Multiple Sclerosis
Multiple sclerosis (MS) is a central nervous system demyelinating disorder, frequently occurring between the ages of 25 and 40 years. The main clinical characteristics include multifocal lesions scattered throughout the central nervous system's white matter, with a disease course marked by relapses and remissions. Spatial dissemination of symptoms and signs, combined with temporal progression, is a hallmark of the disease. Commonly affected areas include the optic nerves, spinal cord, and brainstem. Ocular manifestations are common and may include decreased vision in one or both eyes, visual field defects such as central scotomas, and retrobulbar optic neuritis in 50% of cases. Retrobulbar optic neuritis often shows partial recovery within weeks but is prone to recurrence. Severe optic nerve involvement may lead to optic atrophy. Ocular motor palsy manifests as impaired adduction of the affected eye and monocular horizontal nystagmus when looking laterally. Additional findings may include perivenous white sheathing of retinal veins, small vein occlusion (indicative of retinal periphlebitis), intermediate uveitis, nystagmus, ptosis, Horner's syndrome, and hemianopia.
Neuromyelitis Optica Spectrum Disorder
Neuromyelitis optica spectrum disorder (NMOSD) is a group of rare, immune-mediated inflammatory conditions primarily affecting the optic nerve and spinal cord within the central nervous system. Unlike multiple sclerosis, NMOSD is considered a distinct disease entity. Clinical manifestations include acute optic neuritis or retrobulbar optic neuritis, often accompanied by or followed by paraplegia caused by myelitis. Visual acuity typically declines rapidly, often progressing to mere light perception or complete blindness, with central scotomas or centripetal constriction of the visual field. Oculomotor palsy may be present in some cases.
Paralysis Agitans (Parkinson's Disease)
Paralysis agitans, more commonly known as Parkinson's disease (PD), is a chronic progressive extrapyramidal disorder, most often seen in individuals aged 50–60 years. Ocular manifestations may include blepharospasm, reduced blinking, and diminished ocular motility. Peripheral narrowing or centripetal constriction of the visual field is frequently observed. Additional ocular findings may include retrobulbar optic neuritis or optic atrophy, along with retinal arteriolar sclerosis. Oculogyric crises are observed in postencephalitic Parkinson's syndrome, characterized by paroxysmal upward deviation of the eyes.