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Visual field decay in normal subjects and in cases of chronic glaucoma
Abstract
Visual field information obtained with the automatic Computer-Perimeter ('Competer') can be condensed into a single numerical value. This performance measure was applied to a normal population to determine the physiologic decay of retinal sensitivity with aging. Further, the development of this performance measure was followed in 54 glaucoma eyes which were divided into three groups: Untreated, treated with satisfactory intraocular pressure (IOP) regulation, and treated with satisfactory IOP regulation. All eyes were examined perimetrically on at least three separate occasions. Decaying performance measures were found in the preponderance of glaucoma eyes. Therapy aimed at lowering the IOP did not offer a protective effect. Papillary hemorrhage and a significant decay in performance are usually found in the same eye.
... [3][4][5] The proportion of glaucoma patients who exhibited progressive visual field loss despite treatment in various studies has been reported to be between 5% and 80%, with an average of approximately 10% per year. [6][7][8][9] This suggests that factors independent of IOP may be responsible, in part, for the sustained progression of glaucoma. [10][11][12][13] In this study, we aimed to determine the clinical factors associated with progressive glaucomatous damage and to examine whether there is a relationship between the level of glaucomatous optic disc damage and further progression. ...
Background
Reducing intraocular pressure (IOP) in glaucomatous eyes does not always prevent disease progression.
Objective
To determine the clinical factors associated with progressive optic disc damage in glaucomatous eyes receiving treatment to reduce IOP.
Methods
Baseline and follow-up optic disc photographs as well as demographic and clinical data were retrospectively studied in 186 eyes of 93 patients with primary open-angle glaucoma, and in 138 eyes of 69 patients with normal-pressure glaucoma. The patients with primary open-angle glaucoma were included in the study only if their treated IOPs during a follow-up period of 5 years were less than 21 mm Hg. The patients with normal-pressure glaucoma were included only if their IOPs were reduced by at least 20% during the follow-up period. The association of progressive optic disc damage with patient- and eye-specific characteristics was examined using multivariate analysis.
Results
During the 5-year study period, 141 (43.5%) of the 324 eyes exhibited progressive optic disc damage defined by at least a 5% decrease in the neural rim area-to-disc area ratio. Using multivariate analysis, the following were found to be strongly associated with progressive neural rim damage: a baseline smaller neural rim area-disc area ratio (P<.001); a baseline larger zone β area-disc area ratio (P= .04); a baseline larger parapapillary atrophy length-disc circumference ratio (P = .05); a diagnosis of normal-pressure glaucoma(P = .01); and combined medical and surgical treatment prior to the study period (P = .01).
Conclusions
Clinical factors other than IOP may be important indicators of subsequent progression of glaucomatous optic disc damage. Our findings suggest that eyes with advanced glaucomatous optic disc damage and normal-pressure glaucoma are more likely to progress despite receiving treatment to reduce IOP.
... In accordance with the epidemiological data, our POAG patients were significantly older than the OHT patients or controls. Physiological decay has been demonstrated in both normal and glaucomatous eyes, 34 but many similar studies have been affected by the same drawback [35][36][37] (mainly because of the lack of elderly people with a normal visual field who are eligible as healthy controls) and so we consider this age difference acceptable for the purposes of our study. ...
To assess the ability of retinal nerve fiber layer (RNFL) thickness measurements obtained using GDx-enhanced corneal compensation (ECC) or spectral-domain optical coherence tomography (RTVue), and that of ganglion cell complex (GCC) scan available on RTVue, to detect glaucoma.
One randomly selected eye of 205 subjects (70 normal, 65 ocular hypertension, and 70 glaucoma) underwent a complete clinical and instrumental examination. RTVue spectral-domain optical coherence tomography was used to assess RNFL thickness and GCC parameters, GDx ECC to assess RNFL thickness. Areas under the receiver operating characteristic curves (AUCs) and sensitivity of the RNFL and GCC parameters were calculated at a fixed specificity of 95%, and the diagnostic abilities of the RNFL values obtained using the 2 instruments were compared. We also compared the results obtained in the normal, ocular hypertensive, and glaucomatous subjects.
Best GDx RNFL parameter was nerve fiber indicator (NFI) (AUC 0.99, sensitivity 96%); the best RTVue parameters were average (AUC 0.98, sensitivity 90%), inferior-temporal (AUC 0.97, sensitivity 89%), and superior-temporal RNFL thickness (AUC 0.96, sensitivity 87%). There were no significant differences between the 2 devices (P>0.05). Best GCC parameters were focal loss volume (AUC 0.98, sensitivity 91%) and global loss volume (AUC 0.96, sensitivity 87%).
GDx ECC and RTVue show a very good diagnostic ability to detect glaucoma. Most of the RNFL parameters had high AUCs and sensitivities. The diagnostic validity of GCC was comparable with that of the RNFL parameters, and they may be very useful in detecting RNFL damage.
... However, each clinical trial set different progression criteria, and various individual criteria were suitable only for specific populations or disease stages (Heijl et al, 2008a). Event-type analysis (Hitchings 1994; Casas-Llera et al, 2009) and trend-type analysis (Holmin & Krakau, 1980; McNaught et al, 1995; Wild et al, 1989) have often been used in clinical practice since SAP instruments were introduced. Event-type analysis uses 2 or 3 visual field tests to establish a baseline, then compares subsequent tests to this baseline. ...
The use of automated visual fields to detect and monitor glaucoma is hampered by having no gold standard against which to compare them. In the case of monitoring disease progression visual fields display large amounts of fluctuation that can mask true change. The analysis of fields using pointwise linear regression (PLR) has been developed to more accurately detect change. However the criteria for change using PLR are themselves poorly understood. This thesis examines the collection of field data from a surgical trial of trabeculectomy and then explores the detection of change in the eyes in the study using conventional and PLR grading techniques. Analysis of field data from an initial group of patients in the trial reveals the large amount of change detected using existing criteria. Much of the change detected is due to noise or fluctuations in a patient's response that do not represent real change. The use of modified criteria has variable effects on the detection of change. From this group of modified criteria, 6 can be selected on an empirical basis. All maximise the detection of progression while minimising improvement. Given the data available it is not possible to link any changes in visual field to changes in media opacity, especially cataract. When the selected criteria are tested against a) extended follow up data and b) a second group of patients from the same trial one criterion offers the ability to detect progression in both groups of patients while minimising the detection of improvement. This criterion requires a particular spatial arrangement of points in the field. Analysing groups of patients' fields using PLR without regard to treatment offers a way of developing change criteria prior to analysis within treatment arms.
