| 1. |
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| 2. |
- Frisén, Lars, 1939, et al.
(författare)
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Characterization of vigabatrin-associated optic atrophy.
- 2003
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Ingår i: Acta ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 81:5, s. 466-73
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Tidskriftsartikel (refereegranskat)abstract
- To report the discovery of a previously unknown form of optic atrophy associated with use of the anti-epileptic drug vigabatrin.We conducted a retrospective analysis of digitally enhanced ocular fundus photographs, kinetic visual field maps and treatment parameters for 25 patients, who were selected to represent a large spectrum of visual field defects.In all, 21 patients (84%) evidenced subtle, diffuse atrophy of the retinal nerve fibre layer, in a pattern accessible to scoring. Atrophy scores correlated with visual field remains and cumulative vigabatrin doses. A pathophysiological model is proposed that involves the lengths of intraocular (unmyelinated) retinal ganglion cell axons.Optic atrophy attests to the irreversible nature of vigabatrin's visual toxicity. Ocular fundus imaging should prove useful for objectively monitoring vigabatrin-treated subjects for visual toxicity.
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| 3. |
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| 4. |
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| 5. |
- Frisén, Lars, 1939, et al.
(författare)
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How robust is the optic chiasm? Perimetric and neuro-imaging correlations
- 2008
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 117:3, s. 198-204
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Tidskriftsartikel (refereegranskat)abstract
- Objectives - Analysis of form and function relationships with tumour-mediated dislocations and deformations of the optic chiasm Materials and methods - Results of magnetic resonance tomography and two forms of quantitative, computerized perimetry were contrasted in 31 patients with pituitary adenomata impinging on the chiasm, prior to treatment Results - Perimetric abnormalities ranged from none to modest High-pass Resolution Perimetry (HRP) produced abnormal results in 10 cases and RareBit perimetry (RBP) in 15 cases Overall, field defects and qualitative stages of deformation and dislocation of the chiasm were well correlated Among quantitative indices, the best correlations were obtained by a measure of the cranio-caudal position of the chiasm Conclusions - On average, an elevation of the chiasm by 6 mm will be associated with abnormal visual fields in 50% of the cases An additional elevation of 5 mm will raise the incidence of field defects to 90%
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| 6. |
- Frisén, Lars, 1939
(författare)
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New, sensitive window on abnormal spatial vision: rarebit probing.
- 2002
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Ingår i: Vision research. - 0042-6989. ; 42:15, s. 1931-9
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Tidskriftsartikel (refereegranskat)abstract
- Clinical tests have a poor sensitivity to low to moderate degrees of neuro-visual damage, possibly because their test targets involve numerous receptive fields. A new test used briefly exposed microdots of high contrast. Multiple visual field areas were probed repeatedly, with ever-new microdot positions. Normal subjects responded to a median 96.0% of probes. Patients with different visual field defects missed larger numbers of probes within defects and the deeper the defects, the larger the number of misses. Patients with minor chiasmal lesions averaged 1.8 times larger defects in microdot perimetry than in high-pass resolution perimetry, indicating superior sensitivity to minor damage.
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| 7. |
- Frisén, Lars, 1939
(författare)
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Rarebit perimetrisi
- 2005
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Ingår i: Görme Alani El Kitabi. - Istanbul : Aksu Kitabevi. ; , s. 61-64
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Frisén, Lars, 1939
(författare)
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The Amsler grid in modern clothes.
