Retinal Ganglion Cell Loss and Patterns of Neuroretinal Rim Thinning at the Onset of Visual Field Defects in Glaucoma.
Rabinowitz Aaron Samuel, Vilasboas-Campos Verônica, Filho Marcus Guerreiro, Medeiros Felipe A
AI Summary
This study found diffuse optic rim thinning at early visual field defect onset indicates significantly more retinal ganglion cell loss than localized thinning, highlighting the importance of structural assessment for early glaucoma.
Abstract
Purpose
To compare retinal ganglion cell (RGC) loss in glaucoma suspect eyes with diffuse versus localized neuroretinal rim loss at the time of the first confirmed visual field defect.
Design
Prospective observational cohort study.
Subjects
Fifty-three glaucoma suspect eyes and 124 healthy eyes.
Methods
Fifty-three glaucoma suspect eyes were followed until development of repeatable glaucomatous visual field defects. Estimated RGC counts were derived using a validated model combining standard automated perimetry and optical coherence tomography measurements. Conversion was defined as the first confirmed abnormal field, with RGC estimates taken within three months. Neuroretinal rim loss was classified as diffuse or localized through masked grading of optic disc stereophotographs. A normative cohort of 124 healthy eyes provided reference RGC values.
Main outcome measures
Estimated RGC counts at perimetric conversion.
Results
Of the 53 eyes, 36 (68%) showed diffuse and 17 (32%) localized rim loss. Eyes with diffuse loss had significantly lower RGC counts at conversion (613 543 ± 114 886) than those with localized loss (733 614 ± 65 776, P < .001), corresponding to a 32.6% and 19.4% mean reduction relative to healthy controls, respectively. Mean deviation differed modestly between groups (-2.44 ± 1.36 dB vs -1.62 ± 1.13 dB, P = .033) at time of conversion. Multivariable analysis identified diffuse rim loss, older age, and Black race as independent predictors of lower RGC counts.
Conclusions
Diffuse rim thinning at the earliest stage of functional loss is associated with substantially greater RGC loss than localized thinning. These findings support incorporating structural features into early glaucoma assessment.
MeSH Terms
Shields Classification
Key Concepts4
In glaucoma suspect eyes (n=53) with diffuse neuroretinal rim loss at the time of the first confirmed visual field defect, estimated retinal ganglion cell (RGC) counts were significantly lower (613,543 ± 114,886) compared to those with localized loss (733,614 ± 65,776, P < .001).
Glaucoma suspect eyes (n=53) with diffuse neuroretinal rim loss showed a 32.6% mean reduction in estimated retinal ganglion cell counts relative to healthy controls, while those with localized loss showed a 19.4% mean reduction.
At the time of perimetric conversion, mean deviation differed modestly between glaucoma suspect eyes with diffuse neuroretinal rim loss (-2.44 ± 1.36 dB) and those with localized loss (-1.62 ± 1.13 dB, P = .033).
Multivariable analysis in glaucoma suspect eyes (n=53) identified diffuse neuroretinal rim loss, older age, and Black race as independent predictors of lower estimated retinal ganglion cell counts.
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