Acute Painless Monocular Vision Loss
Acute Painless Monocular Vision Loss
The patient was given a short course of intravenous steroids with oral taper and was referred to a neurologist. She was also instructed to return for a follow-up visit to reassess her visual function in response to treatment.
The patient's painless visual loss is an atypical presentation of optic neuritis secondary to MS. The classic clinical picture is a young woman (with peak onset occurring between 30 and 40 years of age) who reports monocular acute-to-subacute vision loss that progresses over hours to days, color desaturation, and pain with eye movement.
In the Optic Neuritis Treatment Trial, 92% of patients with optic neuritis had ocular pain and 8% did not. The cause of pain in optic neuritis is believed to be distention of the optic nerve sheath irritating the trigeminal sensory fibers, which is further exacerbated by movement. However, the intracanalicular segment of the optic nerve is not disturbed by eye movement to the same degree as the anterior intraorbital segment. Thus, inflammation in this region (and when the intracranial optic nerve is affected) is more likely to be painless.
History and MRI were key to diagnosing this patient with normal-appearing optic discs on funduscopy. Although the patient presented with optic neuritis at 55 years of age, her history of a facial palsy years before and her recent unexplained episode of back pain suggested that this was a relapse of MS rather than a first attack.
Patient Follow-up and Management
The patient was given a short course of intravenous steroids with oral taper and was referred to a neurologist. She was also instructed to return for a follow-up visit to reassess her visual function in response to treatment.
Comment
The patient's painless visual loss is an atypical presentation of optic neuritis secondary to MS. The classic clinical picture is a young woman (with peak onset occurring between 30 and 40 years of age) who reports monocular acute-to-subacute vision loss that progresses over hours to days, color desaturation, and pain with eye movement.
In the Optic Neuritis Treatment Trial, 92% of patients with optic neuritis had ocular pain and 8% did not. The cause of pain in optic neuritis is believed to be distention of the optic nerve sheath irritating the trigeminal sensory fibers, which is further exacerbated by movement. However, the intracanalicular segment of the optic nerve is not disturbed by eye movement to the same degree as the anterior intraorbital segment. Thus, inflammation in this region (and when the intracranial optic nerve is affected) is more likely to be painless.
History and MRI were key to diagnosing this patient with normal-appearing optic discs on funduscopy. Although the patient presented with optic neuritis at 55 years of age, her history of a facial palsy years before and her recent unexplained episode of back pain suggested that this was a relapse of MS rather than a first attack.
