Pattern Deviation Plot Research Articles

Spatial Characteristics of Visual Field Progression Determined by Monte Carlo Simulation: Diagnostic Innovations in Glaucoma Study

To determine the spatial characteristics of glaucomatous visual field progression in persons with glaucomatous-appearing optic neuropathy (GON) from the Diagnostic Innovations in Glaucoma Study (DIGS). Changes in pattern deviation (PD) plot values from the average of two baseline examinations to two follow-up examinations were evaluated in test locations. All were eligible, full threshold, pattern 24-2, standard automated perimetry (SAP) examinations (Humphrey Field Analyzer II; Carl Zeiss Meditec, Inc., Dublin, CA) in visual field series from 200 patients with GON confirmed on two occasions by stereophoto review. The proportion of patients exhibiting PD plot progression was determined at each of 52 locations for patients with a baseline abnormal result (P < 5% or worse) in one or more of 52 PD locations in either the first or second baseline test for a total of 2704 location pairings for each possible level of negative PD change from -1 to -50 dB. Progression was defined as any worsening of PD plot value in the follow-up test relative to the average PD plot value in the baseline tests. Monte Carlo simulation was used to determine the significance of the observed patterns of PD plot progression. Changes in PDs were dependent on their location relative to abnormal PD locations in the first test. Of those patients with an abnormality at a location at baseline (mean, 0.23 +/- 0.07), the proportion of patients changing by -2 dB or more ranged between 0.09 and 0.55 (mean, 0.29 +/- 0.06) across locations. For changes of -6 dB or more, the proportions ranged between 0.00 and 0.26 (mean, 0.08 +/- 0.04) of patients. These proportions and the proportional probabilities for each of 2704 location pairings are reported for selected levels of change. The proportional probabilities are consistent with a map of the retinal nerve fiber layer bundles. Visual field progression occurs in retinotopically constrained patterns consistent with changes along the nerve fiber bundle.

Discriminating Ability of Humphrey Matrix Perimetry in Early Glaucoma Patients

Purpose: To determine the discriminating ability of some parameters provided by Humphrey Matrix perimetry for early glaucoma detection. Methods: A prospective cross-sectional study was performed. Sixty-five primary open-angle glaucoma patients with early-stage visual field defects on standard automated perimetry (mean deviation = –1.98 ± 1.93 dB) and 56 healthy subjects were included. All subjects performed the Humphrey Matrix perimetry with a threshold 30-2 strategy. The receiver operating characteristic (ROC) curve was constructed for each parameter and calculated the area under the ROC curve (AUC) to seek the best discriminating parameter for early glaucoma detection. Results: The AUCs of Humphrey Matrix perimetry with the mean deviation, pattern standard deviation, Glaucoma Hemifield Test, number of points that have a p < 5% in pattern deviation plot (PDP) and number of points that have a p < 1% in PDP were 0.795, 0.808, 0.689, 0.985 and 0.946, respectively. Conclusion: Humphrey Matrix perimetry allowed accurate discrimination between normal and early glaucomatous eyes. The number of points that had a p < 5% in PDP was the best discriminating parameter for early glaucoma detection using Humphrey Matrix perimetry.

Frequency Doubling Perimetry and Short-Wavelength Automated Perimetry to Detect Early Glaucoma