In this chapter, report 1 of the Treatment of Age-Related Macular Degeneration with Photodynamic Therapy (TAP) study details the one-year results of two double-masked, placebo-controlled, randomized clinical trials to determine whether photodynamic treatment with verteporfin reduces the risk of vision loss in patients with age-related macular degeneration (AMD) due to subfoveal choroidal neovascularization (CNV) measuring 5400 µm or less in greatest linear dimension with evidence of classic CNV and best-corrected visual acuity of approximately 20/40 to 20/200. At the month-12 examination, 61% of eyes assigned to verteporfin compared with 46% of eyes assigned to placebo had lost fewer than 15 letters of visual acuity from baseline). Verteporfin therapy was found to be safe and effective in reducing the risk of vision loss, and the authors recommended verteporfin therapy for treatment of patients with predominantly classic CNV from AMD.
It is always difficult to compare visual fields of glaucoma patients, in order to evaluate the progression of the disease. Modern perimetry offers a solution to this problem in replacing the cartographic reading by a number evaluating a ‘deficit ratio’. This quantification in percentage of visual field destroyed is very simple to perform if the results of examination are expressed in classes of Log. L. U.
Primary open-angle glaucoma is a significant cause of visual loss among the elderly, but it is rarely diagnosed by the primary care clinician. Open-angle glaucoma is a disease of unknown etiology associated with increased ocular pressure and characterized by insidious damage to the optic nerve, causing visual field defects. The patient is asymptomatic until significant visual loss has occurred. Although it accounts for 70% of all glaucomas, it is the least understood.
Publications in recent years indicated that high IOP is not necessarily an indication for treatment in ocular hypertension. It was claimed furthermore that even in glaucoma treatment is not more than “a tradition based on obsolete ideas and never shown to be justified by any positive effect” (Bengtson,1981), and that the “pressure theory has lost most of its meaning and has become almost completely useless” (Krakau, 1981). In contrast to these ideas, it is shown in this paper that high IOP produces the same damage as it is known from glaucoma in experimental animal studies, in otherwise healthy persons with secondary glaucoma, or in steroid-induced glaucoma, and that it produces arcuate scotoma in healthy volunteers. It is further shown, that normalization of the IOP prevents in most cases any further functional loss, especially so in early cases. Other diagnostic parameters are uncertain. A close correlation between disc and field changes exists only in the late cases. The usual kinetic perimetry with Goldmann’s perimeter leaves every 3rd beginning field defect in glaucoma undetected, which is found with the computerized Octopus perimeter. For therapy, the IOP can usually be rather easily influenced, while additional risk factors (family history, vasosclerosis, large cupping, haemorrhages near the disc, late phase of glaucoma, low general blood pressure) cannot or only scarcely be influenced by therapy. It is concluded that
1.
high IOP is the most important damaging parameter in glaucoma
2.
that is the only one which is relatively easy to influence
3.
the “normal” in the sense of the most frequent value in the healthy population is an IOP of 15–16 mmHg
4.
that normalization of IOP prevents further damage
5.
and that the advise of no treatment in glaucoma with high IOP has ethical implications which must be clearly understood
In two important respects, computerization has increased the capacity of perimetry. The method has become objective in the sense that the influence exerted by the assistant is eliminated. The results are presented in numerical form, which opens up possibilities for consistent interpretation and statistical evaluation of changes in the visual field (Krakau 1978). Comparisons of actual results with previous examinations or with the outcome in normal or pathological groups require the construction of parameters which summarize the pertinent information. A very simple parameter intended to measure the total performance was used in the study of normals and glaucoma cases during a follow-up (Holmin and Krakau,1980,1982). After some properties of the performance value have been described the results of these investigations, supplemented by some further calculations and arguments, will be discussed in the present article.
Authored by three prominent specialists in the field, this text provides comprehensive coverage of diagnostic and treatment modalities for optimal glaucoma management. Revised throughout, this new edition presents the latest guidance in clinical examination, randomized trials, medical treatment, laser therapy, and surgical procedures. Hundreds of illustrations-with many classic black and white figures from the previous editions supplemented with new color images-depict the features of glaucomas and step-by-step procedures for their management, while expanded use of highlighted boxes, lists, and summary tables make the material easy to access. Evidence-based and updated information on all aspects of the glaucomas-including physiology, genetics, interventional trials, and new surgical techniques-offer a well-rounded foundation of knowledge for making the most informed diagnoses and choosing the most effective course of treatment. Combines the cumulative experience of three prominent glaucoma specialists-addressing a full range of clinical needs for practitioners of all levels-for a uniquely written coherent perspective. Includes extensive references to current and historically important sources to provide comprehensive interpretation of the latest medical literature. Synthesizes a classical approach to the glaucomas-based on seven earlier editions spanning over 40 years-with the most up-to-date evidence-based and epidemiologically-derived classifications and outcomes. Coherently correlates with authoritative consensus documents on key areas of glaucoma, drawn up by the world-wide specialists of the World Glaucoma Association, and reprinted in the text. Revamps traditional teachings on the angle closure glaucomas, in concert with the newest international literature and technologies, to keep you up to date on the latest advances. Illustrates detailed surgical interventions applicable to the complete spectrum of clinical settings-from the developing world through contemporary operating rooms. Examines the newest and most promising developments in pharmacology, laser and surgical advances for glaucoma management, to enable you to choose the most effective patient approach. Illustrates invaluable but little-known instruments for clinical and research diagnoses, including optic nerve cupping scales, bleb assessment instruments, and more.
Objectives
To evaluate safety and short-term visual acuity and fluorescein angiographic effects of photodynamic therapy (PDT) after retreatments with verteporfin for choroidal neovascularization (CNV) in age-related macular degeneration (AMD) that demonstrated fluorescein leakage after at least 1 course of PDT.
Design
Nonrandomized, multicenter, open-label phase 1 and 2 clinical trial using 2 different retreatment dosage regimens.
