Functional and structural measurements in a multifactorial glaucoma risk model

PURPOSE: To evaluate the relationship between a multifactorial probability risk model of developing glaucomatous visual field defects and the assessment of the retinal nerve fiber layer (RNFL) and short-wavelength automated perimetry (SWAP) in glaucoma suspects. METHODS: 157 eyes of 157 glaucoma suspects were included in the study. The risk of developing glaucomatous defects was assessed by applying a multifactorial model that included intraocular pressure, vertical cup-to-disk ratio, age and family history. Photographs of the RNFL and SWAP were performed. RESULTS: The SWAP was abnormal in 54 cases (34.3%); 21% of abnormal perimetries were obtained in the low-risk group, 37% in the moderate risk group and 56% in the high risk group. The nerve fiber layer evaluation in the different risk stages showed a pattern similar to the results obtained with SWAP. Multiple regression analyses, performed with the four variables included in the model with SWAP and RNFL evaluation, showed the relationship between the risk factors and the presence of glaucomatous damage--evaluated by RNFL and SWAP (p<0001). CONCLUSIONS: The probability model showed a good correlation between the risk scale and the RNFL and SWAP assessment.     

Psychophysical investigation of ganglion cell loss in early glaucoma

PURPOSE: To evaluate ganglion cell loss in early glaucoma using a variety of psychophysical tests and to identify optimal perimetric technique(s) for detection of early glaucomatous visual function loss. METHODS: Five perimetric tests, short wavelength automated perimetry (SWAP), temporal modulation perimetry (TMP), frequency doubling technology perimetry (FDT), detection acuity perimetry (DAP), and resolution acuity perimetry (RAP) were compared in their ability to discriminate between normal individuals and patients with early glaucoma or glaucoma suspects. Comparisons were also made by their ability to produce repeatable defects. The tests examined different visual functions that are likely to be mediated by different retinal ganglion cell subpopulations, thereby permitting examination of hypotheses of ganglion cell death in early glaucoma. RESULTS: All visual field tests demonstrated high performance in separating glaucoma patients from normal individuals. SWAP, TMP, FDT, and DAP provided the greatest discrimination between normal individuals and high- and low-risk glaucoma suspects. However, SWAP, TMP, and FDT obtained better consistency across the various analysis approaches (global indices and pointwise) than DAP and RAP. Of all the test types, FDT exhibited the highest proportion of repeatable abnormal test locations, with poor confirmation rates achieved by DAP and RAP. CONCLUSION: The performance of SWAP, FDT, and TMP suggests that these test types may all be suitable for detection of early loss of visual function in glaucoma. Ganglion cell subpopulations with lower levels of redundancy and/or those with larger cell sizes offer the most parsimonious explanation for earliest ganglion cell losses occurring 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.     

Comparison of clinical optic disc assessment with tests of early visual field loss

Purpose: Clinical optic disc assessment may identify glaucomatous optic neuropathy prior to a patient developing visual field abnormalities on achromatic automated peri­metry (AAP). Tests targeting axons that are selectively damaged or whose redundancy is low, such as short wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP), may detect visual field loss before it is seen on AAP. This study investigated whether patients in whom characteristic glaucomatous optic disc damage was present without AAP abnormalities had visual field abnormalities with SWAP and FDP. Methods: A sample of patients (n = 50) with ocular hypertension (normal AAP) were selected, who had SWAP, FDP and stereofundus photography performed. The photographs were then analysed by two glaucoma subspecialists who were masked to the assessments of the other and to the patients’ SWAP and FDP results. A categorization of the optic discs was made as either normal or abnormal and this was compared with their SWAP and FDP findings. Results: On comparing SWAP and FDP with clinical optic disc assessment as the ‘gold standard’, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 33%, 92%, 57% and 81%, respectively, for SWAP and 25%, 89%, 49% and 79%, respectively, for FDP. Conclusion: In glaucoma suspects, the study suggests that SWAP and FDP identify subjects with early glaucomatous optic neuropathy missed by AAP.     

Nerve fiber analyzer and short-wavelength automated perimetry in glaucoma suspects: a pilot study

PURPOSE: To test the relationship between the results of short-wavelength automatic perimetry (SWAP) and retinal nerve fiber layer (RNFL) measurements with scanning laser polarimetry (Nerve Fiber Analyzer, NFA) in age-matched normal subjects, glaucoma suspects, and early glaucoma patients. DESIGN: Case-control study. PARTICIPANTS AND METHODS: Thirty-eight normal subjects, 32 glaucoma suspects, and 14 early glaucoma patients were recruited. All subjects underwent RNFL assessment by NFA, achromatic visual field testing (24-2 threshold), and repeated SWAP (24-2 threshold blue-on-yellow). MAIN OUTCOME MEASURES: Mean deviation (MD) of visual field testing and RNFL values were obtained. RESULTS: Glaucoma suspects were divided into two groups according to their SWAP results: high risk (with SWAP abnormalities) and low risk (with normal SWAP result). No statistically significant difference in SWAP MD and RNFL values were observed between normal and low-risk groups (P > 0.05), but these values were found to be significantly lower in high-risk and early glaucoma groups (P < 0.01). CONCLUSIONS: This study suggests that RNFL examination by NFA may be a useful test for the early detection of glaucomatous damage of glaucoma suspects. It appears to provide agreement with SWAP abnormalities and is more sensitive than conventional standard automated perimetry.     

