scholarly journals Compressive behaviour of soft contact lenses and its effect on refractive power on the eye and handling off the eye

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247194
Author(s):  
Ahmad H. Shihab ◽  
Ashkan Eliasy ◽  
Bernardo T. Lopes ◽  
Richard Wu ◽  
Lynn White ◽  
...  
Keyword(s):  
Contact Lenses ◽  
Fe Analysis ◽  
Nonlinear Behaviour ◽  
Soft Contact ◽  
Material Models ◽  
Soft Contact Lenses ◽  
Soft Contact Lens ◽  
Strain Behaviour ◽  
N Loading ◽  
Moduli Of Elasticity

Purpose To investigate the stress-strain behaviour of 9 soft contact lens materials, that are commonly used in the market, under uniaxial compression loading. Methods Seven types of hydrogel and two types of silicone-hydrogel soft contact lens materials were hydrated in phosphate-buffered saline (PBS) solution then subjected to uniaxial compression loads. The load rate was set to 16.0 N/min starting with two consecutive initial 5.0 N loading cycles followed by three relaxation periods of 4.0 min within which there were two more 5.0 N loading cycles and eventually, a full loading cycle that stopped at a load of 49.0 N. The load and contraction data obtained experimentally were analysed to derive the stress-strain behaviour. Finite Element (FE) analysis was then utilised to evaluate the performance of soft contact lenses on the human eye and handling lenses off the eye. Results Unlike tensile tests, all tested materials showed nonlinear behaviour when tested under compression. When fitted to first-order Ogden hyperelastic model, parameter μ was found to be varying in the range 0.12 to 0.74 MPa and material parameter α was found to be varying in the range 8.2 to 20.326 among the nine tested materials. Compression modulus of elasticity was 2.2 times higher than the tensile modulus of elasticity on average. FE simulation with nonlinear Ogden constitutive model showed a limited change (8%~12%) in the optical performance when compared to other material models, however, it predicted higher stress when the lens was simulated under bending during off-eye handling. Conclusions Compression tests revealed slightly nonlinear behaviour when materials were strained under compression stress down to 15% ~ 30% of their nominal heights. Considering the physiological compression loading range of 8 mmHg, secant moduli of elasticity were 1.5% to 6.9% higher than the tension moduli of elasticity depending on the material. Tensile-based moduli of elasticity could be used in FE analysis as a step towards simulating the optical performance of soft contact lenses on-eye. However, nonlinear compression-based material models are recommended for FE analysis of soft contact lenses when lens-handling is investigated off-eye.

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

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.

scholarly journals Characterization of nanophotonic soft contact lenses based on poly (2-hydroxyethyl methacrylate) and fullerene

2013 ◽  
Vol 67 (6) ◽  
pp. 861-870 ◽  
Author(s):  
Aleksandra Debeljkovic ◽  
Lidija Matija ◽  
Djuro Koruga
Keyword(s):  
Contact Lens ◽  
Near Infrared ◽  
Contact Lenses ◽  
Base Material ◽  
Optical Power ◽  
Sem Analysis ◽  
Hydroxyethyl Methacrylate ◽  
Soft Contact ◽  
Soft Contact Lenses ◽  
Soft Contact Lens

This work presents comparative research of characteristics of a basic and new nanophotonic material, the latter of which was obtained by incorporation fullerene, C60, in the base material for soft contact lenses. The basic (SL38) and nanophotonic materials (SL38-A) for soft contact lenses were obtained by radical polymerization of 2-hydroxyethyl methacrylate and 2-hydroxyethyl methacrylate and fullerene, which were derived by the technology in the production lab of the company Soleko (Milan, Italy). The materials were used for production of soft contact lenses in the company Optix (Belgrade, Serbia) for the purposes of this research. Fullerene was used due to its apsorption transmission characteristics in ultraviolet, visible and near infrared spectrum. For the purposes of material characterization for potential application as soft contact lenses, network parameters were calculated and SEM analysis of the materials was performed while the optical properties of the soft contact lenses were measured by a Rotlex device. The values of the diffusion exponent, n, close to 0.5 indicated Fick's kinetics corresponding to diffusion. The investigated hydrogels could be classified as nonporous hydrogels. With Rotlex device, values of optical power and map of defects were showed. The obtained values of optical power and map of defects showed that the optical power of synthesized nanophotonic soft contact lens is identical to the nominal value while this was not the case for the basic lens. Also, the quality of the nanophotonic soft contact lens is better than the basic soft contact lens. Hence, it is possible to synthesize new nanophotonic soft contact lenses of desired optical characteristics, implying possibilities for their application in this field.

