| 1. |
- Frisén, Lars, 1939, et al.
(författare)
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A simple relationship between the probability distribution of visual acuity and the density of retinal output channels.
- 1976
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Ingår i: Acta ophthalmologica. - 0001-639X. ; 54:4, s. 437-44
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Tidskriftsartikel (refereegranskat)abstract
- Throughout the retina, the parameters of the probability distribution of visual acuity for monochromatic interference fringes are closely proportional to the number of retinal ganglion cells per degree of visual angle. There are no simple relationships to receptor spatial frequencies. These findings suggest that neuro-retinal acuity is determined principally by the spatial frequency of neural output channels.
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| 2. |
- Frisén, Lars, 1939, et al.
(författare)
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Micropsia and visual acuity in macular edema. A study of the neuro-retinal basis of visual acuity.
- 1979
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Ingår i: Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. Albrecht von Graefe's archive for clinical and experimental ophthalmology. - 0065-6100. ; 210:2, s. 69-77
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Tidskriftsartikel (refereegranskat)abstract
- Relative micropsia was measured by a matching technique in patients with unilateral, benign, macular edema. Quantitative assessment of foveolar micropsia to be a sensitive indicator of receptor displacement in this disorder, and may be a useful tool both for diagnosing and for monitoring macular edema. Parallel measurements of grating acuity showed a close proportionality between acuity and micropsia parameters. This result validates a new quantitative theory for the neuro-retinal basis of visual acuity. The theory allows prediction of the proportion of working visual neurons in patients with impaired acuity due to diseases that produce a diffuse loss, or disconnection, of macular cones. Our results indicate that so-called normal visual acuity (1.0 or 20/20) requires no more than 44% of the normal quantity of fovelar, neuro-retinal channels.
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| 3. |
- Frisén, Lars, 1939, et al.
(författare)
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Objective recognition of abnormal isopters.
- 1975
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Ingår i: Acta ophthalmologica. - 0001-639X. ; 53:3, s. 378-92
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the hypothesis that normal and only normal isopters of the central visual field are elliptical, except for random deviations. Statistical methods capable of recognizing small deviations from elliptical shape have been developed. Theses methods have been devised to meet the special demands of clinical testing of visual fields and require only simple calculations. The qualities of these methods were examined by theoretical analysis, by large-scale simulations, and by experimental comparison with subjective evaluations. The new methods proved very useful in these examinations. A clinical study using a servo-equipped Goldman perimeter demonstrated that normal central isopters are elliptical enough for the proposed test characteristic to be of practical value in clinical work. The method allows an objective recognition of abnormal isopters with a high degree of sensitivity.
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| 8. |
- Frisén, Lars, 1939, et al.
(författare)
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Communicating exophthalmos: a sign of bilateral orbital roof defects.
- 1978
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Ingår i: Acta neurochirurgica. - 0001-6268. ; 41:1-3, s. 157-61
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Tidskriftsartikel (refereegranskat)abstract
- The term communicating exophthalmos is suggested for a condition where manual retropulsion of one eye results in proptosis of the other eye. This sign was observed in a patient with bilateral pulsating exophthalmos. The pulsating exophthalmos was ascribed to orbital roof defects in combination with post-traumatic hydrocephalus. It was controlled by a shunting procedure.
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| 9. |
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| 10. |
- Frisén, Lars, 1939, et al.
(författare)
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Cyclic compression of the intracranial optic nerve: patterns of visual failure and recovery.
- 1976
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Ingår i: Journal of neurology, neurosurgery, and psychiatry. - 0022-3050. ; 39:11, s. 1109-13
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Tidskriftsartikel (refereegranskat)abstract
- A patient with a cystic craniopharyngioma below the right optic nerve had several recurrences requiring surgery. Finally the cyst was connected with a subcutaneous reservoir by means of a fine catheter. Symptoms of optic nerve compression recurred more than 50 times during the following year, and were relieved within seconds upon drainage of the reservoir. In each cycle, a drop in visual acuity preceded a measurable change in the visual field. The pattern of field changes was an increasingly severe, uniform depression. Optic nerve ischaemia induced by compression was probably the most important factor causing visual failure in this case.
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| 11. |
- Frisén, Lars, 1939, et al.
(författare)
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Detection of extracranial carotid stenosis by computed tomography.
