Frequency doubling technology perimetry abnormalities as predictors of glaucomatous visual field loss

PURPOSE: To determine whether frequency doubling technology (FDT) perimetry results predict glaucomatous visual field defects, as assessed by standard automated perimetry (SAP), in a glaucoma suspect population. DESIGN: Longitudinal observational study. METHODS: The study included 105 eyes of 105 glaucoma suspect patients, with a mean follow-up time of 41 +/- 17 months. Glaucoma suspects had either intraocular pressure (IOP) higher than or equal to 23 mm Hg or glaucomatous optic neuropathy by stereophotograph assessment. All patients had normal SAP visual fields at baseline. A baseline FDT test was performed within 3 months of the normal SAP examination. Several baseline FDT parameters and other variables (age, gender, IOP, central corneal thickness, SAP visual field indices, and stereophotograph assessment) were investigated by univariate and multivariate Cox proportional hazards models to obtain hazard ratios (HR) and identify factors that predicted which patients had SAP glaucomatous visual field loss during follow-up. RESULTS: Seventeen patients (16%) developed repeatable SAP visual field abnormality during follow-up. An abnormal FDT examination at baseline predicted the development of SAP visual field conversion in both univariate (HR = 3.17; 95% confidence interval [CI] = 1.22-8.25; P =.018) and multivariate models (Adjusted HR = 3.68; 95% CI = 1.06-12.8; P =.04). The analysis of FDT examinations during follow-up revealed that in 59% of converters the FDT abnormalities preceded SAP visual field loss by as much as 4 years. Also, the initial development of glaucomatous visual field loss as measured by SAP occurred in regions that had previously demonstrated abnormalities on FDT testing. CONCLUSION: Functional abnormalities detected by FDT perimetry were predictive of the future onset and location of SAP visual field loss among glaucoma suspect patients.     

Frequency-doubling perimetry: comparison with standard automated perimetry to detect glaucoma

PURPOSE: To compare second generation frequency-doubling perimetry (FDP) with standard automated perimetry (SAP) to detect glaucomatous visual field abnormalities. DESIGN: Prospective, cross-sectional, controlled observational study. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.     

The relationship between standard automated perimetry and GDx VCC measurements

PURPOSE: To investigate the relationship between retinal light sensitivity measured with standard automated perimetry (SAP) and retardation of the peripapillary retinal nerve fiber layer (RNFL) measured with the GDx VCC (Laser Diagnostic Technologies, Inc., San Diego, CA). METHODS: Forty-seven healthy subjects and 101 patients with glaucoma were examined with SAP and with the commercially available scanning laser polarimeter GDx VCC, with automated individualized compensation of anterior segment birefringence. Individual visual field test points and peripapillary RNFL retardation measurements were grouped into six corresponding sectors. The correlation between perimetry and GDx VCC measurements was determined, and the relationship between RNFL retardation and perimetry, expressed both in the standard decibel scale and in an unlogged scale, was described with linear regression analysis. RESULTS: A statistically significant correlation was found in most sectors between perimetry and GDx VCC measurements in patients with glaucoma, but not in healthy subjects. A linear relationship was found between the unlogged sensitivities and GDx VCC measurements for the superotemporal and inferotemporal sectors. In the decibel scale, this relationship was curvilinear. CONCLUSIONS: GDx VCC measurements of the peripapillary RNFL relate well with functional loss in glaucoma. Based on the observed relationships between function and structure, patients with mild to moderate visual field loss in glaucoma may be better monitored with the GDx VCC and patients who have severe loss, with SAP.     

