OCTA Imaging Inaccuracies Are Common Among Patients With Edematous Optic Discs

Optical coherence tomography angiography (OCTA) less accurately  identifies disc boundaries and radial peripapillary capillary (RPC) network segmentation in eyes with edematous optic discs following acute nonarteritic anterior ischemic optic neuropathy (NAION), according to research published in the Canadian Journal of Ophthalmology.

Researchers enrolled 20 patients with NAION who had optic disc edema and visual impairment onset within 2 weeks of diagnosis along with 18 healthy control individuals in the retrospective, observational analysis. Participants underwent comprehensive eye exams which included best corrected visual acuity, biomicroscopy, and intraocular pressure (IOP) measurement. 

Researchers captured 2 en face OCTA images of the optic disc of 1 eye per participant and 2 graders corrected the disc boundary and radial peripapillary capillary (RPC) segmentation generated by the image. The team assessed the frequency of segmentation errors and impact on vessel density and nerve fiber layer thickness.

The report shows misidentified disc borders in 5 healthy eyes (27.7%) and 19 eyes with NAION (95.0%; P <.001) and segmentation errors at the RPC level in 6 control eyes (33.33%) and 19 eyes with NAION (95.0%; P <.001).

Interrater agreements for detecting disc boundary misidentification and segmentation error at RPC slabs were .95 and .96 with Cohen’s kappa coefficient, according to the report.

“We demonstrated a high frequency of misidentified optic disc border and segmentation artifacts at the RPC slab in peripapillary OCTA images of eyes with acute NAION,” according to the researchers. “Disc boundaries and RPC segmentation should be checked and, if needed, manually corrected in comparative quantitative measurements.”

Study limitations include the use of only 1 OCTA instrument and failure to assess outer retinal slabs.