Visual functioning

The longitudinal effects of experimental vitamin E deficiency on visual function in the rat have been studied by Goss-Sampson et al. (1992). After 12 months of deficiency, visual function as assessed by electroretinography was absent or grossly abnormal. This was associated with... 

Headache and compromised visual function (loss of peripheral vision and blurred vision) caused by the actual tumor mass and its close proximity to the optic structures. 

The goals of therapy are to prevent further loss of visual function minimize adverse effects of therapy and its impact on the patient s vision, general health, and quality of life control intraocular pressure in order to reduce or prevent further optic nerve damage and educate and involve the patient in the management of their disease. 

Altmann L, Sveinsson K, Kraemer U, et al. 1998. Visual functions in 6-year-old children in relation to lead and mercury levels. Neurotoxicology and Teratology 20(1) 9-17. 

Dagnelie, G., I. S. Zorge et al. (2000). Lutein improves visual function in some patients with retinal degeneration A pilot study via the Internet. Optometry 71(3) 147-164. 

Schupp, C., E. Olano-Martin et al. (2004). Lutein, zeaxanthin, macular pigment, and visual function in adult cystic fibrosis patients. Am. J. Clin. Nutr. 79(6) 1045-1052. 

Strauss, O, 2005. The retinal pigment epithelium in visual function. Physiol Rev 85, 845-881. 

Olmedilla B, Granado F, Blanco I and Vaquero M. 2003. Lutein, but not a-tocopherol, supplementation improves visual function in patients with age-related cataracts a 2-y double-blind, placebo-controlled pilot study. Nutrition 19(1) 21 —24. 

The goal of drug therapy in patients with glaucoma is to preserve visual function by reducing the IOP to a level at which no further optic nerve damage occurs. 

Visual disturbances If treatment continues beyond 28 days, the effect of voriconazole on visual function is not known. If treatment continues beyond 28 days, monitor visual function including visual acuity, visual field, and color perception. Hepatic toxicity There have been uncommon cases of serious hepatic reactions during treatment with voriconazole (eg, clinical hepatitis, cholestasis, and fulminant hepatic failure, including fatalities). Liver dysfunction usually has been reversible on discontinuation of therapy. 

Barbizhayev, M. A. (2004). Rejuvenation of visual function in older adult drivers and drivers with cataract during a short-term administration of N-acetylcarnosine lubricant eye drops. Rejuvenation Res. 7,186-198. 

Stewart et al. 1961). Impaired visual functions have also been observed (Johnstone 1948 Smyth et al. 1936 Wirtschafter 1933). It should be noted that central nervous system effects disappear rapidly as carbon tetrachloride is eliminated from the body. Therefore, they will be detectable for only relatively short periods after exposure. 

Its most important adverse effects are visual disturbances. This ocular toxicity is dose dependent and has an incidence of lower than 1 % at low doses but can reach 5% at high dose regimens. Ocular toxicity manifests itself as retrobulbar neuritis usually after the second month of use. If therapy is discontinued immediately it is mostly reversible but not always. During the treatment visual function should periodically be tested. Age under 8 years is a relative contraindication as visual symptoms are difficult to monitor. 

Stringham, J.M., Hammond, B.R. (2005). Dietary lutein and zeaxanthin possible effects on visual function. Nutrition Reviews, 63, 59-64. 

The spontaneous evolution of this type of ulcer is dramatic and within a few weeks results in the conjunctival covering. This phenomena begins in the zone where limbal stem cells are the most insufficient, that is, as a general rule, in the inferior part. It gradually develops over the entire corneal surface and Anally results in a complete conjunctiva that is completely covered and a loss of visual function of the damaged eye (Figs. 7.13 and 7.14). 

The most common drug delivery method for treating ocular disorders is topical administration, due to its convenience and safety. However, the anterior segment of the eye also has various protective mechanisms for maintaining visual functions. After instillation of an ophthalmic drug, most of it is rapidly eliminated from the precorneal area due to drainage by the nasolacrimal duct and dilution by the tear turnover (approximately 1 pL/min) [17,18]. In addition, there is a finite limit to the size of the dose that can be applied and tolerated by... 

Gene Therapy Rescue of Visual Functions in a Blind Mouse Model of Leber Congenital Amaurosis. PLoS. Med. 2 e333. 

The effect of FTIs on retinal function also needs to be carefully examined. Several proteins involved in retinal signal transduction are farnesylated in vivo, presumably by FTase. These include rod cell cGMP phosphodiesterase a-subunit,108,109 rod cell transducin y-subunit,110,111 and rhodopsin kinase.112 Since the retina consists of terminally differentiated, nondividing cells, the anti-proliferative properties of FTIs should be inconsequential. Visual function could possibly be affected by alterations in the prenylation of proteins involved in retinal signal transduction, although any changes of this sort should be reversible. 

Several studies have tested visual function after exposure to carbon monoxide. To minimize variability, McFarland et al. (1944) studied brightness discrimination in a small group of well-trained subjects. The subjects reported decreases in visual sensitivity at approximately 4.5% COHb. Another study reported no adverse effects on visual discrimination or depth perception in subjects with 8% or 12% COHb (Ramsey 1973). Luria and McKay (1979) reported no decrement in night vision with COHb of 9%. Davies et al. (1981) reported that at 7% COHb there was no effect on visual function. The studies described above used various visual paradigms, which could account for the differences in results. 

Precorneal Tear Film Corneal transparency and good visual function require a uniform eye surface. This is achieved by the tear film, which covers and lubricates the cornea and the external globe. It is about 7-8 pm thick and is the first structure encountered by topically applied drugs. The trilaminar structure of the tear film is shown in Figure 2. 

Lens The lens is the transparent biconvex structure situated behind the iris and in front of the vitreous. It plays an important role in the visual function of the eye and also enables accommodation together with the ciliary muscle. The lens is made up of slightly more than 30% protein (water-soluble crystallins) and therefore has the highest protein content of all tissues in the body [20], The lens receives its nutrients from the aqueous humor and its transparency depends on the geometry of the lens fibres. 

Bryan PC, Efiong DO, Stewart-Jones J, Turner P. Propranolol on tests of visual function and central nervous activity. Br J Clin Pharmacol 1974 1 82. 

In this chapter, we extend the one-dimensional MRTM transport and adsorption model (Zeng et al., 2002 Selim et al., 1990) to three-dimensional applications, using the altemating-direction-implicit (ADI) numerical algorithm to reduce computational complexity. We also discuss the development of a web-based system with a user-friendly interface providing client-side and server-side computing applications and web-based visualization functionality. The accuracy and efficiency issues of solution algorithms will be addressed in future publications. 

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