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.     

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: Abnormality criteria

This study was conducted to determine the sensitivity and specificity of different perimetric algorithms and their combination in short-wavelength automated perimetry (SWAP), for detection of early glaucomatous damage. Retinal nerve fiber layer assessment and SWAP were performed in 160 eyes, of glaucoma suspects. Perimetric abnormality criteria based on presence of clusters of points with significant sensitivity losses showed higher sensitivity in detection of early glaucomatous changes than did criteria based on global visual field indexes.     

Long-term fluctuation in short-wavelength automated perimetry in glaucoma suspects and glaucoma patients

PURPOSE: To determine the magnitude of the homogeneous, LF(Ho), and the heterogeneous, LF(He), components of the long-term fluctuation (LF) in glaucoma suspects and in stable primary open angle glaucoma (POAG) patients undergoing short-wavelength automated perimetry (SWAP) and to compare the magnitude of the SWAP LF components with those elicited by standard white-on-white (W-W) perimetry. METHODS: The sample comprised 33 glaucoma suspects and 17 patients with early-to-moderate stable POAG who underwent W-W perimetry and SWAP at each of six visits over a mean period of 12.75 months (SD, 2.29). The LF(Ho), LF(He), and error components of the long-term fluctuation were determined between the third and seventh visual field examinations. The intervening visual field examinations and the optic nerve head parameters, derived both by stereo observation and by the Heidelberg Retinal Tomograph, were used to confirm stability over the follow-up period. RESULTS: The LF(Ho) and LF(He) components were larger in the POAG patients than in the glaucoma suspects for both W-W perimetry and SWAP; the magnitude was independent of the depth of defect and of the short-term fluctuation. All three components of long-term fluctuation were greater for SWAP than for W-W perimetry, both in the glaucoma suspects and in the POAG patients. CONCLUSIONS: SWAP exhibits greater long-term fluctuation than white-on-white perimetry. The usefulness of SWAP will be limited if the extent of this variability is not overcome in future statistical procedures developed to detect progressive visual field loss.     

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.     

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.     

Structure and function evaluation (SAFE): II. Comparison of optic disk and visual field characteristics

PURPOSE: To evaluate the relationship between glaucomatous structural damage to the optic nerve and development of visual field loss with standard automated perimetry (SAP) and short wavelength automated perimetry (SWAP). DESIGN: Cohort study. METHODS: Patients with elevated intraocular pressure and normal SAP visual fields were enrolled in this prospective study. Stereo optic disk photographs, SAP, and SWAP visual fields were obtained annually over a period of 4 or more years. Trained readers evaluated baseline and follow-up optic disk photographs for evidence of glaucomatous damage. Standard automated perimetry and SWAP examinations were evaluated according to previously validated criteria for development of confirmed visual field changes. RESULTS: Two-hundred ninety-five subjects (479 eyes) were enrolled. Following masked assessment of stereo photographs by an optic disk reading center, 272 of the 479 eyes were judged to have glaucomatous optic neuropathy at the time of study entry. Depending on the criteria employed, approximately 10% to 17.5% of all eyes developed confirmed visual field loss for SAP (conversions). Of the conversions, 75% to 80% had baseline glaucomatous optic disk damage, whereas normal and glaucomatous optic disks were equally divided (50%) among the nonconversion eyes. This difference was statistically significant (P <.003). Depending on the criteria employed, 4% to 12% of the eyes had confirmed SWAP deficits at baseline, and 4% to 8% developed confirmed SWAP defects at a follow-up examination. There was a greater percentage of eyes with a glaucomatous optic neuropathy in the group with SWAP deficits (75%-100%) than for those eyes in which SWAP remained normal (45%-60%). Some of these differences were statistically significant (P <.05). CONCLUSIONS: A strong relationship exists between glaucomatous optic disk damage at study entry and the subsequent development of a confirmed glaucomatous SAP visual field defect. A higher percentage of glaucomatous optic disks were also found in patients with SWAP deficits at baseline and in those who later developed SWAP deficits. These findings support the premise that a glaucomatous optic disk is predictive of the subsequent development of glaucomatous visual field loss.     

Quantification of glaucomatous visual field defects with automated perimetry

A method to quantify different glaucomatous visual field defects is presented. Three visual field indices are calculated: the short-term fluctuation, the mean defect, and the corrected loss variation. The method was applied to visual fields tested with program JO on the Octopus automated perimeter. The indices of 130 glaucoma suspects and 50 glaucoma patients were compared with 100 normal controls. The indices provide good detectability of visual field defects and easy follow-up.     

