SciCombinator

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Concept: Rigid gas permeable

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Purpose: To alter the composition and structure of silicone hydrogel contact lenses to achieve controlled release of dexamethasone and evaluate the lens optical and mechanical properties compared to commercial lenses. There is a tremendous need for controlled release of drugs from ocular biomaterials as the majority of ophthalmic drugs are delivered via topical eye drops, which have low bioavailability and patient compliance. Methods: Poly(PDMS-co-TRIS-co-DMA) contact lenses were synthesized with varying PDMS/TRIS:DMA ratios (0.25:1, 0.67:1, 1.5:1) as well as with additional crosslinking monomers. Lenses were characterized via in vitro release studies in a microfluidic device at ocular flowrates and in large well-mixed volumes, optical quality studies over visible wavelengths, mechanical analysis, and determination of polymer volume fraction in the swollen state. Results: Extended and controlled release of therapeutically relevant concentrations of dexamethasone was achieved for multiple day, continuous wear up to 60 days at in vitro ocular flowrates. Release was delayed due to a combination of increased hydrophobic to hydrophilic composition and the inclusion of additional structural constraints, both of which decreased the polymer volume fraction in the swollen state. However, decreased mass release rates were at the expense of increased modulus and decreased lens flexibility. All lenses had high optical clarity (∼90% transmittance) and contained highly oxygen permeable siloxane composition similar to those found in commercial silicone hydrogel lenses, but they had poor flexibility for use as soft contact lenses. Conclusions: Based on our results, the lenses described herein likely have too high of a modulus for use as extended-wear, soft contact lenses with drug release. Therefore, other controlled release methods would be better suited for maintaining adequate mechanical properties and achieving controlled and extended release for the duration of wear in soft, silicone hydrogel contact lens biomaterials. However, these biomaterials may find clinical use as more rigid gas permeable contact lenses or inserts.

Concepts: Polymer, Cornea, Lens, Contact lens, Contact lenses, Corrective lens, Visible spectrum, Rigid gas permeable

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To investigate changes in tear and ocular surface of patients with keratoconus using rigid gas permeable contact lenses (RGPCL) and compare them against keratoconus patients who were not using lenses as well as a control group of healthy subjects.

Concepts: Cornea, Contact lens, Contact lenses, Keratoconus, Scleral lens, Oxygen permeability, Rigid gas permeable

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The aim of this exploratory study was to investigate the micromorphology of surfaces of rigid gas permeable (RGP) contact lenses (CLs) using atomic force microscopy (AFM) followed by fractal analysis.

Concepts: Surface, Contact lens, Contact lenses, Differential geometry, Rigid gas permeable

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To determine the effect of rigid gas permeable contact lenses (RGPCL) on involuntary eye movements and visual function in hyperopic patients with infantile nystagmus syndrome.

Concepts: Eye movement, Visual acuity, Cornea, Myopia, Contact lens, Contact lenses, Corrective lens, Rigid gas permeable

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To calculate and validate a new web-based algorithm for selecting the back optic zone radius (BOZR) of spherical gas permeable (GP) lens in keratoconus eyes.

Concepts: Cornea, Lens, Contact lens, Contact lenses, Corrective lens, Keratoconus, Scleral lens, Rigid gas permeable

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To determine the short-term effect of rigid gas permeable (RGP) contact lenses on corneal aberrations in keratoconic patients.

Concepts: Cornea, Myopia, Lens, Contact lens, Contact lenses, Keratitis, Corrective lens, Rigid gas permeable

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To assess the percentage of successful rigid gas permeable (GP) contact lenses (CLs) fit for both refractive and therapeutic reasons.

Concepts: Cornea, Myopia, Lens, Contact lens, Contact lenses, Corrective lens, Intraocular lens, Rigid gas permeable

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To determine the repeatability of the back optic zone radius (BOZR) of rigid gas permeable (GP) contact lens (CL) proposed by new software for fitting in healthy and keratoconus eyes and to compare with the diagnostic CL fitting method.

Concepts: Cornea, Lens, Contact lens, Contact lenses, Corrective lens, Keratoconus, Scleral lens, Rigid gas permeable

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To evaluate the clinical value of rigid gas permeable contact lenses (RGPCLs) in patients with traumatic corneal scarring and address implications of primary corneal repair.

Concepts: Cornea, Orthokeratology, Contact lens, Contact lenses, Keratitis, Rigid gas permeable

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