The Relationship between Corneal Biomechanics and Intraocular Pressure Dynamics in Patients Undergoing Intravitreal Injection.

PRCIS A higher 'Corneal Resistance Factor' (CRF) was associated with greater intraocular pressure elevation after intravitreal injection of bevacizumab. Both higher 'Corneal Hysteresis' (CH) and CRF were associated with more rapid intraocular pressure recovery post-injection. PURPOSE To evaluate the relationship between measurable corneal biomechanical properties and acute intraocular pressure (IOP) elevation after rapid intraocular volume expansion from routine intravitreal injection. MATERIALS AND METHODS 100 patients necessitating unilateral intravitreal injection with 0.05▒mL of bevacizumab for retinal pathology were analyzed prior to injection with Goldmann Applanation Tonometry (GAT) to measure IOP, Ocular Response Analyzer (ORA) to measure corneal biomechanical properties, and optical biometry to calculate globe measurements. IOP and ORA were measured again within 5 minutes of the injection and then IOP measurements were taken every 10 minutes until the IOP was less than or equal to 150% of the pre-injection IOP. Linear regression and logistic regression were used to test variables associated with acute IOP increase. A Cox proportional hazard model accounting for pre-injection IOP and post-injection IOP was used to test the effect of corneal hysteresis (CH) or corneal resistance factor (CRF) on the time required to return to 150% of baseline IOP. RESULTS Higher CRF was associated with greater immediate post-injection IOP (P=0.026) elevation. A pre-injection IOP>15.5▒mmHg moderately predicted post-injection IOP≥35▒mmHg (AUC, area under the receiver operating characteristics curve=0.74). A pre-injection IOP>18.5▒mmHg combined with CH poorly predicted post-injection IOP>50▒mmHg (AUC=0.67). A higher CH (HR=1.24; 95% CI=1.08-1.42; P=0.002) and pre-injection IOP (HR=1.16; 95% CI=1.09-1.22; P 50▒mmHg. Higher CH and CRF were associated with faster IOP recovery after intravitreal injection, demonstrating the dynamic relationship between ocular biomechanical properties and aqueous outflow pathways.