The effect of soft contact lenses with L-Menthol to enhance soft contact lens end of the day comfort

2021 ◽  
Vol 44 (1) ◽  
pp. 18
Author(s):  
Ruby Chiang ◽  
Rebecca Gao ◽  
Terry Chang ◽  
Jerry Chen ◽  
George Hsu
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Soft Contact ◽  
Soft Contact Lenses ◽  
Soft Contact Lens

scholarly journals Evaluation of Pollen Adhesion to Verofilcon-A Soft Contact Lenses

2021 ◽  
Vol 15 (1) ◽  
pp. 305-313
Author(s):  
Tatsuya Mimura ◽  
Hiroshi Fujishima ◽  
Eichi Uchio ◽  
Kazumi Fukagawa ◽  
Yuji Inoue ◽  
...  
Keyword(s):  
Contact Lenses ◽  
Pollen Grains ◽  
Soft Contact ◽  
Silicone Hydrogel ◽  
Soft Contact Lenses ◽  
Soft Contact Lens ◽  
Different Types ◽  
Protein Components ◽  
Cedar Pollen ◽  
Number Of Particles

Purpose: A new 1-day disposable soft contact lens (SCL), verofilcon-A, constructed of silicone hydrogel material, has recently become available in Japan. This SCL has a very smooth surface produced by using the SMARTSURFACE ® Technology, and it was expected that pollen particles and protein components would not adhere easily to its surface. We examined the degree of pollen adhesion to the surface of the verofilcon-A material SCL and compared the results with those of other 1-day disposable SCLs (1DSCL). Methods: To determine the number of pollen grains attached to the surface of different types of SCLs, 0.01 mg/ml of cedar pollen solution was dropped onto the surface of 13 types of 1DSCL. After 24 h, each 1DSCL was rinsed in a shaker and washed five times with saline (n = 10 for each 1DSCL type). The number of pollen particles adhered to the 1DSCL and the percentage of surface area occupied by pollen was determined. Results: The number of pollen particles on the 1DSCLs ranged from 0 to 185 in the 200 × 200 µm area. The number of particles was lowest in the delefilcon-A and verofilcon-A SCLs with 0 particles, and the number was higher in the other 11 1DSCLs. The number of pollen particles was negatively correlated with the water content (r = −0.48), oxygen permeability (Dk; r = −0.43), oxygen transmissibility (r = −0.42), and center thickness (r = −0.33) of the 1DSCLs. The pollen adhesion area ranged from 0.0% to 3.1% and was lowest in the delefilcon-A and verofilcon-A 1DSCLs. There were significant differences in the pollen adhesion area between colored 1DSCLs (2.73 ± 1.97%) and clear 1DSCLs (1.03 ± 1.01%, P<0.001) and between hydroxyethyl methacrylate-based 1DSCLs (1.84 ± 1.45%) and silicone hydrogel-based 1DSCLs (0.05 ± 0.16%, P<0.001). Conclusion: These findings indicate that the verofilcon-A 1DSCL processed with SMARTSURFACE™ Technology is an excellent option for SCL users with allergic conjunctivitis during the high pollen season.

Keratitis induced by soft contact lens

2021 ◽  
pp. 111-114
Author(s):  
Е.L. Usubov ◽  
◽  
I.A. Rusakova ◽  
E.M. Rakhimova ◽  
◽  
...  
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Antimicrobial Effect ◽  
Term Treatment ◽  
Soft Contact ◽  
Soft Contact Lenses ◽  
Uv Crosslinking ◽  
Soft Contact Lens ◽  
Long Term Treatment ◽  
Improper Use

A clinical case demonstrates that improper use of soft contact lenses can induce serious changes in the cornea, followed by long-term treatment, which in turn may be ineffective due to the developed antibiotic resistance. In similar cases, the use of UV crosslinking provides an additional antimicrobial effect, which ultimately allows the inflammatory process to be resolved. Key words: keratitis, soft contact lens, crosslinking.

The Conformity of a Soft Contact Lens on the Eye

1996 ◽  
Vol 118 (3) ◽  
pp. 341-348 ◽  
Author(s):  
GuoMing T. Funkenbusch ◽  
Richard C. Benson
Keyword(s):  
Contact Lens ◽  
Transverse Shear ◽  
Contact Lenses ◽  
Elastic Shell ◽  
Deformation Model ◽  
Soft Contact ◽  
Reaction Pressure ◽  
Soft Contact Lenses ◽  
Soft Contact Lens ◽  
Shear Loads

An axisymmetric elastic shell deformation model has been created to predict the conformity of a soft contact lens when pressed against the eye. Regions of contact and gap may be predicted, and the nonuniform reaction pressure between the lens and eye may also be found. This is important for issues like abrasion and comfort. Bending, membrane and transverse shear loads within the lens are also computed. Commercial soft contact lenses and a representative eye shape are used for the examples. We find that the uniformity of loading against the eye is strongly affected by the degree to which the lens is shaped to fit the eye, and relatively unaffected by the thickness of the lens.

