Discriminatory Power of Superficial Vessel Density and Prelaminar Vascular Flow Index in Eyes With Glaucoma and Ocular Hypertension and Normal Eyes

Abstract

PURPOSE. We evaluate the ability of optical coherence tomography angiography parameters, such as the peripapillary vessel density of the superficial retina and prelaminar flow index of the optic disc (PLFI), to differentiate primary open-angle glaucoma (POAG) and ocular hypertension (OH) from normal eyes. METHODS.The vessel density, PLFI, mean deviation of the visual field, circumpapillary retinal nerve fiber layer thickness (cpNFLT), and global loss volume of the ganglion cell complex were evaluated in one eye of 105 subjects with POAG and OH and normal eyes. The discriminatory powers of these parameters were evaluated based on the area under the curve (AUC) of the receiver operation characteristic curve and multiple comparisons.RESULTS. The vessel density (P < 0.001) and PLFI/unit area (PLFI/UA; P ¼ 0.020) in eyes with POAG were significantly less than in normal eyes. The vessel density in eyes with OH was significantly (P ¼ 0.018) reduced, whereas the PLFI/UA, global loss volume and cpNFLT were unaffected. The AUCs of the vessel density to discriminate glaucoma and OH from normal eyes were 0.832 and 0.724, respectively, and were significantly better than the PLFI/UA, in which the AUCs were 0.662 (P ¼ 0.002) and 0.569 (P ¼ 0.038), respectively. The powers of the vessel density and PLFI/UA to discriminate POAG from normal eyes were inferior to the global loss volume (P ¼ 0.006 and <0.0001) and cpNFLT (P ¼ 0.055 and P < 0.0001, respectively). CONCLUSIONS.The vessel density and PLFI/UA decreased significantly in glaucomatous eyes. The vessel density was more efficient than the PLFI/UA for differentiating glaucoma and OH from normal eyes.

Optical Coherence Tomography Angiography in Glaucoma: A Review

“…Significantly lower OCTA parameters (vessel density, blood flow index, and flow index) were found in glaucoma eyes in comparison with normal eyes in the peripapillary area [6, 16-50], the optic disc [19, 23, 25, 32, 36, 51-60] and the whole image macular area [16, 21, 32, 34, 36-38, 61-64]. In all of those areas, the diagnostic abilities increased with increasing severity of glaucoma [32, 34, 52].…”

“…The area under the curve (AUC) for the best discriminating OCTA parameter (vessel density and blood flow index) ranged between 0.75 and 1.00, while for the OCT parameter (RNFL) the values ranged between 0.76 and 0.97 [17, 19, 20, 22, 23, 25, 27, 31, 32, 34, 36, 37, 41, 49]. Most studies found an AUC above 0.850 both for the OCTA parameters [17, 20, 22, 23, 25, 31, 32, 37, 41] and for the RNFL [19, 20, 22, 25, 31, 34, 37, 49].…”

“…Most studies found an AUC above 0.850 both for the OCTA parameters [17, 20, 22, 23, 25, 31, 32, 37, 41] and for the RNFL [19, 20, 22, 25, 31, 34, 37, 49]. Only 2 studies found a significant difference, with a better AUC for the RNFL [19, 34] in both cases. The fact that only 2 studies, both including more than 100 eyes, found a significant difference could mean that OCT and OCTA provided a similar discriminatory ability and that only studies with sufficient power could find a significant difference.…”

“…Other studies found only a moderate AUC for the OCTA parameters (flow index and vessel density) of the optic disc (between 0.66 and 0.83) [19, 32, 34, 52], with a significantly better AUC for the OCT parameters (RNFL, GCC, and rim area) [19, 34]. A possible explanation for this discrepancy is the greater number of eyes included in the studies that found a significant difference, which might have resulted from a greater power [19, 34]. …”

“…All studies assessing the optic disc of nonhighly myopic eyes found significantly different OCTA parameters (flow index, blood flow index, and vessel density) between normal and glaucoma eyes [19, 23, 29, 32, 36, 51-60]. On the other hand, Akagi et al [30] found no significant difference in optic disc vessel density between groups in highly myopic eyes.…”