Setting
Four ophthalmic centers in Europe and North America providing retinal care.
Methods
Standardized protocol refraction, visual acuity testing, ophthalmic examinations, color photographs, and fluorescein angiograms were used to evaluate the results of multiple PDT treatments. Two regimens (regimens 2 and 4) for treatment and retreatment were chosen from 5 used in a single-treatment study. Both regimens used a verteporfin dose of 6 mg/m² infused for 10 minutes. However, regimen 2 used a light dose of 100 J/cm² applied 20 minutes after the start of the verteporfin infusion, whereas regimen 4 used a light dose of 50, 75, or 100 J/cm² applied 15 minutes after infusion commenced. Posttreatment evaluations were planned in 31 participants up to 3 months after up to 2 retreatments given at 2- or 4-week intervals after initial PDT treatment. Similar posttreatment evaluations were planned after retreatments in 5 additional participants who were reenrolled some time more than 12 weeks after an initial PDT treatment.
Results
The average visual acuity change for the 31 participants who had retreatment within 2 to 4 weeks after the initial treatment and a follow-up examination 16 to 20 weeks after the initial treatment was 0.2 lines (range, −4 to 4 lines) in regimen 2 and −1.0 line (range, − 5 to 3 lines) in regimen 4. Similar outcomes were noted in the 5 reenrolled participants. Cessation of fluorescein leakage from classic CNV for at least 1 to 4 weeks could be achieved without loss of visual acuity after at least 2 treatments in 2 (6.5%) of 31 patients. Similar to single-treatment effects, the disappearance of leakage was documented regularly at 1 week after each retreatment. Fluorescein leakage reappeared by 4 to 12 weeks after a retreatment in almost all cases. However, compared with baseline, leakage activity appeared to be reduced after multiple PDT courses. For the 31 patients who had follow-up for 3 months after the last retreatment and had received retreatment 2 to 4 weeks after the initial treatment, progression of CNV beyond the area identified before the retreatment was noted in 10 (48%) of the 21 eyes with classic CNV in regimen 2 and 9 (90%) of 10 eyes in regimen 4. The rate and severity of ocular or systemic adverse events were not increased by multiple applications.
Conclusions
Multiple applications of PDT with verteporfin achieve repetitive, short-term cessation of fluorescein leakage from CNV secondary to AMD, without loss of visual acuity. This strategy can be used in randomized clinical trials investigating the efficacy of verteporfin in PDT for recurrent fluorescein dye leakage from persistent or recurrent CNV, following an initial or subsequent PDT treatment, with maintenance of visual acuity. Retreatments may achieve progressive cessation of leakage and prevent further growth of CNV and subsequent visual loss.
Objective
To investigate the rate of visual field (VF) loss in progressive glaucoma.
Setting
Outpatient department, nonreferral base.
Methods
A cohort of 34 patients with normal-pressure glaucoma (NPG), 68 patients with primary open-angle glaucoma (POAG), and 125 patients with ocular hypertension (OHT) were followed up for an average of 9 years. Visual fields were obtained annually with automated perimetry. The rate of VF loss as a percentage per year was calculated.
Results
Twenty-three eyes with NPG, 31 with POAG, and 10 with OHT showed progression of VF loss. The mean (±SD) rates of VF deterioration were 3.7% ± 3.3% per year in NPG, 2.5% ± 1.8% in POAG, and 2.3% ± 1.3% in OHT converting to POAG, and did not differ significantly. No difference in the rate of VF loss was found between eyes with and without optic disc hemorrhages (2.7% ± 2.9% and 3.1% ± 2.1%, respectively). The rate of VF loss was not related to the initial VF status. The rate of VF loss between the superior and inferior hemifields was correlated in patients with NPG (rs=0.67, P=.04). Comparison of visual field loss with linear regression analysis showed significant slopes in only 37.5% of eyes with progression, which had a progression rate of 4.2% ± 3.0%.
Conclusions
The rate of VF loss did not differ between patients with NPG and POAG. The rate of deterioration was related neither to initial VF status nor to the presence of disc hemorrhages. Linear regression is applicable only in a portion of the patients who have progression of VF loss.
Due to the recent rapid increase in the aging population, glaucoma in the over-eighties population will become a significant problem of ocular health in the coming decades. It is important to determine the natural effects of aging on the optic nerve head and aqueous humor dynamics in these patients for early diagnosis and monitoring of glaucoma. Its characteristics, context, management, and treatment are very perceptibly different from those of the younger glaucomatous patient. For many reasons, such as its frequent association with macular age-related degeneration, diagnosis of glaucoma in the over-eighties may be difficult. Management of the over-eighties glaucoma is frequently difficult and time-consuming. Less aggressive than in a younger patient and based on topical medications in most cases, it must be discussed case by case and will be based on the general context, the quality of compliance, and especially on the potential consequences of the glaucomatous visual-field defects on the patient's quality of life. In any case, overtreatment as well as treatments that are too complex must be avoided. Given the reduced metabolism in the very elderly, the safest medications must also be selected. It is important to always consider glaucoma medications as part of the patient's medicine regimen. Associated risk factors, especially concomitant systemic hypotension, will be simultaneously treated. Laser trabeculoplasties probably have broader indications than in younger patients. Except for phacoextraction, which is very frequently helpful in controlling IOP, incisional filtering procedures or laser diode cyclophotocoagulations remain infrequently indicated in over-eighties glaucoma patients.
Seventy-five patients with CNS disorders and normal visual fields or hemianopsia were examined on one to 11 occasions by the modified computerized perimeter 'Competer'. The aim of the work was to evaluate the previously introduced statistical parameters. Of these, the performance values of the central (Pc) and mid-peripheral field (Pp) express the total ability and the difference values (Dc and Dp) the size of a hemianopsia.
In patients with normal fields gradual changes of Pc seemed to reflect changes of the general condition. For detecting small hemianopsias Dc was of great help, but for following up hemianopsias both Dc and Pc were indispensable. As a rule, a series of examinations demonstrating a trend was required for deciding whether the involvement of the visual pathway had changed or not. There were co-variations of the Pc-values of the right and left fields and also of the Dc-values in patients with homonymous hemianopsia, in whom the defects were usually congruous, but not in patients with bitemporal hemianopsia, in whom the defects were usually asymmetrical.
