Spotting of disc haemorrhages on fundus pictures; on Kodachrome slides and on digitally enhanced images.

Purpose: To find out whether digital processing can facilitate interpretation of fundus photographs.

Methods: Digitised fundus pictures were manipulated and enhanced by a process called histogram equalisation. Essentially, the gamma values for red (R), green (G), and blue (B) were separately modified.

A computerised adaptometer.

Purpose: The design of an automatic instrument for the estimation of subjective dark adaptation (minimum perceptible for light) by an uninterrupted chain of trials.

Methods: A light emitting diode is used as test light. The patient answers by pressing a button when light is perceived.

An instrument for recording the ocular pulse wave.

An instrument for recording the ocular pressure pulse is described. Examples of recordings showing individual differences in the shape of the pulse curve are demonstrated. The properties of the instrument as to the frequency response in the range 0.

A model for pulsatile and steady ocular blood flow.

Background: The aim was to elucidate two controversial questions. (1) is the pulsatile inflow dominant or is there a sizeable steady inflow component? (2) Is the outflow of blood steady or pulsatile in induced and in glaucomatous hypertension?

Methods: The OBF system (Langham) was used for pulse recording. A simple electric flow model was conceived and analysed in terms of Fourier series, using linear circuit theory.

Disk hemorrhages and retinal vein occlusions in glaucoma.

There are several reasons to consider disk hemorrhages, branch retinal vein occlusions and central retinal vein occlusion as manifestations of the same vascular disease, the only difference among them being the size of the vessel affected. There is a close association of these vascular events with open angle glaucoma, and all of them increase with increasing follow-up time. The morphological changes described in the retinal veins in glaucoma and in central vein occlusions are endothelial proliferations causing progressive increase of flow resistance.

Arguments for a vascular glaucoma etiology.

A material of Open Angle Glaucoma (G) collected by an eye practitioner (B S) from 1980 to 1991 is analysed with special respect to the occurrence of disc haemorrhages (Hs) and retinal vein occlusions (VOs). There is a close association between Hs and VOs and G, which in all categories increases with increasing follow-up time. Furthermore, the occurrence of mixed cases--H in one eye and VO in the same or the other--support the opinion that Hs, branch vein occlusions and central vein occlusions are manifestations of the same vascular disease, the difference between them being the size of the vessel affected.

Measurement of progressive disc change in glaucoma.

We describe a videographic procedure for detecting minute changes in disc topography of glaucomatous eyes that involves measuring the displacement of selected circumlinear vessels. The problem of recognizing the difference between parallactic errors and true changes in topography is emphasized.

Calculation of the pulsatile ocular blood flow.

Based on reasonable assumptions, it is theoretically possible to determine the pulsatile ocular blood flow. The pertinent parameter is not the pulse amplitude but the steepest decay value of record (ie, the minimum of dV(t)/dt). Some advantages of developing the record in Fourier series are discussed.

Correction of optic disc measurements on fundus photographs.

If defined as diameter of image/diameter of object, the magnification M of the eye-camera system is kB, where k is a camera constant and B represents the vergence of the internal axis of the eye. The magnification may be assessed (1) from the length l of the eye, using the formula 1.336 k/(l-0.

Correlations in series of perimetric performance values.

The correlation function for consecutive performance (P) values in a material of simple glaucoma is studied. The outcome of perimetry sessions recorded with about 2 min intervals are significantly correlated, whereas those obtained 2 h apart or more are not so. Partial correlations of the right and left P values as well as IOP and P value are estimated and discussed in connection with a statistical model for the sensitivity fluctuations.

Computerized patient record system for the glaucoma ward.

A system for computerized glaucoma patient record, developed from a data base called 'Advanced Revelation', is described. The record is made up from free text as well as from choices among listed alternatives. All data are stored on magnetic media and also printed out on paper in a well disposed and easily surveyable form.

High frequency of asymptomatic visual field defects in subjects with transient ischaemic attacks or minor strokes.

The hypothesis that asymptomatic visual field defects can be found in patients with carotid transient ischaemic attacks (TIA) or minor strokes was tested. Twenty-two consecutive male patients with TIA and 18 patients with minor strokes from the carotid artery territory were examined by perimetry, cerebral computerised tomography and regional cerebral blood flow. Asymptomatic visual field defects were found in many TIA and minor stroke patients, 29% (5/17) and 57% (8/14), respectively (NS).

