Intravitreal is a route of administration of a drug, or other substance, in which the substance is delivered into the vitreous humor of the eye. "Intravitreal" literally means "inside an eye". Intravitreal injections were first introduced in 1911 when Ohm gave an injection of air into the vitreous humor to repair a detached retina. In the mid-1940s, intravitreal injections became a standard way to administer drugs to treat endophthalmitis and cytomegalovirus retinitis. Epidemiology Intravitreal injections were proposed over a century ago however the number performed remained relatively low until the mid 2000s. Until 2001, intravitreal injections were mainly used to treat end-ophthalmitis. The number of intravitreal injections stayed fairly constant, around 4,500 injections per year in the US. The number of injections tripled to 15,000 in 2002 when triamcinolone injections were first used to treat diabetic macular oedema. This use continued to drive an increase to 83,000 injections in 2004. In 2005 bevacizumab and ranibizumab intravitreal injections for the treatment of wet-AMD caused a rise in injections to 252,000. In 2008, over 1 million intravitreal injections were performed. This doubled to 2 million just 3 years later in 2011 when another anti-VEGF intravitreal injection aflibercept became available for the treatment of wet AMD. Intravitreal injections hit an all-time high in 2016 reaching over 5.9 million injections in the US. Uses Anti-Vascular Endothelial Growth Factor (anti-VEGF) The most common reason intravitreal injections are used is to administer anti-vascular endothelial growth factor (anti-VEGF) therapies to treat wet age related macular degeneration (AMD) and diabetic retinopathy. Both of these conditions cause damage to the retina leading to vision loss. There are three widely used Anti-VEGF drugs to treat these conditions: ranibizumab (Lucentis®; Genentech), bevacizumab (Avastin®; Genentech), and aflibercept (Eylea®; Regeneron Pharmaceuticals). Bevacizumab has not been FDA approved to treat wet AMD however in the US it is the first line anti-VEGF therapy for over half of ophthalmologists due to its efficacy and drastically lower cost. These three drugs bind to VEGF molecules preventing them from binding to VEGF receptors on the surface of endothelial cells thereby stopping the abnormal angiogenesis that causes wet AMD. All three of these therapies have vastly improved outcomes for sufferers who had limited treatment options prior to their invention but must be administered via intravitreal injection. Steroids Steroids may be administered via intravitreal injection to treat diabetic and vasculo-occlusive macular edema, exudative macular degeneration, pseudophakic cystoid macular edema,