Spatial Summation in the Glaucomatous Macula: A Link With Retinal Ganglion Cell Damage.
Montesano Giovanni, Redmond Tony, Mulholland Pádraig J, Garway-Heath David F, Ometto Giovanni, Romano Dario, Antonacci Federica, Tanga Lucia, Carnevale Carmela, Rossetti Luca M
AI Summary
Glaucoma causes macular sensitivity loss, which is better explained by an enlargement of Ricco's area due to RGC damage, rather than just sensitivity reduction. This suggests altered spatial summation in glaucoma.
Abstract
Purpose
The purpose of this study was to test whether functional loss in the glaucomatous macula is characterized by an enlargement of Ricco's area (RA) through the application of a computational model linking retinal ganglion cell (RGC) damage to perimetric sensitivity.
Methods
One eye from each of 29 visually healthy subjects <40 years old, 30 patients with glaucoma, and 20 age-similar controls was tested with a 10-2 grid with stimuli of 5 different area sizes. Structural estimates of point-wise RGC density were obtained from optical coherence tomography (OCT) scans. Structural and functional data from the young healthy cohort were used to estimate the parameters of a computational spatial summation model to generate a template. The template was fitted with a Bayesian hierarchical model to estimate the latent RGC density in patients with glaucoma and age-matched controls. We tested two alternative hypotheses: fitting the data by translating the template horizontally (H1: change in RA) or vertically (H2: loss of sensitivity without a change in RA). Root mean squared error (RMSE) of the model fits to perimetric sensitivity were compared. Ninety-five percent confidence intervals were bootstrapped. The dynamic range of the functional and structural RGC density estimates was denoted by their 1st and 99th percentiles.
Results
The RMSE was 2.09 (95% CI = 1.92-2.26) under H1 and 2.49 (95% CI = 2.24-2.72) under H2 (P < 0.001). The average dynamic range for the structural RGC density estimates was only 11% that of the functional estimates.
Conclusions
Macular sensitivity loss in glaucoma is better described by a model in which RA changes with RGC loss. Structural measurements have limited dynamic range.
MeSH Terms
Shields Classification
Key Concepts6
The root mean squared error (RMSE) was 2.09 (95% CI = 1.92-2.26) for the model where Ricco's area (RA) changes with retinal ganglion cell (RGC) loss (H1) in patients with glaucoma and age-matched controls.
The root mean squared error (RMSE) was 2.49 (95% CI = 2.24-2.72) for the model where there is a loss of sensitivity without a change in Ricco's area (RA) (H2) in patients with glaucoma and age-matched controls.
The comparison of root mean squared error (RMSE) between the two models (H1 vs H2) showed a statistically significant difference (P < 0.001) in describing macular sensitivity loss in glaucoma.
The average dynamic range for the structural retinal ganglion cell (RGC) density estimates was only 11% that of the functional estimates in patients with glaucoma and age-matched controls.
Macular sensitivity loss in glaucoma is better described by a computational model in which Ricco's area (RA) changes with retinal ganglion cell (RGC) loss, compared to a model where sensitivity loss occurs without a change in RA.
The purpose of this study was to test whether functional loss in the glaucomatous macula is characterized by an enlargement of Ricco's area (RA) through the application of a computational model linking retinal ganglion cell (RGC) damage to perimetric sensitivity.
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