RESUMO
Purpose: The hallmark of non-arteritic anterior ischemic optic neuropathy (NAION) is vascular compromise to the anterior optic nerve and thinning of the retinal nerve fiber layer (RNFL) and secondary degeneration of the retinal ganglion cell body or thinning of the ganglion cell complex (GCC). This study investigates optical coherence tomography (OCT) and OCT Angiography (OCTA) changes in chronic NAION and identifies imaging biomarkers that best predict disease. Methods: We performed a retrospective case-control study of 24 chronic NAION eyes (18 patients) and 70 control eyes (45 patients) to compare both whole-eye and regional OCT, OCTA, static perimetry measurements. OCT measurements were quantified automatically using commercial software, and OCTA was analyzed using custom MATLAB script with large vessel removal to measure 154 total parameters per eye. Results: We confirmed that static perimetry mean deviation (MD) was significantly worse in chronic NAION (-13.53 ± 2.36) than control (-0.47 ± 0.72; P < 0.001) eyes, and NAION eyes had 31 µm thinner RNFL (control: 95.9 ± 25.8 µm; NAION: 64.5 ± 18.0, P < 0.001), and 21.8 µm thinner GCC compared with controls (control: 81.5 ± 4.4 µm; NAION: 59.7 ± 10.5, P < 0.001). Spearman correlation analysis of OCTA parameters reveal that vessel area density (VAD) and flux are highly correlated with visual field MD and OCT measurements. Hierarchical clustering two distinct groups (NAION and control), where standardized measurements of NAION eyes were generally lower than controls. Two-way mixed ANOVAs showed significant interaction between patient status (control and chronic NAION) and structure (optic disk and macula) for annulus VAD and flux values and mean RNFL and GCC thickness. Post-hoc tests showed this effect stems from lower peripapillary values in NAION compared to controls. Separate logistic regression models with LASSO regularization identified VAD and flux are one of the best OCTA parameters for predicting NAION. Conclusion: Ischemic insult to the optic disk is more severe likely from primary degeneration of the affected peripapillary region while macula is affected by secondary retrograde degeneration and loss of retinal ganglion cells. In addition to OCT measurements, peripapillary and macular vascular parameters such as VAD and flux are good predictors of optic nerve and retinal changes in NAION.
RESUMO
Purpose: The purpose of this study was to investigate how axial length (AL) changes the relationship of intraocular pressure (IOP) with peripapillary vessel density (pVD) in glaucoma versus non-glaucomatous eyes. Methods: A population-based, cross-sectional study of 2127 African Americans aged 40 years and older in Inglewood, California, were imaged with 6 × 6-mm optic disc optical coherence tomography angiography scans. There were 1028 healthy subjects (1539 eyes) and 65 subjects with glaucoma (86 eyes) who met inclusion criteria. A multivariable linear mixed effects regression model investigated the relationship of IOP on pVD after controlling for signal strength, retinal nerve fiber layer thickness, and age. These results were stratified by AL groups. Results: Higher IOP was a significant predictor of lower pVD among subjects with glaucoma (P = 0.009), but not among healthy subjects (P = 0.26). After stratifying by the sample median AL (23.46 mm), higher IOP was associated with lower pVD among subjects with glaucoma with longer AL (≥ 23.46 mm, P = 0.005), but not among those in the shorter AL (< 23.46 mm, P = 0.45). IOP was not significantly associated with pVD among healthy subjects in either AL stratum. Conclusions: Among subjects with glaucoma with longer AL, IOP was significantly associated with pVD. This relationship was not seen among subjects with glaucoma with shorter AL or non-glaucomatous subjects in either AL group. These findings support the hypothesis that disturbed retinal autoregulation may be present in subjects with glaucoma with longer AL. Longitudinal studies are needed to further investigate whether axial elongation increases glaucoma risk by compromising retinal autoregulation.