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Biomedical subjects

A Heijl

Publications and source records attributed to A Heijl.

At least 55 records · Page 3Linked to original sources
PubMed1996

Diabetic retinopathy before and after cataract surgery.

AIMS/BACKGROUND: Increased retinopathy progression has been reported after cataract surgery in patients with diabetes mellitus. To assess the influence of cataract surgery on visual acuity and retinopathy progression, all diabetic patients who were subjected to cataract surgery during 1991-3 have been followed up at the Department of Ophthalmology in Helsingborg. The average follow up time was 2 years. METHODS: One eye of each of 70 patients was included in the study, 35 monocularly and 35 binocularly operated on. Sixteen of the 70 patients had proliferative diabetic retinopathy (PDR) at baseline. The Wisconsin scale was used for the grading of retinopathy. The degree of glycaemic control was assessed by measurements of HbA1c. RESULTS: Most patients obtained improved visual acuity; a postoperative visual acuity of 0.5 or better was achieved in 89% of diabetic surgical eyes. Progression of the retinopathy occurred in 30 out of the 70 eyes, and was associated with mean level of HbA1c (p = 0.04), duration of diabetes (p = 0.02), insulin treatment (p = 0.001), and presence of retinopathy at baseline (p = 0.01). Patients who progressed had a significantly higher incidence of macular oedema (p = 0.006) than those who did not progress. No significant differences were found when operated and non-operated eyes were compared in the 35 patients with monocular surgery. Two patients in this group, however, ended up with macular oedema and worse vision in the operated eye than in the eye which was not operated on. Both patients had background retinopathy before surgery. CONCLUSIONS: Patients in this study, also those with PDR, obtained good visual acuity, better than in most previous studies. Poor glycaemic control was a factor of importance for the progression of diabetic retinopathy after cataract surgery.

Aged↗
PubMed1995

Pitfalls of automated perimetry in glaucoma diagnosis.

Perimetry is a cornerstone in glaucoma management. The detection of glaucomatous visual field loss is of crucial importance for diagnosing the disease. Automated threshold perimetry makes thorough testing of the central visual field very possible and high-quality data are often achieved. Certain factors, however, may hamper the visual field examination or visual field interpretation. Many diseases other than glaucoma are known to influence the visual field in more or less predictable ways. Of interest is also low patient reliability, learning and fatigue effects, as well as test artifacts and suboptimal test strategies or parameters. Finally, statistical aids provided by the built-in computer of the perimeter must be judged keeping in mind the population from which the patient is derived. We describe such pitfalls in glaucoma perimetry, how they can be identified, and dealt with clinically.

False Positive Reactions↗
PubMed1995

Latanoprost administered once daily caused a maintained reduction of intraocular pressure in glaucoma patients treated concomitantly with timolol.

The long term effects of two dose regimens of latanoprost (PhXA41) administered to eyes concomitantly treated with timolol which had not adequately been controlled by timolol alone were compared. A total of 50 patients, 17 with primary open angle glaucoma and 33 with capsular glaucoma, were recruited from five clinics. All had glaucomatous visual field defects and an intraocular pressure (IOP) of at least 22 mm Hg despite treatment with 0.5% timolol twice daily. Patients were randomised to two treatment groups. In one group 0.006% latanoprost was given twice daily, in the other group placebo was given at 8 am and latanoprost at 8 pm for 3 months, with concomitant timolol treatment in both groups. Average daytime IOP (mean (SD)) at baseline (on timolol alone) and after 4 and 12 weeks' treatment was 24.8 (3.6), 16.8 (4.3), and 15.7 (2.4) mm Hg respectively with once daily application of latanoprost and 24.9 (2.9), 18.1 (3.0), and 18.0 (3.6) mm Hg respectively with latanoprost twice daily. No clinically significant side effects were observed during treatment. Latanoprost causes a marked and sustained IOP reduction in eyes which are also being treated with timolol. Latanoprost given once daily is at least as effective and probably superior to a twice daily dose regimen.

Aged↗
PubMed1994

Diffuse visual field loss and glaucoma.

