Protection from UV radiation.
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Cataract↗
Biomedical subjects
T G Quinn
Publications and source records attributed to T G Quinn.
Component evaluation of cup/disk ratio estimation.
Cup/disk (C/D) ratio estimation is frequently used to evaluate cupping within the optic nerve head. Two components are involved in the determination of this value: (1) the cup and disk margin determination, and subsequently (2) the magnitude estimation of the cup size relative to the disk size. This study investigated the magnitude estimation component by asking fourth year optometry students to estimate C/D ratios on optic nerve head photographs and drawings. The importance of the magnitude estimation was demonstrated by the high degree of variability among subjects on the nerve head drawings upon which cup and disk margins were presented unambiguously. A subsequent survey of faculty clinicians indicated a large percentage of practitioners (41%) have no method they consciously use to help determine their C/D ratio estimate. A specific method is presented which allows clinicians to simply and logically deduce this magnitude estimation.
Glaucoma↗
Polymorphic corneal abnormalities.
Alterations of the deep corneal layers, which are manifest primarily as Hassall-Henle bodies in older patients, are a relatively frequent finding in the normal population. Changes which occur in Descemet's membrane and the endothelium earlier in life can be ascribed to various causes, including dystrophy, herpetic infections, and birth trauma. Six cases in which clear vesicles and scalloped lesions were found exclusively at the level of Descemet's membrane and the endothelium are reported. Although the polymorphic changes were in some cases extensive, visual acuity and, apparently, corneal physiology remained normal. The etiology for all cases was uncertain, but the evidence suggested a dystrophic origin or the occurrence of posterior corneal vesicles of a nonfamilial variety.
Adult↗
Human corneal epithelial oxygen demand--population characteristics.
Observed differences in corneal response to contact lens wear have been attributed to variations in individual corneal oxygen requirements. Anterior corneal oxygen flux was measured on 100 human eyes using a polarographic oxygen sensor to determine if differences could be measured among subjects. A distribution in corneal epithelial oxygen use was found to exist in the population.
Adolescent↗
Solubility effects on corneal oxygen measurement.
Various membrane materials have been attached to oxygen sensors during measurement of corneal oxygen uptake. Differences in the oxygen solubility characteristics of these membranes directly affect resulting flux values. Human corneal epithelial oxygen uptake values were obtained using an oxygen sensor in conjunction with polyethylene, Teflon, and polypropylene membranes attached to its tip. Conversion coefficients were calculated to relate findings obtained with each membrane-sensor system. New solubility constants were derived for polyethylene, Teflon, and polypropylene based on previous findings obtained with a saline (hydrophilic lens) membrane reservoir.
Cornea↗