Effects of novel multifocal soft contact lens on peripheral refraction of myopic eyes when looking at distant and near targets

2020 ◽  
Author(s):  
Fan Lu ◽  
Xinjie Mao ◽  
Shuyun Wen ◽  
Liang Lin
Keyword(s):  
Contact Lenses ◽  
The Novel ◽  
Soft Contact ◽  
Myopia Progression ◽  
Soft Contact Lenses ◽  
Soft Contact Lens ◽  
Long Time ◽  
Hyperopic Shift ◽  
Accommodative Lag ◽  
Near Work

Abstract Background It is generally accepted the association between hyperopic peripheral defocus and myopia progression. To search for a good optical method to slow the myopia progression for the children who need long-time near work, we compared the effects of novel multifocal soft contact lenses (MFSCLs) with single vision soft contact lenses (SVSCLs) on peripheral refraction when looking at both distant and near targets. Methods The refraction of 25 young myopic subjects’ right eye were measured at horizontal retina eccentricities in 10º steps from 30º temporal to 30º nasal, with no correction (baseline), novel MFSCLs and SVSCLs when looking at distant (5 m) and near (0.4 m) targets. Results Subjects wearing MFSCLs presented significantly more myopic relative peripheral refractive error (RPRE) profile than SVSCLs at all horizontal retina eccentricities when looking at distant targets (all p<0.01). Compared with looking at distant targets, subjects wearing SVSCLs or MFSCLs showed a hyperopic shift of peripheral defocus when looking at near targets, owning to the effects of accommodative lag and hyperopic RPRE change during accommodation (except T20º and T30º wearing SVSCLs and N30º wearing MFSCLs, p=0.822, p=0.950, p=0.390, respectively, all other eccentricities p<0.05). But subjects wearing MFSCLs could still maintain a certain magnitude of myopic peripheral defocus at horizontal retina eccentricities when looking at near targets (T20° and T30°, p=0.023 and p<0.001, respectively). Conclusions The novel MFSCLs imposed strong myopic peripheral defocus when looking at distant targets. They also maintain a certain magnitude of myopic peripheral defocus when looking at near targets, regardless of the hyperopic effect of accommodation lag and hyperopic shift in RPRE during accommodation.

scholarly journals Characterization of Soft Contact Lens Fitting Using Ultra-Long Scan Depth Optical Coherence Tomography

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Lele Cui ◽  
Ming Li ◽  
Meixiao Shen ◽  
Fan Lu ◽  
Jianhua Wang
Keyword(s):  
Optical Coherence Tomography ◽  
Contact Lens ◽  
Contact Lenses ◽  
Repeated Measurements ◽  
Optical Coherence ◽  
Soft Contact ◽  
Soft Contact Lenses ◽  
Soft Contact Lens ◽  
Good Repeatability ◽  
The Right

Objectives. To evaluate the centration and movement of soft contact lenses and to verify the repeatability of two repeated measurements of the lens centration and movement using ultra-long scan depth optical coherence tomography (UL-OCT). Methods. A 1-day Acuvue® Define™ lens was tested on both eyes of 10 subjects (5 males and 5 females; mean age, 31.6 years). The centration and blink-induced movement of the contact lens were measured using UL-OCT at 5 min and 30 min after insertion. The measurements were repeated once at each checkpoint. Results. Good repeatability was found in the lens centration and movement between the two repeated measurements at either checkpoint. The values of the lens movement were 0.457 ± 0.248 mm and 0.402 ± 0.229 mm at 5 min and decreased to 0.197 ± 0.065 mm and 0.211 ± 0.110 mm at 30 min after insertion for the right and left eyes, respectively (P<0.05). Conclusions. The custom-built UL-OCT presented good repeatability of centration and movement in Define lenses at 5 min and 30 min after insertion. Most of the lenses were centered temporal and inferior to the cornea during the first 30 min wearing period. Compared with 5 min after insertion, the lens was centered better and exhibited less movement at 30 min.

scholarly journals Pigmentation of the Cornea Secondary to Tinted Soft Contact Lens Wear

2012 ◽  
Vol 2012 ◽  
pp. 1-2
Author(s):  
Natasha Spiteri ◽  
Anshoo Choudhary ◽  
Stephen Kaye
Keyword(s):  
New York ◽  
Contact Lenses ◽  
Retrospective Case ◽  
Soft Contact ◽  
Contact Lens Wear ◽  
Soft Contact Lenses ◽  
Soft Contact Lens ◽  
Pathological Conditions ◽  
Normal Ageing ◽  
Lens Wear

Purpose. To report a case of pigmented corneal iron lines following use of tinted soft contact lenses (CL).Methods. A retrospective case report.Results. A 16-year-old girl was referred with suspected CL-related keratopathy OU, having recently switched to tinted soft monthly disposable CLs (8.4/14.0 −3.00 OD, −3.25 OS Aquamarine SofLens Natural Colours, Bausch and Lomb, New York, USA). Both corneas exhibited symmetric superficial corneal pigmented iron lines, which gradually disappeared following discontinuation of CL wear.Conclusions. Pigmented corneal rings have been reported in normal ageing corneas, in certain pathological conditions, and in association with altered corneal topography following LASIK and orthokeratology. We suspect a poorly fitting CL resulted in localised tear pooling between the CL and cornea, and subsequent iron pigment deposition, similar to that seen with orthokeratology. Cosmetic CLs bought via the Internet can be used in an unsupervised manner, with possible impacts on visual function and potential complications.

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