[Excimer laser technique--a revolution in refractive surgery?].
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History, 20th Century↗
Biomedical subjects
B Tengroth
Publications and source records attributed to B Tengroth.
[Para-trochlear chondroma of the orbit].
We report on a 19-year-old male patient who was operated on for an orbital tumor close to the trochlea. The microscopical examination showed a cartilaginous tumor classified as differentiation grade II. Because of the close topographic location to the trochlea the tumor is characterized as a chondroma. Its rare location does not give us any further information concerning the final dignity. Benign cartilaginous tumors of the orbital trochlea region are extremely uncommon.
Adult↗
[Progress in refractive surgery--myopia and astigmatism are treated by a new laser technic].
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Astigmatism↗
Effect of spectral flash on readaptation time.
The effects of an adapting flash of different colors on human vision were investigated with various flashes and target luminances. The readaptation time (RAT) was measured using optokinetic nystagmus elicited by a projected moving striped pattern in a hemisphere. The RATs were recorded from 26 subjects with a multichannel pen recorder. Two target luminances (1.1 X 10(-5) cd/m2 and 2.6 X 10(-5) cd/m2) and 12 flash wavelengths (449 nm, 456 nm, 468 nm, 477 nm, 498 nm, 502 nm, 520 nm, 565 nm, 580 nm, 591 nm, 622 nm, and 703 nm) were used. A spectral RAT curve was obtained, which showed that the chromatic response of RAT follows this order: green greater than blue greater than yellow greater than red. A larger influence of the variation of the target luminance on the RAT was demonstrated at shorter wavelengths. The results also showed that the energy density of the flash has a larger variation with the RAT in blue and green than in red.
Adaptation, Ocular↗
Preliminary notes on vulnerability of the retina to injury from peripheral laser exposure conditions.
If laser exposures to the periphery of the retina from low-energy lasers cause a hemorrhage obscuring the optical pathway to the fovea, resulting in loss of visual function, the risks for soldiers on the battlefield may be greater than previously expected. Two off-axis experiments were undertaken to obtain an indication of the hazards involved in exposing the peripheral retina to visible laser irradiation. Both off-axis exposures caused immediate vitreal hemorrhages in the periphery. After 80 min, the hemorrhage in the first eye had diminished, and in the other it was significantly smaller than immediately after exposure; even the central hemorrhage was smaller. Another observation after 120 min revealed the same result. These results indicate that an obvious risk exists on the battlefield for peripheral hemorrhages due to lasers operating within the retinal hazard spectrum. However, it is necessary to make more observations to establish the findings firmly.
Animals↗
Vulnerability of the retina to injury from a military ruby rangefinder at battlefield distances.
This study investigates the possibility of causing a vitreal hemorrhage with a standard ruby rangefinder at battlefield engagement distances when the laser is observed with the naked eye or through magnifying optics or filters. The experiments were undertaken on the eyes of anesthetized pigs. The pigs were anesthetized with Mebumal and given 0.5% thropicamid in the eyes. They were then exposed to the radiation from a standard military ruby rangefinder (pulsewidth 25 ns, pulse energy 180 mJ). The rangefinder was aligned with a He-Ne laser and a beamsplitter. Eight experiments were performed, each with several exposures. The range was varied from 0.5-850 m. Some of the experiments were made using the naked eye, some with a filter, some with binoculars (7 x 50) and some with a combination of filter and binoculars. The pulse energy was varied from 91-6500 muJ. Vitreal hemorrhages were caused at distances of 410 and 850 m when a pair of binoculars (7 x 50) was placed in front of the eyes. The intraocular energy varied between 1500 and 4400 microJ. Results indicate that there is a possibility of causing a vitreal hemorrhage in a soldier who is using standard field binoculars and looking in the direction of an ordinary military rangefinder at distances at least up to 850 m.
Animals↗
A comparative analysis of the collagen type and distribution in the trabecular meshwork, sclera, lamina cribrosa and the optic nerve in the human eye.
