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Editors Selection IGR 16-3
Medical Therapy: Can IOP increase after intravitreal injection be prevented?
Comment by Jost Jonas on:
26939 Effect of Prophylactic Intraocular Pressure–Lowering Medication on Intraocular Pressure Spikes After Intravitreal Injections, MPC Frenkel; SA Haji; REP Frenkel, Archives of Ophthalmology, 2010; 128: 1523-1527
Intravitreal application of medication for the treatment of diseases of the macula has markedly improved the prognosis of major diseases such as proliferative diabetic retinopathy, diabetic macular edema, and exudative age-related macular degeneration, to mention only a few. Since the ocular globe is mostly a closed system, any increase in its volume by an intraocular injection inevitably leads to an acute increase in intraocular pressure (IOP), which is partially compensated for by a rapid decrease in the volume of the choroid and a backward movement of the lamina cribrosa. The IOP is eventually normalized to its pre-injection level, presumably by a decrease in the production and an increase in the outflow of aqueous humor. Since any major increase in intraocular pressure may be considered to be a risk for a damaged optic nerve, in particular in patients with glaucoma, Frenke et al. (1936) addressed the question whether a topical anti-glaucomatous pre-treatment of eyes undergoing an intravitreal injection is helpful to prevent or to mitigate the injection induced increase in IOP.
Paracentesis may be the method of choice to prevent an intravitreal injection related increase in IOP
Frenkel et al. found that the pre-treatment did not markedly influence the IOP changes and concluded that a routine prophylactic use of IOP-lowering medications was not useful. This result may have several clinical implications. Firstly, a healthy eye may have only a low risk to develop major optic nerve damage by a short-term increase in IOP, since experimental studies by Hayreh et al. showed that the retinal ischemic tolerance time was 90 to 240 minutes in monkeys with an experimental and temporary occlusion of the central retinal artery. Secondly, if one fears that an increase in IOP may lead to progressive optic nerve damage in eyes with advanced glaucoma, the surgeon may consider performing a paracentesis prior to the intravitreal injection to relieve aqueous humor and to make space for the volume to be injected. This may be the method of choice to prevent an intraocular injection related increase in IOP.
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