Retinal nerve fiber layer measurement by optical coherence tomography in glaucoma suspects with short-wavelength perimetry abnormalities

PURPOSE: To compare retinal nerve fiber layer (RNFL) measurements in normal and glaucoma subjects with short-wavelength automatic perimetry (SWAP) abnormalities and in chronic primary open-angle glaucoma (CPOAG) patients using optical coherence tomography (OCT). METHODS: Forty-eight eyes of normal subjects, 34 eyes of glaucoma suspects with SWAP abnormalities, and 38 eyes of early CPOAG subjects were recruited. All normal and glaucoma suspects had normal conventional automated perimetry visual field results. All participants underwent full clinical ophthalmologic evaluation followed by OCT RNFL measurements. RESULTS: Compared with normal controls, OCT RNFL thickness was significantly lower in glaucoma suspects with abnormal SWAP (inferotemporal and superotemporal thickness values) and CPOAG patients (average, superior, inferior, inferotemporal, and superotemporal thickness values) (P < 0.01). Some parameters were found to be significantly lower in CPOAG patients than the glaucoma suspects with abnormal SWAP (average, inferior, inferotemporal, and superotemporal thickness values) (P < 0.01). CONCLUSIONS: OCT RNFL measurements appear to correlate well with SWAP abnormalities in glaucoma, and may detect glaucomatous damage earlier than standard conventional automated perimetry. This study suggests that OCT may recognize the earliest evidence of structure alterations in CPOAG.     

Corneal thickness measurements and frequency doubling technology perimetry abnormalities in ocular hypertensive eyes

OBJECTIVE: It has been suggested that some patients currently diagnosed with ocular hypertension (OHT) may have thicker than average corneas that result in an overestimation of their true intraocular pressure. Consequently, patients with OHT with greater corneal thickness may be at a lower risk for functional glaucomatous damage, including visual field loss measured with frequency doubling technology (FDT) perimetry. The purpose of this study was to evaluate the frequency of FDT perimetry deficits in patients with OHT and to correlate these findings with central corneal thickness (CCT) measurements. DESIGN: Observational case control study. PARTICIPANTS AND CONTROLS: Sixty-five patients with OHT with normal optic discs and normal standard achromatic automated perimetry (SAP) visual fields and 52 normal control subjects. METHODS: All participants underwent SAP, FDT perimetry, and CCT measurements using ultrasound pachymetry. MAIN OUTCOME MEASURES: CCT measurements in patients with OHT with abnormal repeatable FDT test results were compared with CCT measurements in patients with OHT with normal FDT results. In addition, CCT measurements in patients with OHT were compared with CCT measurements in normal control subjects. RESULTS: Fourteen of 65 patients with OHT (21.5%) demonstrated repeatable FDT abnormalities. The mean CCT of patients with OHT with abnormal FDT results was significantly lower than the mean CCT of patients with OHT with normal FDT results (542+/-35 microm versus 575+/-35 microm; P = 0.003). The mean CCT in the normal control group was 556+/-36 microm. The mean CCT in patients with OHT with normal FDT results was significantly higher than in normal subjects (P = 0.008). No statistically significant difference was found between mean CCT in normal subjects and in patients with OHT with abnormal FDT results (P = 0.18). CONCLUSIONS: Patients currently diagnosed with OHT, but with visual field loss detected by FDT perimetry, had significantly lower CCT measurements than patients with OHT with normal FDT results. These findings suggest that patients with OHT with thinner corneas are more likely to develop early glaucomatous functional damage and that CCT measurements should be taken into account when assessing risk for the development of glaucoma among OHT subjects.     

Variability components of standard automated perimetry and frequency-doubling technology perimetry