- 2009
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Ingår i: The British journal of ophthalmology. - : BMJ. - 1468-2079 .- 0007-1161. ; 93:6, s. 714-6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Amsler chart, a printed grid with a central fixation mark, is widely used to test for central/paracentral scotomata and metamorphopsias. Abnormal results are easily recognised but are not directly accessible to quantitative analysis. Negative results may be misleading, because it is never known how good an observer the subject is. METHODS: A new version was created in computer graphics. The grid was made to sweep the tested area in an optic flow manner. The sweeps provided seamless coverage, counteracted the Troxler fade-from-view effect, and encouraged stable fixation. Simulations of scotomata and metamorphopsias allowed quantitative evaluations of subject performance. RESULTS: Normal observers consistently detected absolute paracentral scotomata subtending > or =2 degrees . Grid deformation was consistently detected at 4' near fixation, whereas up to 20' was needed at the grid border. A patient with real metamorphopsia reproducibly nulled the apparent deformation of the grid in a manner closely matching his own renditions. CONCLUSIONS: The classical Amsler grid can be made to meet modern demands of quality control and quantitative measurements. The new "MacuFlow" test is freely accessible on the internet. Test results can easily be transmitted electronically for evaluation at distance.
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| 9. |
- Frisén, Lars, 1939
(författare)
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The lazy shadow: a monocular counterpart to the Pulfrich stereo phenomenon.
- 2007
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Ingår i: The British journal of ophthalmology. - : BMJ. - 0007-1161. ; 91:10, s. 1296-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Pulfrich phenomenon is a dynamic stereo dysmetropsia attributed to an asymmetry of neural conduction between the eyes. The phenomenon may arise spontaneously with ocular and neurological disease and may be induced in normal subjects by placing a light-attenuating filter before one eye. By analogy, it is predicted that a localised variation of retinal illumination within one and the same eye should affect the perception of moving targets. METHODS: A rotating, nesting square display was generated by computer graphics. The inner square was painted bright white, the outer dim grey. Luminances, rates of rotation and angular sizes were varied. RESULTS: On rotation, the outer, dimmer square appeared to lag behind the inner, brighter one, as a "lazy shadow". The lag was measured quantitatively in normal observers by applying a compensatory lead to the lagging square. The magnitude of lag was found to depend on luminance, spin rate and visual angle. Lags exceeding 10 degrees were observed under optimum conditions. CONCLUSIONS: The experimental results confirm the existence of a monocular counterpart to the binocular Pulfrich phenomenon. Distortions of moving images are likely to occur spontaneously with monocular, localised visual field defects.
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| 10. |
- Frisén, Lars, 1939
(författare)
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Vigabatrin-associated loss of vision: rarebit perimetry illuminates the dose-damage relationship
- 2004
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 82:1, s. 54-8
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The utility of vigabatrin in the treatment of epilepsy is partially offset by its retinal toxicity. The relationship between dosage and damage is obscure. This may be due to perimetric shortcomings. The new technique of rarebit ('microdot') perimetry might be more informative. METHODS: Twelve patients who had been treated with vigabatrin for various durations were examined by manual, kinetic perimetry and by rarebit perimetry. RESULTS: Rarebit results differed significantly between patients and normal controls and rarebit deficits were directly proportional to cumulated vigabatrin doses (correlation coefficients were - 0.92 in the nasal field and - 0.82 in the temporal field). Manual perimetry results were less clearly related to dosage (r = - 0.54 and r = - 0.73, respectively). CONCLUSION: Rarebit perimetry indicates that each treated subject will develop visual loss and that visual loss will be proportional to the accumulated dose. Conventional perimetry is less well suited to detecting and quantifying vigabatrin-associated visual loss.
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| 11. |
- Lindberger, M, et al.
(författare)
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Gabapentin versus vigabatrin as first add-on for patients with partial seizures that failed to respond to monotherapy: a randomized, double-blind, dose titration study. GREAT Study Investigators Group. Gabapentin in Refractory Epilepsy Add-on Treatment.
