| 1. |
- Asman, P, et al.
(författare)
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Evaluation of adaptive spatial enhancement in suprathreshold visual field screening
- 1988
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Ingår i: Ophthalmology. - 0161-6420. ; 95:12, s. 62-1656
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Tidskriftsartikel (refereegranskat)abstract
- Sixty-three normal subjects and 94 abnormal patients, most of whom had glaucoma, were tested in the central visual field using a threshold-related, eccentricity-compensated, spatially adaptive suprathreshold screening program and a full-threshold program on the Humphrey field analyzer. The initial stimulus locations on the screening test were identical to those of the threshold test; additional screening stimuli were presented surrounding each missed initial stimulus. Surprisingly, this spatial enhancement strategy did not improve sensitivity or specificity rates of the screening beyond that achieved by considering the initial stimulus locations alone. Points missed during screening often showed a depressed sensitivity rate (measured threshold greater than 6 dB below the age-corrected normal reference value) in the same area of the threshold field. This was true in fields from abnormal and normal subjects. This finding of persistent shallow defects in the same test session among otherwise normal persons has disturbing implications for the importance of "confirmed" defects in the diagnosis of disease.
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| 2. |
- Heijl, A, et al.
(författare)
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A clinical study of perimetric probability maps
- 1989
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Ingår i: Archives of Ophthalmology. - : American Medical Association (AMA). - 0003-9950. ; 107:2, s. 199-203
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Tidskriftsartikel (refereegranskat)abstract
- Perimetric probability maps depict visual field results in terms of the frequency with which the measured findings are seen in a normal population. We tested clinically the importance of the model of the normal visual field used to calculate such maps. Forty-one eyes of 41 normal subjects and 58 eyes of 46 glaucomatous patients were studied. Probability maps were calculated by means of two different models of the normal visual field. The first model assumed gaussian threshold distributions with constant variability across the field. The second used empirically determined nongaussian location-dependent threshold distributions. Probability maps using the empiric model allowed better separation between glaucomatous and normal eyes, and the number of significant points in normal subjects was in better agreement with the theoretically expected number. The gaussian model yielded an unacceptably high frequency of significant points in normal fields, particularly in the midperiphery. The clinical usefulness of perimetric probability maps depends critically on the choice of normal visual field model.
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| 3. |
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| 4. |
- Heijl, A
(författare)
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Computerised perimetry
- 1985
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Ingår i: Transactions of the ophthalmological societies of the United Kingdom. - 0078-5334. ; 104:Pt 1, s. 76-87
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- During the last few years computerised perimetry has become a clinical reality. This new technique eliminates the operator's error, ensures reproducibility of test procedures and parameters and makes visual field testing of large numbers of patients possible. Great differences exist between computerised perimeters. Differences in hardware for example, the way in which stimuli or field charts are produced may be striking but even more important are differences in software, especially test algorithms. The results obtained with some instruments and test programmes are of such high quality that the same level of performance may be almost impossible to obtain with manual perimetry, at least in a clinical setting. Nevertheless, improvements can be expected in the future particularly in adaptive tests and in computerised interpretation of the fields.
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| 5. |
- Heijl, A
(författare)
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Computerized perimetry in glaucoma management
- 1989
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Ingår i: Acta Ophthalmologica. - : Wiley. - 0001-639X .- 1755-375X. ; 67:1, s. 1-12
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Forskningsöversikt (refereegranskat)abstract
- The present article discusses the role of computerized perimetry in the management of patients with suspect and manifest glaucoma. The value of visual field examination is compared to that of inspection and photography of the optic disc and to some extent to retinal nerve fibre layer photography. Computerized perimetry is related to standard manual visual field examination. Guidelines are offered for the choice of test programs and for the interpretation of results.
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| 6. |
- Heijl, A, et al.