PURPOSE. To evaluate and compare intra- and intertest variability components for both standard automated perimetry (SAP) and frequency-doubling technology (FDT) perimetry in a small group of normal individuals and patients with glaucoma. METHODS. The method of constant stimuli (MOCS) was used to examine matched test locations with both SAP and FDT perimetry stimuli in a group of eight normal individuals and seven patients with glaucoma. Subjects were tested weekly at three predetermined visual field loci for 5 consecutive weeks. Frequency-of-seeing (FOS) curves were generated and used to quantify threshold sensitivity (50% seen on FOS, in decibels), intratest variability (FOS interquartile range, in decibels), and intertest variability (interquartile range of weekly repeated threshold determinations, in decibels). RESULTS. In patients with glaucoma, SAP intra- and intertest variabilities were found to increase with sensitivity reductions, as previously reported. FDT perimetry revealed that both intra- and intertest variability components did not appreciably change with reductions in sensitivity. With the measurement scales used in this investigation, both intra- and intertest variability components were significantly greater for SAP than for FDT perimetry (P < 0.001 and P = 0.003, respectively). Intratest variability exceeded intertest variability for both SAP (P = 0.001) and FDT perimetry (P < 0.001). CONCLUSIONS. For both SAP and FDT perimetry, variability occurring within a single test session contributed more to total variability than between-session variability. When the measurement scales available on commercial instrumentation were used, FDT perimetry exhibited significantly less variability than SAP, especially within regions of visual field sensitivity loss. FDT perimetry therefore shows promise as an effective test for detecting progressive glaucomatous visual field loss, although prospective longitudinal validation is still required to determine sensitivity to change.     

Short wavelength automated perimetry, frequency doubling technology perimetry, and pattern electroretinography for prediction of progressive glaucomatous standard visual field defects

PURPOSE: To evaluate the clinical use of a test battery of short wavelength automated perimetry (SWAP), frequency doubling technology perimetry (FDT), and pattern electroretinography (PERG) in predicting progressive glaucomatous visual field defects on standard automated perimetry (SAP). STUDY DESIGN: A prospective, longitudinal, observational case series. PARTICIPANTS: One hundred and fifty-two patients with primary open-angle glaucoma (POAG) with bilateral glaucomatous visual field defects on SAP were followed at 6-month intervals over a period of 30 months. MAIN OUTCOME MEASURES: Short wavelength automated perimetry, FDT, and PERG results were compared between POAG eyes with and without progressive field loss on SAP. These two groups were used to evaluate whether PERG, SWAP, and/or FDT is predictive of future progression of field loss on SAP. RESULTS: Using the criteria of progressive field loss on SAP defined by the Collaborative Normal Tension Glaucoma Study, 54 eyes (study group) of 54 POAG patients showed progressive defects, whereas 84 eyes (control group) of 84 POAG patients showed no progression. Only 11.1% (6 of 54) of the eyes with a progression of field loss on SAP showed no increase of deficits on the three functional tests before progression. Short wavelength automated perimetry detected early progressive defects on SAP in 43 of the 54 eyes (79.6%). Of these 54 POAG eyes, FDT showed progressive deficits in 40 eyes (74.1%), whereas PERG amplitude P1N2 showed progressive deficits in 35 eyes (64.8%) before progression of field loss on SAP. A test battery consisting of SWAP and PERG P1N2-amplitude was able to detect 88.9% of eyes before a prediction of field loss on SAP. When comparing the results of the two functional tests, SWAP and FDT in the 84 eyes without progression of field loss on SAP between baseline and at 30 months, SWAP and FDT showed progressive deficits in 34.5% and 35.7%, respectively. CONCLUSIONS: All three tests (SWAP, FDT, and PERG) have been successful in detecting glaucoma eyes with a future progression of standard visual field defects. A test battery of SWAP and PERG P1N2-amplitude improved the power to predict these progressive defects on SAP. It remains to be seen whether the long-term follow-up in POAG eyes will improve the false-positive rate of SWAP and FDT.     

Short-wavelength automated perimetry can predict glaucomatous standard visual field loss by ten years

Examination of visual fields using standard achromatic automated perimetry (SAP) is essential for glaucoma management. However, as many as 35-50% of retinal ganglion cells can be lost before a visual field defect is detected. Previous studies have indicated that examination of the short-wavelength (blue) sensitive color system may be able to detect early functional loss in glaucoma. Moreover, it has been reported to detect glaucomatous visual field loss as many as 5 years earlier than SAP. We describe the case of a patient who demonstrated visual field defects on short-wavelength automated perimetry (SWAP) ten years prior to developing visual field defects in SAP.     

