עמוד 1 מ 282 תוצאות
Microbial keratitis with Pseudomonas aeruginosa is the most common corneal infection associated with contact lenses (CLs). Pseudomonas organisms are ubiquitous in nature, and can colonize CLs without a prior breach in lens care or hygiene. Although poor lens care is often found in affected patients,
The ocular lens somehow remains pellucid despite bombardment by ultraviolet radiation and endogenous hydrogen peroxide (present in the humoral fluids which bathe this tissue). The lens and adjacent aqueous and vitreous humors contain exceptionally high concentrations of reducing substances,
OBJECTIVE
The lens grows continuously throughout life, but the factors that influence the size of the adult lens are not known. Lens thickness is a significant risk factor for age-related cataract. It has been postulated that the hypoxic environment in the eye protects the lens from nuclear
OBJECTIVE
To show that hypoxia is necessary to prevent opacification of the lens. Protein kinase C (PKC)-epsilon serves a role that is distinct from PKC-gamma when both PKC isoforms are expressed in the lens. PKCepsilon serves a very important role in hypoxic conditions, helping to prevent
Restriction of both oxygen influx to the cornea and carbon dioxide efflux from the cornea by contact lenses results in adverse tissue changes. We measured the extent of hypoxia and hypercapnia at the corneal surface of 10 human volunteers during static, dynamic (blinking), and closed-eye wear of
OBJECTIVE
Changes in pH in the corneal epithelium, stroma, endothelium and aqueous humor following contact lens wear were evaluated.
METHODS
Intracellular pH, stromal pH, and aqueous humor pH were measured either in vivo or in vitro in humans and in rabbits using pH-sensitive fluorescent dyes.
BACKGROUND
Lens transmissibility (Dk/L) and corneal relief from hypoxia are not linearly related. We describe graphically and by equations the relationship between corneal relief (scaled in oxygen shortfall units) and Dk/L across the transmissibility range of 1.2 to 189 x 10(-9) (cm/sec)(ml O2/ml
In the U.S. Air Force, aircraft can be divided into two categories--those with cabin pressures equivalent to high altitudes and aircraft with cabin pressures equivalent to lower altitudes, with longer duration exposures. The purpose of this study was to determine the effects of soft contact lens
Glycogen, adenosine triphosphate, and hydration were measured in rabbit corneal epithelium to determine whether the corneal epithelium glycogen decrease, increase in epithelial hydration, and decrease in epithelial adenosine triphosphate stores, seen as a result of contact lens wear, were secondary
High Dk silicone hydrogel lenses have overcome many of the hypoxic problems associated with traditional extended wear, and the popularity of continuous wear with these lens types is increasing. Despite the elimination of hypoxia, several noninflammatory clinical complications have been reported to
Common types of contact lens are hard, rigid gas-permeable or soft lenses. Most lenses are worn on a daily basis. Cosmetic lenses are worn for non-medical indications. Microbial keratitis, a rare but most significant complication is discussed in this article. Pseudomonas aeruginosa and staphylococci
BACKGROUND
Although contact lens-induced corneal warpage is most frequently associated with PMMA lenses, approximately 27% of reported cases of corneal warpage have been attributed to hydrogel lens wear. The change in corneal contour may be the result of either mechanical deformation, chronic
The cornea normally receives its oxygen from both the atmosphere and the aqueous humor. When a thick polymethylmethacrylate contact lens is placed on the cat cornea, access of atmospheric oxygen to the cornea is restricted, and the outer part of the cornea becomes hypoxic. This results in an