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Biomedical subjects

M Norn

Publications and source records attributed to M Norn.

53 records · Page 3Linked to original sources
PubMed1985

Tear pH after instillation of buffer in vivo.

UNLABELLED: The pH of the conjunctival fluid was measured with a micro-electrode at the middle of the inferior conjunctival fornix of 160 eyes (86 subjects). After instillation of buffer of pH 5 (in 22 eyes pH 9) the linear course of pH changes was followed until the starting value had been regained. The coefficient of regression K was computed (pH-units/min.). In normal eyes the K-value declines with increasing age from 1.0 to 0.5, corresponding to a return to the starting value after 2 to 5 minutes. The K-value is reduced significantly in keratoconjunctivitis sicca (K = 0.21, pemphigoid (0.36), during local anaesthesia (0.38 +/- 0.03 against 1.04 +/- 0.10 prior to 0.4% oxibuprocain), in the presence of a cotton plug in the inferior fornix, and in wearers of soft contact lenses. The K-value is normal in cases of lacrimal occlusion (owing to overflow), in exophthalmos and endothelial dystrophy, following corneal grafting, in conjunctivitis and keratitis, and in wearers of hard contact lenses. In cadaveric eyes we find incomplete, irregular neutralization. CONCLUSION: Tear dilution is the most important factor in the elimination of buffered eye drops in vivo, compared with the proper buffering capacities of the tears and the tissue.

Adult↗
PubMed1985

The effects of drugs on tear flow.

Systemic administration of drugs can diminish the tear flow as with timolol and atropine, or can increase the tear production as with bromhexine. Turpentine fumes (100 ppm/30 min or 30 ppm/8 h) have been shown to diminish the break up time (BUT) of tears by diminishing the lipid layer of the precorneal film. Ointment and drugs suspended in oil also diminish BUT, not only do they dry the corneal and conjunctival epithelium (judged by the rose bengal score) but also diminish the outflow as judged by the tear river dye dilution test in both normal people and those with keratoconjunctivitis sicca. Benzalconium chloride in concentrations used as a preservative and cocaine have also been shown to reduce BUT.

Castor Oil↗
PubMed1984

Spheroid degeneration, keratopathy, pinguecula, and pterygium in Japan (Kyoto).

The prevalences of various possibly sunlight-induced degenerations of the exposed section of the eye have been studied in a series of 189 Japanese (Mongols) in Kyoto (subtropical climate, 35 degrees N. lat.). The results were compared with those of the author's examinations, using the same method and apparatus, in Jordan near the Red Sea (Arabs, N = 127) in Greenland (Eskimos, N = 659), and in Denmark (Caucasians, N = 810). In the Japanese series conjunctival spheroid degeneration was noticed in 31% and pinguecula in 60%, i.e. less frequently than in the sunny Jordan, but more frequently than in Greenland and Denmark. Climatokeratopathy was more rarely observed than in Greenland. This goes to show that the risk of corneal complications is lower in Japan despite the high prevalence of solar conjunctival degenerations. Pterygium was seen in a surprisingly small number of cases (1%), indicating that pterygium bears no relation to the conjunctival degenerations.

Adolescent↗
PubMed1984

Pigmentation of plica and lacrymal caruncle. Prevalence among Caucasians, Eskimos, and Japanese.

Consecutive screenings by the same examiner (the author) disclosed among 380 white North Europeans (Copenhagen, Denmark) pigmentation of the plica semilunaris and/or lacrymal caruncle in 2%, among 189 Mongols (Kyoto, Japan) in 4%, and among 257 Eskimos (East Greenland) in 45% (P less than 0.001). In Eskimos the phenomenon was found to be bilateral in 60% and confluent with pigmentation of the bulbar conjunctiva in 18%. The prevalence is the highest among males, rising with increasing age. It is correlated to the prevalence of pigmentation of the bulbar conjunctiva, whereas not to that of subconjunctival pigmentation round scleral emissaries.

Adolescent↗
PubMed1983

Lipid deposits subconjunctivally and episclerally. Number, location, relation to external degenerations, and blood pressure.

