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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three different components contribute to the modulation transfer function of the visual system: (1) formation of the optical image (refractive media, pupil); (2) scattering of light in the prereceptoral layers of the retina; (3) neuronal processing in the retina und superior visual centers. In the presence of media opacities or non-correctable refractive errors, the clinical question often arises as to which macular function can be expected under the assumption of normal optical image formation (e.g. prior to cataract extraction, corneal transplantation, or vitrectomy). Simple tests such as light projection, color discrimination, and two-point discrimination cannot provide adequate information about macular function. The same holds true for the global luminance ERG. The X-ray phosphene is obsolete. The Maddox rod (with limitations), transilluminated Amsler grid, and various entoptic phenomena (Purkinje vascular phenomenon, foveal chagrin, Haidinger's brushes, blue field phenomenon) are available as qualitative subjective tests. Maxwellian view systems with pinhole aperture (potential acuity meter PAM) and the interferometers (retinometer, visometer, SITE-IRAS interferometer) provide quantitative subjective methods. The flash VECP is primarily a qualitative objective test that allows semiquantitative acuity prediction under special conditions (unilateral opacities). Psychophysical criteria that are less affected by the quality of the retinal image show promising developments in future subjective tests, e.g. optotypes in positive contrast, optotypes or targets superimposed on a background of optical noise, or hyperacuity. Future objective test developments are pattern VECP or even pattern ERG elicited by interferometric stimulation, speckle VECP and focal ERG.
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PMID:[Predicting visual acuity in media opacities and uncorrectable refractive errors. Assessing so-called "retinal visual acuity"]. 208 91

Data obtained with the neutral red cytotoxicity assay reveal that human lens epithelial cells in culture are highly sensitive to low micromolar concentrations of unsaturated, cis-configured fatty acids in the following order: arachidonic acid>linolenic acid=linoleic acid=oleic acid, whereas the saturated fatty acids are much less effective. Though the cytotoxic effects of the unsaturated fatty acids could not be discerned from effects of their oxidation products, the fact that oleic acid is equally cytotoxic as linoleic acid or linolenic acid as well as previously reported findings with bovine lens epithelial cells support the idea that the unsaturated fatty acid molecules directly account for the cytotoxicity and not their products of lipid peroxidation. Bleb formation and cell retraction are early morphological signs of fatty acid-induced lens cell damage. These cellular alterations are accompanied by an aggregation of intermediate filaments in a first step, whereas the disorganization of microfilaments occurs at a later time and only at higher fatty acid concentrations. Measurements of protein-, RNA- and DNA-synthesis turned out to be much less sensitive parameters for the fatty acid-induced damage of lens cells. The uptake rate of linoleic acid by human lens cells is relatively high (4.35 fmol sec(-1) per 1000 cells), 30 and 50% higher as compared with diploid human embryonal lung fibroblasts and chemically transformed mouse fibroblasts, respectively. Saturation kinetics in combination with competition between linoleic acid, oleic acid and palmitic acid on one hand and ineffectiveness of trypsin and DIDS treatment on the other hand hint at cytoplasmic fatty acid binding proteins as receptors with high binding affinity (5.55 micromol l(-1), calculated for the linoleic acid-albumin complex) to be involved in the fatty acid uptake in human lens cells. Cellular fatty acid uptake is mainly influenced by the albumin concentrations present in physiological solutions. Albumin determinations in aqueous humor from 177 cataract patients reveal an age-dependent, statistically significant albumin rise with average values below 2 micromol l(-1) up to the age of 40 years to about 4 micromol l(-1) at the age between 80 and 90 years with single values up to 10 micromol l(-1). Using physiological fatty acid mixtures it is demonstrated that fatty acid-induced lens cell damage is strongly increased by elevated albumin concentrations found in aqueous humor of the elderly, who already have cataracts. Free fatty acid induced lens cell damage as a possible cause for age-dependent cataracts as well as a molecular link between systemic diseases such as diabetes and cataract formation is discussed.
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PMID:Fatty acid cytotoxicity to human lens epithelial cells. 1550 Aug 27

International variation in breast and colon cancer incidence is positively related to total fat intake. However, total fat consists of different fatty acid families, e.g., saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and n-3 and n-6 polyunsaturated fatty acids (PUFAs). Epidemiological evidence and experimental studies suggest that these fatty acid families have different effects on breast and colon carcinogenesis. Therefore the action of each fatty acid on carcinogenesis should be evaluated separately. Although it is difficult to establish firm conclusions on the effect of each fatty acid in human epidemiological studies, experimental studies on animals and cultured cells suggest that n-6 PUFAs (linoleic acid and arachidonic acid) may have a tumor promoting effect, while n-3 PUFAs (eicosapentaenoic acid, docosahexaenoic acid and alpha-linolenic acid) and conjugated fatty acids (CFAs; a mixture of positional and geometric isomers of PUFAs with conjugated double bonds) exert an inhibitory effect on tumor growth. SFAs such as palmitic acid and stearic acid show little or no tumor promoting effect, and the action of oleic acid, a MUFA, is inconclusive. In addition to regulation of abnormal cell growth seen in cancers, fatty acids also control cell loss seen in degenerative eye diseases, such as degeneration of lens material in cataract and degeneration of photoreceptor cells in retinitis pigmentosa. Experiments suggest that n-6 PUFAs cause deleterious effects, while n-3 PUFAs result in beneficial effects on the lens and retina. In particular, docosahexaenoic acid is known to be effective in rescuing photoreceptor cells from damage. Thus, understanding the function of each fatty acid is likely to be important for making progress in treating these and other diseases.
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PMID:Role of fatty acids in malignancy and visual impairment: epidemiological evidence and experimental studies. 1908 38

Background/Aims. To report the safety and efficacy of strontium (Sr(90)) beta radiotherapy as adjuvant treatment for conjunctival melanoma. Methods. A retrospective cohort study was undertaken from 1999 to 2007 of all patients who underwent Sr(90) beta radiotherapy for incompletely excised conjunctival melanoma. Failure of treatment was defined as recurrence of a conjunctival melanoma at the same location following beta radiotherapy. Results. Twenty patients underwent Sr(90) beta radiotherapy for incompletely excised conjunctival melanoma. Median follow-up interval was 59 months (8-152). All patients had conjunctival melanoma involving the bulbar conjunctiva. Underlying diagnoses included PAM with atypia in 60% (12 of 20), PAM without atypia in 15% (3 of 20), and de novo conjunctival melanoma in 25% (5 of 20). Following Sr(90) beta radiotherapy, in 90% (18 out of 20) local control was achieved and visual acuity was not affected in any patient. Three patients (15%) had dry eye symptoms, episcleritis, and descemetcoele, respectively. No cataract or secondary glaucoma was reported. Conclusions. Sr(90) treatment is a very effective adjuvant treatment after excisional biopsy and cryotherapy for conjunctival melanoma with a local success rate of 90%. The treatment is not associated with significant side effects and visual acuity is not affected.
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PMID:The use of strontium-90 Beta radiotherapy as adjuvant treatment for conjunctival melanoma. 2343 Dec 99