To compare the ability of short-wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP) to detect early glaucoma damage. Prospective case-control study using a comparative case series. Forty-two patients with preperimetric glaucomatous optic nerve damage and a normal standard achromatic perimetry (SAP) in 1 eye, but with contralateral SAP abnormalities, and 35 normals. Forty-two patients and 35 normals underwent SWAP and FDP (Humphrey 24-2; Carl Zeiss Meditec, Inc., Dublin, CA). Correlations of mean deviation (MD) and pattern standard deviation (PSD) of the 2 groups were calculated. The number of defects at P<0.05 and P<0.01 on total deviation (TD) and pattern deviation (PD) plots were compared. Diagnostic precision and agreement on location of abnormalities were determined. Correlations and comparisons of global indices between SWAP and FDP: MD, PSD, TD, and PD abnormal number of points. Significant correlations in the glaucoma group were found between SWAP and FDP for MD (r = 0.54; P<0.008) and PSD (r = 0.49; P<0.001). Defects on the TD and PD plots were detected more frequently by FDP in the glaucoma group, although they were significant only for PD at P<0.01 (P = 0.024). Areas under receiver operator characteristic curves for MD of SWAP and PSD of FDP were 0.74 and 0.67, respectively (P = 0.37). Using defined defect criteria, FDP had a significantly higher sensitivity (72% vs. 54%; P = 0.02) and similar specificity (53% vs. 44%; P = 0.12) compared with SWAP. Agreement on defect location was moderate (kappa, 0.46). Testing time for SWAP was longer than for FDP in both glaucomatous and normal eyes (P<0.001). Short-wavelength automated perimetry and FDP showed similar ability to detect visual dysfunction in patients with preperimetric glaucoma. Long-term follow-up is required to define their role in predicting subsequent SAP defects.

Early Glaucoma Detection Using the Humphrey Matrix Perimeter, GDx VCC, Stratus OCT, and Retinal Nerve Fiber Layer Photography

To compare the effectiveness of Humphrey Matrix perimetry, GDx VCC, Stratus OCT, and retinal nerve fiber layer (RNFL) photography using the Heidelberg Retina Angiograph 1 (HRA1) for early glaucoma detection. Cross-sectional comparative study. Seventy-two primary open-angle glaucoma patients with early-stage visual field defects and 48 healthy controls were included. Measurements using Humphrey Matrix perimetry, GDx VCC, Stratus OCT, and RNFL photography using HRA1, as well as standard automated perimetry, were obtained. We constructed receiver operating characteristic (ROC) curves for all available parameters and calculated the area under the ROC curves (AUC) to seek the best discriminating parameter of each test. Subsequently, the ROC curves were calculated for the combinations of the best discriminating parameters of each test to seek the most effective combination for early glaucoma detection. The AUC for various parameters of Humphrey Matrix perimetry, GDx VCC, Stratus OCT, and RNFL photography using HRA1. The AUCs of Humphrey Matrix perimetry, GDx VCC, Stratus OCT, and RNFL photography using HRA1 with the best discriminating parameter were 0.990, 0.906, 0.794, and 0.751, respectively. The AUC of the following best combination was 0.972, more than 5 points depressed below the level of 5% on the pattern deviation plot from Humphrey Matrix perimetry, and the nerve fiber indicator was larger than 20 from GDx VCC. The AUC of the Humphrey Matrix perimetry was greater than that of the GDx VCC, Stratus OCT, and RNFL photography using HRA1.

Classifying Patterns of Localized Glaucomatous Visual Field Defects on Automated Perimetry

To classify the classic patterns of glaucomatous visual field defects on automated perimetry and to study their proximity to fixation. Cross-sectional observational study. About 1120 full threshold 30-2 reliable visual fields of glaucoma patients were analyzed by 2 glaucomatologists. Classically described patterns of visual field defects were identified on the pattern deviation plot and definitions proposed. Interreader agreement between 3 independent (not involved in the classification) readers was determined. Proximity to fixation of the different patterns was assessed. Interreader agreement with 3 readers was found to be 93% or more between any 2 readers using the present system of classification. Central fixation was seen to be involved in 45% of the glaucomatous visual field defects studied overall. The proposed definitions of topographical glaucomatous field defects based on the pattern deviation probability plot are simple to use in clinical practice with good interreader agreement.