A theory has been advanced (Tengroth et al 1984) that one common factor might be involved in the pathogenesis of chronic open angle glaucoma. The mechanical properties of the collagen could be one such factor. To characterize the collagen composition of the critical structures in cases with chronic open angle glaucoma i.e. the trabecular meshwork and the lamina cribrosa in the human eye, the following investigations were performed. Using immunoperoxidase technique and type specific antibodies to the genetically distinct collagen types I, III, IV and procollagen I along with the major non collagen proteins in the extracellular matrix laminin and fibronectin a light microscopic study was undertaken on the trabecular meshwork, cornea, sclera, lamina cribrosa and the optic nerve of the human eye. Furthermore biochemical analysis was performed on the collagen associated aminoacids hydroxyproline (Hyp), hydroxylysine (Hyl) and prolin (Pro) from microdissected samples of trabecular meshwork, sclera, lamina cribrosa and optic nerve. Both the immunohistological and the biochemical findings suggested similarities in the collagen composition between the trabecular meshwork and the lamina cribrosa. The immunohistochemical findings showed stronger staining of type III and IV in the trabecular meshwork and lamina cribrosa as compared to sclera or cornea while the opposite was true for type I and procollagen I. Fibronectin and laminin were present in both the trabecular meshwork and lamina cribrosa. These findings were in agreement with the amino acid analysis when the Hyp/Hyl ratio was calculated for each sample.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
[The retinoblastoma team at Karolinska hospital].
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Eye Neoplasms↗
The effect of oxazepam on ocular readaptation time.
The readaptation time (RAT) is the interval during which a person exposed to a bright intense light flash cannot perceive a given target. In this study the target used was an optokinetic pattern and the elicited nystagmus (OKN) was registered with electrooculography (EOG), thus giving an objective registration of RAT. Oxazepam in therapeutic doses was given to five healthy subjects and the RAT and serum concentrations of the drug were registered simultaneously at different time intervals. An almost parallel increase of RAT and serum concentration of oxazepam was recorded. This suggests that RAT reflects the depressant effect on the CNS of this drug and it may be used as an objective method of following the clinical effect of a depressant drug as a function of time after intake.
Adaptation, Ocular↗
Readaptation time after photo stress. Alcohol-induced acute and post-alcohol 'hangover' changes in ocular readaptation time.
The effect of alcohol intake on readaptation time (RAT) after photo stress is studied. Ten healthy subjects were given 0.72 g alcohol per kg body weight to be consumed within 20 min. The tests were made during a total period of 11-12 h. The findings demonstrate that moderate blood alcohol concentrations induce definite changes in RAT. An average RAT-prolongation of 60-70% was seen during the acute phase of intoxication. RAT-prolongation ended before the blood alcohol concentration had reached zero, but did not have the same downward slope. Following a period of reduction, a new prolongation of RAT was observed. The lack of congruence between the RAT-curve and the blood alcohol curve in the acute phase of intoxication and the post-alcohol increase are discussed. It is concluded that the alcohol-induced RAT-changes probably are CNS-effects and that the equipment used constitutes a sensitive method of estimating these effects.
Adaptation, Ocular↗
Retinoblastoma treated with a 60CO applicator.
The 60Co applicator for treatment of retinoblastoma, described in 1963, has the advantage of exact local positioning. It is suitable in cases with solitary small tumours. The complications and the results of treatment in 20 patients followed up for at least 2 years are reported and discussed.
Cataract↗
Welding light.
Two types of electric welding, welding with gas-shielded arcs and welding with coated electrodes, are considered in this paper. The possible radiation injuries to the eye are described, and the measures for protection discussed.
Eye Injuries↗
Safety glasses in welding.
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Accidents, Occupational↗
Readaptation time after photo stress. Readaptation time as a function of oxygen concentration.
Optokinetic nystagmus (OKN) is used to study the eye's ReAdaptation Time (RAT) after a brief exposure to a light flash. The effects on RAT of breathing different concentrations of O2 are examined. Significant changes in RAT have been registered, showing that inhalation of 100% O2 as compared with room air, results in a shortened RAT (i.e. improvement), while inhalation of 9% O2 leads to an increased RAT (i.e. impairment). The physiology of RAT and the possible mechanisms behind the changes caused by different O2 concentrations are discussed. The findings of this group are compared with those of other studies.
Adaptation, Ocular↗
The appointment of Johan Widmark to the first chair in ophthalmology in Stockholm 1891.
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Academies and Institutes↗
Radiographic exophthalmometry.
Radiographic exophthalmometry is based on the simultaneous exposure of a radiograph and a photograph. The fixed reference point for both eyes is the tuberculum sellae, which is a midline structure. Eye position is correlated with skull size and race to provide a sensitive detection of exophthalmos. A statistically significant difference in the position of the eyes in US black and white people has been found to exist. No difference in the position of left or right eyes has been found in either US black or white people.
Black or African American↗
Localization of intraorbital foreign bodies: an improved photoradiographic method.
A previously described photoradiographic camera used to localize intraocular or intraorbital foreign bodies has been modified to a more versatile unit. One photograph and one radiograph are taken simultaneously, and the pictures are combined, whereby the eye appears as its own indicator on the radiophotograph. More than 50 foreign bodies have been successfully localized with the camera which is easy to handle and can be used in any x-ray film room where an overhead tube is available.
Eye Foreign Bodies↗