How does tourniquet effect the intraocular pressure during lower extremity surgery under spinal anesthesia?

Objective: There are many factors which may affect intraocular pressure (IOP). Tourniquet, which is used in extremity surgery, also affects IOP. There are many studies about the effect of tourniquet on IOP in patients under general anesthesia. However, there was no study about the effect of tourniquet on IOP in patients under spinal anesthesia (SA). Design: Non-randomized prospective comparative study Setting: Selcuk Medicine Faculty Hospital, Konya, Turkey Subjects: Sixty American Society of Anesthesiology physical status I-II patients aged between 18-65 years planned for elective lower extremity surgery were included in the study. They were divided into Group 1 (with tourniquet) and Group 2 (without tourniquet). Exclusion criteria included chronic diseases except for controlled hypertension, known allergies to any anesthetic drugs used in the study, history of eye disease or surgery, any contraindications for spinal anesthesia and if the expected tourniquet time was longer than 120 minutes. Intervention: Measurement of IOP Main outcome measure: Changes in IOP at various stages of the procedure Results: IOP decreased with SA. Tourniquet inflation increased the IOP. In both groups, IOP was lower than the baseline IOP five minutes after spinal anesthesia. However, IOP after tourniquet inflation was higher than the baseline. Conclusion: SA decreases IOP but application of tourniquet to the lower limb increases IOP even above the baseline.