Correlation of functional and structural measurements in eyes suspected of having glaucoma.

PURPOSE: This study was conducted to determine the correlation between structural changes in the retinal nerve fiber layer (RNFL) and functional loss detected on short-wavelength automated perimetry (SWAP) in a population of patients with suspected glaucoma. METHODS: With a selection criteria of intraocular pressure (IOP) more than 21 mmHg and normal results of conventional automated perimetry, 49 eyes of 49 patients with ocular hypertension were enrolled in the study. The SWAP was performed with a modified Humphrey field analyzer, and visual field indexes (mean deviation [MD], corrected pattern standard deviation [CPSD]) were calculated. Semiquantitative RNFL scores were given separately to diffuse and localized defects of the RNFL. RESULTS: The MD increased significantly with higher diffuse and total RNFL scores, with good correlation coefficients. A weak correlation was found between CPSD and diffuse, total, and localized RNFL scores. CONCLUSION: Diffuse RNFL loss are associated with abnormalities in visual field indexes (MD), whereas focal structural damage showed no correlation with visual field loss.     

High spatial resolution automated perimetry in glaucoma

BACKGROUND—Automated perimetry is of fundamental importance in assessing visual function in glaucoma. A technique was evaluated to perform high spatial resolution automated perimetry to allow a more detailed assessment of the luminance sensitivity in selected regions of the visual field than is possible with conventional perimetry.
METHOD—High spatial resolution perimetry was performed using a Humphrey automated perimeter by measuring luminance sensitivity across a 9 by 9 degree custom grid of 100 test locations with a separation between adjacent locations of 1 degree. Quantitative analysis of the raw and Gaussian filtered thresholds was performed to assess the repeatability of the technique in normals, glaucoma suspects, and glaucoma patients.
RESULTS—The testing protocol was well tolerated by all subjects. High spatial resolution perimetry in glaucomatous eyes demonstrated fine luminance sensitivity loss not suspected with conventional perimetry. High spatial resolution perimetry also demonstrated reproducible areas of sensitivity loss in some glaucomatous eyes in areas of the visual field which appear normal with conventional programmes. The repeatability of the technique correlated with mean threshold sensitivity and was substantially improved to clinically acceptable levels by Gaussian filtering the thresholds.
CONCLUSION—This technique of high spatial resolution perimetry allows the practical assessment of selected regions of the visual field at higher resolution than conventional perimetry, and may be clinically useful in glaucoma.

     

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

OBJECTIVE: Reevaluation 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. DESIGN: Prospective comparative observational study. PARTICIPANTS: Four 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. INTERVENTION: All 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 MEASURES: For 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. RESULTS: In 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). CONCLUSIONS: SWAP 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.     

Relationship of optic disk topography and visual function in patients with large cup-to-disk ratios

PURPOSE: To determine if topographic differences exist between large cup-to-disk ratio (C/D) eyes with standard achromatic automated perimetry (SAP) abnormalities and those with only short-wavelength automated perimetry (SWAP) abnormalities. DESIGN: Cross-sectional study. METHODS: The setting was a referral university-based clinical practice. We selected one eye of 72 patients with a vertical C/D of at least 0.8 by ophthalmoscopy. Patients performed SWAP, SAP, and confocal scanning laser ophthalmoscopy. We compared optic disk topography in eyes with and without visual field abnormalities and controlled for the influence of disk area. RESULTS: Disk area was a confounder of many topographic measures. After controlling for disk area, eyes with abnormal SAP had differences in rim volume, cup shape, rim area, retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area when compared with eyes with normal SAP (P <.05). Rim volume and rim area were different in the SWAP comparison (P <.05). CONCLUSIONS: Investigators should control for disk area when evaluating topographic measures by confocal scanning laser ophthalmoscopy. In eyes with a large C/D, optic disk topography is more glaucomatous in eyes with SAP abnormalities than in those with only SWAP abnormalities. Eyes with large C/D and only SWAP abnormalities may have fewer glaucomatous optic disk changes than such eyes with SAP abnormalities. This indicates that SWAP is likely to correspond to abnormalities in optic disk topography at an earlier stage of glaucomatous optic neuropathy than SAP. Therefore, clinicians should consider SWAP testing in glaucoma suspects to detect glaucomatous visual field loss at an earlier stage of structural loss.     

