OCT: new perspectives in neuro-ophthalmology

Optical coherence tomography [OCT] has become essential to evaluate axonal/neuronal integrity, to assess disease progression in the afferent visual pathway and to predict visual recovery after surgery in compressive optic neuropathies. Besides that OCT testing is considered a powerful biomarker of neurodegeneration and a promising outcome measure for neuroprotective trials in multiple sclerosis [MS]. Currently, spectral-domain OCT [SD-OCT] technology allows quantification of retinal individual layers. The Ganglion Cell layer [GCL] investigation has become one of the most useful tools from a neuro-ophthalmic perspective. It has a high correlation with perimetry, is predictive of future progression and is a highly sensitive, specific of several neuro-ophthalmic pathologies. Moreover the superior correlation with clinical measures compared to peripapillary retinal nerve fiber layer [pRNFL] suggests that GCL analysis might be a better approach to examine MS neurodegeneration. In disorders with optic disk edema, such as ischemic optic neuropathy, papillitis and papilledema, reduction in RNFL thickness caused by axonal atrophy is difficult to distinguish from a swelling resolution. In this setting, and in buried optic nerve head drusen [ONHD], GCL analysis may provide more accurate information than RNFL analysis and it might be an early structural indicator of irreversible neuronal loss. Enhanced depth imaging OCT [EDI-OCT] provides in vivo detail of ONHD, allowing to evaluate and quantify the drusen dimensions. OCT is improving our knowledge in hereditary optic neuropathies. Furthermore, there is growing evidence about the role of OCT as an adjunctive biomarker of disorders such as Alzheimer and Parkinson's disease

Ocular Dipping in Creutzfeldt-Jakob Disease

BACKGROUND: Ocular dipping (OD), or inverse ocular bobbing, consists of slow, spontaneous downward eye movements with rapid return to the primary position. It has been mainly reported following hypoxic-ischemic encephalopathy, but has also been described in association with other types of diffuse or multifocal encephalopathies and structural brainstem damage. CASE REPORT: We report the case of a previously asymptomatic 66-year-old woman who presented with confusion, recent memory disturbances, and abnormal involuntary movements, followed by a coma. Abnormal spontaneous vertical eye movements consistent with OD developed from the fourth day after admission, and the patient died 20 days later. The pathological examination of the brain confirmed the diagnosis of Creutzfeldt-Jakob disease. CONCLUSIONS: The precise location of damage causing OD is unknown. In contrast to ocular bobbing, OD has no localizing value itself, but structural brainstem damage is likely when it appears combined with other spontaneous vertical eye movements.