Differences between Non-arteritic Anterior Ischemic Optic Neuropathy and Open Angle Glaucoma with Altitudinal Visual...

Area of Science:

• Ophthalmology
• Neuro-ophthalmology
• Medical Imaging

Background:

• Non-arteritic anterior ischemic optic neuropathy (NAION) and open angle glaucoma (OAG) can present with similar altitudinal visual field defects.
• Differentiating these conditions is crucial for appropriate patient management and treatment.

Purpose of the Study:

• To compare retinal nerve fiber layer (RNFL) changes and optic nerve head (ONH) parameters between NAION and OAG patients with altitudinal visual field defects.
• To evaluate the utility of spectral domain optical coherence tomography (SD-OCT) in distinguishing between these two optic neuropathies.

Main Methods:

• Prospective enrollment of 17 NAION and 26 OAG patients.
• Assessment of standard visual field indices (mean deviation, pattern standard deviation) using Humphrey visual field testing.
• Analysis of ONH and RNFL parameters using Cirrus HD-OCT, including disc area, rim area, and RNFL thickness by quadrant.

Main Results:

• No significant difference in visual field indices (mean deviation, pattern standard deviation) between NAION and OAG groups.
• OAG group had a smaller rim area in the affected eye compared to the NAION group (p < 0.001).
• Inferior RNFL thickness was reduced in both affected and unaffected eyes in the OAG group compared to the NAION group.

Conclusions:

• Optic disc head analysis using SD-OCT, examining both affected and unaffected eyes, can aid in differentiating NAION from OAG in cases of altitudinal visual field defects.
• RNFL and ONH parameters, particularly rim area and inferior RNFL thickness, show distinct patterns between NAION and OAG.