It is often claimed that general reduction, or diffuse loss, of perimetric sensitivity is an early sign of glaucoma. Our clinical experience and the results of a few other studies led us to believe otherwise. To investigate factors associated with diffuse field loss we reviewed 4222 Humphrey 30-2 threshold tests from 1582 eyes of 862 patients followed at our department. Most of these patients had ocular hypertension or glaucoma. Each field test was evaluated with the Glaucoma Hemifield Test of the Statpac 2 program. The Glaucoma Hemifield Test classifies field test results as within or outside normal limits regarding localized field loss and general shifts in sensitivity. General reduction of sensitivity without concomitant localized loss was found in 117 tests from 81 eyes of 69 patients. Corresponding patient records were found for 60 eyes of 60 patients. Media opacities or miotic therapy were noted in 46 eyes (77%), 10 eyes (17%) had end-stage field loss, and in 2 eyes (3%) other non-glaucomatous ocular pathology explained the diffuse loss of sensitivity. Thus, general reduction of differential light sensitivity as an isolated finding was almost always associated with reasons other than early to moderate glaucoma in this material mainly consisting of patients with glaucoma or increased intraocular pressure. Since only 2 out of the 1582 eyes had general reduction of sensitivity that was not explained by non-glaucomatous reasons, we conclude that purely diffuse field loss was not a sign of glaucoma.

Aged↗
PubMed1994

Visual fields at different stages of diabetic retinopathy.

Available studies on visual field disturbances in diabetic retinopathy have shown conflicting results, obtained with different and often non-comparable techniques. We have studied visual fields at different stages of diabetic retinopathy with modern sensitive computerized technique taking precautions to limit disturbing effects of random field variation and lack of perimetric experience. Sixty-three diabetic patients, insulin-dependent and non-insulin dependent, were each subject to three test sessions using the 30-2 full threshold program of the Humphrey perimeter. Retinopathy levels ranged from 10 to 65 in the ETDRS Final scale. In eyes without retinopathy or with very mild and mild disease (levels 10-35) mean deviation values exceeding the p < 5% level occurred in only 4% of eyes in trained sessions, and the number of test points with significantly reduced sensitivity did not exceed that expected in normal eyes. In moderate and moderately severe diabetic retinopathy (level 43-47) and in severe non-proliferative and proliferative retinopathy (levels 53-65) there was clear evidence of field loss, however, with significantly reduced mean deviation values in 44% of the eyes and 6.5% of tested points showing reproducible loss of sensitivity. Thus, there was no evidence of field loss in eyes with mild disease, but clear field defects in eyes with more advanced disease. Significantly reduced sensitivity was often correlated with retinal non-perfusion and there was seen a tendency towards more correlation in the midperiphery than paracentrally.

Adult↗
PubMed1994

The effect of panretinal laser photocoagulation on visual acuity, visual fields and on subjective visual impairment in preproliferative and early proliferative diabetic retinopathy.

The effect of panretinal laser scatter treatment on visual fields, visual acuity and subjective complaints was assessed in 11 patients with severe nonproliferative or early proliferative diabetic retinopathy. Patients were prospectively examined before and after panretinal treatment using automated static threshold perimetry with program 30-2 on the Humphrey perimeter, and they were interviewed. Visual field sensitivity was often depressed even before treatment with mean MD -4.3 (-1, -11.6) dB, but was significantly lower (p < 0.01, ANOVA) 2 weeks after treatment with mean MD -8.6 dB. Visual fields remained stable 4 months later. Treatment increased the number of eyes with visual fields as defined by abnormal MD values at the p < 0.05 level from 8 to 16 among the 17 treated. In spite of considerable impairment of visual fields after treatment, subjective problems were small and the visual field impairment seemed to have little influence on everyday life.

Adult↗
PubMed1993

Perimetric point density and detection of glaucomatous visual field loss.

Eighty-three patients with high risk ocular hypertension were followed between 9 and 120 months with computerized threshold perimetry every three months in a prospective clinical study. Twenty eyes developed definite glaucomatous visual field defects. Analysis of these cases showed that definite field loss was preceded by increased variability of measured threshold values. Already at this early stage up to the time when a definite diagnosis of field loss first could be made, was, in all eyes, the disturbed area large enough to cover several test locations in the standard test point pattern used during the study. The results indicate that test point density of standard central field automated threshold tests is entirely sufficient, and that early field loss is unlikely to be extremely focal in nature and able to escape detection between tested points. While early recognition of glaucomatous field loss obviously is facilitated by access to large amounts of threshold data, the current results imply that test point density is usually not a limiting factor, but that testing an eye twice using the same standard test point pattern might be as effective as if two interlocking grids were used.