Frequency-Doubling Perimetry: Comparison With Standard Automated Perimetry to Detect Glaucoma

To compare second generation frequency-doubling perimetry (FDP) with standard automated perimetry (SAP) to detect glaucomatous visual field abnormalities. Prospective, cross-sectional, controlled observational study. Fifty eyes of 50 patients with glaucoma with confirmed SAP visual field abnormalities and 42 eyes from 42 normal control subjects were studied. Swedish Interactive Thresholding Algorithm (SITA) standard 24-2 SAP and FDP visual fields were performed. The correlation of global indices and the number of defects on total deviation (TD) and pattern deviation (PD) plots were compared. The spatial concordance of FDP and SAP defect locations was determined. In patients with glaucoma, significant correlations of mean deviation (MD) and pattern standard deviation (PSD) were found between SAP and FDP (P < .001 for MD and P < .001 for PSD), but not in the normal group. FDP had significantly greater defect scores than SAP on total deviation and PD plots in the glaucoma group (P = .028 and P = .01, respectively). In comparison with SAP, sensitivity and specificity of FDP were 92% and 98% with glaucoma hemifield test criteria and 98% and 93% with PSD <5% criteria, respectively. Similarly high diagnostic precision was found with MD and PSD (at 95% specificity; MD and PSD sensitivity was 82% and 90%, respectively). The location of defects within 12 hemifield clusters found with FDP agreed moderately well with those detected with SAP (kappa = .48). FDP and SAP perform similarly in their ability to detect visual field defects in early to moderate glaucoma. Larger and deeper defects detected with FDP suggests the possibility of earlier detection at high specificity.

Comparison of Visual Field Defects Using Matrix Perimetry and Standard Achromatic Perimetry

To compare visual field (VF) defects found by Swedish interactive thresholding Algorithm (SITA) perimetry and Matrix perimetry, a new VF device that utilizes frequency doubling technology in a 24-2 test pattern. Prospective cross-sectional study. Fifty eyes from 50 subjects with SITA field defects were recruited for an observational study. Swedish Interactive Threshold Algorithm and Matrix VF testing were performed on patients from a glaucoma practice. To evaluate the learning effect on the performance of the VF, we tested subsets of each group who had previous experience with standard automated perimetry (SAP). Test duration, mean threshold, mean deviation (MD), pattern standard deviation (PSD), glaucoma hemifield test, and number of abnormal points on the pattern deviation plot were evaluated for each device. Test duration was significantly shorter for Matrix (SITA, 357.0+/-85.6 seconds; Matrix, 319.5+/-16.5 seconds; P = 0.0002, paired t-test). Thirty-six percent of eyes with SITA VF defects showed a normal Matrix field. In 30 of 32 eyes (94%) where both devices showed VF defects, the defects were congruent. Mean threshold value was significantly lower with Matrix compared to SITA (P<0.0001, paired t-test), as was MD (-5.34+/-5.42 dB, -4.14+/-5.29 dB, respectively; P = 0.03, paired t-test). There was no significant difference in PSD between the 2 devices (P = 0.78, paired t-test). Matrix delineated significantly smaller (P = 0.005, Wilcoxon's test) and deeper (P<0.001, Wilcoxon's test) defects than those found with SITA. Similar results were observed in the subgroups with prior SAP experience. The Matrix examination did not detect 36% of abnormal SITA fields. Matrix field defects were smaller and deeper than those appearing in SITA perimetry.

Study of Patients with Ocular Hypertension with Scanning Laser Polarimetry and Short-Wavelength Automatic Perimetry

