Doctors usually recommend B12 injections only in cases of severe deficiency, like in people with pernicious anaemia or absorption disorders
doi: 10.2337/diabetes.52.2.380 [DOI] [PubMed] [Google Scholar] 63

INGREDIENTS Water\Aqua\Eau , Caprylic/Capric Triglyceride , Prunus Armeniaca (Apricot) Kernel Oil , Butylene Glycol , Squalane , Peg-100 Stearate , Glycerin , Glyceryl Stearate , Isopropyl Isostearate , Saccharide Isomerate , Cetearyl Alcohol , Polysorbate 60 , Ribes Nigrum (Black Currant) Seed Oil*, Prunus Amygdalus Amara (Bitter Almond) Kernel Oil*, Cinnamomum Camphora (Camphor) Bark Oil*, Citrus Aurantium Dulcis (Orange) Peel Oil*, Prunus Armeniaca (Apricot) Kernel Oil*, Osmanthus Fragrans Flower Extract, Rosa Damascena Extract, Citrus Aurantium Amara (Bitter Orange) Flower Extract, Linalool, Limonene , Oryza Sativa (Rice) Bran Oil , Algae Extract , Polyaminopropyl Biguanide , Caffeine , Hypnea Musciformis (Algae) Extract , Gigartina Stellata (Algae) Extract , Sodium Hyaluronate , Carbomer , Sorbitol , Caprylyl Glycol , Hexylene Glycol , Sodium Acrylates/Acrylonitrogens Copolymer , Potassium Hydroxide , Sodium Dehydroacetate , Phenoxyethanol * Essential Oil 10.23.19 15mins said: Looks ok

Usually, its given once or twice a week based on deficiency severity
In DR, these alterations can impair retinal microvascular function
Copper peptides and retinol work differently