To assess whether neuroprotective drugs administered topically (somatostatin and brimonidine) are able to prevent or arrest the development and progression of neurodegenerative changes

To assess whether neuroprotective drugs administered topically (somatostatin and brimonidine) are able to prevent or arrest the development and progression of neurodegenerative changes related to diabetic retinopathy.

Inclusion Criteria:

1. Patients with type 2 diabetes mellitus
2. Diabetes duration ≥ 5 years
3. Aged between 45-75 years-old
4. ETDRS level < 20 (microaneurysms absent) (50% of enrolled patients) Or ETDRS levels 20 or 35 with presence of at least one microaneurysm in Field 2 between the superior and inferior arcades (50% of enrolled patients) in the Study Eye as determined by the Reading Centre.
5. Informed Consent

Exclusion Criteria:

1. Previous laser photocoagulation
2. Other diseases which may induce retinal degeneration (e.g. glaucoma)
3. Subject with a refractive error ≥ ± 5 diopter
4. Inadequate ocular media and/ or pupil dilatation that do not permit good quality fundus photography.
5. Renal failure (creatinine > 1.4 mg/dl)
6. HbA1C > 10 % in the previous 6 months and at Screening
7. Subjects taking somatostatin or brimonidine, for any indication, in the previous 3 months
8. Subject has a condition or is in a situation which may put the subject at significant risk, may confound the study results or may interfere significantly with the patient's participation in the study.
9. Pregnancy or nursing
10. Hypersensitivity to the active substances to be tested or to any of the excipients
11. Subject receiving systemic monoamine oxidase (MAO) inhibitor therapy or antidepressants which affect noradrenergic transmission (e.g. tricyclic antidepressants and mianserin)