Aims: To compare and correlate retinal nerve fiber layer (RNFL) measurements obtained by scanning laser polarimetry (SLP) with defects detected by short-wavelength automatic perimetry (SWAP) in eyes with ocular hypertension (OHT). Methods: SLP and SWAP were performed in 96 eyes of 48 consecutive patients with OHT. Results: Twenty-five eyes (26%) had SWAP visual field defects. Twenty-seven eyes (28.1%) had abnormal RNFL evaluation defined by the GDx neural network (‘number’ >29). Fourteen eyes of 10 patients (14.5%) had abnormal RNFL evaluation and SWAP visual field defects. RNFL thickness measurements were significantly reduced in eyes with abnormal SWAP. A weak but statistically significant correlation between the ‘number’ and pattern standard deviation (r = 0.3, p = 0.006) and the corrected pattern standard deviation (r = 0.3, p = 0.007) in SWAP was found. Areas of abnormal RNFL thickness corresponded to the localization of the SWAP visual field defects in corrected pattern deviation plots in 10 of the 14 eyes with defects in both tests. Conclusions: SWAP visual field defects frequently coexist and correspond with abnormalities of RNFL detected by SLP in eyes with OHT. In certain eyes, however, the two methods detect different glaucoma properties.

Visual field testing with the new Humphrey Matrix: a comparison between the FDT N‐30 and Matrix N‐30‐F tests

To determine if the N-30-F test with the new Humphrey Matrix instrument is comparable to the traditional frequency-doubling technology (FDT) N-30 test. A sample of 47 eyes from 47 patients (five normal subjects, 27 with ocular hypertension and 15 with glaucoma) underwent visual field (VF) testing with standard automated perimetry, and with FDT, using the FDT N-30 program, and the Matrix N-30-F program (using the same 19 tested points, full-threshold strategy, but with an enhanced algorithm to reduce testing time). The plots, mean deviation (MD), pattern standard deviation (PSD), defect locations and test time were compared. The agreement between the two tests was shown to be good, except for subjects with large VF defects, in which greater PSD values were observed with the FDT test, whereas the Matrix test gave a higher MD and number of abnormal test locations in the total deviation plot. A lack of agreement was also found for the number of abnormal test locations on the pattern deviation plot at any VF loss severity level. The test time for the Matrix test was significantly shorter. The FDT N-30 and Matrix N-30-F tests proved to be comparable in cases of early to moderate VF defects.

Melhora dos limiares de sensibilidade do campo visual após redução da pressão intra-ocular em pacientes com glaucoma: tratamento cirúrgico vs. clínico

To verify the influence of modality of treatment in regions of the glaucomatous visual field after reduction of intraocular pressure (IOP). Glaucoma patients that had undergone a reduction of IOP of at least 20% in a period of 2 months were retrospectively selected and divided into 2 groups: 1) after trabeculectomy; 2) after clinical treatment. Visual field global indices and thresholds (average, divided according to the severity based on the Pattern Deviation plot) were compared before and after IOP reduction. Thirty-one eyes of 22 patients were selected (15 in group 1, and 16 in group 2). Both groups showed good ability regarding improvement of different regions of the visual field after IOP reduction. Only the percentage of reduction of IOP (52.3+/-18.9% and 37.8+/-15.2% for groups 1 and 2, respectively, p=0.02) and the percentage of improvement in the points damaged at p<0.5% (186.0+/-213.3% and 30.1+/-35.2% for groups 1 and 2, respectively, p=0.02) were different, but not statistically significant after alpha error correction between groups. The reduction of IOP above 20% may be associated with improvement in regions of the glaucomatous visual field, regardless of treatment modality.

The effect of artificial tear administration on visual field testing in patients with glaucoma and dry eye

To examine the effects of artificial tear administration on perimetry of primary open-angle glaucoma patients with dry eye. A total of 40 patients with primary open-angle glaucoma experienced in automated perimetry with symptoms of dry eye were enrolled in this study. After their pretest visit, they were instructed to use artificial tear four times a day in both eyes for 1 week. After 1 week, patients had visual field testing. Test taking time, reliability parameters (false-positive and false-negative errors) visual field indices and number of depressed points at different probability levels (P<5%, P<2%, P<1%, P<0.5%) in both total and pattern deviation plots were compared using paired Ttest. We found significant improvement in reliability parameters (false-positive errors from 2.4+/-2.1 to 2.1+/-1.9, P=0.02; and false-negative errors from 7.3+/-6.4 to 4.8+/-3.6, P=0.01) and visual field indices (MD increased from 5.97+/-5.61 to 4.57+/-4.53, P=0.001; PSD from 4.67+/-2.95 to 4.13+/-2.77, P=0.04 and SF decreased from 2.24+/-1.23 to 1.83+/-0.77, P=0.04) in the second testing after artificial tear administration. Test time significantly increased from 11.66+/-2.55 min to 14.26+/-1.36, P=0.001. The number of depressed points at probability levels P<1% (P=0.03) and P<0.5% (P=0.04) at total deviation plot and P<2% (P=0.02) and P<0.5% (P=0.009) in pattern deviation plot decreased significantly. Artificial tear administration in glaucomatous patients with dry eye seems to improve significantly reliability parameters and visual field indices.

