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Biomedical subjects

R H Rengstorff

Publications and source records attributed to R H Rengstorff.

At least 19 recordsLinked to original sources
PubMed1986

Adaptation to Paraperm extended wear lenses: a clinical study in Sweden.

Paraperm EW, a new, rigid gas-permeable material with a Dk of 56 X 10(-11) was manufactured into contact lenses in Sweden. One hundred-five patients were fitted including three patients with aphakia, seven with keratoconus and 17 with astigmatism of 2.5 D or more. In this initial study of adaptation, these lenses were worn on a daily basis with a 95% success rate. Over one-third of the patients were previously unsuccessful with PMMA, other rigid gas-permeable, or soft lenses. Complications such as corneal staining (7%) and lens coating (9%) were all reversible. The results during a three-month period showed a high success rate for daily wear and a favorable potential for extended wear. The major advantages of these lenses over other rigid gas-permeable lenses are a high Dk, initial comfort, quick adaptation and minimal complications.

Adaptation, Physiological↗
PubMed1985

Cutaneous acetone depresses aqueous humor ascorbate in guinea pigs.

The purpose of the present investigation was to determine the concentration of ascorbate in the aqueous humor of guinea pigs over a 1-year period following the cutaneous application of a potential cataractogenic agent, acetone. Forty young guinea pigs received 15 ml acetone in small doses on their backs over a 6-week period; the ascorbate in their aqueous humor did not increase above 10 mg/100 ml during a 1-year test period. Ten control animals received only saline on their backs and the ascorbate concentrations steadily increased from 12 to over 18 mg/100 ml during the same time period. Three months after acetone treatment 12 animals (30%) developed cataracts and their ascorbate levels dropped to below 9 mg/100 ml after 1 year.

Acetone↗
PubMed1985

Accidental exposure to sarin: vision effects.

Two men were accidentally exposed to vapors of sarin, a cholinesterase inhibitor and extremely toxic nerve gas. Diagnosis was confirmed by depressed cholinesterase activity, and fixed extremely miotic pupils. No other signs or symptoms developed and neither man required treatment. Recovery to normal cholinesterase activity was gradual over a 90-day period. Pupillary reflexes were not detectable until 11 days after exposure; the miotic pupils dilated slowly over a 30-45 day-period. Eye pain and blurred vision did not occur; visual acuity and amplitude of accommodation were improved for several weeks. Other functions not affected significantly were intraocular pressure, visual fields, color vision, heterophorias, and vergences.

Accommodation, Ocular↗
PubMed1985

Long-term effects of extended wear lenses: changes in refraction, corneal curvature, and visual acuity.

Extended wear lenses (Scanlens 75) +4.25 to -10.00 D were worn monocularly by 19 patients for an average of 5.4 years. The other eye of each patient was either emmetropic or amblyopic and no lens was worn. Both eyes were tested after lens removal and again 2 days and 7 days later. No significant differences in refraction, keratometry, or visual acuity were found between the experimental and control eyes. The amount of changes in both groups was not clinically significant: refractive changes averaged less than 0.37 D, keratometric changes averaged an equivalent 0.25 D, astigmatism increases were less than 0.25 D, and visual acuity was fully correctible to previous best visual acuity with spectacles in all cases.

Adolescent↗
PubMed1985

Corneal refraction: relative effects of each corneal component.

The refractive power of the cornea may change after wearing contact lenses and as a result of disease or surgery. Each corneal component that contributes to the refractive power was analyzed and their relative significance was determined by comparing the refractive effects of a 10% change. In order of magnitude, the effect of a 10% change in each component was as follows: anterior corneal curvature (4.87 D), index of refraction (1.87 D), depth of anterior chamber (1.20 D), posterior corneal curvature (0.62 D) and corneal thickness (0.01 D). Refractive changes are the result of increases and decreases of each component and the total effect is the sum of the individual changes in each component.

Anterior Chamber↗
PubMed1985

Combat spectacles: military testing of a new spectacle frame.

An improved spectacle frame has been developed for use during periods of extreme physical activity, particularly by military personnel during combat operations, and which can be used under protective face masks and headgear. The frame has a wrap-around shape, made of nylon with a contoured, recessed bridge and safety lens groove. U-shaped bridles snap on the frame front and an adjustable, interlocking strap fits over the bridles and passes under a protective mask sealing area. Field tests were conducted with 1231 soldiers at 12 military installations. Over 90% of those tested found combat spectacles were comfortable to wear, extremely durable, compatible with headgear and superior to existing military eyewear.

Equipment Design↗
PubMed1982

Mydriatic and cycloplegic drugs: a review of ocular and systemic complications.

Complications from mydriatic and cycloplegic drugs are rare compared with their extensive use. Adverse effects are often related to dosage or other factors. The ocular complications include increased intraocular pressure, pigmentation of the conjunctiva and cornea, pigment in the anterior chamber, lacrimal duct blockage, macular edema, corneal endothelium damage, hyperemia, allergy, discomfort, and blurred vision. The systemic complications are those common to sympathomimetic and parasympatholytic drugs and include tachycardia, hypertension, headache, faintness. pallor, trembling, excessive sweating, palpitations, arrhythmias, confusion, hallucinations, drowsiness, ataxia, flushed skin, high fever, dysarthria, thirst, dry mouth, convulsions, disorientation, nervousness, coma, and death. An understanding of all possible side effects is of paramount importance to those using these drugs in the treatment of anticholinesterase poisoning. This review is intended as a ready reference to the adverse effects of mydriatic and cycloplegic drugs.

Adolescent↗
PubMed1979

Continuous wearing of Duragel contact lenses by Swedish air force pilots.

This is a report of the application of contact lenses for prolonged wear by military pilots. The safety and effectiveness of wearing these non-HEMA hydrophilic lenses in a highly demanding visual environment is described in the case of an individual jet-fighter pilot who has worn these lenses continuously for 3 years without any complications.

Adult↗
PubMed1977

Astigmatism after contact lens wear.

With-the-rule astigmatism increased by more than 3 D in 2 habitual long-term wearers of contact lenses after they abruptly stopped wearing their lenses. Reducing wearing time gradually over a 2- to 3-month period caused less than 1 D increase in with-the-rule astigmatism in 2 other long-term wearers. All 4 persons had worn polymethylmethacrylate contact lenses for 12 or more years.

Adult↗
PubMed1977

Adaptation to hydrogel contact lenses: variations in myopia and corneal curvature measurements.

Forty patients wearing lenses (soflens) were examined regularly for 3 months. During the first month the mean myopia gradually increased to 0.12 D more myopia and increased linearly to 0.50 D more myopia at 3 months. The mean corneal curvature flattened during the first 3 weeks, but steepened to about 0.37 D at 3 months. The process of myopia changes are not attributed solely to the anterior corneal curvature, but may also be the result of variations in the posterior corneal curvature, corneal thickness and index refraction as well as a change in the depth of the anterior chamber.

Adult↗