Optic Disc Microvasculature Dropout in Pre-perimetric Glaucoma.

PURPOSE:To investigate factors associated with optic disc microvasculature dropout (MvD-D) in pre-perimetric primary open-angle glaucoma (PPG) patients. METHODS:139 eyes of PPG patients were categorized according to the presence of MvD-D with optical coherence tomography angiography (OCTA). Factors including visual field (VF) mean deviation (MD), retinal nerve fiber layer (RNFL) thickness, focal lamina cribrosa (LC) defect, optic disc hemorrhage (DH), and parapapillary deep-layer microvasculature dropout (MvD-P) were compared between eyes with and without MvD-D. RESULTS:MvD-D was observed in 69 PPG eyes (49.6%). Compared with eyes without MvD-D, the ones with MvD-D had a significantly thinner RNFL in all areas except the nasal sector, worse VF MD, and a focal LC defect and MvD-P (P<0.05): male gender also was more highly prevalent. A considerable number of eyes with MvD-D lacked focal LC defect (62.3% (43/69)) or MvD-P (71.0% (49/69)), while a few eyes without MvD-D had focal LC defect (10.0% (7/70)) or MvD-P (2.9% (2/70)). In a multivariable logistic regression analysis, male gender (odds ratio [OR], 3.96; P<0.001), worse VF MD (OR, 1.44; P=0.019), thinner global RNFL (OR, 1.13; P<0.001), higher prevalence of focal LC defect (OR, 3.71; P=0.014) and MvD-P (OR, 7.85; P<0.001) were significantly associated with MvD-D. CONCLUSIONS:MvD-D was related to worse disease severity in PPG patients, and often was not accompanied by focal LC defect or MvD-P. This suggests that impaired optic disc circulation can be an early sign of glaucoma without noticeable changes in functional or structural features (i.e., VF, focal LC defect, MvD-P).