Visual field changes after cataract extraction: The AGIS experience

To test the hypothesis that cataract extraction in glaucomatous eyes improves overall sensitivity of visual function without affecting the size or depth of glaucomatous scotomas. Experimental study with no control group. One hundred fifty-eight eyes (of 140 patients) from the Advanced Glaucoma Intervention Study with at least two reliable visual fields within a year both before and after cataract surgery were included. Average mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD) were compared before and after cataract extraction. To evaluate changes in scotoma size, the number of abnormal points (P < .05) on the pattern deviation plot was compared before and after surgery. We described an index ("scotoma depth index") to investigate changes of scotoma depth after surgery. Mean values for MD, PSD, and CPSD were -13.2, 6.4, and 5.9 dB before and -11.9, 6.8, and 6.2 dB after cataract surgery (P < or = .001 for all comparisons). Mean (+/- SD) number of abnormal points on pattern deviation plot was 26.7 +/- 9.4 and 27.5 +/- 9.0 before and after cataract surgery, respectively (P = .02). Scotoma depth index did not change after cataract extraction (-19.3 vs -19.2 dB, P = .90). Cataract extraction caused generalized improvement of the visual field, which was most marked in eyes with less advanced glaucomatous damage. Although the enlargement of scotomas was statistically significant, it was not clinically meaningful. No improvement of sensitivity was observed in the deepest part of the scotomas.

Patterns of glaucomatous visual field progression identified by three progression criteria

To determine typical patterns of repeatable glaucomatous visual field progression. Retrospective analysis of data obtained from two prospective studies. Included were 72 eyes of 72 patients tested up to six times over 2 years, and 40 eyes of 40 patients followed annually for up to 12 years. Each patient had two abnormal baseline visual fields, abnormal optic nerves, and serial fields. Progression was identified using three methods: by glaucoma change probability using total deviation (GCP-TD) and pattern deviation (GCP-PD) plots and by a clinical criteria. Progression was categorized as deepening or expansion of an existing scotoma, or a new scotoma. The percentage of eyes repeatably progressed ranged from 17% to 27%. The most common pattern of progression was a deepening of an existing scotoma in the annual group, followed by expansion. With two follow-ups required, percentages for deepening only were 20% (clinical classifier). A combination of expansion and deepening was most common for the GCP criteria: 15% (GCP-TD classifier), and 10% (GCP-PD classifier) for the annual group. For the semiannual group, deepening was most common with the clinical criteria (11% of eyes), and deepening with expansion was most common by GCP criteria (14%, GCP-TD and GCP-PD). No eyes showed repeatable new scotomas. Glaucomatous visual fields progress in the area of the visual field where baseline testing showed an existing scotoma. Follow-up testing might be improved by concentrating on already defective locations and using sparser test patterns or screening algorithms in normal areas of the visual field.

