The Efficacy of Intravitreal Aflibercept Injection in Improvement of Retinal Nonperfusion in Diabetic Retinopathy

Retinal nonperfusion drives vision-threatening complications such as pathological neovascularization, which can lead to neovascular glaucoma, vitreous hemorrhage, or tractional retinal detachments and macular edema in various retinal vascular diseases including diabetic retinopathy and retinal vein occlusion. Silva et al revealed that retinal nonperfusion area was correlated highly with diabetic retinopathy severity in their recent paper. It should be clarified that retinal nonperfusion is not synonymous with retinal ischemia, which implies tissue hypoxia, but is a useful surrogate.

Retinal nonperfusion has known to be associated with the production of vascular endothelial factor (VEGF). Recently, Campochiaro et al reported that neutralization of VEGF using ranibizumab improved macular edema and reversed the worsening of retinal nonperfusion in patients with retinal vein occlusion and diabetic macular edema. The precise mechanism for improved perfusion in the VEGF treated eye is uncertain. The authors suggested that VEGF exacerbates retinal ischemia by increasing leukostasis, and intravitreal anti-VEGF agents may break the feedback loop, allowing reperfusion to occur. There might be a portion of circulation that is closed but not permanently, and this reversible closure is modulated by VEGF.

The study by Campochiaro et al, however, was limited in that they reviewed retinal nonperfusion within a template consisting of the Early Treatment Diabetic Retinopathy subfields mainly confined to posterior pole of the fundus. Wide-field retinal imaging is an imaging technique that allows a view of almost 200° of the fundus in a single image. It has been well shown that wide-field scans allow the detection of peripheral pathology that may be missed on 75 degrees of achieved by montaging the Early Treatment Diabetic Retinopathy Study 7-standard fields.

To investigators knowledge, there has been no previous study evaluating the longitudinal change of retinal nonperfusion after aflibercept treatment in a larger area of the retina by taking advantage of the 200° field of view in diabetic retinopathy. The main purpose of this study is to determine the efficacy of intravitreal aflibercept injection in improvement of retinal nonperfusion and identify associated factors in patients with nonproliferative diabetic retinopathy with moderate retinal nonperfusion.

Inclusion criteria

• A subject must meet the following criteria to be eligible for inclusion in the study:

• Adults ≥ 18 years with type 1 or 2 diabetes mellitus
• Patients diagnosed as nonproliferative diabetic retinopathy with retinal nonperfusion (Ischemic index >20%) Severe nonproliferative diabetic retinopathy - Early proliferative diabetic retinopathy
• Willing and able to comply with clinic visits and study-related procedures
• Provide a signed informed consent form

Exclusion criteria

• A subject who meets any of the following criteria will be excluded from the study.

• Systemic exclusion criteria 1. Renal failure requiring hemodialysis or peritoneal dialysis within 6 months prior to baseline or anticipated need for hemodialysis, peritoneal dialysis at any time during the study 2. Acute cardiovascular events (acute myocardiac infarction and/or cerebral infarction) within 1 year before Visit 1 3. Blood HbA1c level greater than 12% at Visit 0
• Ocular exclusion criteria

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• Diabetic macular edema involving the center of the macula (Defined as the area of the center subfield of OCT, Heidelberg Spectralis: ≥305 in women; ≥320 in men) in the study eye
• Presence of rubeosis (neovascularization of the iris or the angle) in the study eye
• Any current or history of retinal diseases that affects visual acuity in the study eye
• Previous treatment of panretinal photocoagulation
• Previous treatment with anti-VEGF in study eye within 6 months before Visit 1
• Previous treatment with intraocular or periocular corticosteroids in the study eye within 6 months before Visit 1
• Previous history of intraocular surgery other than cataract surgery in the study eye
• Cataract surgery within 3 months before Visit 1 in the study eye
• Yttrium-aluminium-garnet (YAG) capsulotomy in the study eye within 1 month before Visit 1
• Aphakia in the study eye
• Elevated intraocular pressure (≥ 22 mmHg) in spite of using topical IOP lowering agents at Visit 1 or a diagnosis of glaucoma (Visual field defect corresponding to glaucomatous optic neuropathy) in the study eye
• Presence of a visually significant cataract in the study eye
• BCVA score < 34 letters in the fellow eye
• Hypersensitivity to aflibercept
• Ocular or periocular infection
• Active intraocular inflammation