- 2000
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Ingår i: Epilepsia. - : Wiley. - 0013-9580 .- 1528-1167. ; 41:10, s. 1289-95
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Tidskriftsartikel (refereegranskat)abstract
- Our objective was to compare the efficacy and safety of gabapentin and vigabatrin as first-line add-on treatment in patients with partial epilepsy.This was a multicenter, double-blind, randomized dose titration study. After baseline assessment and randomization, the dose could be increased if seizures persisted and reduced if side effects occurred. Health-related quality of life was assessed at baseline and at the end of the study. By a protocol amendment post hoc, all randomized patients were offered a standardized perimetry examination at the end of the study. Improvement rate was the proportion of patients with a reduction of seizure frequency of at least 50% during an 8-week period without any adverse events causing withdrawal.One hundred two patients were randomized and analyzed on an intent-to-treat basis. The improvement rate was 48% in the gabapentin group and 56% in the vigabatrin group. The improvement rate, when per protocol criteria were fulfilled, was 57% in the gabapentin group and 59% in the vigabatrin group. The proportion of seizure-free patients was 31% in the gabapentin group and 39% in the vigabatrin group. There was no difference in quality-of-life scores between the groups. Perimetry after termination of the study on 64 patients showed abnormal results in 3 of 32 patients in the vigabatrin group.Approximately one third of the patients in both groups became seizure-free. Although no major differences were seen in terms of the improvement rate between the groups, equivalence between the two drugs was not found.
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| 12. |
- Lycke, Jan, 1956, et al.
(författare)
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Asymptomatic visual loss in multiple sclerosis.
- 2001
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Ingår i: Journal of neurology. - : Springer Science and Business Media LLC. - 0340-5354 .- 1432-1459. ; 248:12, s. 1079-86
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Tidskriftsartikel (refereegranskat)abstract
- Visual disturbances are common in multiple sclerosis (MS) and often a result of acute demyelinating optic neuropathy. Careful examination of MS patients, who have never suffered optic neuritis, may also reveal asymptomatic visual loss. This type of silent disease activity was investigated by computerised resolution perimetry, which has the potential to reflect the percentage of functional retino-cortical neural channels. The time of onset and the evolution of asymptomatic visual loss was investigated. One approach was to retrospectively select patients who never had suffered acute optic neuritis from a closely monitored MS population and re-examine them again. Sixteen patients were identified and vision was evaluated during a period of 5.5-9 years of follow-up and compared with that in 14 healthy controls. The mean channel percentage of the MS group was 89 +/- 19 % (SD) on entry into the study, compared with 110 +/- 15% (SD) of controls (p < 0.003). At termination of the study the mean percentage was essentially unchanged both in MS patients (87 +/- 21%, SD) and controls (110 +/- 19%, SD). The second approach was to test a group of 7 patients with MS or strongly suspected MS, with the same method, in close connection with their first clinical exacerbation. All cases lacked visual symptoms and none had previously had acute visual loss. Again, virtually all performed subnormally in the vision tests, and to the same degree as in the first group of patients. Results were compared with those obtained from 25 MS patients who had experienced one or more attacks of optic neuritis. Compared with controls the loss of functional retino-cortical neural channels was 20% in patients without a previous history of optic neuritis and 30 % in patients who previously had experienced optic neuritis. We conclude that asymptomatic visual loss seems to be a universal feature of MS and has a substantial impact on the visual pathways, that it is present already at the time of clinical onset of the disease, and that any progression thereafter is slow enough to elude detection during several years of follow-up.
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| 13. |
- Malmgren, K, et al.
(författare)
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Vigabatrin visual toxicity: evolution and dose dependence.
- 2001
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Ingår i: Epilepsia. - 0013-9580. ; 42:5, s. 609-15
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the prevalence and prognosis of visual field defects (VFDs) in epilepsy patients with and without vigabatrin (VGB) treatment; to investigate the possible relationship between VFDs and cumulative VGB dose, and to characterise the evolution of VFDs.A cohort of 155 presurgical candidates who had undergone full-field Goldmann perimetry (GP) was studied, 99 (64%) of whom had been treated with VGB. All GPs were reevaluated in 1998 by one experienced examiner, blinded to medication. Duration of treatment and total VGB dose were related to perimetric results.Twenty-five (16%) of the 155 patients had VFDs: Nineteen (19%) of the 99 VGB-treated patients, and six (11%) of the 56 patients unexposed to VGB. VGB-treated patients with VFDs had been treated significantly longer than those without VFDs. Cumulative VGB dose could be calculated for 84 patients. The prevalence of VFDs increased significantly with increasing total VGB-dose, from 4% in the 51 patients who had been exposed to
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| 14. |
- Nilsson, Daniel, 1973, et al.