- 1979
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Ingår i: Lancet (London, England). - 0140-6736. ; 1:8130, s. 1319-20
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Tidskriftsartikel (refereegranskat)abstract
- Ten patients with transient ischaemic attacks (T.I.A.) within the carotid territory were examined by aortic-arch angiography and computed tomography (C.T.) of the neck. C.T. showed evidence of carotid calcifications in all 17 angiographically abnormal arteries, and there was no evidence of calcification in the 3 normal arteries. C.T. of the neck promises to be a useful technique for the investigation of patients with T.I.A.s.
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| 12. |
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| 13. |
- Frisén, Lars, 1939, et al.
(författare)
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Drusen in the optic nerve head. Verification by computerized tomography.
- 1978
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Ingår i: Archives of ophthalmology (Chicago, Ill. : 1960). - 0003-9950. ; 96:9, s. 1611-4
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Tidskriftsartikel (refereegranskat)abstract
- Five patients with a clinical diagnosis of buried or exposed drusen of the optic nerve head were examined by computerized tomography (CT). The relative x-ray absorption within their nerve heads was significantly larger than in controls, reflecting the high calcium content of drusen. Computerized tomography, and particularly high-definition CT, therefore merits consideration in the investigation of disc swelling.
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| 14. |
- Frisén, Lars, 1939
(författare)
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Forced motion attachment for the Goldmann perimeter.
- 1972
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Ingår i: Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift fur Augenheilkunde. - 0030-3755. ; 165:5, s. 482-8
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Tidskriftsartikel (refereegranskat)
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| 20. |
- Frisén, Lars, 1939, et al.
(författare)
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Optical and neural resolution in peripheral vision.
- 1975
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Ingår i: Investigative ophthalmology. - 0020-9988. ; 14:7, s. 528-36
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Tidskriftsartikel (refereegranskat)abstract
- Visual acuity along the horizontal meridian in the peripheral field of vision was determined at a photopic level in two normal subjects. Two types of sinusoidally modulated, monochromatic test patterns of high contrast were used. One was produced directly on the retina by an interferometric technique. The other type was imaged on the retina by the dioptric apparatus of the eye; the resulting image suffered ordinary optical image degradation. The results from the interferometric acuity determinations represent maximal neural discrimination across the visual field. Acuity decreases monotonically toward the periphery, from about 45 cycles per degree in the fovea, to about 0.8 at 80 degrees of eccentricity in the temporal field. The decline is well described by a second-degree polynomial. Acuity for test patterns imaged by the optics of the eye was consistently lower than interferometric acuity. The difference increases toward the periphery. It is attributable to effects of optical aberrations. The discrepancy between optical and neural resolving power on oblique incidence needs to be taken into account whenever results obtained with external, extra-axial stimuli are to be analyzed in terms of retinal architecture.
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| 23. |
- Frisén, Lars, 1939
(författare)
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Quadruple sectoranopia and sectorial optic atrophy: a syndrome of the distal anterior choroidal artery.
- 1979
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Ingår i: Journal of neurology, neurosurgery, and psychiatry. - 0022-3050. ; 42:7, s. 590-4
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Tidskriftsartikel (refereegranskat)abstract
- Loss of upper and lower homonymous sectors in the visual field, and wasting of corresponding sectors in the retinal nerve fibre layer, followed ligation of the distal part of the anterior choroidal artery in a patient with a meningioma of the velum interpositum. Clinical and radiological evidence indicated that the visual pathway was damaged within that part of the lateral geniculate body that is served by the anterior choroidal artery.
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| 24. |
- Frisén, Lars, 1939, et al.
(författare)
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Relationship between perimetric eccentricity and retinal locus in a human eye. Comparison with theoretical calculations.
- 1977
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Ingår i: Acta ophthalmologica. - 0001-639X. ; 55:1, s. 63-8
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Tidskriftsartikel (refereegranskat)abstract
- A blind but grossly normal eye was removed because of severe pain. With the patient's consent, photo-coagulation markers were placed along the horizontal meridian of the retina prior to surgery. The angular coordinates in visual space of the markers were determined by an ophthalmoscopic procedure. The loci of the markers were also determined in a flat preparation following enucleation. The relationship between retinal arc and perimetric eccentricity was found to be approximately linear up to at least 50 degrees. Our findings validate earlier theoretical calculations within this range.
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