Variability and Power to Detect Progression of Different Visual Field Patterns

Optical coherence tomography angiography in glaucoma

The use of optical coherence tomography angiography (OCTA) holds significant promise for optometrists in the diagnosis and management of glaucoma. It offers reliable differentiation of glaucomatous eyes from healthy ones and extends monitoring capabilities for advanced cases. OCTA represents a valuable addition to traditional assessment methods, particularly in complex cases. Glaucoma, a major cause of irreversible blindness, is traditionally diagnosed using structural and functional metrics. With growing interest, OCTA is being explored to diagnose, monitor, and manage glaucoma. This review focuses on the application of OCTA in glaucoma patients. A database search was carried out using Embase Elsevier (n = 664), PubMed (n = 574), and Cochrane Central Register of Controlled Trials (n = 19) on 15 August 2023. After deduplication and screening, 272 original papers were included in the narrative review. Inclusion criteria comprised English-language original studies on OCTA use in human glaucoma patients, with or without healthy controls. Exclusion criteria encompassed animal studies, in-vivo/in-vitro research, reviews, and congress abstracts. OCTA has good repeatability and reproducibility. OCTA metrics have good discriminatory power to differentiate glaucomatous eyes from healthy eyes and show strong associations with structural changes and visual field defects. OCTA can extend the monitoring of advanced glaucoma, addressing the 'floor effect' of traditional structural measurements. OCTA metrics can be affected by the choice of OCTA machine, post-image processing algorithms, systemic diseases, and ocular factors. Image artefacts can affect the accuracy of OCTA measurements, and proper scan quality evaluation is crucial to ensure reliable results. Additionally, artificial intelligence techniques offer promise for enhancing the diagnostic accuracy of OCTA by combining data from various retinal layers and regions. OCTA complements traditional methods in assessing glaucoma, especially in challenging cases, providing valuable insights for detection and management. Further research and clinical validation are needed to integrate OCTA into routine practice.

Which glaucoma patients benefit from 10-2 visual field testing? Proposing the functional vulnerability zone framework

CLINICAL RELEVANCE

A method for determining 10-2 deployment in glaucoma with the goal of detecting additional visual field sensitivity for the purpose of functional monitoring is proposed.

BACKGROUND

To provide a pilot method for determining when to deploy the 10-2 visual field (VF) test grid in glaucoma by characterising the 'functional vulnerability zone'.

METHODS

The cross-sectional 24-2 (central 12 locations) and 10-2 VF results from 133 eyes of 133 glaucoma subjects were used to describe the central Hill of Vision using VF sensitivity. The 'volume' (defined using arbitrary units, A.U.) under the Hill was calculated. A greater A.U. on the 10-2 indicated a functional vulnerability zone (FVZ), signifying additional clinical dynamic range for potential future monitoring. The main outcome measures were calculated A.U. and 24-2 factors which were significantly related to A.U. differences between 24-2 and 10-2.

RESULTS

Over 55% of patients had an FVZ (A.U. greater using 10-2). Several 24-2 features (worse mean deviation, worse central 24-2 mean defect, and a higher proportion of defective locations) were significant in the FVZ cohort compared to non-FVZ. 24-2 mean deviation levels at which 10-2 may be favoured were low at -3.16 to -3.62 dB. Specifically, 5 or more defective central 24-2 test locations were associated with an FVZ. Subjects exhibiting a less severe defect on the 10-2 were more likely to have an FVZ, indicating its potential for future VF monitoring.

CONCLUSIONS

The authors propose several clinical markers, focussing on the 24-2, which can guide clinicians on when the 10-2 may have utility in glaucoma assessment. The authors provide a pilot reference spreadsheet for clinicians to visualise the likelihood of 10-2 utility in the context of an FVZ.

Assessment of visual field progression in glaucoma

PURPOSE OF REVIEW

Perimetry plays an important role in the diagnosis and management of glaucoma. This article discusses the assessment of visual field progression in patients with glaucoma.

