Effect of intravitreal injections and volume changes on intraocular pressure: clinical results and biomechanical model

Abstract

ABSTRACT.Purpose: Intravitreal injections are used extensively to treat retinal diseases. Performing an intravitreal injection increases intraocular volume by the amount of fluid brought into the eye. Whether this influences intraocular pressure (IOP) was investigated here. Methods: A biomechanical model relying on 3-dimensional elasticity theory was developed to determine the short-term effect of volume changes on IOP. We calculated the effect for intravitreal injections of 0.1 ml in myopic, emmetropic and hyperopic eyes. Our calculations were compared with IOP measurements obtained immediately after intravitreal injection of 4 mg triamcinolone in 0.1 ml solution (IVTA) in 22 patients. Shortly after the measurement had been taken, IOP was reduced by paracentesis. Results: Immediately after IVTA, measured IOP was elevated by a mean of 40.6 ± 12.1 mmHg compared with initial pressure (p < 0.001). Measured and calculated IOP were comparable. Eyes with shorter axial length had higher IOP immediately after the injection (p < 0.05). Conclusions: The effect of injected volumes on IOP can be calculated with a biomechanical model. Our results show that paracentesis might be recommended when injecting 0.1 ml of a substance to avoid a short-term increase in IOP. As intravitreal injections are mostly applied in diseases that are due to vascular compromise, it might be prudent not to impair perfusion in those eyes, even for short periods of time.

Short-term intraocular pressure trends following intravitreal ranibizumab injections for neovascular age-related macular degeneration—the role of oral acetazolamide in protecting glaucoma patients

“…These include sheer volume increase inside the eye, which is in turn related to vitreous reflux and needle bore size, 5 as well as the actual volume injected. 5,13 This study found no significant reduction in IOP immediately after injection between the control vs treatment group, which further supports the idea of a sheer volume-related pressure effect immediately after injection. Measurement of the IOP just before injection, although not done in this study, may have been useful to confirm the efficacy of pre-injection acetazolamide administered 60-90 min earlier in the treatment arm.…”

“…13 A positive correlation has been found between rigidity coefficient and age, 14 which suggests that a similar volume injected into an older more rigid eye might induce a higher IOP. 13 Although worth considering, the phakic status and status of vitreous/posterior hyaloid face were not evaluated in this study.…”

Asymptotic Analysis of Deformations of the Slightly Orthotropic Spherical Layer Under Normal Pressure

“…The change of the scleral thickness under intraocular pressure (IOP) well agree with clinical data on decrease of scleral thickness in primary open-angle glaucoma (POAG) [8].…”

İntravitreal Bevacizumab Uygulamasının Erken Dönem Göz İçi Basıncına Etkisi

“…15 Erken dönemde saptanan akut ve genellikle geçici özellikteki yükselmelerin ise ilacın özelliklerinden ziyade, göz içindeki hacmin ani artışı sonucunda ortaya çıktığı düşünülmektedir. 16 İntravitreal bevacizumab enjeksiyonuna bağlı erken dönem GİB değişikliklerini değerlendirmeyi hedeflediğimiz çalışmamızda; hastalarımıza uygulanan 0,05 ml bevacizumab sonrası ortalama GİB'in birinci dakikada 17,91±3,7 mmHg düzeyinden, 34,58±13,5 mmHg düzeyine yükseldiği saptanmıştır. Cacciamani ve ark.17 benzer şekilde intavitreal bevacizumab enjeksiyonu öncesi ölçülen ortalama GİB'in 16,52±3,32 mmHg olduğunu, enjeksiyon sonrası birinci dakikada bu değerin 38,44±7,92 mmHg'ye yükseldiğini bildirmişlerdir.…”