Abstract
Purpose :
Optic nerve head (ONH) swelling due to non-arteritic anterior ischemic optic neuropathy (NAION) spreads edema into the peripapillary retina that can extend into the macula. The induced retinal deformations, we previously described with papilledema, have not been studied in NAION. We hypothesized these folds, which are related to stresses and strains in the region of the neural canal, would have features different from those in papilledema reflecting different biomechanical processes or forces.
Methods :
We prospectively studied eyes with NAION, within 2 weeks of vision loss and at 1-2 months, with perimetry and spectral domain OCT (SDOCT) images of the optic disc and macula. NAION eyes were evaluated for deformations including peripapillary fluid (PPF), peripapillary wrinkles (PPW), retinal folds (RF), choroidal folds (CF), and peripapillary creases using transaxial and en face views. Deformations were evaluated in relation to the retinal nerve fiber layer (RNFL) thickness, visual acuity and mean deviation (MD).
Results :
At presentation, 50 study eyes had mean RNFL of 223 ± 75 µm, 37 (74%) had PPF, 28 (56%) had PPW, 21 (42%) had RF (all which were concentric), 8 (16%) had creases, and 0 had CF or vitreal traction on the optic disc. Folds or fluid affected the macula in 9 (18%) eyes. Visual acuity or MD did not correlate with having any type of fold. The RNFL was thicker in eyes with PPF (p = 0.001), PPW (p=0.001), RF (p=0.01) and macula involvement (p=0.002). At 1-2 months of the 39 eyes (mean RNFL of 112 ± 40 µm), and PPF (82%), PPW (90%), RF (87%), edema/folds in the macula (100%), and creases (82%) were absent; none of which had impact on the visual acuity or MD.
Conclusions :
Retinal deformations in NAION reflect dynamic processes due to local tissue distortion and extracellular fluid. The lack of CF and radial RF, which occur with papilledema, suggests the peripapillary ONH region is not under significant pressure. All folds in NAION rapidly resolve as ONH swelling lessens and axons are lost, in contrast to papilledema where the intracranial hypertension induced pressure effect on the neural canal and folds persist despite less ONH swelling.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.