Effect of Unilateral Application of Timolol 0.5% on Systemic Cardiovascular Parameters and Intraocular Pressure and Perfusion

Aim: To study the effect of unilaterally applied timolol 0.5% on systemic blood pressure (BP), heart rate (HR), cerebrospinal fluid pressure (CSFP), intraocular pressure (IOP), ocular perfusion pressure (OPP) and translaminar pressure difference (TLPD). Methods: This is an experimental clinical study of 14 healthy subjects. Ophthalmic examination included best corrected visual acuity (BCVA), slit lamp examination and autorefractometry. Systemic BP, HR and IOP were taken after the basic examination. Two drops of ophthalmic solution timolol 0.5% were instilled in the right eye (RE) of the subjects. Systemic BP and IOP were measured 30 minutes, one hour, one and a half hour and two hours after the local application. We evaluated the following parameters: systolic blood pressure (SBP) (mmHg), diastolic blood pressure (DBP) (mmHg), mean blood pressure (MBP) (mmHg), HR (bpm), estimated CSFP, IOP (mmHg), estimated TLPD (mmHg) and (OPP) (mmHg). Results: After unilateral topical application of timolol 0.5%, there was a significant reduction of IOP and TLPD in both eyes (IOP RE p<0.001, IOP LE p=0.006; TLPD RE p<0.001, TLPD LE p=0.006) and a significant decrease of HR (p=0.003). OPP significantly increased only in the treated eye (p=0.021). There was a statistically significant correlation between IOP and HR in both eyes (RE R=0.95, p=0.01; LE R=0.85, p=0.04). Conclusion: Unilateral application of timolol 0.5% significantly reduced IOP and TLPD in both treated and untreated eyes, but OPP significantly increased only in the treated eye. HR decreased after unilateral application of timolol 0.5% and was significantly associated with IOP reduction.