Epalrestat-loaded silicone hydrogels as contact lenses to address diabetic-eye complications

2018 ◽  
Vol 122 ◽  
pp. 126-136 ◽  
Author(s):  
Fernando Alvarez-Rivera ◽  
Angel Concheiro ◽  
Carmen Alvarez-Lorenzo
Keyword(s):  
Contact Lenses ◽  
Silicone Hydrogels

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.

scholarly journals Patient and practitioner compliance with silicone hydrogel and daily disposable lens replacement in Canada

2010 ◽  
Vol 72 (1) ◽  
pp. 10
Author(s):  
Doris Richter ◽  
Kathy Dumbleton ◽  
Sarah Guthrie ◽  
Craig Woods ◽  
Lyndon Jones ◽  
...  
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Common Reason ◽  
Type Distribution ◽  
Reminder System ◽  
Silicone Hydrogel ◽  
Actual Contact ◽  
Survey Questions ◽  
Silicone Hydrogels ◽  
Improve Compliance

Purpose: To assess current recommendations by optometrists for replacement frequency (RF) of silicone hydrogels (SH) and daily disposable (DD) contact lenses in Canada, determine rates of non-compliance with recommendations by both the optometrist and patient, and investigate reasons for non-compliance. Methods: Survey packages were sent to optometrists in Canada who had agreed to participate. Patients completed survey questions regarding demographics and contact lens wearing patterns, including recommended and actual contact lens RF. Optometrists were asked to provide lens information and their recommendation for RF. Fifty-eight optometrists returned 654 surveys, of which 578 were eligible for analysis. Results: Seventy percent of patients were female with a median age of 32 years. Lens type distribution was 18% DD, 35% two-week SH, and 47% one-month SH. Six percent were worn for extended wear. Daily wear median wearing time was 12 hours/day, a median of five days/week for DD, seven days/week for SH (two-week and one-month). Optometrists’ recommendations were non-compliant with the manufacturers’ recommended RF for 6% of DD, 35% of two week, and 2% of one-month patients. Patients were non-compliant with recommendations from both the manufacturer and optometrist for 12% of DD, 43% of two-week, and 31% of one-month lens wearers. The most common reason for non-compliance was forgetting which day to replace lenses. Fifty-six percent thought a reminder system would help with compliance. A higher proportion of compliant patients followed the RF because of confidence in their optometrist. Conclusions: Optometrists generally recommended RFs consistent with manufacturers’ recommendations for DD and one-month SH lenses but often recommended longer intervals for two-week SH lenses. Patients were most compliant when wearing DD lenses and least compliant when wearing two-week SH lenses. Communication between the patient and optometrists concerning the risks of non-compliance, or initiating a reminder system might improve compliance.

Quality Control of Silicone Hydrogel Contact Lenses by Impedance Spectroscopy

2014 ◽  
Vol 1626 ◽  
Author(s):  
M. Torres ◽  
K.S.V. Santhanam
Keyword(s):  
Quality Control ◽  
Phase Angle ◽  
Contact Lens ◽  
Contact Lenses ◽  
Electrochemical Impedance ◽  
Spectroscopic Method ◽  
Impedance Change ◽  
Impedance Measurements ◽  
Silicone Hydrogel ◽  
Silicone Hydrogels

ABSTRACTWe wish to propose an impedance spectroscopic method for the quality control of contact lenses by measuring the pore resistance. Silicone hydrogels are excellent materials for use as contact lenses and their on eye performance is dependent on salt intrusion characteristics which are related to the pore resistance and water uptake. When the contact lenses are placed on the eye, they are expected to permeate ions and molecules to maintain ocular health. The hydrogel pores control the permeability and can be viewed as a quality control parameter. Two models are considered here: in one, the contact lenses are considered as strong rigid films with no permeability. In another, the hydrogels are having ionic permeability. We designed a silicone hydrogel contact lens attachment holder that is amenable for electrochemical impedance measurements. The electrochemical impedance measurements were carried out in an inert medium of 0.1 M Na2SO4. The impedance measurement experimental parameters used were a) AC potential 10 mV rms b) frequency range 0.1-210 kHz and c) open circuit potential of 0.207 V. The impedance variation with frequency was constructed for a number of hydrogels. The ideally acceptable silicone hydrogel contact lenses showed an impedance change with frequency in a sigmoidal fashion with a characteristic phase angle (acceptable in the range of 70-75o). The hydrogel pore resistances for the acceptable contact lenses are in the range of 4.5-11 kΩ. When the impedance showed a linear decrease or no well defined phase angle, the contact lens is considered acting as an insulator-a test for rejection. A test of the model was done with several acceptable contact lenses in the market. This study revealed interesting aspects of the influence of pulsating electric field on the silicone hydrogels.

scholarly journals Resveratrol-Loaded Hydrogel Contact Lenses with Antioxidant and Antibiofilm Performance

Pharmaceutics ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 532
Author(s):  
María Vivero-Lopez ◽  
Andrea Muras ◽  
Diana Silva ◽  
Ana Paula Serro ◽  
Ana Otero ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Contact Lenses ◽  
Ex Vivo ◽  
Chorioallantoic Membrane ◽  
Preferential Adsorption ◽  
Ocular Infections ◽  
Silicone Hydrogels ◽  
Hen’S Egg ◽  
Wide Range ◽  
And Staphylococcus Aureus

Contact lenses (CLs) are prone to biofilm formation, which may cause severe ocular infections. Since the use of antibiotics is associated with resistance concerns, here, two alternative strategies were evaluated to endow CLs with antibiofilm features: copolymerization with the antifouling monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) and loading of the antioxidant resveratrol with known antibacterial activity. MPC has, so far, been used to increase water retention on the CL surface (Proclear® 1 day CLs). Both poly(hydroxyethyl methacrylate) (HEMA) and silicone hydrogels were prepared with MPC covering a wide range of concentrations (from 0 to 101 mM). All hydrogels showed physical properties adequate for CLs and successfully passed the hen’s egg-chorioallantoic membrane (HET-CAM) test. Silicone hydrogels had stronger affinity for resveratrol, with higher loading and a slower release rate. Ex vivo cornea and sclera permeability tests revealed that resveratrol released from the hydrogels readily accumulated in both tissues but did not cross through. The antibiofilm tests against Pseudomonas aeruginosa and Staphylococcus aureus evidenced that, in general, resveratrol decreased biofilm formation, which correlated with its concentration-dependent antibacterial capability. Preferential adsorption of lysozyme, compared to albumin, might also contribute to the antimicrobial activity. In addition, importantly, the loading of resveratrol in the hydrogels preserved the antioxidant activity, even against photodegradation. Overall, the designed hydrogels can host therapeutically relevant amounts of resveratrol to be sustainedly released on the eye, providing antibiofilm and antioxidant performance.

Complications associated with the wearing of contact lenses

JAMA ◽  
1966 ◽  
Vol 195 (11) ◽  
pp. 901-903 ◽  
Author(s):  
J. M. Dixon
Keyword(s):  
Contact Lenses
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