Short-wavelength automated perimetry can predict glaucomatous standard visual field loss by ten years

Examination of visual fields using standard achromatic automated perimetry (SAP) is essential for glaucoma management. However, as many as 35-50% of retinal ganglion cells can be lost before a visual field defect is detected.^1,2,3 Previous studies have indicated that examination of the short-wavelength (blue) sensitive color system may be able to detect early functional loss in glaucoma. Moreover, it has been reported to detect glaucomatous visual field loss as many as 5 years earlier than SAP.^4,5,6,7 We describe the case of a patient who demonstrated visual field defects on short-wavelength automated perimetry (SWAP) ten years prior to developing visual field defects in SAP.     

Can frequency-doubling technology and short-wavelength automated perimetries detect visual field defects before standard automated perimetry in patients with preperimetric glaucoma?

PURPOSE: To assess the ability of frequency-doubling technology (FDT) perimetry and short-wavelength automated perimetry (SWAP) to detect glaucomatous damage in preperimetric glaucoma subjects. PARTICIPANTS: Two hundred seventy-eight eyes of 278 subjects categorized as normal eyes [n=98; intraocular pressure <20 mm Hg, normal optic disc appearance, and standard automated perimetry (SAP)]; preperimetric glaucoma eyes (n=109; normal SAP and retinal nerve fiber layer defects or localized optic disc notching and thinning); and glaucoma patients (n=71; intraocular pressure >21 mm Hg, optic disc compatible with glaucoma, and abnormal SAP). METHODS: The preperimetric glaucoma group underwent at least 2 reliable full-threshold 24-2 Humphrey SAPs, full-threshold C-20 FDT, full-threshold 24-2 SWAP, optic disc topography using the Heidelberg Retina Tomograph II, laser polarimetry using the GDx VCC, and Optical Coherence Tomography (Zeiss Stratus OCT 3000). Receiver operating characteristic curves were plotted for the main Heidelberg Retina Tomograph, Optical Coherence Tomography, and GDx VCC parameters for the normal and glaucoma patients. The area under the receiver operating characteristic curve was used to determine the parameters indicating glaucomatous damage in the optic disc or retinal nerve fiber layer, which were used to establish additional subgroups of patients with preperimetric glaucoma. FDT and SWAP sensitivities were calculated for the patient subsets with structural damage and normal SAP. RESULTS: At least 20% of the patients with preperimetric glaucoma demonstrated functional losses in FDT and SWAP. The more severe the structural damage, the greater the sensitivity for detecting glaucomatous visual field losses. CONCLUSIONS: FDT and SWAP detect functional losses in cases of suspected glaucoma before glaucomatous losses detected by SAP.     

Correlation between early retinal nerve fiber layer loss and visual field loss determined by three different perimetric strategies: white-on-white,frequency-doubling,or flicker-defined form perimetry

Purpose

To compare the significance of white-on-white standard automated perimetry (SAP), matrix frequency doubling technology (FDT), and flicker-defined form perimetry (FDF) for early detection of nerve fiber layer loss in early glaucoma patients.