A negative correlation and linear regression between D-and P-values was found in hemianopsias, but the calculated regression lines were displaced from the expected ones because of additional defects in the non-hemianopic hemifields. In fatigued patients false positive defects were common, particularly in the mid-peripheral area. Consequently. Pp and Dp were less reliable than Pc and Dc, and this area should be examined by the 'Competer' only in alert patients.
To sum up. the elaborated statistical parameters were suitable for quantitative studies of visual fields in well-cooperating patients.
In order to study the pattern of progression of visual field defects in glaucoma we performed a retrospective study of 48 eyes of 48 patients with glaucoma. In those eyes showing progression the scotomas became denser in 79% whereas enlargement occured in 52% and 50% developed new scotomas. 63% of eyes maintained a defective single hemifield during the entire follow up. Patients with a longer follow up were more likely to show progression while age and mean or maximum IOP were not related to progression or non progression.
Nach 5 Jahren Verwendung des automatisierten statischen Projektionsperimeters Octopus mit Retest-Logik und änderbarer Software wird zusammengefaßt, was an neuen Erkenntnissen über glaukomatöse Gesichtsfelder die automatisierte Perimetrie und insbesondere dieses Gerät gebracht hat: 1. Die Entdeckungswahrscheinlichkeit von glaukomatösen Gesichtsfelderausfällen wurde gegenüber der Handperimetrie verbessert. - 2. Die Resultate einer Gesichtsfeld-Untersuchung wurden dank Auswertprogrammen mathematisch-statistisch behandelbar. - 3. Es hat sich gezeigt, dass vor allem für die Beurteilung von frühen Gesichtsfeld-Veränderungen und für Verlaufskontrollen nur eine Schwellenwert-Perimetrie sinnvoll, eine überschwellige Perimetrie unbrauchbar ist. - 4. Es bestehen früheste Alterationen in vermehrten Fluktuationen um die normalen Altersschwellen. - 5. Im Bereich beginnender Skotome sind Gesichtsfeld-Veränderungen reversibel, der Funktionszustand einzelner Netzhautbezirke ist also wechselnd. - 6. Relative Skotome haben häufig keine eindeutig bestimmbaren Schwellen, sondern es handelt sich um Bereiche großer Streuung; damit offenbaren sich die Grenzen nicht nur einer überschwelligen statischen, sondern auch der kinetischen Perimetrie. - 7. Die Schwierigkeiten der Verlaufskontrolle glaukomatöser Gesichtsfelder wird mit der automatisierten statischen Perimetrie und den Auswertprogrammen erst richtig aufgezeigt. - 8. Mit großer Wahrscheinlichkeit sind frühe Alterationen im Gesichtsfeld bereits Spätveränderungen im Verlauf der Glaukomkrankheit.
Summary
The results of studying patients with glaucomatous field defects over a 5-year period using the Octopus automated perimeter are summarized. This instrument relies on a retest logic and problem-orientated adaptation of the test points as well as of the software is possible with it. Automated perimetry offers significant advantages over conventional field testing and has increasing our understanding of glaucoma considerably. (1) The probability of detecting glaucomatous field defects is substantially greater than with manual perimetry ; (2) the results of a visual field examination can be treated mathematically and statistically, especially when Bebie and Fankhauser's Delta program is used; (3) the evaluation of progressive field loss is only possible using threshold perimetry, as supra-threshold stimuli are too crude; (4) increased fluctuations around the normal age-corrected threshold represent the earliest detectable changes in glaucoma; (5) loss of sensitivity is reversible in early relative scotomatfe; (6) the depth of relative scotomata cannot be sharply defined on account of rapid fluctuations in sensitivity; (7) early visual field changes probably represent late changes in the course of chronic simple glaucoma.
The automatic computerized perimeter ‘Competer’ has been used in several clinical studies for detection and follow-up in glaucomatous cases and also for the control of field defects in neuro-ophthalmological cases. The procedure is static and the central visual field is tested at 64 fixed test points.
By replacing the assistant by a computer the test conditions are kept under strict control. Time factors such as stimulus exposure time and maximal reaction time are fixed. The test result is given as the threshold sensitivity at each test point.
The numerical presentation makes the results suitable for statistical analysis. By adding all 64 threshold sensitivity values the information of a test session is condensed into a single number: the performance value (P).
The development of the performance value in a series of 5 consecutive perimetry sessions during more than one year (13—17 months) has been studied in a group of 55 eyes with glaucomatous field defects. The interval between 2 test sessions was 3—5 months. In 45 cases there was a tendency towards decay. The negative trend in the whole group was significantly more pronounced than that to be expected in normals where a slight tendency towards decay with increasing age is also found (Fig. 1). The tendency towards decay was similar in 2 subgroups separated with respect to the intraocular pressure (mean levels of < 22 and ≥ 22 mmHg, respectively).
Similar measures have turned out to be of value in the follow-up of field defects in neuro-ophthalmological cases. The difference between the left and right half of the field defines the value (D) which is well suited for detection of slight hemianopias.
Although the test point pattern of the computerized perimeter ‘Competer’ has been enlarged, focal diagnosis is difficult in many cases since the area outside 35° of eccentricity cannot be examined. Further improvements of the instrument requires knowledge about the depth at various eccentricities of common neurological field defects. This was calculated in 41 eyes with chiasmal defects and in 36 eyes with suprageniculate defects. Twenty-six normal visual fields were used for comparison. Generally, the central area was more or less intact in relative hemianopic defects, probably because of the large proportion of macular fibres in the visual pathway, and the depth was found to increase towards the mid-periphery. These results indicate that with a simplified test strategy for the mid-peripheral area, few hemianopic defects would be missed by the ‘Competer’. In this way, the examination of the mid-peripheral area could be shortened. Without prolonging the total test session, which is already 15–20 minutes per eye, focal diagnosis could be facilitated by adding and testing a number of points in the area outside 35° of eccentricity.
The present material comprises 51 patients with at least one disc haemorrhage in at least one eye. A total of 127 hh were observed. The probability of finding a disc h increases with the number of examinations. The hypothesis that hh occur in all cases of glaucomatous destruction of the papillary tissue cannot be rejected, though not proven. H. seems to be connected with progression of field defects, though its effects are not immediately recognized. H. is detectable very early in the glaucomatous process; the denotation ‘forerunner’ is most likely justified. Hh. are highly specific for a glaucomatous process, but it has not been possible to connect h. with some clearly delimited group of glaucoma.