Follow-Up Studies↗
PubMed1993

Optic disc diameter influences the ability to detect glaucomatous disc damage.

We studied the influence of optic disc diameter on the diagnostic power of subjective disc evaluation of glaucoma. One hundred and thirteen colour disc photographs of 91 patients with primary open angle glaucoma and 174 photographs of 89 randomly selected normal subjects were studied. Five ophthalmologists independently classified all eyes as glaucomatous or normal by disc appearance using a masked forced choice design. Sensitivities and specificities varied strongly as a function of disc diameter. Overall sensitivity for recognizing glaucoma by disc inspection was 58% in small discs, 72% in the middle group and 85% in the group of large discs. These differences were significant, and the odds of recognizing a glaucomatous disc as such increased by a factor of 2.07 between each group. Overall specificity was 99.6% in small discs, 95% in the middle group, and 79% in large normal discs. Thus, larger discs were more likely to be classified as glaucomatous whether they were glaucomatous or not, while small discs were more likely to be classified as normal.

Adult↗
PubMed1993

Computer-assisted instruction in emergency ophthalmological care.

The use of computer-assisted instruction in medical education has increased steadily in the last decade with the availability of personal computers. Many computer-assisted instruction programs train the user to handle various forms of disease or injury. Our intent was to provide medical students with more experience in managing ophthalmological emergencies, and we therefore designed a computerized teaching system for emergency ophthalmological care. The system makes it possible for inexperienced students to develop these skills, without jeopardizing the patient's health during training. Colour illustrations help teach the student to judge clinical signs. First, two classes of altogether 35 students used the teaching system. The students were shown to have gained significantly better knowledge of conditions which had been presented to them by the computerized teaching, than of conditions which had not been presented in this way. After having used the system, two other classes were asked about their attitudes towards this teaching modality. A majority regarded it as a valuable or very valuable addition to traditional methods of teaching. This type of instruction system may improve the quality of ophthalmic teaching without increasing teaching staff requirements.

Attitude of Health Personnel↗
PubMed1992

Glaucoma Hemifield Test. Automated visual field evaluation.

We have developed an algorithm, the Glaucoma Hemifield Test (GHT), for automated evaluation of single static threshold visual field test results in glaucoma. The GHT uses empirically determined limits of normality for up-down differences in the Statpac probability maps of the Humphrey Field Analyzer to detect localized visual field loss. It is also constructed to detect field loss that is symmetric around the horizontal meridian. Analysis is done in five corresponding pairs of sectors that are based on the normal anatomy of the retinal nerve fiber layer. Deviations from the age-corrected normal threshold in the most sensitive portions of the visual field are used to detect general reductions of sensitivity or abnormally high sensitivities. The GHT provides brief visual field evaluations printed on the field chart as plain text. The aim of this article is to describe the fundamentals of the analysis program and to provide clinical examples.

Adult↗
PubMed1992

Evaluation of methods for automated Hemifield analysis in perimetry.

A new aid to perimetric analysis, the Glaucoma Hemifield Test, primarily evaluates up-down differences in automated static visual field tests. We analyzed the visual fields of 163 eyes of 163 normal subjects and 77 eyes of 77 patients with glaucoma diagnosed on bases other than perimetry using the Glaucoma Hemifield Test and a similar, previously developed, hemifield analysis method. The performance of the Glaucoma Hemifield Test was compared with that of the earlier method and the differences in test design were evaluated individually. The Glaucoma Hemifield Test allowed significantly improved separation between the normal group and the group with glaucoma than did the earlier method. This improvement was due to an increase in sensitivity, and was associated with the use of test point significances instead of threshold values, and a large normal database alone in the determination of normal limits.

Adult↗
PubMed1992

Weighting according to location in computer-assisted glaucoma visual field analysis.

