Performance assessment testing may be a useful tool to evaluate the impact of ranibizumab on day-to-day visual function in patients with Diabetic Macular Edema (DME).

Inclusion Criteria:

• Ability to provide written informed consent and comply with study assessments for the full duration of the study

• Age 18 ≤ x ≤ 65 years and currently employed at the baseline study visit

• Diagnosis of diabetes mellitus (type 1 or 2)

  o Any one of the following will be considered to be sufficient evidence that diabetes is present:

• Current regular use of insulin for treatment of diabetes

• Current regular use of oral anti-hyperglycemia agent for the treatment of diabetes

• Clinical evidence of retinal thickening due to macular edema involving the center of the macula, associated with diabetic retinopathy.

• Central diabetic macular edema present on clinical examination or or evidence indicating disease activity on spectral domain OCT.

• Visual acuity score greater than or equal to 19 letters (20/400) and less than or equal to 73 letters (20/40) by the ETDRS visual acuity protocol.

• Media clarity, pupillary dilation and patient cooperation sufficient to allow OCT testing and retinal photography

Exclusion Criteria:

• Pregnancy (positive pregnancy test) or known to be pregnant; also pre-menopausal women not using adequate contraception.
• Participation in another ocular investigation or trial simultaneously
• Blood pressure > 180/110 (systolic above 180 OR diastolic above 110)
• Any condition that, in the opinion of the investigator, would preclude participation in the study (e.g. chronic alcoholism, drug abuse)
• Evidence of vitreoretinal interface abnormality after ocular exam or OCT that may be contributing to the macular edema
• An eye that, in the investigator's opinion, has no chance of improving in visual acuity following resolution of macular edema (e.g. presence of subretinal fibrosis or geographic atrophy)
• Presence of another ocular condition that may affect the visual acuity or macular edema during the course of the study (e.g. AMD, uveitis, Irvine-Gas)
• Evidence of active neovascularization of the iris or retina
• Evidence of central atrophy or fibrosis in the study eye
• Presence of substantial cataract, one that might decrease the vision by 3 or more lines of vision at sometime during the study.
• Previous use of intraocular or periocular corticosteroids in the study eye in the previous 120 days
• Previous treatment with anti-angiogenic drugs in the study eye i.e. pegaptanib sodium, bevacizumab, ranibizumab, aflibercept within 120 days prior to baseline
• History of vitreous surgery in the study eye
• History of cataract surgery within 3 months of enrollment.
• History of YAG capsulotomy within 2 months of enrollment.
• Visual acuity <20/400 in the fellow eye
• Uncontrolled glaucoma (pressure >30) despite treatment with glaucoma medications.
• History of cerebral vascular accident or myocardial infarction within 3 months prior to Day 0.