We retrospectively revised the ophthalmological,
neurological and imaging data of patients who presented to our Emergency Department (ED) with the first episode of acute ON from january 2015 to January 2017 (N= 85).
We excluded some patients according to the following criteria:
- patients aged<18 years
- previous episodes of ON
- history of MS or NMO
- patients affected by known ophthalmological diseases
- patients affected by known immunological / infective disorders
- patients with previous neurological events
- patients with family history of Leber hereditary optic neuropathy
- lack of complete ophthalmological,
neurological,
imaging data
- time between symptoms onset and presentation > 14 days
- time between ED arrival and MRI execution > 14 days
- MRI executed in other Institutions
- lack of follow up data
- clinical follow up < 1 year
We therefore included in our study 37 patients (age range: 21-57 years; mean age: 33 years),
26 female and 11 male,
20 had right ON,
14 had ON in the left eye and 4 had bilateral ON,
for a total of 41 affected eyes.
After the arrival,
every patient underwent a complete ophthalmological examination,
including fundoscopic examination,
visual acuity assessment,
visual field and Optic Coherence Tomography (OCT),
brain and orbits unenhanced Computed Tomography,
blood tests to exclude infective/autoimmune causes of ON and to test AQP4 antibodies.
Following the neuro-ophthalmological confirmation of the diagnosis of optic neuritis,
steroid therapy was administered intravenously within 24 h from the patient access (methylprednisolone 1 g/d for five days,followed by a low-dose steroid oral regimen for 15 days).
MRI of brain,
orbits,
cervical spine was executed within 7 +/- 6 days from ON onset with the following acquisition protocol
Imaging exams were transferred to the MRI workstation (Leonardo,
Siemens,
Forchheim,
Germany ) and revised by 2 experienced neuroradiologist in consensus.
Brain MRIs were classified as:
- normal
- nonspecific
- suspected demyelination (lesion with MS-like shape,
localized in typical MS sites -periventricular,
juxtacortical,
infratentorial,
or spinal cord with dissemination in space) [5]
- MS-like (lesions with dissemination in space and time: coexistence of asymptomatic gadolinium-enhancing and non-enhancing lesions) [6]
Optic nerves MRIs were reported as:
normal
STIR- alteration without contrast enhancement (CE)
STIR signal abnormalities + CE
Optic nerves pathologic findings were localized in 3 sites:
intraorbital (IO)
canalicular (CA)
chiasmal (CH)
The extension of altered signal or CE was measured in cm.
OCT
OCT test was acquired using the same machine (Spectralis version 6.3.2, Eye Explorer Software 1.6.1.0,
Heidelberg Engineering™,
Heidelberg,
Germany) to be reproducible,
after mydriasis induced with 1% tropicamide.
OCT produces a cross sectional image of the peripapillary retina which is color-coded and shows the temporal,
superior,
nasal,
inferior and temporal sections on the same image.
The software automatically recognizes the retinal nerve fiber layer (RNFL) layer, measures the RNFL thickness along the scan and reports the results on a graphic display showing the RNFL thickness (in μm).
We use the average global value of RNFL
VISUAL ACUITY
Visual acuity was measured at patients’ arrival and at 6 months follow up,
according to Snellen chart (decimal).
Light perception and motus manus (mm) were assigned a decimal visual acuity of 0.
Follow up
Each patient underwent a clinical follow up of at least 12 months.
Ophthalmological evaluation including visual acuity assessment was executed at 6 months to establish the visual outcome.
Visual outcome at follow up were classified in 3 groups:
1: complete visual recovery: visual acuity back to the value before NO
2: partial visual recovery: recovery of visual acuity of at least 50% compared to the value before ON
3: stable deficit: recovery of visual acuity < 50% compared to the value before ON,
or persistence of the visual deficit,
as during ON episode
Assignment of CIS or MS diagnosis was based on revised McDonald criteria [6].