Examination of 1029 subjects disclosed 30-60 micron-sized frog's egg-like lipid deposits subconjunctivally and episclerally in 34%. The prevalence was found to rise steadily with increasing age to a maximum between 70 and 80 (52%). The prevalence declined after the age of 80. Both sexes were equally represented, except in the age groups over 70, where females predominated. In 48% lipid deposits were presented in both eyes, located nasally, temporally, inferiorly, and superiorly in decreasing order of frequency. Vertical location alone was found in 13%. The number of lipid globules was the greatest horizontally (median value nasally 20, temporally 30) and the smallest vertically (median value inferiorly 8, superiorly 15). The lipid deposits were generally found in relation to anterior ciliary arteries, most frequently off the upper corner of the horizontal muscles. In no more than 13% were such deposits seen as pads bearing no relation to vessels, and in 1% between tendon fibres, likewise non-related to vessels. No relation was noticed to presence of pinguecula, pterygium, and scleral plaques, nor to blood pressure or particularly thick conjunctiva. Lipid deposits were rarer in cases with an extraordinarily thin conjunctiva. Presence of lipid deposits may possible be accountable for by injuries of the arterial wall due to eye muscle movements with subsequent exudation of lipids into the surrounding episcleral connective tissue.

Adolescent↗
PubMed1982

Ophthamologic effects of man-made mineral fibers.

The effect of man-made mineral fibers on the human eye was investigated in a cross-sectional study of 15 workers exposed to Rockwool and a matched reference group of 15 people. Eye symptoms, changes in the cellular and mucous content of the conjunctival fluid, break-up time of the precorneal film, the number of microepithelial defects, and the number of dead and degenerated cells on the cornea and bulbar conjunctiva were used as measures of effect. The number of fibers accumulated in the eye and conventional dust sampling methods were used as measures of dose. A significantly higher frequency of eye symptoms related to work conditions (p less than 0.001) was found among exposed workers. Similarly, the number of microepithelial defects on the medial bulbar conjunctiva increased significantly (p = 0.009) after 4 d of exposure. Six exposed workers had a pathological increase in the neutrophil count of the conjunctival fluid after 4 d of exposure, and an increase was seen in only one worker after a weekend free from exposure. Significant correlation was found between microepithelial defects on the medial bulbar conjunctiva and measures of dose (p less than 0.01). The symptoms and cellular changes can be explained by the assumption that man-made mineral fibers have the same mechanical and reversible effect on the eye as on the skin. The described dose-effect relationship suggests that a much lower hygienic standard is needed for man-made mineral fibers than what has been recommended by the American Conference of Governmental Industrial Hygienists.

Adult↗
PubMed1980

Astigmatism and surface phenomena in pterygium.

Examination of 39 eyes with pterygium and 17 contralateral eyes revealed increased astigmatism with the rule (greater than 0.5 D in 46%, greater than or equal to 4 D in 13%) without associated impairment of vision. Intensified vital staining was seen to be provoked over the pterygium by tetrazolium and rose bengal, whereas this was not the case with fluorescein or alcian blue. There were no signs of desiccation (Break up time normal). Stocker's line in front of the pterygium was observed in 46%. In 13% this was continuous with Hudson Stahli's line. A quantitative cytologic study disclosed keratinisation in 5%. Increased desquamation was seen in 10%. The central thickness of the cornea was the same as in normal eyes.

Adult↗
PubMed1980

Spheroid degeneration of conjunctiva and cornea. Two years' follow up.

Twenty-six subjects with spheroid degeneration were followed up after two years. The number of colourless conjunctival droplets was seen to have increased by on an average 46% (2 alpha = 0.05) and that of autofluorescent conjunctival droplets by 223% (2 alpha less than 0.01). Counting within the individual sites sites disclosed that some droplets will disappear (not less than 30 and 21% respectivelY), while recently formed will constitute at least 76 and 243%. The number of areas with band-shaped keratopathy was found to rise from 3 to 26 (P less than 0.001) out of 104 possibilities, (nasally and temporally of right and left eye). Vital staining (fluorescein, rose bengal, tetrazolium, alcian blue) showed the epithelium above the droplets to be intact, and the droplet-containing eyes were found not to be abnormally dry (break up time, tear production).

Alcian Blue↗