Optical Coherence Tomography Angiography of a Pale Optic Disc in Demyelinating Optic Neuritis and Ischemic Optic Neuropathy.

BACKGROUND: In the setting of a pale optic disc, distinguishing a previous episode of optic neuritis (ON) from that of nonarteritic anterior ischemic optic neuropathy (NAION) may be difficult on clinical examination. Differences in peripapillary vascular network structures, if present, might be of diagnostic utility. METHODS: Thirty-five eyes with demyelinating ON, 33 eyes with NAION, and 81 eyes of normal subjects were imaged with optical coherence tomography angiography (OCT-A) to assess peripapillary vascular density (VD). In addition, OCT was used to measure peripapillary retinal nerve fiber layer (RNFL) thickness. Areas under the receiver operating characteristic curves were used to differentiate ON vs NAION. RESULTS: NAION eyes had significantly thinner RNFL thickness than ON eyes. Age-adjusted analysis showed that the peripapillary VD values were significantly reduced in NAION (48.3 ± 7.4%) and ON eyes (54.7 ± 6.1%) compared with healthy controls (62.1 ± 4.6%); pairwise comparisons showed statistically significant differences among all 3 groups. After adjustment for severity of optic nerve injury according to mean RNFL thickness, all VD parameters were not significantly different between ON and NAION eyes. The area under the receiver operating characteristic curves for differentiating NAION from ON eyes was similar for VD (0.75) and RNFL thickness (0.74). CONCLUSIONS: Peripapillary VD measurement performs as well as RNFL thickness for distinguishing previous episodes ON and NAION. VD decline might be secondary to RNFL damage and, therefore, VD data have a limited role differentiating these 2 disorders.

Survey of Nerve Fiber Layer Thickness in Anisometropic and Strabismic Amblyopia.

. To investigate the effect of anisometropic and strabismic amblyopia on the nerve fiber layer thickness. This cross-sectional study was done on 54 amblyopic subjects, equally in both strabismic and anisometropic groups. The thickness otonerve fiber layer measured in superior, inferior, nasal, temporal quadrants and as a whole in both eyes of both groups. The means of thickness were compared in amblyopic and sound eyes. In strabismus group, the average nerve fiber layer thickness of the sound eye , in superior, inferior, nasal and temporal quadrants and as a whole were 113.23±14, 117.37±25, 68.96±6, 69.55±14 and 93.40±8 microns respectively. In amblyopic eyes of the same group, these measurements were 103.11±18, 67.74±11, and 69.59±16 and 89.59±12 microns in superior, inferior, nasal, temporal quadrants and as whole respectively. In anisometropic groups, the sound eye measurements were as 130.96±22, 129.07±29, 80.62±12, and 83.88±20 and 107.7±13 microns in superior, inferior, nasal and temporal quadrants and as a whole orderly. In amblyopic eyes of this group the mean thicknesses were 115.63±29, 133.15±25, 78.8±15, 80.2±16 and 109.17±21 microns in superior, inferior, nasal, temporal quadrants and as a whole respectively. Statistically, there were no significant differences between amblyopic and sound eyes (P>0.5). Our study did not support any significant change in a nerve fiber layer thickness of amblyopic patients; however, decreased thickness in superior and nasal quadrants of strabismic amblyopia and except inferior quadrant and as a whole. These measurements may be a clue for management and prognosis of amblyopia in old age.