The purpose of this study was to determine the intraocular pressure characteristics in glaucoma suspects and patients whose visual fields were classified as stable or progressing over a long-term follow-up. We present data from 64 patients who received either medical or laser treatment and who were followed up for a median of 7.4 years. The visual fields of 27 patients were classified as stable and 37 as progressing using pre-determined criteria on either the Tbinger or Goldmann perimeter. Patients with initially normal and initially abnormal fields were analysed separately to avoid bias. There were no significant group differences in the mean, highest or interquartile range of intraocular pressure in the follow-up. The largely overlapping distributions over a wide spectrum of the pressure variables in patients with stable and progressing fields show that intraocular pressure alone cannot separate these two groups of patients. Our study does not suggest that pressure reduction in glaucoma has no beneficial effect, but that there may be other factors which determine the fate of the visual field in glaucoma.
Visual-field areas to a I2e stimulus were measured planimetrically using an X-Y digitizer and a computer program. Sampling of normal subjects and patients suspected of having glaucoma was done at two points in time. Calculations of eye-wall stress were done using ultrasonic data and intra-ocular pressure (IOP) measurements from patient records. For those suspected of having glaucoma who developed chronic open-angle glaucoma (COAG), the time of transition was the second point in time. The visual field area was regressed against patient age at the two points in time. No difference in the regression slopes was found for the normal subjects and unchanged patients. The patients who did develop glaucoma were significantly different. The mean annual rate of visual-field change (rate of decay) was calculated and found to be 28.5 mm2/year for the normals, 153.5 mm2/year for the suspects, and 376.4 mm2/year for those patients who developed glaucoma. The rate of visual-field decay only correlated with patient age (P = 0.03) and eye-wall stress (P < 0.01) in the patients who developed glaucoma.
Until recently, the evidence that lowering intraocular pressure (IOP) protects the optic nerve from glaucomatous damage was weak. Several randomized controlled trials have provided stronger evidence that lowering IOP prevents glaucomatous progression. Optic nerves appear to be highly variable in their susceptibility to raised IOP. Elevated IOP likely triggers several parallel, but interacting mechanisms, including direct axonal damage, failure of load-bearing tissues, and disturbances in microvascular supply. The cellular mechanisms that translate these mechanical and physiologic stresses and that lead to excavation of optic nerve tissue are beginning to be understood.
The understanding of primary open-angle glaucoma has changed over the past 20 years and recommendations on early detection are being revised. In this paper the use of Shiotz tonometry is critically examined, and the problems encountered in instituting alternative screening techniques are reviewed.
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.
We present results from 64 glaucoma patients and glaucoma suspects followed up for a median period of 7.4 yr who had a median of seven examinations using Program 31 on the Octopus perimeter. The patients also had manual visual fields recorded on either the Tübinger or Goldmann perimeter during the same period. By examining all manual fields over the follow-up, we classified 37 patients as deteriorating and 27 as nondeteriorating by using predetermined field criteria which we believed to be clinically significant. In a masked fashion, the indices mean defect (MD) and corrected loss variance (CLV), in addition to the three cluster analysis indices SIZ, CLUS, and PCLUS were computed for each patient and regressed on time. When a significant positive index/time slope (P less than 0.05) was defined as indication of deterioration, all indices had remarkably poor sensitivities because their slopes did not reach statistical significance in the great majority of patients. When, regardless of statistical significance, positive slopes were defined as indication of deterioration and negative slopes as nondeterioration, the most sensitive index, PCLUS, still had a sensitivity of less than 65%. The indices were better in detecting the presence or absence of visual field deterioration in fields that were initially normal than in those that were initially abnormal. Since the testing modalities of manual and automated perimetry are different, our study was not designed to compare the sensitivity of one technique over the other. Our study does, however, demonstrate that the indices used currently may not be clinically reliable in the assessment of changes in the visual field.
This paper addresses the complex questions of the definition of primary open-angle glaucoma, its pathological changes, the sites at which these changes could operate, and the temporal order in which they might occur. A vascular model is proposed that could satisfy the several clinical forms of presentation of open-angle glaucoma. Questions are raised concerning areas deserving of research that will help solve the existing enigma of glaucoma.
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.
Visual-field areas to a I2e stimulus were measured planimetrically using an X-Y digitizer and a computer program. Sampling of normal subjects and patients suspected of having glaucoma was done at two points in time. Calculations of eye-wall stress were done using ultrasonic data and intra-ocular pressure (IOP) measurements from patient records. For those suspected of having glaucoma who developed chronic open-angle glaucoma (COAG), the time of transition was the second point in time. The visual field area was regressed against patient age at the two points in time. No difference in the regression slopes was found for the normal subjects and unchanged patients. The patients who did develop glaucoma were significantly different. The mean annual rate of visual-field change (rate of decay) was calculated and found to be 28.5 mm2/year for the normals, 153.5 mm2/year for the suspects, and 376.4 mm2/year for those patients who developed glaucoma. The rate of visual-field decay only correlated with patient age (P = 0.03) and eye-wall stress (P less than 0.01) in the patients who developed glaucoma.
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.
Fifty-one patients with raised intraocular pressure (IOP) were treated for up to four years with one of three ophthalmic solutions: 0.5% levobunolol, 1% levobunolol, or 0.5% timolol. The study was conducted as a double-masked, randomised trial in which medications were administered twice daily to both eyes. Levobunolol and timolol were equally effective in reducing overall mean IOP; reductions were greater than 8.8 mmHg in all three treatment groups. The study showed levobunolol to be as safe and effective as timolol in the long-term control of raised IOP.
