scholarly journals Equivalences between refractive index and equilibrium water content of conventional and silicone hydrogel soft contact lenses from automated and manual refractometry

2006 ◽  
Vol 80B (1) ◽  
pp. 184-191 ◽  
Author(s):  
José M. González-Méijome ◽  
Antonio López-Alemany ◽  
Madalena Lira ◽  
José B. Almeida ◽  
M. Elisabete C. D. Real Oliveira ◽  
...  
Keyword(s):  
Refractive Index ◽  
Water Content ◽  
Contact Lenses ◽  
Equilibrium Water Content ◽  
Soft Contact ◽  
Silicone Hydrogel ◽  
Soft Contact Lenses

Refractive index and equilibrium water content of conventional and silicone hydrogel contact lenses

2006 ◽  
Vol 26 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Jose M. Gonzalez-Meijome ◽  
Madalena Lira ◽  
Antonio Lopez-Alemany ◽  
Jose B. Almeida ◽  
Manuel A. Parafita ◽  
...  
Keyword(s):  
Refractive Index ◽  
Water Content ◽  
Contact Lenses ◽  
Equilibrium Water Content ◽  
Silicone Hydrogel

Modification of therapeutic silicone-hydrogel soft contact lenses

2016 ◽  
Vol 16 (3) ◽  
pp. 117-120 ◽  
Author(s):  
T.N. Safonova ◽  
◽  
I.A. Novikov ◽  
V.I. Boev ◽  
O.V. Gladkova ◽  
...  
Keyword(s):  
Contact Lenses ◽  
Soft Contact ◽  
Silicone Hydrogel ◽  
Soft Contact Lenses

scholarly journals Water Properties of Soft Contact Lenses: A Comparative Near-Infrared Study of Two Hydrogel Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Jelena Munćan ◽  
Ivana Mileusnić ◽  
Jovana Šakota Rosić ◽  
Aleksandra Vasić-Milovanović ◽  
Lidija Matija
Keyword(s):  
Water Content ◽  
Near Infrared ◽  
Contact Lenses ◽  
Polymer Network ◽  
The State ◽  
Vinyl Pyrrolidone ◽  
Soft Contact ◽  
Infrared Study ◽  
Soft Contact Lenses ◽  
State Of Water

The functionality of soft contact lenses depends strongly on the water content and their water-transport ability. This study was conducted in order to examine the state of water in two sets of soft contact lenses: VSO38, pHEMA Filcon I 1, and VSO50, copolymer of HEMA and VP Filcon II 1 (HEMA = 2-hydroxy-ethyl methacrylate; VP = vinyl pyrrolidone). Hydrogel lenses were studied using near-infrared spectroscopy and the novel Aquaphotomics approach in order to determine the state of water in materials based on their near-infrared spectra. Aquaphotomics approach investigates absorption at specific vibrational bands of water’s covalent and hydrogen bonds which can provide information on how the water structure changes with the structural change of the polymer network. Principal component analysis and specific star-chart “aquagram” were used to analyse water spectral pattern in hydrogel materials. The findings show that material VSO38 has water predominantly organized in bound state, while material with higher water content, VSO50, has more free and weakly hydrogen bonded water. Our findings define in detail exact water species existing and interacting with the polymer network. The results show qualitative and quantitative possibilities of Aquaphotomics for better modelling and understanding water behaviour in hydrogel materials.

scholarly journals Accurate measurements of phase refractive index of soft contact lenses

2020 ◽  
Vol 28 (8) ◽  
pp. 10818
Author(s):  
Todd Szarlan ◽  
Donald Gibson ◽  
Xin Wei ◽  
Filipp Ignatovich
Keyword(s):  
Refractive Index ◽  
Contact Lenses ◽  
Soft Contact ◽  
Soft Contact Lenses

scholarly journals Refractive behavior changes with six months daily wear of high and low oxygen permeability hydrogel contact lenses

