Abstract
Purpose: :
To evaluate in vivo the macular changes occurring after an attack of optic neuritis (ON)
Methods: :
Eight eyes of 8 patients affected by a single attack of unilateral ON (ONEs) were studied. Sixteen eyes of 16 healthy age–matched subjects were used as controls (CEs) All subjects had ametropia <3D and underwent clinical examination including visual acuity (VA) evaluation with ETDRS chart. The macular morphology was studied with a Stratus OCT3 using the test Fast Macula, that analyzes a region with a radius of 3 mm centred with respect to the fixation point (FP). According to this test, the macular region was divided into 3 areas: central area (CA) covering a circle 0.5 mm radius around FP; intermediate area (IA) between 0.5 and 1.5 mm radius from FP and peripheral area (PA) between 1.5 and 3 mm radius from FP; total macular volume (TMV) and mean thickness in each area was calculated
OCT evaluation was performed immediately after the onset of the visual impairment (baseline) and after 3 and 12 months
Data were analysed by one–way ANOVA
Results: :
At baseline, ONEs showed a significant reduction compared to the CEs in VA [ONEs 0.81±0.23 vs CEs 0.00±0.00, p<0.0001], TMV [ONEs 6.66±0.38 vs CEs 7.19±0.28, p=0.0008] and mean thickness in each areas [CA: ONEs 193.88±15.67 vs CEs 207.50±18.45, p=0.0008; IA: ONEs 264.66±24.66 vs CEs 282.39±14.34, p=0.039; PA: ONEs 226.97±11.93 vs CEs 247.97±8.67, p<0.0001] After 3 months a VA recover occurred [0.09±0.06 vs 0.81±0.23, p=0.0001], TMV was almost unchanged, whereas a significant increase of the mean thickness in the IA was found [272.47±21.46 vs 264.66±24.66, p=0.002]
After 12 months the VA was stable, TMV was slightly reduced compared to the baseline and a significant decrease of the mean thickness of the IA compared to the 3 months examination was found [259.25±23.66 vs 272.47±21.46, p=0.017]
Conclusions: :
Our data support the following considerations: 1. In ONEs the symptoms probably occur in already "defective" eyes, since at the baseline a reduction of the TMV is present. 2. The attack of ON could be a symptomatic recurrence of the disease related to the involvement of a conspicuous population of macular ganglion cells; this hypotesis is consistent with the transient thickening in the perifoveal region occurring 3 months after the onset of the visual impairment, potentially related to edema of the ganglion cell bodies. 3. An atrophy of several population of retinal cells could occur later, determining the resolution of the perifoveal thickening and the sligthly reduction of TMV observed at 12 months
Keywords: macula/fovea • ganglion cells • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)