Monitoring intraocular pressure changes after intravitreal Ranibizumab injection using rebound tonometry

Direct drug delivery by intravitreal injection is an essential tool in the treatment of retinal diseases and can trigger transient and intermediate intraocular pressure (IOP) peaks. So far no reliable risk factors for pronounced IOP increments have been outlined, which might be particularly important for patients with increased IOP susceptibility such as glaucoma. In this prospective, interventional study IOP changes were analysed directly before and after injection in sitting and supine positions using the Icare rebound tonometer (RT).

The IOP of 29 patients with macular oedema, who underwent intravitreal injection of 0.05 mL Ranibizumab, was measured in a sitting position 5 min before and two, five and 10 min after surgery. In addition, IOP was also acquired 30 s before and 10 s after injection in a supine position. The effect of age, gender, pseudophakia, axial length, anterior chamber depth, central corneal thickness, scleral thickness and iridocorneal angle width was analysed.

Mean pre-injection IOP sitting was 14.3 ± 2.6 mmHg for the treated and 15.5 ± 2.2 mmHg for the control eye. After injection mean IOP rose to 47.2 ± 11.2 mmHg on the treated eye. The IOP of 17 patients returned to values ≤21 mmHg within 10 min. In 12 patients, IOP remained above 21 mmHg after 10 min. No specific risk factor for this group was found. The absolute IOP increase 10 s after injection was significantly correlated to scleral thickness (r = 0.49, p = 0.036) and to the absolute (r = 0.40, p = 0.03) and relative increase (r = 0.39, p = 0.035) of IOP from sitting 5 min before injection to supine position 10 s before injection.

Posture change related IOP increments might have a predictive value for post injection IOP increase. In 40% of the eyes higher IOP-levels (>21 mmHg) remained persistent for a longer period of time. This should be considered especially for glaucomatous eyes.