Peripapillary and Macular Vascular Changes of Unilateral Anterior Ischemic Optic Neuropathy: An Optical Coherence Tomography Angiography Study

After approval of the local institutional ethics committee and local institutional review board, This study was conducted upon 30 patients diagnosed with acute NAION attending at Ophthalmology outpatient clinic in Fayoum University Hospitals. The participants were informed about the objectives of the study, the examination, investigations and the confidentiality of their information and their right not to participate in the study. OCT and OCTA was done for all subjects and control group with Optovue, Inc., Fremont, CA, USA. Patients were examined on presentation, after 6 weeks and lastly after 3 months. OCT was used for evaluation of Central macular thickness (CMT), nerve fiber layer thickness (NFLT) and ganglion cell complex (GCC). OCTA was done for quantitative evaluation of vessel density in the following: optic nerve head and peripapillary area, macular superficial vessel density, macular deep vessel density and foveal avascular zone. Vessel density was reported as the percentage of the total area that was occupied by blood vessels. All parameters were calculated automatically by the machine software. Poor quality scans and those with motion artifacts were excluded. Statistical analysis was performed using SPSS software (version 22; SPSS, Chicago, IL, USA). The data were presented as the mean ± SD values. P-value <0.05 was considered significant.

Inclusion criteria

• Patients diagnosed with unilateral NAION and acute or sudden painless drop of vision.
• A normal fellow eye.
• Age ≥ 40 years old.

Exclusion criteria

• Arteritic type of AION.
• NAION patients in chronic phase.
• Acute phase NAION patients with any other optic neuropathy in the other eye.
• Eyes with opaque media.
• Elevated intraocular pressure (>22 mmHg).
• Refractive errors greater than 6 diopters of spherical equivalent.
• Poor cooperation with fixation or the OCTA examination.