Isolation of short-wavelength sensitive mechanisms in normal and glaucomatous visual field regions

PURPOSE: To determine whether "isolation" of short wavelength sensitive mechanisms (i.e., exclusive detection of a threshold stimulus by a short wavelength sensitive mechanism) is maintained in areas of glaucomatous visual field damage as measured with short-wavelength automated perimetry (SWAP). METHODS: Data from conventional automated perimetry and SWAP were analyzed for both eyes of 60 normal control subjects, 38 patients with ocular hypertension, and 22 patients with early to moderate glaucomatous field damage (mean defect better than -12 dB). Comparisons of results of SWAP and conventional perimetry were performed by determining the deviation from the mean normal sensitivity for the two procedures. Locations with sensitivity <3 dB for either procedure were rejected, as 3 dB is near the maximum stimulus luminance and may have introduced a bias by underestimating defects. The interval between deviation from normal (the isolation interval) on conventional perimetry and SWAP was examined to determine the likelihood of short wavelength mechanism isolation loss for different levels of glaucomatous visual field damage. RESULTS: Using normal isolation estimates of 13 dB and 10 dB as bases for determining the likelihood that isolation of short wavelength sensitive mechanisms may have been lost, it was found that this was an infrequent possibility, as low as 0.39 to 1.63% for normal control subjects and 2.53 to 10.44% for patients with glaucoma. CONCLUSION: Analyses indicate that isolation of short wavelength sensitive mechanisms is mostly maintained for SWAP, even in areas of moderate glaucomatous field damage. One limitation of SWAP for evaluating extensive glaucomatous damage is its dynamic range. This could be overcome by using a more intense stimulus light source.     

Glaucoma detection with frequency doubling perimetry and short-wavelength perimetry

PURPOSE: The aim of this analysis was to evaluate the diagnostic usefulness of frequency doubling technology (FDT) perimetry and short-wavelength perimetry (SWAP). Moreover, to study a combination of both methods using the machine-learning technique double-bagging, which was recently established in glaucoma research. METHODS: Forty-three patients with "preperimetric" open-angle glaucoma (glaucomatous optic disc atrophy and no visual field defect in standard perimetry), 26 patients with "perimetric" open angle glaucoma (glaucomatous optic disc atrophy and visual field defect in standard perimetry), and 40 control subjects had FDT screening (protocol: C-20-5) and SWAP (Octopus 101, G2). Criteria for exclusion were color vision abnormalities, media opacities, and an age below 31 years or above 63 years. Data of 1 eye of each patient and control subject entered the statistical evaluation. A point wise evaluation of the diagnostic power of SWAP values was performed to derive spatial patterns of visual field loss. A double-bagging machine-learning algorithm was used to train classification rules on the basis of a combination of FDT scores and nerve fiber related visual field losses in SWAP. The diagnostic power of the classifiers was compared regarding their misclassification error rates and area under the receiver-operating characteristic curve. RESULTS: The combination of FDT perimetry and SWAP yielded better diagnostic results compared with FDT or SWAP separately. The overall estimated misclassification error rate of the combined classifier was 24% compared with 28% for both SWAP and FDT perimetry. Regarding the estimated performance of classifier at high specificities (>80%) in control eyes as measured by the partial area under the receiver-operating characteristic curve, the combination of both instruments is also superior to the individual instruments. CONCLUSIONS: A combination of SWAP and FDT perimetry, each targeting different neuronal pathways, may improve early glaucoma detection.     

Short-wavelength automated perimetry in patients with migraine

Background The aim was to investigate short-wavelength sensitivity deficits in patients with migraine.Methods Fifteen migraine and 18 age-matched healthy volunteers with normal ophthalmologic examination participated in this study. Migraine characteristics were graded by the Migraine Disability Assessment Questionnaire (MIDAS). All participants underwent SWAP (short wavelength amplitude perimetry) testing using a Humphrey field analyzer; there was a 30-2 presentation pattern.Results Short wavelength amplitude perimetry parameters for mean deviation (MD; p<0.0001) and pattern standard deviation (PSD; p<0.0001) were significantly worse in the migraine group. In the migraine group 53.3%. of eyes had glaucoma hemi-field tests (GHT) outside normal limits and 10 of these had early glaucomatous visual field loss. Statistically significant correlations were found between frequency of migraine attacks and MD (p=0.02; r=0.56) and PSD (p=0.03; r=0.41) and also between the MIDAS score and MD (p=0.03; r=0.49) and PSD (p=0.04; r=0.51). In all migraine cases with early glaucomatous visual field defect a corresponding site of the head was predominantly involved in headache (p=0.03).Conclusion Some patients with severe migraine have earlier defects on SWAP suggesting a common vascular insult of glaucoma and migraine, and all migraine cases with high MIDAS scores should be further evaluated for early glaucomatous visual field defects using SWAP.     

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.     

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.     

Testing for glaucoma with the spatial frequency doubling illusion

We examined the performance of tests for glaucoma based on the spatial frequency doubling (FD) illusion. Contrast thresholds for seeing the FD illusion in four large visual field regions were measured from 340 subjects who were tested up to seven times over 2 years. Median sensitivities of 91% at specificities of 95% were obtained. Test-retest variability for the worst hemifield thresholds averaged 2.22 db +/- 0.09 S.E. for all tested groups, and significant progression was observed for glaucoma suspects over the seven visits, indicating that tests based on the FD illusion can detect diffuse early glaucomatous 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.