2006 ◽  
Vol 65 (2) ◽  
Author(s):  
W.D.H. Gillan
Keyword(s):  
Oxygen Permeability ◽  
Contact Lenses ◽  
The Other ◽  
Behavior Changes ◽  
Low Oxygen ◽  
Soft Contact ◽  
Silicone Hydrogel ◽  
Refractive State ◽  
Soft Contact Lenses ◽  
Silicone Hydrogels

Introduction: The investigation of myopia and soft contact lenses is not new. Many reports show  that  the  wearing  of  silicone  hydrogel lenses as opposed to conventional disposable hydrogel lenses results in little progression of myopia in the eyes wearing silicone hydrogels. Method: Six subjects wore a silicone hydro-gel lens on one eye while the other eye wore a habitual disposable hydrogel lens for six months of daily wear. Fifty measurements of refractive state in each eye were taken prior to the subjects wearing a silicone lens in one eye and a conven-tional hydrogel lens in the other eye. After six months of daily wear another fifty measurements of refractive state were taken for each subject. Results:  Although  there  is  no  statisti-cal  support  for  the  findings  of  this  study, comet stereo-pairs are used to show the chang-es in refractive state for each subject. Four of  the  six  subjects  showed  an  increase  in myopia in the eye wearing the silicone lens. Discussion:  The  increase  in  myopia in eyes wearing a silicone hydrogel lens is contrary  to  the  findings  of  other  studies.

Effect of the medicine “Cationorm” on lacrimal film in obstructive dysfunction of meibomyus glands among users of soft contact lenses

2020 ◽  
pp. 39-45
Author(s):  
Ekaterina B. GORSHENYOVA ◽  
Nataliya M. SUTORMINA
Keyword(s):  
Hyaluronic Acid ◽  
Contact Lenses ◽  
Control Group ◽  
Delayed Effect ◽  
Soft Contact ◽  
Silicone Hydrogel ◽  
Soft Contact Lenses ◽  
Pathogenetic Therapy ◽  
Tear Substitute

There are more than 80 million users of soft contact lenses in the world - 10-15 % of the population. The prevalence of meibomyus gland dysfunction is 43-61 % with the prevalence of obstructive form and the development of lipodeficiency in lacrimal film. At the same time, the use of traditional tear substitutes based on hyaluronic acid is ineffective and the problem of finding a tear substitute with exposure to all 3 layers of lacrimal film becomes relevant. Nanoemulsion “Cationorm” is created as a means of pathogenetic therapy of dry eye syndrome against the background of lipodeficiency, however, there weren't any studies of its effectiveness in obstructive form of meibomyus gland dysfunction among users of soft contact lenses. We examined 3 layers of lacrimal film with the help of Norn's sample with determination of time of lacrimal film break, bio-measurement of lacrimal meniscus and biomicoscopy of eyelid edge region at painting of lissamino-om green. The study involved 28 young carriers of silicone-hydrogel contact lenses with signs of obstructive form of meibomyus gland dysfunction, who we divided into two groups: a control group used to eliminate the symptoms of a hyaluronic acid-based tear substitute, and an experimental group using the drug “Cationorm”. We revealed prolonged effect of nanoemulsion “Cationorm” on all three layers of lacrimal film, which hasn't only symptom lacrimal, but has pathogenetic therapeutic delayed effect among users of soft contact lenses with obstructive form of dysfunction of meibomyum glands, and nanostimer of lipid microspheres provides full compatibility even with material of silicone-hydrogel soft contact lenses. We proved the protective effect of the preparation on ocular epithelium cells.

Measurement of the Refractive Index of Soft Contact Lenses During Wear

2010 ◽  
Vol 36 (1) ◽  
pp. 2-5 ◽  
Author(s):  
Jalaiah Varikooty ◽  
Nancy Keir ◽  
Craig A. Woods ◽  
Desmond Fonn
Keyword(s):  
Refractive Index ◽  
Contact Lenses ◽  
Soft Contact ◽  
Soft Contact Lenses
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