Abstract
Purpose:
To compare retinal nerve fiber layer thickness (RNFLT) in patients with optic disc swelling of different etiologies. Measurements were made with scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (SD-OCT).
Methods:
Both GDx SLP (enhanced corneal compensation) and Spectralis SD-OCT measurements of RNFLT were made in 19 eyes with papilledema (PE), 10 eyes with optic neuritis (ON), and 18 eyes with non-arteritic anterior ischemic optic neuropathy (NAION). Differences in SLP (SLP-RNFLT) and OCT (OCT-RNFLT) measurements among cases with different etiologies were investigated.
Results:
Average OCT-RNFLT in eyes with PE, ON, and NAION was 169.8 ± 47.0, 145.6 ± 24.7, and 162.5 ± 55.4 µm, respectively. No statistical differences were noted in these values. Average SLP-RNFLT in patients with PE, ON, and NAION was 63.5 ± 10.5, 62.7 ± 5.3, and 51.7 ± 10.9, respectively. Average SLP-RNFLT in NAION patients was smaller than in PE (p < 0.01) or ON (p = 0.02) patients. When RNFLT in each retinal quadrant was compared, no difference among etiologies was noted on OCT, but on SLP, the superior quadrant was thinner in NAION than in PE (p < 0.001) or ON (p = 0.001) patients. Compared with age-adjusted normative data of SLP-RNFLT, average SLP-RNFLT in PE (p < 0.01) and ON (p < 0.01) patients was greater. Superior SLP-RNFLT in NAION patients was smaller (p = 0.026). The average OCT-RNFLT: SLP-RNFLT ratio was smaller in NAION than in PE (p = 0.001) patients.
Conclusions:
In the setting of RNFL thickening, despite increased light retardance in PE and ON eyes, SLP revealed that NAION eyes have less retardance, possibly associated with ischemic axonal loss.
Keywords: 613 neuro-ophthalmology: optic nerve •
550 imaging/image analysis: clinical •
627 optic disc