RECENT FINDINGS

Selecting the best visual field test strategy and establishing a baseline of visual fields will assist clinicians in the detection of glaucomatous progression. Repeat testing serves to confirm or refute changes on visual field testing. More frequent testing after initial diagnosis is recommended to establish a baseline and to identify patients with rapid progression who may need more aggressive management. Statistically significant changes on event analysis can prompt examination of a patient's trend analysis to determine whether clinically significant deterioration may be occurring. Future applications of machine learning can complement existing methods of visual field interpretation.

SUMMARY

Many treated patients with glaucoma will experience visual field progression. Optimal utilization of visual field testing strategy and analytical software can help clinicians identify patients with glaucomatous progression likely to cause functional visual disability.

Baseline 10-2 Visual Field Loss as a Predictor for Future Glaucoma Progression

PRCIS

Presence of baseline 10-2 visual field (VF) loss was the strongest predictor of future rate of 24-2 VF loss and development of new 24-2 progression events, suggesting a role for 10-2 VF testing in baseline glaucoma risk analysis.

PURPOSE

The purpose of this study is to examine the relationship between baseline 10-2 VF loss and future 24-2 VF loss.

MATERIALS AND METHODS

Subjects were participating in a prospective longitudinal study within a VA Medical Center outpatient eye clinic. Eligibility required 2 good quality baseline 10-2 VF tests followed by a minimum of 5 good quality 24-2 VF tests over at least 3 years. Longitudinal 24-2 VF testing was completed every 4-6 months after baseline 10-2 testing. Mixed model regression analyses and Cox Proportional Hazard regression analyses were completed to identify predictors of 24-2 mean deviation change rate and new VF loss events.

RESULTS

We studied 394 eyes of 202 subjects (119 primary open angle glaucoma and 83 glaucoma suspect). Over 6.7 (±1.5) years, 9.9 (±2.3) good quality 24-2 VF tests were completed. In mixed model regression analyses, baseline variables that predicted faster rate of 24-2 VF loss in order of strength of association were presence of baseline 10-2 VF defect, lower 24-2 mean deviation, and higher age. When analyses were completed without 10-2 variables, predictive capability of the model was reduced compared with when 10-2 variables were included. In Cox Proportional Regression analyses evaluating progression events, baseline 10-2 VF defect demonstrated the largest hazard ratio (22 times greater risk for developing future VF loss event in eyes with vs. without baseline 10-2 VF loss).

CONCLUSIONS

Baseline 10-2 VF defect was the most effective predictor of subsequent 24-2 VF progression in this study. These findings imply that presence of baseline 10-2 VF loss may provide unique value for predicting future glaucoma progression.

The 24-2 Visual Field Guided Progression Analysis Can Miss the Progression of Glaucomatous Damage of the Macula Seen Using OCT

PURPOSE

To better understand the efficacy of the 24-2 guided progression analysis (GPA) in the detection of progression in eyes with early glaucoma (i.e., 24-2 mean deviation [MD] better than -6 dB) by comparing 24-2 GPA with a reference standard (RS) based on a combination of OCT and 24-2 and 10-2 visual field (VF) information.

DESIGN

Cross-sectional study.

PARTICIPANTS

Ninety-nine eyes from 99 individuals, including 70 suspected or early glaucomatous eyes (24-2 MD better than -6 dB) and 29 healthy controls (HCs).

METHODS

All the eyes had at least 4 OCT and VF test dates over a period that ranged from 12 to 59 months. The 24-2 VF tests included 2 baseline tests and at least 2 follow-up tests. The 2 baseline tests were performed within an average of 5.6 days (median, 7 days), and the last follow-up test was performed at least 1 year after the first baseline visit.

MAIN OUTCOME MEASURES

A commercial 24-2 GPA software, with default settings, characterized the eyes as having "likely progression" (LP) or "possible progression" (PP); both were considered "progressing" for this analysis. For RS, 3 authors graded progression using strict criteria and a combination of a custom OCT progression report and commercial 24-2 and 10-2 GPA reports for the same test dates as GPA.

