Magnetic resonance imaging of intraocular optic nerve disorders: review article

Maculopathies Referred to Neuro-Ophthalmology Clinic as Optic Neuropathies: A Case Series

BACKGROUND

The clinical features of maculopathies and optic neuropathies often overlap: Both present with decreased visual acuity and variable loss of color vision; thus, maculopathy can be misdiagnosed as optic neuropathy, leading to patient harm. We aimed to determine what findings and/or tests were most helpful in differentiating between optic neuropathy and maculopathy.

METHODS

A retrospective chart review of consecutive patients over 4.5 years who were referred to neuro-ophthalmology clinics with the diagnosis of optic neuropathy but whose final diagnosis was maculopathy. Patient demographics, mode of presentation, clinical profile, complete ophthalmological examination, results of all ancillary testing, and final diagnosis were recorded.

RESULTS

A total of 47 patients (27 women) were included. The median age was 55 years (range, 18-85). Most referrals were by ophthalmologists (72.3%) and optometrists (12.8%). The diagnosis of maculopathy was made in 51.1% of patients at the time of first neuro-ophthalmic consultation. Only 6.4% patients (3) had relative afferent pupillary defect. Benign disc anomalies (tilted, myopic, small, or anomalous discs) were present in 34.0%, and 21.3% had pathologic disc changes unrelated or secondary to maculopathy. Macular ocular coherence tomography (OCT) was abnormal in 84.4% (with outer retinal pathology in 42.2% and inner retina pathology in 17.8%). Retinal nerve fiber layer (RNFL) thickness was normal in 82.6% of patients.

CONCLUSIONS

Macular OCT is a high-yield test in differentiating between optic neuropathy and maculopathy and should be obtained in patients with suspected optic neuropathies who have normal RNFL thickness. Macular dystrophies, particularly cone dystrophies, unspecified retinal disorders, and macular degeneration were the most common mimics of optic neuropathy. The diagnosis was often present on OCT of the macula. The presence of coexistent benign and pathological disc anomalies may lead to maculopathy being misdiagnosed as optic neuropathy.

Differences in the involved sites among different types of demyelinating optic neuritis in traditional MRI examination: A systematic review and meta-analysis

Background

Magnetic resonance imaging (MRI) plays a significant role in assessing optic neuropathy and providing more detailed information about the lesion of the visual pathway to help differentiate optic neuritis from other visual disorders. This study aims to systematically review the literature and verify if there is a real difference in lesion location among different demyelinating optic neuritis (DON) subtypes.

Methods

A systematic search was conducted including 8 electronic databases and related resources from the establishment of the database to August 25th, 2020. We classified DON into 5 subtypes and divided the visual pathways into five segments mainly comparing the differences in the involved visual pathway sites of different subtypes.

Results

Fifty-five studies were included in the analysis, and the abnormal rate was as high as 92% during the acute phase (within 4 weeks of symptom onset). With respect to lesion location, the orbital segment of the optic nerve was the most frequently involved (87%), whereas optic tract involvement was very rare. Involvement of the orbital segment was more common in myelin oligodendrocyte glycoprotein antibody-related optic neuritis (MOG-ON) (78%) and chronic relapsing inflammatory optic neuropathy (CRION) (81%), while the lesion was found to be located more posteriorly in neuromyelitis optica spectrum disorder-related optic neuritis (NMOSD-ON). With respect to lesion length, approximately 77% of MOG-ON patients had lesions involving more than half of the optic nerve length.

Conclusions

MRI examination is recommended for DON patients in the acute phase. In MOG-ON, anterior involvement is more common and the involved length is mostly more than 1/2 of the optic nerve length, whereas posterior involvement, intracranial segment, optic chiasm, or optic tract, is more common in NMOSD-ON.

Prospero registration number

CRD42020222430 (25-11-2020).