Standard achromatic perimetry, short wavelength automated perimetry, and frequency doubling technology for detection of glaucoma damage

ObjectiveReevaluation of the relationship between short wavelength automated perimetry (SWAP), standard achromatic perimetry (SAP), and frequency doubling technology (FDT) in glaucoma and ocular hypertensive patients and in glaucoma suspects. DesignProspective comparative observational study. ParticipantsFour age-matched groups were evaluated (42 patients with early to moderate glaucoma, 34 ocular hypertensives, 22 glaucoma suspects, and 25 normal controls) using SAP, SWAP, and FDT. InterventionAll participants underwent full clinical ophthalmologic evaluation followed by SWAP, SAP, and FDT perimetry within a period of not more than 3 months. Mean defect (MD), pattern standard deviation (PSD), visual field (VF) indices, and the percentage of depressed visual field points with P value <5% and <1% in the pattern deviation plot were evaluated. Main outcome measuresFor each of the four study groups, the MD, PSD, and the percentage of abnormal points significantly depressed <5% and <1% were compared for the three VF testing modalities. ResultsIn the glaucoma group, the mean percentage of the total number of abnormal points in SWAP was significantly less than abnormal points in SAP and FDT, both for 5% (P values were 0.0001 and 0.0001, respectively) and 1% (P values were 0.0001 and 0.0001, respectively). The same applied to the ocular hypertensives group. However, in the suspects group, no significant difference was detected. In normal controls, the abnormal points in SWAP were significantly lower than those in SAP for 5% (P value was 0.01) and 1% (P value was 0.05). FDT detected significantly larger defects (percentage of points <5%) than SAP in ocular hypertensives and suspects (P values were 0.01 and 0.004, respectively). ConclusionsSWAP in its existing condition is markedly less efficient than either SAP or FDT in detecting VF defects, especially in glaucoma patients and ocular hypertensives (defects detected with SWAP are less than both SAP and FDT). Defects detected with FDT are equivalent to SAP and sometimes larger, especially in ocular hypertensives and glaucoma suspects; this makes it a useful tool for picking up early glaucomatous defects in populations at risk.

Glaucomatous damage patterns by short-wavelength automated perimetry (SWAP) in glaucoma suspects.

To determine the glaucomatous visual field damage patterns by short-wavelength automated perimetry (SWAP) in glaucoma suspects, and to compare the frequency of diffuse visual field losses and localized defects. 157 eyes of 157 ocular hypertensive subjects who met the selection criteria (intraocular pressure greater than 21 mm Hg and normal standard visual fields) were studied. SWAP was done with a modified Humphrey Field Analyzer. Total (TD) and Pattern Deviation (PD) probability maps were calculated for SWAP. The frequency of abnormlities in the TD and PD were determined, analyzing the visual field loss components. The involvement of the test points was more frequent on the TD plots than on the PD plots for all levels of defects (p< 0.001). The glaucomatous defects also showed certain topographical distribution. A diffuse sensitivity component of visual field loss was found at all SWAP defect depths in glaucoma suspects.

Sensitivity of Swedish interactive threshold algorithm compared with standard full threshold algorithm in Humphrey visual field testing

Objective To compare the sensitivity of Swedish interactive threshold algorithm (SITA) strategies with the standard full threshold algorithm in the Humphrey Field Analyzer. Design Observational case series. Participants Forty-eight glaucoma patients who were experienced in automated perimetry. Testing Central field testing was performed with the 30-2 program using standard full threshold (SFT), SITA standard (SS), and SITA fast (SF) strategies. All three tests were carried out on each of four different days in a span of 4 weeks. Main outcome measures Sensitivity, repeatability, time saved, and the extent of defect in the SITA strategies were compared with those of the SFT. Results The sensitivity of SS and SF were 95.12% and 92.68%, respectively. The time saved in SS and SF was 53.12 ± 9.51% and 70.69 ± 8.81%, respectively. The repeatability as assessed by intraclass correlation showed excellent repeatability for the SFT and SS strategies and excellent to poor repeatability with the SF strategy. With increasing mean deviation, the defects (significant at P < 0.5%) in the pattern deviation plots tended to be more in the SITA strategies as compared with SFT. Conclusions Swedish interactive threshold algorithm strategies have good sensitivity and are significantly faster as compared with the standard threshold algorithm. The repeatability of the SFT and SS strategies are excellent, whereas that of the SF strategy is variable.