Two patients (one with glaucoma with field loss, one with ocular hypertension) with previously known optic disc haemorrhage were followed with frequent disc photography, computerized perimetry and tonometry for a period of one year. Nine haemorrhages were seen in three of the four eyes studied. Three bleedings showed sudden enlargements, interpreted as re-bleedings, during the absorption phase. Haemorrhages were not associated with any stepwise localized or general worsening of the visual field, nor did the fields deteriorate during the period of the study. No structural changes of the optic nerve head were seen after the bleedings during the observation time of one year. The duration of the haemorrhages varied, but no bleeding lasted less than one week. Before disappearing they were often so small that they could only be detected when series of photographs were examined in chronological order. Haemorrhages large enough to be discernible on isolated slides were present in 20% of the disc photographs. Thus disc haemorrhages are transient and easy to overlook. Many careful observations may be necessary before the first haemorrhage is seen. Each individual bleeding is a minor vascular incident which usually leaves no measurable functional or structural trace.
We conducted a retrospective study of 45 eyes of 45 patients with chronic open-angle glaucoma to evaluate the rate of progression of scotomas. "Scotoma mass" was calculated and regressed on time to obtain the rate of visual field change. Twenty-two eyes (49%) showed a linear type of progression, nine (20%) showed a curvilinear progression, three (7%) showed episodic progression, and 11 (24%) showed no significant progression. The mean scotoma mass was significantly lower in the curvilinear group than in the linear group.
This paper estimates the value of performing Schiotz tonometry to detect glaucoma in an asymptomatic patient. About 9% of adults over 40 will be found on a single Schiotz tonometry test to have elevated intraocular pressure (IOP). On work-up, about 1 out of 50 of these individuals with high IOP will be found to have glaucoma. Tonometry, however, will miss about half of all patients with glaucoma because they do not have elevated IOPs at the time of the test. Pilocarpine or epinephrine are the most commonly used drugs to treat the disease, but they are not always effective in lowering a patient's IOP or in stopping the progression of field defects. From the available evidence it does not appear that earlier diagnosis makes a substantial difference in the patient's outcome. If all individuals over 40 years of age in a city of 1,000,000 were screened, the total cost of finding and treating about 484 people with chronic simple glaucoma would be on the order of 13,000 per patient potentially benefited. Screening with tonometry does not appear to be warranted.
We retrospectively studied 42 eyes of 42 patients with glaucoma to determine the pattern of progression of their visual field defects. In 33 eyes (79%) the scotomas became denser. Enlargement occurred in 22 eyes (52%) and 21 eyes (50%) developed new scotomas. Increased density of the scotomas was the only manifestation of change in ten eyes (24%), three eyes (7%) showed enlargement only, and six (14%) showed only new scotomas. Seventeen eyes (57%) with single hemifield involvement maintained a defective single hemifield throughout the follow-up period.
90 glaucoma cases (160 eyes) with field defects in at least one eye have been subjected to automatic perimetry on at least 5 occasions. The condition of the field defect is represented by the regression coefficient. The frequency distribution of the coefficients in groups based on references to age, sex, intraocular pressure, exfoliations, haemorrhages and therapy illustrates the possible importance or insignificance of these factors to the decay. The need for several consecutive examinations to establish with some significance a progression of field defects is demonstrated.
This article describes a large number of points that have to be considered when evaluating computer-assisted-perimeters (CAP). With the ever increasing numbers of commercially available CAP over a large quality-range the choice of a CAP for a certain type of practice becomes very difficult indeed. The authors starting position and presentday manual perimetry are first described. The shortcomings of kinetic perimetry are demonstrated. A differentiation of several types of visual field defects is given. Such a differentiation is indispensable for the evaluation of CAP. Each phase of the visual field examination: detection, limited-and extended assessment is considered. Special attention has been given to examination-strategies. They are the most important part of the software of CAP and usually the least comprehensible part. The existing threshold and suprathreshold-techniques are explained. The author expresses a preference for a threshold-related gradient-adapted suprathreshold detection strategy. Random presentation, stimulus-timing, zero-fear presentations and reliability measurements among many other points are mentioned. The possibilities for an extended assessment and especially the data-base for follow-up examinations are described. The extended (or intermediate) assessment should provide sufficient information on spatial and intensity distribution of the defects. The important matter of the graphical display of CAP-results is elucidated.
Statistical considerations may be one of the most promising features of CAP. Repetition of measurements will be necessary for such statistical treatments. The accurate numerical description of defectvolume and its fluctuation, and subsequently the absence or presence of significant change are ultimate goals of statistical programmes. General data on the hardware and software of a particular CAP provide the basis for understanding the results of a clinical evaluation of this CAP. The ultimate answer concerning the usefulness of a CAP can only be given by this clinical evaluation. The criteria and problems of such evaluations are discussed and illustrated with an example. In the addendum a suggestion for a classification of glaucomatous visual field defects is presented. The list of references gives over 160 publications related to CAP.
The present material comprises 51 patients with at least one disc haemorrhage in at least one eye. A total of 127 hh were observed. The probability of finding a disc h increases with the number of examinations. The hypothesis that hh occur in all cases of glaucomatous destruction of the papillary tissue cannot be rejected, though not proven. H. seems to be connected with progression of field defects, though its effects are not immediately recognized. H. is detectable very early in the glaucomatous process; the denotation 'forerunner' is most likely justified. Hh. are highly specific for a glaucomatous process, but it has not been possible to connect h. with some clearly delimited group of glaucoma.
A procedure is suggested to also utilize the computer of the automatic perimeter for the evaluation of the visual field recordings. Parameters are constructed describing the general performance level of a test, size of a defect and its location etcetera. Comparisons with normal values, with the contralateral eye and, when possible, with previous test results are carried through. Trends towards decay or improvement in series of consecutive test results are analyzed.--The information of the field test is printed out in a concise form, verbally and numerically.
The present study was based on already existing clinical data concerning 599 persons born before 1907, examined during a general ophthalmic survey 1969-72 and still remaining in the same district in July 1980. At the survey 1969-72, 19 out of 1057 persons had manifest glaucoma, 14 were already treated for ocular hypertension, 54 had an IOP greater than 20.5 mmHg and 970 were considered normal. Immediately after the survey, 17 patients were treated for manifest glaucoma and 19 for ocular hypertension. During the following 9 years treated persons were lost to a greater extent (64%) than untreated persons (43%). In July 1980 only 6 persons treated for manifest glaucoma since the survey remained, and 3 of them were socially blind. One out of 7 treated and 2 out of 28 untreated persons with ocular hypertension at the survey had developed visual field defects 9 years later. Manifest glaucomas, often advanced cases, were also detected in 9 persons considered normal at the survey. 5 out of 12 persons with manifest glaucoma detected after the survey had an IOP less than 20.5 mmHg at detection. The visual capacity of persons still remaining in the district 1980 was largely independent of all efforts to prevent blindness from glaucoma in the present population.
