Chancellery Research - Research Publications
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ItemThe Proportion of Individuals Likely to Benefit from Customized Optic Nerve Head Structure-Function Mapping(ELSEVIER SCIENCE INC, 2017-04)PURPOSE: Interindividual variance in optic nerve head (ONH) position, axial length, and location of the temporal raphe suggest that customizing mapping between visual field locations and ONH sectors for individuals may be clinically useful. Herein we quantify the proportion of the population predicted to have structure-function mappings that markedly deviate from "average," and thus would benefit from customized mapping. DESIGN: Database study and case report. PARTICIPANTS: Population database of 2836 eyes from the Beijing Eye Study and a single case report of an individual with primary open-angle glaucoma. METHODS: Using the morphometric fundus data of the Beijing Eye Study for 2836 eyes and applying a recently developed model based on axial length and ONH position relative to the fovea, we determined for each measurement location in the 24-2 Humphrey (Carl Zeiss Meditec, Dublin, CA) visual field the proportion of eyes for which, in the customized approach as compared with the generalized approach, the mapped ONH sector was shifted into a different sector. We determined the proportion of eyes for which the mapped ONH location was shifted by more than 15°, 30°, or 60°. MAIN OUTCOME MEASURES: Mapping correspondence between locations in visual field space to localized sectors on the ONH. RESULTS: The largest interindividual differences in mapping are in the nasal step region, where the same visual field location can map to either the superior or inferior ONH, depending on other anatomic features. For these visual field locations, approximately 12% of eyes showed a mapping opposite to conventional expectations. CONCLUSIONS: Anatomically customized mapping shifts the map markedly in approximately 12% of the general population in the nasal step region, where visual field locations can map to the opposite pole of the ONH than conventionally considered. Early glaucomatous damage commonly affects this region; hence, individually matching structure to function may prove clinically useful for the diagnosis and monitoring of progression within individuals.
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ItemEnhancing Structure-Function Correlations in Glaucoma with Customized Spatial Mapping(Elsevier Inc., 2015-01-20)Purpose: To determine whether the structure-function relationship in glaucoma can be strengthened by using more precise structural and functional measurements combined with individualized structure-function maps and custom sector selection on the optic nerve head (ONH). Design: Cross-sectional study. Participants: One eye of each of 23 participants with glaucoma. Methods: Participants were tested twice. Visual fields were collected on a high-resolution 3°× 3° grid (164 locations) using a Zippy Estimation by Sequential Testing test procedure with uniform prior probability to improve the accuracy and precision of scotoma characterization relative to standard methods. Retinal nerve fiber layer (RNFL) thickness was measured using spectral-domain optical coherence tomography (OCT; 4 scans, 2 per visit) with manual removal of blood vessels. Individualized maps, based on biometric data, were used. To customize the areas of the ONH and visual field to correlate, we chose a 30° sector centered on the largest defect shown by OCT and chose visual field locations using the individualized maps. Baseline structure-function correlations were calculated between 24-2 locations (n= 52) of the first tested visual field and RNFL thickness from 1 OCT scan, using the sectors of the Garway-Heath map. We added additional data (averaged visual field and OCT, additional 106 visual field locations and OCT without blood vessels, individualized map, and customized sector) and recomputed the correlations. Main Outcome Measures: Spearman correlation between structure and function. Results: The highest baseline correlation was 0.52 (95% confidence interval [CI], 0.13-0.78) in the superior temporal ONH sector. Improved measurements increased the correlation marginally to 0.58 (95% CI, 0.21-0.81). Applying the individualized map to the large, predefined ONH sectors did not improve the correlation; however, using the individualized map with the single 30° ONH sector resulted in a large increase in correlation to 0.77 (95% CI, 0.47-0.92). Conclusions: Using more precise visual field and OCT measurements did not improve structure-function correlation in our cohort, but customizing the ONH sector and its associated visual field points substantially improved correlation. We suggest using customized ONH sectors mapped to individually relevant visual field locations to unmask localized structural and functional loss.