Gaze tracker parameters have little association with visual field metrics of intrasession frontloaded SITA-Faster 24-2 visual field results

Quantification and Predictors of Visual Field Variability in Healthy, Glaucoma Suspect, and Glaucomatous Eyes Using SITA-Faster

PURPOSE

The newly released Swedish Interactive Thresholding Algorithm (SITA)-Faster (SFR) has significantly shorter testing durations compared with older SITA algorithms, but its variability is uncertain. This study quantified and established threshold limits of test-retest variability across the 24-2 test grid using SFR.

DESIGN

Cross-sectional study with prospective longitudinal arm.

PARTICIPANTS

1426 eyes of 787 patients with healthy, suspected glaucoma, or manifest glaucoma eyes from hospital- and university- eye clinics.

METHODS

Two SFR tests per eye at a baseline visit and at two follow-up visits.

MAIN OUTCOME MEASURES

Pointwise variability measured by test-retest difference in pointwise sensitivity between tests one and two, mean global variability (test-retest variance) measured by average of pointwise variability for each participant, global sensitivity, and reliability indices of each eye.

RESULTS

Of the 1426 eyes, 540 eyes (37.9%) had a diagnosis of glaucoma, 753 eyes (52.8%) were suspected of having glaucoma, and the remaining 133 eyes (9.3%) were healthy. Of 74 152 pointwise sensitivities obtained, the mean test-retest difference was 2.17 ± 2.9 dB, whereas the mean test-retest variance for each participant was 2.17 ± 1.2 dB. Pointwise and global variability increased with worsening threshold sensitivity and (MD), respectively, and was greater for peripheral compared with central test locations. In the longitudinal cohort, no significant difference in mean test-retest variance was found across the 3 visits (mean variability, 2.10 dB vs. 2.16 dB vs. 2.16 dB at visits F0 vs. F1 vs. F2; P = 0.53, repeated-measures analysis of variance). Baseline MD (-0.19 dB; 95% CI, -0.22 to 0.16 dB; P < 0.0001) and abnormally high sensitivity on glaucoma hemifield test (1.14 dB; 95% CI, 0.78-1.51 dB; P < 0.0001) were significantly associated with increased variability. Finally, test-retest MD showed minimal change around the recommended 15% false-positive cutoff threshold.

CONCLUSIONS

The variability of SFR increases with worsening threshold sensitivity, is stable over time, and is greater for peripheral compared with central test locations. Worse baseline MD and abnormally high sensitivity are significant predictors of increased variability. A cutoff of 15% in false-positive results may be inappropriate as a threshold for judging test reliability in SFR.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Frontloading visual field tests detect earlier mean deviation progression when applied to real-world-derived early-stage glaucoma data

PURPOSE

To examine the diagnostic accuracy of performing two (frontloaded) versus one (clinical standard) visual field (VF) test per visit for detecting the progression of early glaucoma in data derived from clinical populations.

METHODS

A computer simulation model was used to follow the VFs of 10,000 glaucoma patients (derived from two cohorts: Heijl et al., Swedish cohort; and Chauhan et al., Canadian Glaucoma Study [CGS]) over a 10-year period to identify patients whose mean deviation (MD) progression was detected. Core data (baseline MD and progression rates) were extracted from two studies in clinical cohorts of glaucoma, which were modulated using SITA-Faster variability characteristics from previous work. Additional variables included follow-up intervals (six-monthly or yearly) and rates of perimetric data loss for any reason (0%, 15% and 30%). The main outcome measures were the proportions of progressors detected.

