Because of their antiinflamatory effects, glucocorticoids are often used to reduce edema in neurologic tissue and to otherwise mitigate the consequences of neural inflammation. For example, high dose prednisolone treatment has been shown to be an effective therapy for different eye diseases including severe Graves´ Ophthalmopathy and acute optic neuritis. However, contradictory results exists for the influence of high dose prednisolone therapy per se on tissue blood flow. Thus, in the current study, we plan to investigate the effect of high dose, short time therapy with intravenous prednisolone in patients with optic neuritis and severe Graves´ Ophthalmopathy.

Inclusion Criteria:

• Men and women aged between 19 and 65 years, nonsmokers
• Group A: Patients with Graves´ Ophthalmopathy (moderate to severe and active ophthalmopathy; i.e. clinical activity score >3 or =3) suitable for high-dose treatment with prednisolone as assessed by an independent ophthalmologist
• Group B: Patients with acute onset of optic neuritis suitable for high-dose treatment with prednisolone suitable for high-dose treatment with prednisolone as assessed by the ophthalmologist
• Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant and not to interfere with prednisolone treatment (normal liver blood parameter and hepatitis serology).
• Ametropy of less than 3 dpt.

Exclusion Criteria:

• Regular use of medication which could interfere with the study objectives, especially treatment with vasoactive drugs
• Active peptic ulcer or insulin dependent diabetes mellitus
• Hepatitis or elevated hepatic blood parameters
• Abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
• Symptoms of a clinically relevant illness in the 3 weeks before the first study day
• Blood donation during the previous 3 weeks
• Pregnancy