Influencia del tamaño del disco óptico en la medición de la Capa de Fibras Nerviosas de la Retina realizada por Cirrus OCT

Resumo

Purpose: To evaluate the relationship between the optic disc size and the retinal nerve fibre layer (RNFL) thickness measurement using Cirrus OCT. To investigate the influence on glaucoma diagnosis. Design: Observational, cross-sectional study. Methods: Five hundred eighty eight eyes (290 controls and 298 glaucomatous) were included . The disc size was determined by measuring the vertical and horizontal diameters, as well as the area. The relationship between RNFL measurements and disc size in the control group was evaluated by linear regression analysis. To evaluate the effect of the optic size on the diagnosis accuracy of Cirrus OCT, the total sample was divided in quartiles (area ≤1.56 mm2; 1.57-1.78 mm2; 1.79-2.08 mm2; ≥ 2.09 mm2). Areas under the receiver operating characteristic curves (AUCs) were calculated for each group. T-Student independent data analysis was used to stablish a comparison between the disc size in eyes with an incorrect diagnosis (false positive –FP– and false negative –FN–) and those with a correct diagnosis (true positive –TP– and true negative –TN–). Results: For the average RNFL measurement, only a statistically significant correlation (r = 0.16, p = 0.02) with the vertical diameter was found. However, for the inferior quadrant measurement, this association was also observed in the area (r = 0.13, p = 0.03). Best AUC was obtained for group 2 (areas between -1.78 - 1.57 mm2), (AUC: 0.89, IC95%: 0.82 a 0.93, p< 0.001, and AUC: 0.90, IC95%: 0.83 a 0.95, p< 0.001, Average and inferior quadrant, respectively). Disk sizes were higher in the FN group than in the TN. These differences were not found between the FP and TP. Conclusion: The disc size influences the ability of Cirrus OCT to diagnose glaucoma, which is reduced in large and small discs.