Influence of laser photocoagulation for clinically significant diabetic macular oedema (DMO) on short-wavelength and conventional automated perimetry.

The aim of the study was to determine the effect of laser photocoagulation for clinically significant diabetic macular oedema (DMO) on macular visual function as assessed by conventional and short-wavelength automated static threshold perimetry. The sample comprised 24 patients who required laser photocoagulation for clinically significant DMO (mean age 59.75 years, range 45-75 years). One eye of each patient was selected for the study. Patients underwent conventional and short-wavelength perimetry using programme 10-2 of the Humphrey Field Analyser on two separate occasions prior to treatment and subsequently within 1 week of, and at 1, 2, 4 and 12 weeks after, treatment. The pointwise pattern deviation plot was analysed for conventional perimetry and a pointwise horizontal and vertical hemifield asymmetry analysis was derived for short-wavelength perimetry (thereby negating the influence of pre-receptoral absorption). The extent of sensitivity loss was determined by counting the number of stimulus locations with statistical probability levels of p less than 0.05. Group mean log minimum angle of resolution (logMAR) visual acuity was largely unchanged over the course of the study. Conventional perimetry showed an increase in the group mean number of abnormal contiguous stimulus locations from 2.4 (SD 4.3, range 0-14) immediately prior to treatment, to 12.4 (SD 7.8, range 0-30) within 1 week of treatment; at 3 months post-treatment, the group mean number of abnormal contiguous stimulus locations was 8.1 (SD 6.5, range 0-20). A similar but less pronounced change was found for short-wavelength perimetry. The spatial position of the post-treatment localised sensitivity loss corresponded with the area of retinal photocoagulation. Despite proven benefit in the stabilisation of visual acuity, laser photocoagulation for clinically significant DMO invariably results in a localised loss of perimetric sensitivity within 10 degrees eccentricity of the fovea. Evidence for the value of laser therapy for clinically significant DMO must be re-examined.

Diffuse and localised visual field defects to automated perimetry in primary open angle glaucoma.

The occurrence of generalised or diffuse visual field depression in primary open angle glaucoma (POAG), in contrast to the presence of characteristic localised defects, is controversial. The frequency of diffuse visual field loss to automated static perimetry in the early stages of POAG was determined and compared with the frequency of localised defects. Twenty-five eyes of 25 consecutive POAG patients who met the selection criteria were tested on the Humphrey Visual Field Analyser with the Central 30-2 Threshold Test. Patients' mean age was 68 years. All eyes had visual acuity better than 6/9 with correction, refractive error of less than +/- 7 dioptres, no media opacities and normal pupils (3-6 mm). For all eyes, the frequency of abnormality on the STATPAC Total Deviation (TD) and Pattern Deviation (PD) plots were determined for all individual test points. Mean values and standard deviations were compared. The TD plots represent a composite of both diffuse and localised visual field depression, while PD plots are intended to reflect localised field defects. The frequency of involvement of the test points on the TD plots was higher than on the PD plots (mean +/- SD: 41.5 +/- 11.2% vs 27.5 +/- 10.9%) for all presenting defects. When only deep defects (STATPAC p < 1% and p < 0.5%) were evaluated, TD involvement was still more frequent than the PD (20.1 +/- 9.4% vs 13.2 +/- 7.2%). The topographical pointwise incidence of pure generalised sensitivity loss in the visual field was less frequent when only deep defects were taken into consideration (6.9 +/- 5.7%), and the incidence increased progressively with the inclusion of intermediate and shallow field defects (9.6 +/- 6.8% and 14.0 +/- 8.4% respectively). A component of diffuse sensitivity depression is present at all significant levels of visual field loss in glaucoma. This component of generalised loss decreases as the depth of the field defects increases. This finding suggests that early diffuse field loss converts into well-defined pattern defects at later stages.