RESULTS

When the Swedish cohort was reviewed six-monthly, the frontloaded strategy detected more progressors compared to the non-frontloaded method up to years 8, 9 and 10 of follow-up for 0%, 15% and 30% data loss conditions. The time required to detect 50% of cases was 1.0-1.5 years less for frontloading compared to non-frontloading. At 4 years, frontloading increased detection by 26.7%, 28.7% and 32.4% for 0%, 15% and 30% data loss conditions, respectively. Where both techniques detected progression, frontloading detected progressors earlier compared to the non-frontloaded strategy (78.5%-81.5% and by 1.0-1.3 years when reviewed six-monthly; 81%-82.9% and by 1.2-2.1 years when reviewed yearly). Accordingly, these patients had less severe MD scores (six-monthly review: 0.63-1.67 dB 'saved'; yearly review: 1.10-2.87 dB). The differences increased with higher rates of data loss. Similar tendencies were noted when applied to the CGS cohort.

CONCLUSIONS

Frontloaded VFs applied to clinical distributions of MD and progression led to earlier detection of early glaucoma progression.

Comparing a head-mounted virtual reality perimeter and the Humphrey Field Analyzer for visual field testing in healthy and glaucoma patients

PURPOSE

To compare clinical visual field outputs in glaucoma and healthy patients returned by the Humphrey Field Analyzer (HFA) and virtual reality (Virtual Field, VF) perimetry.

METHODS

One eye of 54 glaucoma patients and 41 healthy subjects was prospectively tested (three times each in random order) using the HFA and VF perimeters (24-2 test grids). We extracted and compared global indices (mean deviation [MD] and pattern standard deviation [PSD]), pointwise sensitivity (and calculated 'equivalent' sensitivity after accounting for differences in background luminance) and pointwise defects. Bland-Altman (mean difference [Mdiff ] and 95% limits of agreement [LoA]) and intraclass correlation analyses were performed.

RESULTS

The VF test was shorter (by 76 s) and had lower fixation losses (by 0.08) and false-positive rate (by 0.01) compared to the HFA (all p < 0.0001). Intraclass correlations were 0.86, 0.82 and 0.47 for MD, PSD and pointwise sensitivity between devices, respectively. Test-retest variability was higher for VF (Mdiff 0.3 dB, LoA -7.6 to 8.2 dB) compared to the HFA (Mdiff -0.3 dB, LoA -6.4 to 5.9 dB), indicating greater test-retest variability. When using each device's underlying normative database, the HFA detected, on average, 7 more defects (at the p < 0.05 level) out of the 52 test locations compared to this iteration of VF in the glaucoma cohort.

CONCLUSIONS

Virtual Field returns global results that are correlated with the HFA, but pointwise sensitivities were more variable. Differences in test-retest variability and defect detection by its current normative database raise questions about the widespread adoption of VF in lieu of the HFA.

Evaluation of the Consistency of Glaucomatous Visual Field Defects Using a Clustered SITA-Faster Protocol

PURPOSE

Frontloading SITA-Faster (SFR) visual fields (2 tests per eye on the same visit) has been shown to provide repeatable perimetric data at minimal time cost. This study reports the outcomes of using frontloaded SFR in the evaluation of pointwise visual field (VF) defects in a cohort of patients with glaucoma when transitioned from SITA-Standard (SS).

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

A total of 144 eyes of 91 patients with confirmed or suspected glaucoma who had an SS test on a previous visit.

METHODS

Two SFR tests (T1, T2) per eye on the same visit.

MAIN OUTCOME MEASURES

Global sensitivity, reliability indices, and pointwise deviation map probability scores from the pattern deviation grid of each patient were compared across the 3 sequential tests to evaluate the consistency of VF defects.

RESULTS

The mean age was 68.6 years, and 79.2% of patients had a diagnosis of glaucoma. There was no significant difference in mean deviation (MD) across the 3 tests (-5.83 decibels [dB], -5.28 dB, and -5.71 dB in SS, SFR1, and SFR2, respectively, repeated-measures analysis of variance [ANOVA], P = 0.48). The frontloaded SFR tests provided repeatable VFs that confirmed existing pointwise data on the SS in 4661 (62.3%) locations, reversed an SS defect in 614 (8.2%) locations, and demonstrated a new repeatable defect in 406 (5.4%) locations of the pattern deviation grid. A new defect of at least 3 contiguous points was identified in 20.1% of eyes. The non-repeatable points on the 2 SFR tests displayed no significant difference in the distribution of defect/nondefect points based on test order or peripheral versus central locations. There was no significant difference in the rate of obtaining at least 1 reliable test result between SS and the frontloaded SFR T1 and T2 (P = 0.77). Test duration significantly decreased from SS to SFR1/2 (379 vs. 160 vs. 158 seconds, P < 0.0001).

