Opaque, corneas

Opaque cornea, iris not discernible through the opacity... 

The condition in which patients have a decreased vision, ocular pain, red eye, and often a cloudy/opaque cornea. Keratitis is mainly caused by bacteria, viruses, fungi, protozoa and parasites. 

IV Opaque cornea iris and pupil are not visible > i Poor... 

CHRONIC HEALTH RISKS prolonged exposure may have harmful effects on the liver, kidneys and lungs may cause serious eye damage, including opaque cornea, keratoconus, and extensive necrosis of cornea liquid may cause defatting of skin. 

Mannosidosis (an oligosaccharidosis). a-Mannosidase (EC 3.2.1.24). Accumulation of mannose-rich, glucosamine-containing oligosaccharides. Brain damage, bone abnormalities, opaque cornea and cataracts, hepatosplenomegaly. Skeletal involvement and facial features similar to Hurler s syndrome (below). 

Cl.-idc d Opaque cornea Iris is not visible Major ischemia altering more then half of the limbal arcumference Bad... 

Opaque deposits in the cornea and lens may occur with chronic phenothi-azine treatment, especially with CPZ. Although visual acuity is not usually affected, periodic slit-lamp examinations are recommended with use of long-term phenothiazines. Baseline and periodic slit-lamp examinations are also recommended for quetiapine-treated patients because of cataract development and lenticular changes in animal studies. 

Two drops of a 10% solution instilled in rabbit eyes caused immediate pain, and the epithelium turned gray within seconds the conjunctivae were hyperemic with moderate discharge and corneas were opaque at 2 days. Corneal clouding gradually, but not completely, cleared with in 6 weeks. 

Application of a 0.1M solution of yttrium chloride to the eyes of rabbits caused no injury similar exposure of eyes from which the corneal epithelium had been removed resulted in immediate slight haziness of the cornea, which subsequently became opaque and vascularized. The 2003 ACGIH threshold limit value-time-weighted average (TLV-TWA) for yttrium and compounds is 1 mg/m as Y. 

Night blindness (inability to see in dim light), conjunctival xerosis (dry and non-wettable conjunctiva), corneal xerosis (dry and non-wettable cornea and become opaque), keratomalacia (cornea becomes soft and burst open and vision is lost), Bitot s spots, growth retardation, dry and rough skin, sterility due to faulty spermatogenesis. 

With a size of about 1.3 cm and an average diameter of 11.5 mm in adulthood, the cornea has an ovoid shape with a horizontal axis on its front side and is circular on its back side. It is 0.5-mm thick at the center and 1-mm thick on the edge. As shown by modem measurements, the shape of the cornea can differ for different individuals. On its edge there is the limbus that partly has the same characteristics and ensures the junction with the totally opaque sclera, which surrounds the entire eyeball. 

Located on the edge of the transparent cornea, it maintains the junction with the opaque sclera. On the level of the epithelium, it is the transition between a multilayer scale-like corneal epithelium and a cylindrical conjunctival epithelium with two cellular bases, with continuity of the basement membranes. At the epithelial level, the cells of the comeal epithelium are gradually replaced by a conjunctival epithelium made of two layers of cylindrical cells accompanied by calyciform cells. 

Sclera The sclera is the outermost firm coat of the eye that serves as a protective barrier for the sensitive inner parts. It is composed of the same type of collagen fibers as the corneal stroma. However, the fibers are arranged in an irregular network rather than a lattice pattern, which makes the tissue appear opaque compared to the transparent cornea. The white sclera constitutes the posterior five-sixths of the globe, whereas the transparent cornea comprises the anterior one-sixth [17],... 

The sclera is an opaque vascular structure continuous with the cornea at the limbus.The loose connective tissue overlying the sclera—the conjunctiva—is also vascularized. The conjunctiva and sclera, as routes of drug penetration, are responsible for less than one-fifth of all drug absorption to the iris and ciliary body. This limited absorption is due to the extensive vascularization of these tissues, which results in removal of most dmgs. However, in recent years, the conjunctiva has been studied as a route of possible drug delivery because it contains a larger surface area than the cornea and possesses key transport processes that may allow fc>r penetration into intraocular tissues (Figure 2-4). 

Soft lenses are made of hydrophilic hydrogel polymers that contain 36-74% water. Other plastics and copolymers are added to alter the physical characteristics of the lens. The diameter is 10.5-15.5 mm and the thickness at the center 0.03-20 mm. Soft lenses can correct most optical defects, including myopia, hyperopia, and astigmatism. Bifocal lenses are also available. They can be colored with either transparent hnes or opaque patterns to change apparent eye color or to mask malformations of the cornea or iris. They are available for daily, weekly, and twice-weekly disposable nse, 1-3 months frequent replacement, and annual replacement. 

The cornea is connected at the limbus to the opaque sclera, the tough fibroelastic capsule that encloses the eye and provides support and protection to the interior structures. The visible area of the sclera is generally referred to as the conjunctiva. The stroma has loosely packed collagen fibrils with scattered fibrocytes and few blood vessels, except in the limbal area. No junctional complexes are present, so the sclera presents only a lipophilic barrier to foreign materials. The limbus is rich in blood vessels, and systemic absorption of topically applied drugs occurs here primarily. 

The lens of the eye sometimes becomes opaque (cataract formation), apparently due to cross-linking of its proteinaceous material, and must be removed to restore vision. Intraocular lens implants are normally made from poly(methyl methacrylate), although other materials. Including hydrogels, have been tried. In over 73% of the cases, vision of 20/40 or better can be achieved by these implants (67). The cornea is also subject to cataract formation and... 

Toxicoiogy Acute overexposure inritatbn, inflamm., or bums to eyes conjunctivitis, opaqueness of cornea, possibly vision loss headache, mental confusion, nausea, narcosis in high cones. chronic overexposure severe dermatitis... 

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