OCT measurements in patients with optic disc edema

Area of Science:

• Ophthalmology
• Medical Imaging
• Retinal Diseases

Background:

• Disc edema (DE) can affect optical coherence tomography (OCT) measurements.
• Understanding DE's impact on retinal nerve fiber layer (RNFL) thickness is crucial for accurate diagnosis.

Purpose of the Study:

• To investigate how disc edema (DE) influences OCT-based RNFL thickness measurements.
• To differentiate the effects of DE from inflammatory optic neuropathies and retinal vein occlusions on RNFL thickness.

Main Methods:

• OCT RNFL circle scans were performed on 13 patients with DE and 13 controls.
• RNFL thickness was assessed using the OCT normative database and compared with total retinal thickness.
• Normalized RNFL percentage (nRNFL%) was calculated for affected and unaffected regions.

Main Results:

• Patients with DE showed significantly greater average RNFL thickness (122 ± 23 µm) compared to controls (91 ± 8 µm).
• Peripapillary total retinal thickness was also significantly higher in the DE group (329 ± 56 µm) versus controls (255 ± 12 µm).
• A significant difference in averaged nRNFL% was observed in the optic neuropathy group but not in the retinal vein occlusion group.

Conclusions:

• OCT measurements of RNFL thickness are significantly influenced by disc edema.
• The observed differences in nRNFL% suggest edema affects RNFL more directly in optic neuropathies than in retinal vein occlusions.
• These findings highlight the importance of considering the etiology of DE when interpreting OCT RNFL measurements.