(författare)
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Visual field defects after temporal lobectomy -- comparing methods and analysing resection size
- 2004
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Ingår i: Acta Neurol Scand. - 0001-6314. ; 110:5, s. 301-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The frequency of visual field defects (VFD) after temporal lobe resections (TLR) was compared for two types of TLR and VFD frequency was correlated to resection size. METHODS: Pre- and post-operative perimetry results were analysed for 50 patients with TLR for medically intractable epilepsy. Thirty-three patients had a classical TLR and 17 had a TLR with less lateral extension. Post-operative MRIs were studied in 34 patients by scoring resection size in 12 compartments in the temporal lobe. RESULTS: Twenty-five patients developed a VFD. In the classical TLR group, 16 of 33 developed a VFD, compared with nine of 17 in the other group. The resection points were higher for the VFD group in the most anterior compartment studied, in the superior temporal gyrus. CONCLUSIONS: There was no clearcut difference in VFD frequency between the surgical methods studied. However, the compartmentalized analysis disclosed a relation between the extent of resection in the anterior part of the superior temporal gyrus and VFD frequency.
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| 15. |
- Rodríguez-Catarino, M, et al.
(författare)
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Internal carotid artery aneurysms, cranial nerve dysfunction and headache: the role of deformation and pulsation.
- 2003
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 0028-3940. ; 45:4, s. 236-40
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Tidskriftsartikel (refereegranskat)abstract
- Cranial nerve dysfunction and headache may occur with unruptured aneurysms of the cavernous and supraclinoid portions of the internal carotid artery. Nerve deformation (mass effect) and transmitted pulsations have been suggested as pathogenetic mechanisms. Differentiation may be possible by studying effects of endovascular treatment with Guglielmi detachable coils. Symptoms and signs of cranial neuropathy were retrospectively contrasted with angiographic aneurysm volumes before and after treatment in 10 patients. Mean follow-up was 36 months. Symptoms improved in three of four patients with cranial nerve dysfunction and in all patients with headache. None of the other patients, one with cranial nerve dysfunction, and three who were asymptomatic, developed any new symptoms after treatment. Aneurysm volume ranged from 0.1 to 2.7 cm(3 )before and 0.2 to 5.7 cm(3) after treatment; the size thus increased by 15 to 110%, a change which was statistically significant (P=0.004). The consistent increase in aneurysm volume with treatment is not associated with clinical deterioration, suggesting that deformation and displacement play a minor role in cranial neuropathy and that transmitted pulsations may be more important.
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| 16. |
- Rudolph, Thiemo, et al.
(författare)
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Influence of ageing on visual field defects due to stable lesions.
- 2007
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Ingår i: The British journal of ophthalmology. - : BMJ. - 0007-1161. ; 91:10, s. 1276-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Knowledge about the effects of ageing on visual field defects is very sparse. METHODS: Long-term follow-up records were examined from 28 patients with light-to-moderate visual field defects remaining after surgery for pituitary tumours. All were proven free from tumour recurrences and complicating disorders. Hence, all had isolated, stable lesions of the chiasm. Follow-up periods ranged over 4-18 years (median 9). Using high-pass resolution perimetry, results were analysed from the central-most test locations in the upper temporal and upper nasal quadrants. The former typically bear the brunt of damage whereas the latter are least affected. Each patient contributed results from one eye only. Fixation stability and reproducibility were uniformly good. RESULTS: Measuring values from the nasal quadrants remained essentially constant throughout the follow-up periods. Results from the temporal (T) quadrants were contrasted with those from the nasal (N) quadrants by calculating the T/N ratios, which were then individually regressed over follow-up periods. Hence, each patient was his or her own control. The absolute majority of regression coefficients (25 out of 28) did not significantly differ from 0. CONCLUSION: The rate of age-related loss of neural channels appears to be identical in normal and abnormal visual field areas in subjects with stable mid-chiasmal lesions.
