| 1. |
|
|
| 2. |
- Heijl, A, et al.
(författare)
-
An automatic static perimeter, design and pilot study
- 1975
-
Ingår i: Acta Ophthalmologica. - : Wiley. - 0001-639X .- 1755-375X. ; 53:3, s. 293-310
-
Tidskriftsartikel (refereegranskat)abstract
- An instrument for automatic static perimetry at 14 points across a meridian was constructed and used in a pilot study. The machine was controlled by a computer and the subjects responded to the light stimuli by pressing one of two push-buttons. Most people investigated readily understood the rules at testing. "Blunders" made by the subject were, however, so common, that allowance had to be made in the test programme for a number of mistakes. The test stimuli should be exposed in random order. When the zone of uncertain seeing is wide - this occurs especially in untrained subjects - a simple test logic gives a fairly large variation. An improvement in reproducibility is then obtained by applying a more complicated logic, though at the cost of an increased duration of the test session.
|
|
| 3. |
- Heijl, A
(författare)
-
Computer test logics for automatic perimetry
- 1977
-
Ingår i: Acta Ophthalmologica. - : Wiley. - 0001-639X .- 1755-375X. ; 55:5, s. 53-837
-
Tidskriftsartikel (refereegranskat)abstract
- Using an automatic computerized perimeter developed by Heijl & Krakau (1975b) three different perimetric test logics, one simple (I) and two more complicated and time-consuming (II & III) were investigated in practical experiments on healthy normal test subjects and patients and in computer simulated tests. The patients either had a verified diagnosis of glaucoma or glaucoma was suspected. The best consistency in measured thresholds was obtained with test logic II, in which an averaging procedure is used. The variation of the results was larger in pathological than in normal visual fields. All test logics investigated readily detected the pathological field defects, but blind spots could easier pass unrecognized with the simplest logic than with the other two logics. The conclusion is drawn that a simple test logic can be used for perimetry in glaucoma suspects if no visual field defect has previously been documented. For the follow-up of pathological fields a fairly complicated test logic, e.g. using averaging, is preferable.
|
|
| 4. |
- Heijl, A
(författare)
-
Time changes of contrast thresholds during automatic perimetry
- 1977
-
Ingår i: Acta Ophthalmologica. - : Wiley. - 0001-639X .- 1755-375X. ; 55:4, s. 696-708
-
Tidskriftsartikel (refereegranskat)abstract
- Contrast thresholds were continuously recorded in six points of the visual field through a repetitive up-and-down staircase method using the automatic perimeter developed by Heijl & Krakau (1975b). The uninterrupted sessions lasted about 30 min. Nineteen patients with a verified diagnosis of glaucoma, or in whom glaucoma was suspected, and twelve healthy normal subjects were tested. With increasing test time, a decreased contrast sensitivity was found. In most subjects the mean threshold increment was small (less than 1.5 dB). The threshold increments were larger in the patient group than in the normal subjects--many test points showing increments of 6-10 dB during the test session. Such a large deterioration of sensitivity was most common in eyes with visual field defects. Test points which showed large threshold increments were often situated in the vicinity of documented visual field defects. In eyes with pathological visual fields, the short-term variation increased with increasing test time. An impairment of fixation with increasing test time was found in the patient group.
|
|
| 5. |
- Alm, Albert
(författare)
-
Effects of norepinephrine, angiotensin, dihydroergotamine, papaverine, isoproterenol, histamine, nicotinic acid, and xanthinol nicotinate on retinal oxygen tension in cats
- 1972
-
Ingår i: Acta Ophthalmologica. - : Wiley. - 0001-639X .- 1755-375X. ; 50:5, s. 707-719
-
Tidskriftsartikel (refereegranskat)abstract
- The oxygen tension in the vitreous body close to the retina, PvrO2, was determined continuously in cats. The effects on PvrO2 of intraarterial injections of various vasoactive drugs were determined. The vasoconstrictors norepinephrine, angiotensin and dihydroergotamine did not change PvrO2 in five cats. The same result was obtained with the vasodilators isoproterenol, histamine and xanthinol nicotinate in five cats, and with nicotinic acid in six cats, while papaverine invariably increased PvrO2 in seven cats when injected intraarterially and in two cats when injected intravenously. It is suggested that the ability to penetrate the blood-retinal barrier may play an important role in determining the effect of vaso-active drugs on retinal blood flow.
|
|
