Testing the usefulness of detailed eye scans

OCt.IN.N is a national, monocentric, prospective, observational cohort study evaluating the utility and applicability of Optical Coherence Tomography (OCT) in the diagnostic workup and longitudinal monitoring of neurological diseases. 840 patients with Central Nervous System neurological diseases (Multiple Sclerosis, Alzheimer's disease, Parkinson's disease, migraine/headache) and 210 age-matched healthy controls will undergo OCT examination at baseline and at 6, 12, 18, and 24 months of follow-up at IRCCS San Raffaele Hospital, Milan, Italy. OCT is a non-invasive, rapid, and reproducible technique that automatically measures the thickness of individual retinal layers. Retinal layer thicknesses and their longitudinal changes will be correlated with established clinical scales, neuroimaging, and biological markers used in routine neurological practice.

The retina and optic nerve share the same embryological origins as the central nervous system (CNS). Several neurological diseases - including Multiple Sclerosis (MS), Parkinson's disease (PD), and Alzheimer's disease (AD) - involve the visual system at both pre-chiasmatic (neuro-retina, optic nerve) and post-chiasmatic levels (optic tracts, optic radiations, primary visual cortex). In MS, optic neuritis is one of the most frequent manifestations and can lead to optic nerve damage with retinal nerve fiber degeneration. In neurodegenerative diseases such as AD and PD, degeneration of retinal ganglion cells has been demonstrated. In AD, longitudinal observational studies have shown accelerated RNFL thinning over time compared to age-matched healthy controls, suggesting that neuro-retinal thinning in neurodegeneration reflects underlying neurodegenerative processes independent of normal aging. Spectral-domain Optical Coherence Tomography (OCT) is a non-invasive, highly reproducible technique providing automated, high-resolution information on the thickness of individual retinal layers, including the retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL), and the inner plexiform layer (IPL). OCT could represent a reliable, reproducible, and economically accessible tool for the diagnostic workup and monitoring of neurological diseases. The device used is the Heidelberg SPECTRALIS HRA+OCT (Class IIa CE-marked medical device), operated according to the manufacturer's instructions and indications for use. The device is used according to its approved clinical indication for visualization of the posterior segment of the eye and retinal anatomy measurement. Study design: monocentric, prospective, observational cohort study. Patients are recruited from the neurology outpatient clinics and inpatient wards of IRCCS San Raffaele Hospital. OCT is performed at baseline (T0) and at follow-up visits at 6, 12, 18, and/or 24 months. Ophthalmological evaluation may be requested at the investigators' discretion to exclude concurrent ocular pathology. Three age subgroups are analyzed for all disease groups and controls: 20-40 years, 40-60 years, and over 60 years. Statistical analyses include: descriptive statistics and ANOVA models (or non-parametric tests) for between-group comparisons at baseline; linear mixed-effects models for longitudinal changes over time; generalized estimating equations (GEE) when data from both eyes are considered; Pearson or Spearman correlation analyses between OCT measures and clinical, neuroimaging, and biological markers (EDSS for MS; UPDRS for PD; neuropsychological battery for AD; brain MRI, PET, and CSF biomarkers for migraine/headache).