[Optical Coherence Tomography in Disorders of the Central Nervous System].

Retinal changes and visual symptoms are present in several inflammatory, degenerative and tumorous disorders of the central nervous system (CNS). Optical coherence tomography (OCT) is a method that can be used in clinical practice to detect and quantify the structural correlates of these visual symptoms in neurological disorders. OCT is a non-invasive imaging technique, based on interferometry, which can create high-resolution images of the retina and measure the thickness and volume of the different retinal layers. The combined ganglion cell- and inner plexiform layer (GCIPL) and the peripapillary retinal nerve fibre layer (pRNFL) are of particular interest in the field of neurological disorders, since they contain the neuronal bodies (ganglion cells) and their axons that form the optic nerve. In acute optic neuritis (ON), initial swelling of the pRNFL can be detected by OCT and this may contribute to the diagnosis and differential diagnosis of ON; moreover, the extent of the GCIPL-thinning within the first 4 weeks after an acute ON can contribute to the prediction of the long-term visual recovery. However, the role of OCT in the field of multiple sclerosis (MS) is not restricted in patients with ON, since even eyes without an ON-history show mild thinning of the pRNFL and GCIPL. This thinning seems to be associated with neurodegenerative processes in the entire CNS. Several studies showed correlations between these OCT-parameters and a higher risk of clinical deterioration (disability progression), cognitive deficits and disease activity in patients with MS. However, it is often still unclear how these correlations can be useful in the management of the individual patient. In recent years, OCT has been applied to a greater extent to neurodegenerative diseases, such as Parkinson's disease, amyotrophic lateral sclerosis (ALS) and various forms of dementia. However, routine clinical use is still further away than for inflammatory CNS diseases, since the role of OCT in the diagnosis, differential diagnosis and prediction of the clinical course of neurodegenerative diseases is still unclear. This review article offers a summary of the available study results on OCT parameters and their role in inflammatory, degenerative and tumorous diseases of the central nervous system (CNS).