May 31, 2019 Conference
To determine the minimum distance band (MDB) neuroretinal rim thickness at which visual field (VF) damage becomes detectable and associated with structural loss.
Retrospective cross-sectional study.
57 healthy and 101 glaucoma subjects (one eye per subject) were recruited from an academic institution.
All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey visual field analyzer 750i; Carl Zeiss Meditec, Dublin, CA) and spectral domain optical coherence tomography volumetric scans (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Comparison of MDB thickness values with VF mean deviation values showed a plateau of VF mean deviation values followed by a sharp decline at lower MDB neuroretinal rim thickness values. A broken stick statistical analysis was utilized to estimate the tipping point at which MDB neuroretinal rim thickness values are associated with initial VF defects. The slope was computed for data below the tipping point.
Main Outcome Measures
Point at which VF loss becomes associated with MDB neuroretinal rim thickness values.
158 subjects were recruited for the study (57 healthy and 101 open angle glaucoma patients). 55% of the subjects were female, and 65% were Caucasian. Of the OAG patients, 67 had primary OAG, 14 had pseudoexfoliation glaucoma, 8 had pigmentary glaucoma, and 12 had normal tension glaucoma. The mean MDB thickness was 313 microns for healthy subjects and 175 microns for glaucoma subjects. The mean global MDB value associated with VF loss was 227 ?m, which is a 25.8% loss from the mean normal value.
In open angle glaucoma, substantial MDB neuroretinal rim thickness loss occurs before functional visual field defects become detectable.