Methods

Fifty-one healthy controls and 40 patients with early glaucomatous nerve fiber loss were enrolled in this study. Patients had retinal nerve fiber layer (RNFL) imaging and visual field testing by SAP, FDT matrix, and FDF perimetry at the same visit. Visual field defects were confirmed with two or more consecutive examinations by the same types of perimetry. Significant retinal nerve fiber layer loss and thus early glaucoma was defined with the reference to the RNFL thickness deviation map. The sensitivity, specificity, correlation, MD (mean deviation) and PSD (pattern standard deviation) visual field indexes, and area under the receiver operating characteristic curve (AUC) of MD and PSD of the perimetries were compared.

Results

There was a significant difference in nerve fiber layer thickness between healthy patients (97.7 ± 1.34 μm and patients with early glaucoma (84.1 ± 1.58 μm) (p?p?0.6. AUCs of PSD were not reliable in all of the three VF devices.

Conclusions

The sensitivity for detection of RNFL loss in early glaucoma seems to be higher in FDF and FDT matrix than SAP perimetry, while specifity was highest in SAP. Thus, simultaneous performance of FDF/FDT matrix and SAP perimetry seems beneficial for the correct diagnosis of early glaucoma in patients.     

Evaluation of patients with visual field defects following macular hole surgery using multifocal electroretinography

PURPOSE: To investigate patients with visual field defects following macular hole surgery to determine the cause of such defects, specifically with reference to ischemic damage versus mechanical trauma. METHODS: Five patients with known visual field defects following macular hole surgery were studied with Goldmann perimetry, Humphrey automated perimetry, and multifocal electroretinography (MERG). Three patients returned at a later date for nerve fiber layer analysis. RESULTS: None of the five patients demonstrated evidence of a- or b-wave loss on MERG in the regions corresponding to the visual field defects. Two of three patients studied with the nerve fiber layer analyzer demonstrated significant loss of nerve fiber layer thickness in the quadrant corresponding to the field defect. CONCLUSION: The normal MERG results indicate that the possibility of an arteriolar occlusion as the principal cause for the defects is unlikely in most cases. Data suggest that the site of damage is in the nerve fiber layer, although the specific cause of this damage remains to be determined.     

Fundusperimetrie in der Glaukomdiagnostik

Examination of the visual field using static automated perimetry (SAP) is the method of choice for the detection of functional damage secondary to glaucoma. However, with SAP early visual field defects might be missed even if there is already visible damage of the retinal nerve fibre. The microperimetry or beter fundus perimetry provides a detailed examination of the differential luminance threshold within defined retinal areas. However, in contrast to lesions of the retinal receptors, in cases of glaucomatous damage the retinal fibre course has to be considered resulting in a displacement between the structural lesion and the location of the related functional defect. The functional damage may be detected at earlier stages and with enhanced spatial resolution compared to conventional SAP. The extra costs and time associated with the application of fundus perimetry have prevented its widespread use. Current developments are leading to new options.     

A comparison of diagnostic protocols for interpretation of frequency doubling perimetry visual fields in glaucoma

BACKGROUND: Frequency doubling perimetry (FDP) shows good correlation with achromatic automated perimetry in the assessment of glaucoma. However, many recommended protocols lead to a significant number of false positives and negatives. Therefore, it may be difficult to identify visual field loss owing to glaucoma. We investigated the accuracy of a diagnostic protocol that only considered either temporal wedge, arcuate, or nasal step field loss on an FDP field as significant. METHODS: Sixty-eight subjects who were glaucoma suspects, glaucoma patients or normal controls were recruited selectively. After achromatic automated perimetry and FDP visual field testing, results were compared between a conventional protocol and ones that took into account the position of FDP visual field loss. RESULTS: If an FDP field was considered abnormal only when either a temporal wedge, an arcuate or a nasal step defect was present, the presence of a nasal step yielded the most accurate results with the least false positives (kappa coefficient=0.76) and with only minimal increase in false negatives, compared with a conventional FDP protocol (kappa coefficient=0.70). CONCLUSIONS: Although, not statistically significant in this case, our results suggested a trend that a diagnostic protocol which considers nasal step FDP field loss significant may have a greater degree of accuracy when compared with conventional protocols and may facilitate interpretation in a clinical setting.     

