Acute intraocular pressure after intravitreal injections, what is the mecanism?

Abstract

AbstractPurpose To evaluate the mechanism of acute intraocular hypertension after intravitreal injections (IVI) of anti‐VEGF therapies.Methods A prospective study was performed to evaluate the IOP increase immediately after IVI of 0,05ml ranibizumab in 50 patients. We have also studied the correlation between IOP immediately after IVI and axial length, then with lens status. Moreover we have analysed the anterior chamber anatomic changes (anterior chamber volume and irido corneal angle), measures were taken before and 5mn after IVI by scheimpflug camera from Oculyzer® (Alcon).Results The IOP peak immediately after IVI was higher than 45 mmHg in 67,3% of patients. It was transient, decreasing after 15mn and returning to baseline in all patient after 45 mn. We found no statistically significant difference between pseudophakic eyes (n=30) and phakic eyes (n=20, p=0.80). No correlation was found between the axial length and the IOP spike (r=0.042, p=0,85). The mean change for the anterior chamber volume (ACV) is mild (0,33 mm3).The ACV increased in pseudophakic eyes (+15,64 mm3, +7,7%), but decreased in the phakic eyes (‐7,24 mm3, ‐4,4%). The mean change for irido corneal angle (ICA) is not significant (‐1,61°), it decreases in phakic eyes (‐2,97°, ‐7,2%) versus a quite neutral effect in pseudophakic eyes (+0,78°, + 1,5%).Conclusion The IOP spike is not correlated either with axial lengh or with lens status. ACV and ICA variations are different according to the lens status but remains mild. These results enhance the importance of the scleral biomechanical properties, and highlight an unpredictable peak. This could be an argument to propose a systematic prophylactic hypotensive treatment before IVI.