Optical Coherence Tomography Angiography Vessel Density in Glaucomatous Eyes with Focal Lamina Cribrosa Defects

Abstract

Purpose To investigate whether vessel density assessed by optical coherence tomography angiography (OCT-A) is reduced in glaucomatous eyes with focal lamina cribrosa (LC) defects. Design Cross-sectional case-control study. Participants Eighty-two primary open angle glaucoma (POAG) patients from the Diagnostic Innovations in Glaucoma Study (DIGS) with and without focal LC defects (41 eyes of 41 patients in each group) matched by severity of visual field (VF) damage. Methods OCT-A-derived circumpapillary vessel density (cpVD) was calculated as the percentage area occupied by vessels in the measured region extracted from the retinal nerve fiber layer (RNFL) in a 750-μm-wide elliptical annulus around the disc. Focal LC defects were detected using swept-source OCT images. Main Outcome Measures Comparison of global and sectoral (eight 45 degree sectors) cpVDs and circumpapillary retinal nerve fiber layer (cpRNFL) thicknesses in eyes with and without LC defects. Results Age, global and sectoral cpRNFL thicknesses, visual field mean deviation and pattern standard deviation, presence of the optic disc hemorrhage, and mean ocular perfusion pressure did not differ between the patients with and without LC defects (P > 0.05, for all comparisons). Mean cpVDs of eyes with LC defects were significantly lower than those without a defect globally (52.9 ± 5.6 vs. 56.8 ± 7.7 %, P = 0.013), and in the inferotemporal (IT) (49.5 ± 10.3 vs. 56.8 ± 12.2 %, P = 0.004), superotemporal (ST) (54.3 ± 8.8 vs. 58.8 ± 9.6 %, P = 0.030), and inferonasal (IN) (52.4 ± 9.0 vs. 57.6 ± 9.1 %, P = 0.009) sectors. Eyes with LC defects in the IT sector (n = 33) had significantly lower cpVDs than those without a defect in the corresponding IT and IN sectors (P < 0.05, respectively). Eyes with LC defects in the ST sector (n = 19) had lower cpVDs in ST, IT, and IN sectors (P < 0.05, respectively). Conclusions In eyes with similar severity of glaucoma, OCT-A-measured vessel density was significantly lower in POAG eyes with focal LC defects than those without a LC defect. Moreover, reduction of vessel density was spatially correlated with the location of the LC defect.

Optical Coherence Tomography Angiography in Glaucoma: A Review

“…We tried to minimize this risk by not restricting the publication year. Second, in several studies a considerable number of patients were excluded because of poor image quality secondary to poor fixation, movement artifacts, or the presence of a visually significant cataract [6, 7, 16, 26, 34, 71, 95]. This potentially limits the clinical usefulness of OCTA in populations with cataract, macular lesions, and advanced glaucoma.…”

The Future of Imaging in Detecting Glaucoma Progression

“…In eyes with glaucoma and a single-hemifield defect, diminished vascular density of the macular and peripapillary regions was also demonstrated in unaffected hemifields (41). OCTA of eyes with glaucoma and LC defects portrayed diminished vascular density corresponding to the locations of these defects (42). …”

Revisiting the vascular theory of glaucoma using optical coherence tomography angiography

“…Interes ngly, however, the prevalence of DH was similar in the groups with (4/41) and without (7/41) lamina cribrosa defects in their study. 42 AUCs of structural parameters (rim area, RNFL and GCC thickness) were signifi cantly greater (p<0.05 for all comparisons) than that of the vessel density measurements in the ONH, peripapillary and the macular regions both in POAG eyes with and without DH. This may suggest that structural changes occur before vessel density changes in POAG.…”

“…They found that in eyes with similar visual sensi vity loss, the decrease in vessel density in POAG eyes with focal lamina cribrosa defects was signifi cantly greater than in POAG eyes without focal lamina cribrosa defects. 42 Because of the strong concordance between DH and lamina cribrosa defects, this result would suggest that the decrease in vessel densi es in POAG eyes with DH would also be greater than in POAG eyes without DH. Interes ngly, however, the prevalence of DH was similar in the groups with (4/41) and without (7/41) lamina cribrosa defects in their study.…”

“…It assessed blood fl ow by comparing phase diff erences between adjacent A-scans. 42 Although Doppler OCT was appropriate for large vessels around the disc, it was not sensi ve enough to measure accurately the low veloci es in small vessels that make up the ONH and re nal microcircula on. 7 Of the several OCT-based techniques that have been developed to image microvascular networks in human eyes in vivo, op cal microangiography (OMAG) was a technique that was able to resolve the fi ne vasculature in both re nal and choroid layers.…”