In recent years several aids for automated interpretation of visual field data have been suggested. We believed that incorporation of thorough knowledge of normal visual field variability would allow improvements in the performance of such aids since more attention would be paid to field results in areas with low physiological variability. Two visual field models for classification of fields in glaucoma based on comparisons of sensitivity values in the upper and lower hemifields and on analysis of test point clusters with diminished sensitivity were compared. Both models were constructed using logistic regression analysis in 101 normal eyes and 101 eyes with glaucoma. The first, more traditional model assumed Gaussian distributions of deviations from age-corrected normal thresholds and constant variability across the field (non-weighted model). The second model took into account empirically determined variability of pointwise threshold results and of cluster volumes in various visual field regions (weighted model). The two models were subsequently tested on an independent material of 163 normal eyes and 76 eyes with glaucoma. The weighted model gave significantly better classification of the fields in both materials. Accounting for physiological threshold variability can offer significant advantages in the construction of perimetric analysis aids for detection of glaucoma.

Adult↗
PubMed1992

Spatial analyses of glaucomatous visual fields; a comparison with traditional visual field indices.

Interpretation of numeric automated threshold visual field results is often difficult. A large amount of data is obtained for every single field tested. Various approaches to summarize this data have been suggested, most commonly the mean and standard deviation of departures from age-corrected normal threshold values. These visual field indices differ substantially from subjective field interpretation where spatial relationships are important. We have previously devised two methods for automated field interpretation which take spatial information into account--regional up-down comparisons and arcuate cluster analysis. We now studied the merits of using these new spatial methods and compared them to traditional visual field indices for discrimination between normal and glaucomatous field results. Central static 30 degree field results in 101 eyes of 101 normal subjects and 101 eyes of 101 patients with glaucoma were discriminated using logistic regression analysis. The best field classification was obtained with a spatial visual field model combining up-down differences and arcuate clusters. The advantages of the spatial model were confirmed in an independent material of 163 eyes of 163 normal subjects and 76 eyes of 76 patients with glaucoma where eyes with large field defects had been removed. In this material the spatial model gave 87% sensitivity and 83% specificity while the best non-spatial model gave 82% sensitivity and 80% specificity. Visual field interpretation in glaucoma may be significantly enhanced if detection is focused on circumscribed field loss rather than on averages of differential light sensitivities and similar indices which do not take spatial relationships into consideration.

Adult↗
PubMed1989

Test-retest variability in glaucomatous visual fields.

We measured test-retest variations in computerized visual fields from glaucomatous eyes. Fifty-one patients were tested four times within a four-week period; the severity of disease varied from incipient to advanced. We determined the dependence of threshold variability on defect depth and test point location. In areas of the visual field initially found to have moderate loss of sensitivity, variation in follow-up measurements ranged from normal sensitivity to absolute defect, with little dependence on distance from fixation. Conversely, large changes were considerably more unusual in locations initially showing normal or near-normal sensitivities, and variability was lowest in the most central portion of the field. Our findings suggest that differentiation between true progression and random variation will be facilitated if these factors are taken into account, as well as if comparisons are based on more than two tests. The complex nature of interest variation in glaucoma makes it natural to approach this problem with the help of computer-assisted analyses.

Adult↗
PubMed1989

The effect of perimetric experience in normal subjects.

Two groups of normal subjects were submitted to repeated automated static threshold perimetry. Perimetric results were strongly affected by the level of experience in some subjects; in the majority, however, the effect of experience was small. Initial field tests often showed high numbers of depressed points. Sensitivity increased with perimetric training, particularly between the first sessions. Those subjects who improved most started low, gradually approaching normal levels with experience. Learning effects were more pronounced peripherally than paracentrally and "untrained" fields characteristically showed concentric contraction with numerous points with low sensitivity peripherally. An important practical conclusion is to allow repeated testing of all inexperienced patients in whom initial fields do not agree with clinical findings. A chart showing a concentrically narrowed field should be viewed with particular suspicion. Furthermore, a single initial field may constitute an inadequate baseline for clinical follow-up.

Adult↗
PubMed1989

A clinical study of perimetric probability maps.

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.

Adult↗