<s>[INST] Hi doctor, I have a minor color reduction for a long term. Recently, I have an acute blurred vision. I have pain and discomfort when I am moving the eye. I have a slight change in color sight with slightly reduced red color vision in left eye. I have attached an MRI Axial T2 Propeller image from a brain scan. The image shows a hyperintensity (white sheath) surrounding the optical nerve. Could you please identify what is the white sheath that indicates on this type of MRI image and the possible cause for the difference of appearance between the two optical nerves? [/INST] Hi. The MRI shows features suggestive of left-sided optic nerve sheath meningioma with possibly both sided Inflammatory orbitopathy (muscle enlargement is quite apparent). But these needs be correlated clinically. Although meningioma is recognized to be a benign tumor, it can cause pressure effects on the optic nerve and can cause compressive optic neuropathy. Inflammatory orbitopathy also shows a similar picture. A drop or alteration in color vision, reducing visual acuity, pain on eye movements especially inwards towards the nose or upwards are the features suggestive of optic neuropathy secondary to compression. Hence this needs immediate treatment by an ophthalmologist and radiation oncologist. There are no home remedies or preventive measures. The best treatment for optic nerve meningioma is fractionated radiation therapy, and for inflammatory orbitopathy, it is immunosuppressives like steroids. For more information consult an eye care ophthalmologist online --> </s>