Occurrence of disc haemorrhages in open-angle glaucoma treated with pilocarpine or timolol.

1573 examinations were performed on 397 eyes. hh was found in 55 eyes--thromboses included--at 91 examinations. Part of this material qualified for use in a comparative study with pilocarpine in 81 eyes and timolol in 82 eyes.

Visual field testing with reduced sets of test points. A computerized analysis.

A computerized analysis of visual fields is described. In a second step these results are condensed into a 'reduced' set of test points so constructed that if testing is limited to 6-8 points nearly all defective visual fields would have been spotted with at least one defective point. The 'reduced' set involves the testing of few points several times in a session rather than spending very few trials on a great number of points.

Observations concerning the course of glaucoma.

Four cases with glaucomatous damage to the optic nerve head preceding a rise in intraocular pressure from normal or borderline to high values, are reported. The question of whether such cases are exceptional or typical and, therefore, best explained by a coincidence of diseases or by one disease going through successive stages is discussed on the basis of 10 further cases from a population study. Many clinicians claim that there are two groups of patients: a large one with 'ordinary' glaucomas supposedly caused by high intraocular pressures and a small one with low tension glaucomas presumed to have low perfusion pressures for other reasons.

Temporal summation and perimetry.

The threshold sensitivity at perimetry was determined experimentally as a function of the exposure time of the test objects. The summation capability of the retina is expressed as a 'memory' function with approximately exponential decay. The efficient stimulus is found from the convolution integral of the functions for memory and light stimulus.

Disc haemorrhages and glaucoma in a general ophthalmic practice.

The composition of the clientele from an ophthalmological practitioner's office is described with special reference to the occurrence of glaucoma and disc haemorrhages (h in singular; hh in plural). This study could not be planned as an epidemiological survey and gives no clue to sensitivity or specificity of hh in glaucoma. During a period of about 10 years ending with 1986 there were 731 patients with h and/or glaucoma.

Treatment versus no treatment in chronic open angle glaucoma.

In a controlled randomized study 15 patients (20 eyes) with chronic open angle glaucoma and visual field defects were followed by greater than 1 year, 12 of them were followed for 3 years. Half of the group were untreated controls, the other half treated with pressure reducing medical therapy. At least 5 consecutive computerized visual fields were recorded (COMPETER) on each eye, and the linear regression coefficient was calculated.

Hazards in evaluation of visual field decay.

To evaluate the trend in a series of observations, blurred by random fluctuations, is a problem encountered in follow-up studies of visual fields from glaucoma patients. The imminent risk of falsely estimating, say, the effects of therapy by incautious sampling and insufficient number of observations is described in the present communication.

A system for a computer-assisted glaucoma care unit.

A computerized system for a glaucoma care unit is described. The aim is to examine and record every patient classified as a case of glaucoma in a way which permits subsequent use of the data in studies of the natural history of glaucoma. A main topic concerns the choice of those examinations, treatments etcetera which have to be included in the records to satisfy clinical and scientific requirements.

A statistical trap in the evaluation of visual field decay.

Computerized perimetry has made it possible to evaluate quantitatively the visual field decay in glaucoma and other cases. The performance fluctuates with considerable amplitude and therefore the heart of the matter concerns the detection of a signal in presence of noise. How insufficient number of observations and uncautious sampling may result in false conclusions as to the effect of therapy etc is described in the present paper.

Trabeculoplasty and visual field decay: a follow-up study using computerized perimetry.

15 eyes with glaucomatous visual field defects were followed with computerized perimetry before and nearly one year after Argon Laser Trabeculoplasty. An expected reduction of the IOP was achieved, the pressure being on an average 25.7 mm Hg before and 17.

Separation of background and defect in automatic perimetry.

Separation of the performance values obtained at computerized perimetry (Competer system) into 2 parts, one related mainly to the defect and the other to the general background, opens up new and improved ways for the study of correlations involving the visual field performance.

The glaucoma theory updated.

The natural history of splinter haemorrhages on the optic disc is an argument in favour of the belief that the glaucomatous process starts in the small vessels of the papilla. The probable existence of factors in the aqueous, whose generation depend on the state of oxygenation in the posterior parts of the eye and which affect the outflow resistance, supports the idea that the pressure increase is a secondary effect. Reduced perfusion by increased IOP or reduced blood pressure etc.