Abstract
Purpose: :
To prospectively evaluate the changes in optic nerve head topography and retinal nerve fiber layer (RNFL) thickness in patients following initial optic neuritis using the Heidelberg retina tomograph (HRT) II and scanning laser polarimetry (GDx VCC) .
Methods: :
Eighteen eyes of 8 unilateral and 5 bilateral patients with an initial episode of acute optic neuritis were prospectively followed at the 0, 1, 3 and 6 months after the onset by HRT II, GDx VCC and visual field testing with the Humphrey Field Analyzer (HFA) 30-2 fast pack.
Results: :
During the first 3 months after the onset, significant increase in cup area, cup/disc area ratio and linear cup/disc ratio and significant decrease of rim area in HRT parameters and significant decrease in TSNIT average, superior average and inferior average in GDx parameters were found (repeated measure ANOVA, Scheffe test, P<0.05). These parameters became stable after the month-3. Other HRT and GDx parameters showed no significant changes during the follow-up. At the month-6, superior average in GDx was significantly correlated with visual field damage (i.e. mean deviation of the HFA, R2=0.506, P=0.0007). In 8 unilateral cases, cup/disc area ratio and cup shape measure were significantly smaller in the affected eyes than in the fellow eyes until the month-1 after the onset (P<0.05, paired t-test). These differences were no longer significant after the month-3. No GDx parameters were significantly different between the affected and fellow eyes at any time point (P>0.05).
Conclusions: :
Changes in the optic disc topography and circumpapillary RNFL thickness were found in the first 3 months following the onset of initial optic neuritis, which possibly suggest resolving of the acute optic nerve edema and/or gradual decrease in the number of nerve fibers. Significant correlation between visual field damage and a GDx parameter may indicate the presence of the axonal damages after optic neuritis.
Keywords: neuro-ophthalmology: optic nerve