The goal of this observational study is to learn about the effect of multiple sclerosis on the blood flow of the optic nerve of affected patients compared to normal subjects by OCTA. The main question it aims to answer is:

1. Does MS change the blood flow in the optic nerve?
2. If it does, can measuring this blood flow be used as a simple sign (a biomarker) to help doctors understand and manage MS?

We used a quick and painless eye scan called Optical Coherence Tomography Angiography (OCTA). This special scan takes detailed pictures of the blood vessels in the optic nerve without needing any injections. We performed this scan on two groups of people: one group with MS and one group without MS, and then compare the results.

In simple terms, why is this important? If we can show that MS affects the optic nerve blood vessels, it could give us a new, quick way to monitor the disease and see how it is progressing, just by doing a simple eye scan.

The optic nerve is like the main cable that carries visual information from the eye to the brain. In Multiple Sclerosis (MS), the body's immune system mistakenly attacks the protective covering (called myelin) around nerve fibers, including those in the optic nerve. This often causes a condition called optic neuritis, which can lead to vision loss.

While we know MS damages the nerve fibers, we are now trying to understand how it affects the blood vessels that supply oxygen and nutrients to the optic nerve. Are these blood vessels damaged as well? Does reduced blood flow contribute to the nerve damage?

2. The Technology We Are Using

This study uses a advanced, non-invasive imaging technology called Optical Coherence Tomography Angiography (OCTA).

What it does: The OCTA machine uses a safe, dim light beam to scan the optic nerve and macula. It works like a microscopic radar for blood vessels, allowing us to create very detailed, high-resolution 3D maps of the blood flow in the retina and optic nerve without any needles or injections.

What we measure: From these maps, we can quantitatively analyze the vessel density which is a percentage that tells us how much of a specific area is filled with functioning blood vessels. We will focus this measurement on the Radial Peripapillary Capillaries, which are the blood vessels that directly supply the optic nerve head.

3. The Purpose and Potential Impact of This Research

The main goal of this study is to determine if the blood vessel density in the optic nerve is a reliable biological marker (or biomarker) for MS.

A biomarker is an objective, measurable sign of a medical condition. If we can prove that changes in optic nerve blood flow are a consistent marker of MS, it could provide us with:

A new tool to help understand the disease activity in an individual.

A quick and painless way to potentially monitor how the disease is changing over time and whether treatments are effectively protecting the nervous system.

By comparing these detailed OCTA measurements between participants with and without MS, we hope to better understand the role of blood flow in the disease and contribute to improved future care for people living with MS.

Inclusion Criteria:

• group 1; patients with multiple sclerosis with optic neuritis.
• group 2; normal healthy age matched controls

Exclusion Criteria:

• Other optic nerve diseases as glaucoma, papilledema or conginetal anomalies.
• Other macular diseases as AMD, CSR, scars …
• Errors of refraction outside +4 and -6 D range.
• Media opacity as cataracts or corneal opacities that may interfere with the quality of scans.
• Signal strength index less than 4\10.

This case-control study enrolled two groups: group 1; 26 adults with a clinically definite diagnosis of Multiple Sclerosis (Cases) and group 2; 28 age- and sex-matched healthy adults with no history of neurological or significant ocular disease (Controls).