Evaluating Increment and Decrement Stimuli Responses in Patients with Glaucoma Using Virtual Reality-Based Perimetry

To evaluate increment and decrement stimuli responses in glaucoma using a virtual reality-based perimetric system, Vivid Vision Perimetry (VVP) and to compare these findings with conventional perimetry.

This is a cross-sectional study involving participants with diagnosed perimetric glaucoma, preperimetric glaucoma, and glaucoma suspect or ocular hypertension.

Sixty-nine participants (mean age: 66.9 years; 50.7% female) were recruited from ophthalmology clinics at the University of California, San Francisco, California, United States. Eyes were grouped clinically into perimetric glaucoma (62 eyes), preperimetric glaucoma (31 eyes), and glaucoma suspect or ocular hypertension (41 eyes).

Increment and decrement stimuli were tested at 12 locations per eye using the VVP system.

Contrast sensitivities (CSs) were recorded and mean CS was computed and compared between VVP and conventional perimetry (Humphrey Visual Field [HVF]). Correlations between VVP and HVF results were computed, and statistical analyses were conducted using cluster bootstrapping to account for intereye correlations.

Perimetric glaucoma eyes had stronger correlation of CS between VVP and HVF tests compared to preperimetric glaucoma and glaucoma suspect or ocular hypertension eyes. Across all groups, decrement testing generally showed higher correlations than increment testing (perimetric: 0.48 [increment] vs. 0.61 [decrement]; preperimetric: 0.24 vs. 0.37; glaucoma suspect: 0.35 vs. 0.36). In perimetric glaucoma, particularly in moderate to severe cases, there was a significantly greater CS to decrement stimuli compared to increment stimuli (-1.46 decibels [dB] [95% confidence interval [CI]: -2.59, -0.30]). Preperimetric glaucoma eyes had significantly higher CS to increment stimuli than to decrement stimuli (+0.86 dB [95% CI: 0.11, 1.67]). Throughout all clinical subtypes, areas of the visual field with higher contrast thresholds (lower sensitivity) showed greater sensitivity to increment stimuli, whereas areas with lower contrast thresholds (higher sensitivity) showed greater sensitivity to decrement stimuli (perimetric: m = 0.63, R = 0.71; preperimetric: m = 0.50, R = 0.6; glaucoma suspect: m = 0.45, R = 0.51; all P < 0.01). Additionally, peripheral points generally exhibited lower CS than central points in both increment and decrement testing in all groups (all P < 0.05).

We found significant differences in how preperimetric and perimetric glaucoma eyes respond to varying stimuli. Preperimetric eyes were better at detecting increment stimuli, while perimetric eyes were better at detecting decrement stimuli. Our results confirm earlier studies reporting greater OFF-pathway vulnerability in early glaucoma but suggest a shift to ON-pathway vulnerability in severe glaucoma.

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