Do additional testing locations improve the detection of macular perimetric defects in glaucoma?

Purpose

to evaluate the ability of additional central testing locations to improve detection of macular visual field (VF) defects in glaucoma.

Design

prospective cross-sectional study.

Participants

440 healthy people and 499 patients with Glaucomatous Optic Neuropathy (GON) were tested with a fundus tracked perimeter (CMP, CenterVue, Italy) using a 24-2 grid with 12 additional macular locations (24-2+).

Methods

GON was identified based on expert evaluation of optic nerve head photographs and optical coherence tomography scans, independently of the visual field (VF). We defined macular defects as locations with measurements outside the 5% and 2% normative limits on Total Deviation (TD) and Pattern Deviation (PD) maps within the VF central 10 degrees. Classification was based on the total number of affected macular locations (overall detection) or on the largest number of affected macular locations connected in a contiguous cluster (cluster detection). Criteria based on the number of locations and cluster size were used to obtain equivalent specificity between the 24-2 and the 24-2+, calculated using false detections in the healthy cohort. Partial Areas Under the detection Curve (pAUCs) were also compared at specificities ≥ 95%.

Main Outcome Measure

matched specificity comparison of the ability to detect glaucomatous macular defects between the 24-2 and 24-2+ grids.

Results

at matched specificity, cluster detection identified more macular defects with the 24-2+ compared to the 24-2. For example, the mean (95% confidence interval) increase in percentage of detection was 8 (5, 11)% and 10 (7, 13)% for TD-5% and PD-5% maps, respectively, and 5 (2, 7)% and 6 (4, 8)% for the TD-2% and PD-2% maps respectively. There was good agreement between the two grids. The improvement measured by pAUCs was also significant, but generally small. The percentage of eyes with macular defects ranged from 30 to 50%. Test time for the 24-2+ was longer (21% increase). Between 74% and 98% of defects missed by the 24-2 had at least one location with sensitivity < 20 dB,

Conclusions

VF examinations with additional macular locations can modestly improve the detection of macular defects in GON without loss of specificity when appropriate criteria are selected.

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