Evaluation of VEP perimetry in normal subjects and glaucoma patients

PURPOSE: To estimate sensitivity to glaucomatous visual field loss using multifocal visual evoked potential (VEP) perimetry, to compare these findings to those of conventional achromatic perimetry and to determine specificity of VEP perimetry in normal subjects. METHODS: A total of 33 glaucoma patients with known visual field defects in at least one eye on standard computerized perimetry and 33 healthy subjects were tested with VEP perimetry. The glaucoma patients were also tested with standard computerized perimetry using the 30-2 SITA Fast program of the Humphrey Field Analyzer (HFA). Visual evoked potential perimetry classification and VEP probability maps were used to determine the sensitivity and specificity of the technique. RESULTS: Visual evoked potential perimetry classified 68% of all eyes in the glaucoma group (45/66) as pathological; sensitivity increased to 81% (38/47) when considering only those eyes with HFA field defects. It also identified more test locations with significant loss at the p < 5% level in both groups (48% and 37%, respectively) than did HFA, while HFA identified more loss at the higher significance levels p < 2%, and p < 1%. Visual evoked potential perimetry showed more significant loss in eyes with almost normal or slightly damaged standard fields, while HFA identified more significant field loss in eyes with severe conventional field damage. The mean VEP amplitude of the 66 glaucoma eyes was 1.46e(-7) V; it was 1.676e(-7) V for the 66 control eyes. This difference was significant (p = 0.0033), but the overlap between groups was large. Visual evoked potential perimetry classified 42% of the control eyes as 'outside normal limits', and VEP probability maps showed 30.0% of test segments as significantly depressed at the p < 5% level, 10.8% of sites at p < 2%, and 4.6% at the p < 1% level. CONCLUSION: Mean VEP amplitude differed significantly between normal and glaucoma eyes, but the overlap was considerable. Visual evoked potential perimetry falsely classified a large number of normal eyes as pathological and showed many more significantly depressed test locations than expected. Agreement between VEP and standard perimetry was relatively poor for the glaucoma group. Further refinements are needed before VEP perimetry can be regarded as a reliable clinical method of mapping glaucomatous visual fields.     

Decreased visual field sensitivity measured 1 day, then 1 week, after migraine

PURPOSE: To determine whether perimetric performance is worse the day after a migraine than prior interictal measurements, and if so, to determine whether differences have resolved by 1 week after migraine. METHODS: Twenty-two nonheadache control subjects (aged 18-45 years) and 22 migraineurs (aged 18-45 years: 10 migraine with visual aura, 12 migraine without aura) participated. Standard automated perimetry (SAP) and temporal modulation perimetry (TMP) were measured by perimeter (model M-700; Medmont, Pty Ltd., Camberwell, Victoria, Australia). Control subjects attended two test visits: baseline and retest. Migraineurs attended three times: baseline (>or=4 days after migraine), the day after the offset of the next migraine, and 7 days later. Groups were compared using the global indices of the perimeter: Average Defect (AD) and Pattern Defect (PD), in addition to point-wise comparisons. RESULTS: Group migraineur TMP performance was significantly worse the day after a migraine, showing decreased general sensitivity and increased localized loss. Performance measured 7 days later was not significantly different from that measured the day after a migraine. Group migraineur SAP performance was not significantly worse after migraine; however, a subgroup of six eyes from five patients had 10 or more visual field locations with decreases in sensitivity greater than control test-retest 95% confidence limits. CONCLUSIONS: Decreased visual field performance was present after migraine, as well as greater test-retest variability in the migraine group compared with control subjects. As migraineurs constitute 10% to 15% of the general population, the presence of this subgroup of patients with periodic prolonged decreased visual field sensitivity after migraine has implications for differential clinical diagnosis, and for clinical research using perimetry.