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| 17. |
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| 18. |
- Svendsen, P A, et al.
(författare)
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Direct puncture and sclerotherapy with sotradecol ((r)) . Orbital lymphatic malformations.
- 2001
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Ingår i: Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences. - : SAGE Publications. - 1591-0199. ; 7:3, s. 193-9
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated sclerotherapy in the treatment of orbital lymphatic malformations. Six consecutive patients with unilateral orbital cystic masses and recurrent episodes of orbital swelling were included in this retrospective study. All have been treated with percutaneous puncture and injection of Sotradecol (sodium tetredecyl sulphate) under radiographic guidance, on one or more occasions. Reduction of orbital mass volume was documented clinically and radiologically within a few weeks in all cases. There was total regression of proptosis in three instances. There were no immediate complications. One subject suffered a presumably coincidental orbital hemorrhage two weeks after treatment. Follow-up times ranged between six months and four years. Sotradecol sclerotherapy appears to be a useful adjunct to the therapeutic arsenal for orbitallymphatic malformations.
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| 19. |
- Wall, Michael, et al.
(författare)
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Visual field of high-pass resolution perimetry in normal subjects.
- 2004
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Ingår i: Journal of glaucoma. - 1057-0829. ; 13:1, s. 15-21
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the properties of the visual field of high-pass resolution perimetry in normal subjects. METHODS: Four centers collected normative data for high-pass resolution perimetry. In two of the centers the subjects were stratified by age. One eye was tested per subject using high-pass resolution perimetry (Ophthimus). We tested 640 normal subjects and describe their visual field results by test location. We also analyzed the data by concentric zone, age, and by testing center. RESULTS: The individual test location averages confirmed a reduction in resolution with eccentricity. Resolution thresholds increased with age by 0.025 dB per year (P < 0.001). The mean ring size increased by about 1 dB from age 20 to 70. Among centers there were significant differences in the means and the change in threshold with age (P = 0.009). CONCLUSION: The normal visual field of high-pass resolution perimetry is characterized by an increase in threshold with eccentricity. We found significant differences among the centers that were likely due to multiple factors including differences in subject selection criteria. Whether such differences occur with other perimetric techniques is unknown.
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| 20. |
- Wikkelsö, Carsten, et al.
(författare)
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Subjective visual vertical and Romberg's test correlations in hydrocephalus.
- 2003
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Ingår i: Journal of neurology. - : Springer Science and Business Media LLC. - 0340-5354 .- 1432-1459. ; 250:6, s. 741-5
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Tidskriftsartikel (refereegranskat)abstract
- Exploration of the subjective visual vertical in pitch and Romberg's test in patients with hydrocephalus. Patients Eleven patients with communicating normal pressure hydrocephalus and six with non-communicating hydrocephalus due to aqueductal stenosis were examined before and after surgical treatment.The subjective visual vertical was examined with a simple, custom-made articulated rod. The rod was faintly illuminated from within so as to appear floating in space when presented in darkness. The test task was to manually adjust the rod's position in pitch so that it appeared perfectly vertical. Romberg's test was performed under standardized conditions.Patients with a backward movement on Romberg's test showed a deviation of the subjective visual vertical, tilting the upper end of the rod closer to their eyes. Patients moving in other directions tilted the rod in the opposite direction (p < 0.01). The time in which the patients managed Romberg's test with open eyes correlated with the intratest variability of rod placement (r = 0.86, p < 0.001). After surgery, improvements on Romberg's test correlated with a decreased intratest variability of the subjective visual vertical. There were no differences between the two patient groups.Quantitative measurements of the subjective visual vertical in pitch correlate strongly with results of Romberg's test in patients with hydrocephalus.
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