To develop a suitable mathematical model for the description of the pointwise distribution of sensitivity across the visual field in glaucoma.
The pointwise distribution of sensitivity at any given stimulus location for any given examination was described by a joint topographical and longitudinal model. The topographical element modeled the pointwise distribution of sensitivity using a second-order polynomial function in terms of the respective stimulus coordinates whereas the longitudinal element modeled the pointwise distribution of sensitivity using multiple linear regression in terms of the sensitivity at the given location determined at one or more previous examinations. The sample comprised Humphrey Field Analyser (Humphrey Instruments, San Leandro, CA) Program 30-2 and 24-2 fields from 49 patients attending a glaucoma clinic for an average of 3 years.
The constant term of the polynomial correlated highly with the mean deviation and moderately with the pattern standard deviation. The goodness-of-fit between the modeled and the measured field increased as an exponential function of the number of previous examinations. The median R2 was 19.6% for the first examination and 83.6% for the sixth examination. The group median optimum percentage of error between the measured and modeled sensitivity at each test location was below 10% (i.e., less than 3 dB), increased with increase in eccentricity, was greater at the extremities of the superior field and varied as a function of the severity of the field loss.
The model seems to be a promising way to evaluate visual field progression.
We describe a new method for analysis of change in glaucomatous visual fields with the object to differentiate between changes caused by glaucoma from those caused by cataract. New pattern deviation change probability maps were developed from a prospectively collected glaucoma material and designed to be sensitive to changes in localized field loss, but to be unaffected by media-induced perimetric change. We compared the new change probability maps with the commercially available total deviation change probability maps in series of Humphrey perimetric tests in a glaucoma material of 43 eyes of 35 patients, who had undergone cataract surgery. When using the total deviation maps, considerable differences were seen between fields obtained before and after cataract surgery. Much smaller differences were seen when using the new change probability maps, that almost eliminated the common and disturbing effect of increasing cataract. This new tool could be of considerable help in differentiation between progressive glaucomatous visual field loss and deterioration caused by increasing media opacities.
To investigate the rate of visual field (VF) loss in progressive glaucoma.
Outpatient department, nonreferral base.
A cohort of 34 patients with normal-pressure glaucoma (NPG), 68 patients with primary open-angle glaucoma (POAG), and 125 patients with ocular hypertension (OHT) were followed up for an average of 9 years. Visual fields were obtained annually with automated perimetry. The rate of VF loss as a percentage per year was calculated.
Twenty-three eyes with NPG, 31 with POAG, and 10 with OHT showed progression of VF loss. The mean (+/-SD) rates of VF deterioration were 3.7%+/-3.3% per year in NPG, 2.5%+/-1.8% in POAG, and 2.3%+/-1.3% in OHT converting to POAG, and did not differ significantly. No difference in the rate of VF loss was found between eyes with and without optic disc hemorrhages (2.7%+/-2.9% and 3.1%+/-2.1%, respectively). The rate of VF loss was not related to the initial VF status. The rate of VF loss between the superior and inferior hemifields was correlated in patients with NPG (r(s) = 0.67, P = .04). Comparison of visual field loss with linear regression analysis showed significant slopes in only 37.5% of eyes with progression, which had a progression rate of 4.2%+/-3.0%.
The rate of VF loss did not differ between patients with NPG and POAG. The rate of deterioration was related neither to initial VF status nor to the presence of disc hemorrhages. Linear regression is applicable only in a portion of the patients who have progression of VF loss.
Reducing intraocular pressure (IOP) in glaucomatous eyes does not always prevent disease progression.
To determine the clinical factors associated with progressive optic disc damage in glaucomatous eyes receiving treatment to reduce IOP.
Baseline and follow-up optic disc photographs as well as demographic and clinical data were retrospectively studied in 186 eyes of 93 patients with primary open-angle glaucoma, and in 138 eyes of 69 patients with normal-pressure glaucoma. The patients with primary open-angle glaucoma were included in the study only if their treated IOPs during a follow-up period of 5 years were less than 21 mm Hg. The patients with normal-pressure glaucoma were included only if their IOPs were reduced by at least 20% during the follow-up period. The association of progressive optic disc damage with patient- and eye-specific characteristics was examined using multivariate analysis.
During the 5-year study period, 141 (43.5%) of the 324 eyes exhibited progressive optic disc damage defined by at least a 5% decrease in the neural rim area-to-disc area ratio. Using multivariate analysis, the following were found to be strongly associated with progressive neural rim damage: a baseline smaller neural rim area-disc area ratio (P<.001); a baseline larger zone beta area-disc area ratio (P =.04); a baseline larger parapapillary atrophy length-disc circumference ratio (P =.05); a diagnosis of normal-pressure glaucoma (P =.01); and combined medical and surgical treatment prior to the study period (P =.01).
Clinical factors other than IOP may be important indicators of subsequent progression of glaucomatous optic disc damage. Our findings suggest that eyes with advanced glaucomatous optic disc damage and normal-pressure glaucoma are more likely to progress despite receiving treatment to reduce IOP.
In normal individuals, visual field measures are not perfectly repeatable and individual test locations exhibit both short- and long-term sensitivity variations. This physiologic variability is greatly increased in glaucoma and confounds detection of real progressive loss in visual function. Distinguishing progressive glaucomatous visual field loss from test variability therefore represents a complex task. Procedures used for detection of glaucomatous visual field progression may be broadly grouped into four categories: 1) clinical judgment, which consists of simple subjective observation of sequential visual field test results; 2) defect classification systems, whereby specific criteria are used to stratify field loss by discrete score and define progression as score change over time, such as the Advanced Glaucoma Intervention Study scoring system; 3) trend analyses, which follow test parameters sequentially over time to determine the magnitude and significance of patterns within the data, for example linear regression; and 4) event analyses, which identify single events of significant change relative to a reference examination. All of these methods demonstrate distinct benefits and drawbacks, making each useful in specific circumstances, although no single method appears universally ideal. At the present time the best method of detection of progression may be to rely upon confirmation of change at successive examinations and also by correlation of visual field changes with other clinical observations. Alternative analysis methods may become available in the near future to help identify cases of progressive loss.
