Intravitreal injection
[2][3] It could also minimize adverse drug effects on other body tissues via the systemic circulation, which could be a possible risk for intravenous injection of medications.
[6][7][8] There were also investigations evaluating intravitreal antibiotics injection using sulfanilamide and penicillin to treat endophthalmitis in the 1940s, yet due to the inconsistency of results and safety concerns, this form of drug delivery was only for experimental use and not applied in patients.
[2] There are also increasing off-label use of bevacizumab (Avastin) for the management of various ophthalmologic diseases, like AMD, retinal vein occlusion and diabetic macular edema.
The first use of intravitreal antibiotics was dated back to experiments in the 1940s, in which penicillin and sulfonamides were used to treat the rabbit endophthalmitis models.
[14] Antibiotics, such as moxifloxacin, vancomycin, etc., are used perioperatively and postoperatively as a common method of endophthalmitis prevention in cataract surgery.
[16] If the endophthalmitis is suspected to be a fungal infection, antifungals, such as amphotericin B and voriconazole, could be intravitreally injected to treat the disease.
[10][11] Below are some examples of this type of medication: Triamcinolone acetonide is one of the most commonly used steroid agents for the treatment of several retinal conditions.
[11] It is much more soluble in alcohol than in water, which could be the reason for its longer duration of action (around 3 months after 4 mg intravitreal injection of the drug).
[11] It has proven to be effective for the management of abnormal endothelial cell proliferation-associated disorders, and the accumulation of intraretinal and subretinal fluid.
[11] It is shown to be able to significantly decrease intercellular adhesion molecule-1 mRNA and protein levels and therefore reduce leukostasis and help maintain the blood-retinal-barrier.
[11] Due to its relatively short half-life, the medication is often given as an intravitreal implant for a continuous and stable release to the target site.
[11] Fluocinolone acetonide is a synthetic corticosteroid as potent as dexamethasone, but with a much lower water solubility, which could be accounted for the extended period of release from the intravitreal implant injected.
[11] The medication could be used in treatment for noninfectious posterior uveitis and diabetic macular edema, while applications in the management of other ophthalmic diseases are still under research.
[11][27][28] Gene therapy drugs [Lenadogene nolparvovec (Lumevoq)] for Leber's hereditary optic neuropathy (LHON) are delivered intravitreally.
[30][31] An operation room may be a better option to provide a more sterile environment for the procedure to lower the chance of infections, yet it will also increase the costs.
[12][33] The specialist first applies anesthetics to the eye and eyelid to numb the area, so that the patient will not feel the pain during the procedure.
[12] The anesthetic takes time to show the numbing effect, ranging from 1–5 minutes, depending on the chemical chosen.
[12] The specialist then sterilizes the eye and the surrounding area, often with povidone-iodine (PVP-I) solution, to prevent any infection in the injected site.
[12] The injection of certain medications, such as triamcinolone acetonide (Kenalog or Triesence), may cause a sudden increase in the IOP,[35][36] and the patient should be monitored until the pressure returns to a normal level.
