Abstract
Purpose :
Visual field loss in glaucoma patients is optimized to maximize the binocular field of vision via reciprocally asymmetric scotomal patterns in fellow eyes. (Jigsaw Effect; TVST 3.3.1, 2014). We now observe similar maximization of monocular fields arising over a physiologic time-frame. Discrete scotomal regions appear to be switched on and off via CNS coordinated alternation over a period of minutes. With MD tending to remain stable, one set of scotomal zones become visually active while adjacent segments of the previously intact visual field are switched off. These findings were discovered during a post-hoc analysis of prospective test-retest (TR) reliability of a new virtual reality perimeter.
Methods :
Prospectively enrolled glaucoma patients with ≥5 years of highly reliable (FL, FP, and FN < 20%) and stable (ΔMD<5dB over 5yr) Humphrey SITA visual field testing history were tested with the VisuALL virtual reality perimeter (Olleyes Inc., Summit, New Jersey, USA) using its 24-2 normal threshold algorithm twice, back-to-back. Monte Carlo simulations were used to test the hypothesis that test-retest (TR) variability within ipsilateral visual field measurements could be contribuing to improved function and visual field survival in these diseased eyes. Visual fields were randomized 1,000,000 times and compared using a published method respecting the hill of vision (see TVST 3.3.1, 4.2.8 and 4.3.7).
Results :
44 eyes of 22 patients were included in the analysis. The best composite uniocular TR measurements were significantly worse than the mean randomized composite for the same eye (p<0.05). However, when combined, the resulting oscillating monocular fields were significantly better than the mean from 1,000,000 randomizations (p<0.0001; +1.37 dB), better than the best randomly-generated field (+0.17 dB).
Conclusions :
Composite visual field patterns were significantly better than random variation, indicating CNS-directed throttling of neuronal function to maximize time-averaged visual field function in glaucomatous eyes, optimizing metabolic activation and recovery and minimizing apoptosis. Short-term fluctuation in perimetrically reliable patients may thus be a positive finding reflecting the existence of this dynamic protective phenomenon.
This is a 2021 ARVO Annual Meeting abstract.