The aim of the study was to assess a relationship between circulating platelet aggregates (CPA) and progression of visual field loss in primary open-angle glaucoma patients. CPA was determined in 27 patients with open-angle glaucoma with nonprogressive visual field loss and 15 patients with open-angle glaucoma and progression of visual field loss. Intraocular pressure (IOP) under topical therapy was < 18 mmHg in all patients. CPA in glaucoma patients with progression of visual field loss was not significantly higher than those without visual field progression (p = 0.59). In conclusion, our study shows that increased platelet aggregability is not solely responsible for progression of visual field loss in glaucoma patients, and indicates the role of IOP in the pathogenesis of visual field loss.
Previously, we reported that a relatively selective adenosine A(2A) receptor agonist 2-(6-cyano-1-hexyn-1-yl)adenosine (2-CN-Ado) elicited ocular hypotension in rabbits (Journal of Pharmacological Sciences 2005;97:501-509). In the present study, we investigated the effect of 2-CN-Ado on ocular blood flow in rabbit eyes. An intravitreal injection of 2-CN-Ado increased ocular blood flow, measured by a non-contact laser flowmeter. 2-CN-Ado-induced increase in ocular blood flow was accompanied with the retinal vasodilation. The increase in ocular blood flow was inhibited by an adenosine A(2A) receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine, but not by an adenosine A(2B) receptor antagonist alloxazine or an adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. The repetitive applications of topical 2-CN-Ado twice a day for 7 days produced a persistent increase in ocular blood flow with ocular hypotension. These results suggest that 2-CN-Ado increases the ocular blood flow mainly via adenosine A(2A) receptor, and that the topical application of 2-CN-Ado for several days not only increases the ocular blood flow but also prolong ocular hypotension, indicating that 2-CN-Ado may be a useful lead compound for the treatment of ischemic retinal diseases such as glaucoma.
An apparatus for static perimetry of the central visual field at 64 points is described. The testing is fully automatic: the test logic is programmed into a mini-computer and the results are plotted as a diagram in polar coordinates.
A few cases with small or medium sized visual field defects have been analyzed by conventional methods and by the automatic instrument with satisfying results.
Since the first description (1976) of the computerized perimeter Competer, some small modifications and new routines have been introduced. An account of a new mode for presentation of the test results and a procedure for their storage is therefore provided. Some elementary technical facts are included to make the relations computer--computer language--perimeter comprehensible. The construction of efficient test logics is discussed and the meaning of "threshold level" explored.
• The progression of field damage of 48 eyes with chronic simple glaucoma and a splinter hemorrhage on the disc was compared with that of 48 chronic simple glaucoma eyes without hemorrhage. The incidence of visual field progression was substantially higher among those with a hemorrhage. Similar visual field progression was substantially higher in 29 eyes with elevated intraocular pressure and a disc hemorrhage when compared with 29 ocular hypertensive patients with no hemorrhage. The prognostic importance of a disc hemorrhage is discussed.
(Arch Ophthalmol 95:226-228, 1977)
A retrospective study of 45 patients with low-tension glaucoma revealed the mean age at diagnosis to be 66 years. Seventeen patients had follow-up visual field examinations, the average follow-up period being 6.4 years. There was no significant difference in prognosis of the ocular course between patients with Po/C equal to or greater than 100 and those with Po/C less than 100. The presence of splinter hemorrhages at the optic disk (10% of affected eyes) or of systemic arterial hypertension (diastolic blood pressure greater than 100 mm Hg) was associated with progression of visual field defects. Patients with sudden visual loss or associated hemodynamic events (33% of the total patients) had a more favorable prognosis regarding stability (lack of progression) of visual field defects than those without such an event. Extension of visual field defects across the macula was a common finding (25% of affected eyes). No firm evidence was obtained to indicate that treatment of the low-tension glaucoma improved the prognosis of the ocular course.
An apparatus for static perimetry of the central visual field at 64 points is described. The testing is fully automatic: the test logic is programmed into a mini-computer and the results are plotted as a diagram in polar coordinates. A few cases with small or medium sized visual field defects have been analyzed by conventional methods and by the automatic instrument with satisfying results.
Characteristics of manifest glaucoma in the early stages. Glaucoma, in press Low-tension glaucoma The importance of disc hemorrhage in the prognosis of chronic open angle glaucoma Ann: The effects of age on the central isopter of the normal visual field
- B Begtsson
- Holmin
- Catharina
- C E T Krakau
- L C Chumbley
- R F Brubaker
- S M Drance
- Fairclough
- Meg
- D M Butler
- M S Kottler
- H Goldmann
Begtsson, B., Holmin, Catharina, Krakau, C.E.T.: Characteristics of manifest glaucoma in the early stages. Glaucoma, in press (1980) Chumbley, L.C., Brubaker, R.F.: Low-tension glaucoma. Am. J. Ophthalmol. 81, 761 767 (1976) Drance, S.M., Fairclough, Meg, Butler, D.M., Kottler, M.S. : The importance of disc hemorrhage in the prognosis of chronic open angle glaucoma. Arch. Ophthalmol. 95, 226-228 (1977) Drance, S.M., Berry, Virginia, Hughes, Ann: The effects of age on the central isopter of the normal visual field. Can. J. Ophthalmol. 2, 79 (1967) Goldmann, H. : Grundlagen exakter Perimetrie. Ophthalmologica 109, 57 (1945)
The effects of age on the central isopter of the normal visual field An automatic perimeter for glaucoma visual field screening and control. Construction and clinical cases
- S M Drance
- Berry
- Virginia
- Ann Hughes
- H Goldmann
- A Heijl
- C E Krakau
Drance, S.M., Berry, Virginia, Hughes, Ann: The effects of age on the central isopter of the
normal visual field. Can. J. Ophthalmol. 2, 79 (1967)
Goldmann, H. : Grundlagen exakter Perimetrie. Ophthalmologica 109, 57 (1945)
Heijl, A., Krakau, C.E.T. : An automatic perimeter for glaucoma visual field screening and control.
Construction and clinical cases. Albrecht yon Graefes Arch. Klin. Ophthalmol. 197, 13 23
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