(författare)
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Diagnosis of early glaucoma with flicker comparisons of serial disc photographs
- 1989
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Ingår i: Investigative Ophthalmology & Visual Science. - 0146-0404. ; 30:11, s. 84-2376
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated flicker comparison, a technique for detecting differences in serial fundus photographs. Serial optic disc photographs and computerized threshold visual fields were obtained every 3 months for an average of 40 months in 131 eyes of 81 patients with elevated intraocular pressure and normal visual fields. Two serial monophotographs were projected, optically aligned, and superimposed; analysis was done by alternately viewing first one and then the other image. We found flicker analysis of serial disc photographs to provide results which were closely correlated with those of computerized threshold perimetry. Thus, of those 12 eyes which developed field defects, eight showed definite change and two showed highly suspected change in optic disc configuration. Only two eyes showed a definite alteration in optic disc anatomy without the development of field loss, and field defects appeared in only one of 109 eyes in which there was no change or suspected change on flicker comparison. The flicker method was more sensitive than conventional nonflickered comparisons, but changes could usually be seen also with conventional inspection once they had been detected by the flicker method. Our findings suggest that flicker analysis may offer a considerable improvement over current standard methods of analyzing serial photography and may be a useful complement to routine perimetry. However, this method requires special equipment; requires that the photographs be similarly centered; and is time-consuming. Alignment of photographs by means of computerized image analysis techniques could make the method clinically practicable.
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| 7. |
- Heijl, A
(författare)
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Effect of IOP on the visual field in ocuLar hypertension and glaucoma
- 1989
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Ingår i: International Ophthalmology. - 0165-5701. ; 13:1-2, s. 24-119
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Tidskriftsartikel (refereegranskat)abstract
- The traditional opinion that increased intraocular pressure is the cause of glaucoma is controversial, probably mainly because of the fact that firm evidence for the value of pressure reduction is largely lacking. The present article reviews results from short term studies of visual fields before and after pressure reduction. It also reviews published and unpublished preliminary results from studies addressing the problem of whether the long term visual field prognosis, in glaucoma and in ocular hypertension, is affected by pressure lowering therapy. There is no convincing agreement among results from modern studies using computerized perimetry indicating that acute lowering of the ocular tension results in an improvement of the glaucomatous visual field. Long-term result are equally conflicting, and often negative. We have noted from a preliminary analysis of our own masked, prospective study of patients with 'high risk' ocular hypertension, that the same results may be interpreted in quite different ways. The results of available studies certainly indicate that pressure reduction does not automatically lead to clear and positive effects on the visual field. The studies have often been small, however, and have usually not had the power of detecting small effects of treatment. Also, pressure reduction has usually not been dramatic and many treated patients have maintained 'elevated' pressure levels. Patients with very high pressures have not been included, and the effect of pressure reduction in this situation has therefore not been investigated at all. More controlled, prospective therapeutic studies are necessary and ethical. It seems particularly important to study the long-term effects of non-pharmacologically induced pressure reduction in patients with manifest field loss.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 8. |
- Heijl, A
(författare)
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Lack of diffuse loss of differential light sensitivity in early glaucoma
- 1989
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Ingår i: Acta Ophthalmologica. - : Wiley. - 0001-639X .- 1755-375X. ; 67:4, s. 60-353
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Tidskriftsartikel (refereegranskat)abstract
- We studied the differential light sensitivity in 83 patients who were prospectively followed with computerized threshold preimetry and optic disc pathography because of suspect glaucoma. Eyes with media opacities were excluded from the analysis. Fourteen eyes developed progressive optic disc cupping and/or localized visual field loss. In this glaucoma group light sensitivity in the 10 best points in the visual field did not deviate more from estimated age-corrected standard values than in the remaining groups of 115 eyes with increased intraocular pressure and 18 normotensive eyes. The results do not support the concept that diffuse loss of differential light sensitivity should be common in early glaucoma.
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| 9. |
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| 10. |
- Heijl, A, et al.
(författare)
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Visual field interpretation with empiric probability maps
- 1989
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Ingår i: Archives of Ophthalmology. - : American Medical Association (AMA). - 0003-9950. ; 107:2, s. 8-204
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Tidskriftsartikel (refereegranskat)abstract
- Automated visual field charts may be difficult to interpret partly because of the magnitude and complex nature of normal threshold variability. We devised two types of empiric probability maps in which this variability is taken into account and the significances of measured threshold values are displayed. These maps are highly sensitive to nonobvious but significant paracentral field loss but will at the same time deemphasize false-positive patterns commonly found more peripherally. They also frequently show field defects before these are obvious in conventional threshold printouts. In addition, they differentiate between generalized loss of sensitivity and localized field defects.
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