, 19 had blepharitis, 73 suffered from ?dry eye?, 57 had conjunctival hyperemia, 12 had conjunctivitis, 34 had gigantopapillary conjunctivitis (GPC), 93 had punctiform epitheliopathy, 20 had corneal infiltration, one patient had keratitis, 91 had corneal vascularisation, and 95 patients had corneal deposits. Conclusion. Both the type and frequency of complications related to soft contact lens use in our group of patients, proved to be significant. Some of this complications (keratitis) can significantly damage vision and lead to loss of vision and sometimes can require operative treatment.

Download Full-text

Hydrodynamics of a Soft Contact Lens During Sliding Motion

Journal of Tribology ◽

10.1115/1.555403 ◽

1999 ◽

Vol 122 (3) ◽

pp. 573-577 ◽

Cited By ~ 11

Author(s):

S. Kamiyama ◽

M. M. Khonsari

Keyword(s):

Film Thickness ◽

Pressure Distribution ◽

Contact Lens ◽

Early Stage ◽

Tear Film ◽

Slider Bearing ◽

Soft Contact ◽

Sliding Motion ◽

Soft Contact Lens ◽

Aspect Ratios

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]

Download Full-text

Preocular tear film characteristics of nonwearers and soft contact lens wearers

International Contact Lens Clinic ◽

10.1016/s0892-8967(97)90028-6 ◽

1997 ◽

Vol 24 (5) ◽

pp. 179

Keyword(s):

Contact Lens ◽

Tear Film ◽

Soft Contact ◽

Soft Contact Lens ◽

Film Characteristics

Download Full-text

STUDY OF THE OPTICAL POWER OF NANOPHOTONIC SOFT CONTACT LENSES BASED ON POLY (2- HYDROXYETHYL METHACRYLATE) AND FULLERENE

Contemporary Materials ◽

10.7251/comen1401151m ◽

2014 ◽

Vol 5 (1) ◽

Author(s):

Aleksandra Debeljković Mitrović ◽

Dragomir Stamenković ◽

Manuel Conte ◽

Božica Bojović ◽

Spomenko Mihajlović

Keyword(s):

Contact Lens ◽

Contact Lenses ◽

Measurement Techniques ◽

Optical Power ◽

Soft Contact ◽

Standard Material ◽

Soft Contact Lenses ◽

Soft Contact Lens ◽

Power Cylinder

In this paper results of comparative study of the optical power of soft contact lenses (SCL) made of standard material for SCL and nanophotonic materials with different measurement techniques used for the final contact lens controllers are presented. Three types of nanophotonic soft contact lenses were made of standard polymacon material (Soleko SP38TM) incorporated with fullerene C60, fullerol C60(OH)24 and fullerene metformin hydroxylate C60(OH)12(OC4N5H10)12. For the purposes of material characterization for potential application as soft contact lenses, the optical properties of the soft contact lenses were measured by Rotlex and Nidek device. With Rotlex device the following optical results were obtained: optical power and map of defects, while with the Nidek device: optical power, cylinder power and cylinder axis. The obtained values of optical power and map of defects showed that the optical power of synthesized nanophotonic soft contact lens is same to the nominal value, while this was not the case for the standard soft contact lens. Also, the quality of the nanophotonic soft contact lens is better than the standard one. Hence, it is possible to synthesize new nanophotonic soft contact lenses of desired optical characteristics, implying possibilities for their application in this field.

Download Full-text