A New Method of Subretinal Injection of Tissue Plasminogen Activator and Air in Patients With Submacular Hemorrhage

A New Method of Subretinal Injection of Tissue Plasminogen Activator and Air in Patients With Submacular Hemorrhage Subretinal macular hemorrhage (SRMH) is an important cause of irreversible visual loss1 because it causes permanent functional and anatomical damage to photoreceptors, mainly as a result of 1) barrier effect (separation of photoreceptors from the retinal pigmented epithelium by the blood), 2) tractional changes (clot contraction causing sharing of the photoreceptors),2 and 3) toxic damage (hemosiderin from hemoglobin is toxic to the photoreceptors).3 In fact, Litts et al4 demonstrated histologically that cones overlying an SRMH become degenerated, with translocated mitochondria. Recent and small SRMH may be treated with intravitreal injections of perfluoropropane (C3F8) associated with or without tissue plasminogen activator (tPA) followed by patient positioning in an attempt to move the blood away from the fovea, to avoid the loss of central visual acuity.1 However, if the SRMH is massive, thick, subfoveal, and predominantly inferior, it should be displaced from the macular area using a more direct and invasive procedure. After pars plana vitrectomy (PPV), the most frequently used technique in such cases is subretinal injections of tPA, followed by fluid–air exchange and intravitreal injection of nonexpansible gas.5 According to a recent study, submacular injection of filtered air may be a helpful adjuvant to tPA injection.6 Finally, in SRMH associated with choroidal neovascularization (CNV) caused by age-related macular degeneration (AMD), intravitreal injection of vascular endothelial growth factor antagonist (Avastin, Roche, Basel, Switzerland; Lucentis, Roche, Basel, Switzerland; or Eylea, Bayer, Leverkusen, Germany) should be added at the end of the surgery to ensure regression.7 The technique of choice for subretinal tPA or air injection for treating SRMH usually requires an assistant physician to push the insulin syringe plunger while the surgeon holds the syringe body caring for the cannula to be steady at the subretinal space. However, significant shaking both by the surgeon and the assistant may occur during the procedure, possibly leading to complications, such as hemorrhage, and if the plunger is pushed too fast, macular hole can develop. To reduce the risk of such complications the surgeon can connect the subretinal cannula to a specific flexible tubing; nevertheless, it continues to be assistant dependent and associated with an uncontrolled infusion pressure. Thus, we present a safe and affordable method of delivering tPA and filtered air into the subretinal space using an insulin syringe with a 41-gauge cannula coupled to the viscous fluid control unit of a standard vitrectomy system. Using such a technique, a slower and semiautomated controlled mechanism was obtained, with marked stability during the procedure, which is the primary advantage of this technique.