CONCLUSIONS

Frontloading SFR tests can provide repeatable data for the evaluation of the consistency of pattern deviation defects in glaucoma, with no observable decline in performance from test fatigue. This is achieved at equivalent duration and reliability as a single SS test. Frontloading SFR may be helpful in increasing testing frequency/quantity to meet recommended guidelines for progression analysis.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Visualising structural and functional characteristics distinguishing between newly diagnosed high-tension and low-tension glaucoma patients

PURPOSE

To determine whether there are quantifiable structural or functional differences that can distinguish between high-tension glaucoma (HTG; intraocular pressure [IOP] > 21 mm Hg) and low-tension glaucoma (LTG; IOP ≤ 21 mm Hg) at diagnosis.

METHOD

This was a retrospective, cross-sectional study. Clinical results of one eye from 90 newly diagnosed HTG and 319 newly diagnosed LTG patients (117 with very-low-tension glaucoma [vLTG; ≤15 mm Hg] and 202 with middling LTG [mLTG; >15 mm Hg, ≤21 mm Hg]) were extracted, which included relevant demographic covariates of glaucoma, quantitative optical coherence tomography (including the optic nerve head, retinal nerve fibre layer and ganglion cell-inner plexiform layer) measurements and standard automated perimetry global metrics. We used binary logistic regression analysis to identify statistically significant clinical parameters distinguishing between phenotypic groups for inclusion in principal component (PC) (factor) analysis (PCA). The separability between each centroid for each cohort was calculated using the Euclidean distance (d(x,y)).

RESULTS

The binary logistic regression comparing HTG and all LTG identified eight statistically significant clinical parameters. Subsequent PCA results included three PCs with an eigenvalue >1. PCs 1 and 2 accounted for 21.2% and 20.2% of the model, respectively, with a d(x,y) = 0.468, indicating low separability between HTG and LTG. The analysis comparing vLTG, mLTG and HTG identified 15 significant clinical parameters, which were subsequently grouped into five PCs. PCs 1 and 2 accounted for 24.1% and 17.8%, respectively. The largest separation was observed between vLTG and HTG (d(x,y) = 0.581), followed by vLTG and mLTG (d(x,y) = 0.435) and lastly mLTG and HTG (d(x,y) = 0.210).

CONCLUSION

Conventional quantitative structural or functional parameters could not distinguish between pressure-defined glaucoma phenotypes at the point of diagnosis and are therefore not contributory to separating cohorts. The overlap in findings highlights the heterogeneity of the primary open-angle glaucoma clinical presentations among pressure-defined groups at the cohort level.

Visual fields in glaucoma: Where are we now?

Visual fields are an integral part of glaucoma diagnosis and management. COVID has heightened the awareness of the potential for viral spread with the practice of visual fields modified. Mask artefacts can occur due to fogging of the inferior rim of the trail lens. Fortunately, the risk of airborne transmission when field testing is low. The 24-2c may be useful to detect early disease and the 10-2 more sensitive to detect advanced loss. The SITA faster test algorithm is able to reduce testing time thereby improving clinic efficiency, however, may show milder results for moderate or severe glaucoma. The technician has an important role of supervising the visual field performance to achieve reliable output. Home monitoring can provide earlier detection of progression and thus improve monitoring of glaucoma as well as reduce the burden of in-clinic assessments. Artificial Intelligence has been found to have high sensitivity and specificity compared to expert observers in detecting field abnormalities and progression as well as integrating structure with function. Although these advances will improve efficiency and guide accuracy, there will remain a need for clinicians to interpret the results and instigate management.