RESULTS

The reference standard identified 10 (14%) of the 70 patient eyes and none of the HC eyes as having progression. The 24-2 guided progression analysis identified 13 of the 70 patient eyes as having progression (PP or LP). However, it correctly classified only 4 (40%) of the 10 RS progressors. All 6 of the RS progressors missed by the 24-2 GPA showed progression in the macula. In addition, the 24-2 GPA identified 2 of the 29 HC eyes as progressors and 9 patient eyes without progression based on the RS.

CONCLUSIONS

In eyes with early glaucoma (i.e., 24-2 MD, > -6 dB) in this study, the 24-2 GPA missed progression seen using OCT and exhibited a relatively high rate of false positives. Furthermore, the region progressing typically included the macula. The results suggest that including OCT and/or 10-2 VFs should improve the detection of progression.

The Role of Intraocular Pressure and Systemic Hypertension in the Progression of Glaucomatous Damage to the Macula

PRCIS

Macular structural and functional parameters were better correlated with pressure-dependent glaucomatous damage than conventional parameters. Self-reported systemic hypertension (HTN) was not associated with structural or functional progression in this cohort.

PURPOSE

The aim was to examine the relationships between intraocular pressure (IOP), systemic HTN, and glaucoma progression using structural testing with optical coherence tomography (OCT) and functional testing with visual field (VF).

PATIENTS AND METHODS

A total of 191 eyes of 119 patients enrolled in a prospective, longitudinal study (Structural and Functional Progression of Glaucomatous Damage to the Macula study) with a diagnosis of glaucoma were analyzed. Patients were tested with 10-2 and 24-2 VF and spectral-domain OCT obtained at 4 to 6 month intervals. IOP from each visit was collected. Self-reported diagnoses of HTN were reported in 72 eyes (37%) in the patients included. Linear mixed effects regression was used to test the relationship between summary statistics from VF and OCT and HTN diagnosis. The goodness-of-fit of relationships was assessed with Bayesian information criterion.

RESULTS

Mean follow-up IOP was most associated with the following OCT parameters: global macula ganglion cell layer (GCL), inferior macula GCL, mean macular vulnerability zone GCL, and mean less vulnerable zone macula GCL, and with the following VF parameters: 10-2 PSD and 10-2 MD. There was no significant difference in rates of progression between HTN and non-HTN patients for any OCT or VF parameter. Models with the best goodness-of-fit for the relationship between HTN and progression were the same as those observed for IOP.

CONCLUSION

Macular structural and functional parameters are more sensitive to IOP in terms of glaucomatous progression when compared with more conventional parameters. While HTN was not significantly associated with progression using any parameter, macular structural and functional parameters had a better goodness-of-fit to model progression and may be useful as endpoints.

The Frontloading Fields Study (FFS): Detecting Changes in Mean Deviation in Glaucoma Using Multiple Visual Field Tests Per Clinical Visit

Purpose

To determine the impact of different numbers of visual field tests per visit for detecting mean deviation changes over time in patients with early glaucoma or suspected glaucoma and to identify a practical approach to maximize change detection.

Methods

Intrasession (n = 322) and intersession (n = 323) visual field results for patients with glaucoma or suspected glaucoma were used to model mean deviation change in 10,000 progressing and 10,000 non-progressing computer-simulated patients over time. Variables assessed in the model included follow-up intervals (0.5, 1, or 2 years), reliability rates (70%, 85%, or 100%) and number of visual field tests performed at each visit (one to four).

Results

Two visual field tests per session compared with one provided higher case detection rates at 2 years (99%–99.8% vs. 34.7%–76.3%, respectively), reduced time to detection (three or four visits vs. six to 10, respectively), and more positive mean deviation score (−4 dB vs. −10 dB, respectively) at the point of mean deviation change identification, especially in the context of unreliable results. Performing two tests per visit offered similar advantages compared with more tests. False positive change detection rates (<2.5%), were similar across all conditions. Patients followed up 6 monthly had less severe mean deviation loss at follow-up compared to 1-year and 2-year follow-up intervals.

Conclusions

Performing two tests per clinical visit at 6 months is practical using SITA-Faster and provides higher detection rates of mean deviation change in comparison with only one test performed per visit and more spaced-out intervals.

Translational Relevance

This model provides guidance for selecting the number of tests per visit to detect mean deviation change.