Syncope and falls due to timolol eye drops

The prevalence of glaucoma increases with age. 1 Timolol, a non-selective β blocker, is the first line treatment. We present three cases from our falls clinic, in which we show that even a low dose of timolol eye drops may cause severe systemic adverse effects.

Case reports

Case 1

A 73 year old man was referred by his general practitioner because he had been unconscious for half an hour the previous day. His medical history consisted of a myocardial infarction, glaucoma, and insulin dependent diabetes mellitus. During the past few years, he had experienced four spells of dizziness with severe perspiration. These spells had been ascribed to hypoglycaemia, although low blood glucose values had never been detected. His medication consisted of insulin, acenocoumarol, alfuzosin, and timolol eye drops (0.5%, twice daily in both eyes). During his last dizzy spell, his blood glucose concentration had been 8 mmol/l. According to his wife, the patient had not experienced a convulsion, tongue biting, or urinary incontinence.

At referral to our clinic, the patient was alert and feeling well. Blood pressure was 142/90 mm Hg, with a regular pulse rate of 48 beats/min. There was no evidence of orthostatic hypotension. Further physical examination, including neurological examination, showed no abnormalities. Glycated haemoglobin (HbA_1c ) was slightly increased-8.2% (reference range 4-6%); the glucose day curve showed values of 4.6-17.4 (3.5-11) mmol/l, with no hypoglycaemia. Electrocardiography showed sinus bradycardia of 41 beats/min, and 24 hour Holter monitoring showed a sinus rhythm of 69 beats/min and frequent episodes of bradycardia, with a minimum frequency of 43 beats/min, during which the patient experienced presyncopal symptoms, which he recognised as the dizzy spells mentioned before. His syncopal episodes were diagnosed as resulting from symptomatic bradycardia induced by timolol eye drops. After consultation with the ophthalmologist, the timolol eye drops were changed to latanoprost eye drops, a prostaglandin F2 analogue. Since then (a follow-up period of one and a half years), the patient has had no recurrence of syncope. A few weeks after the change in eye drops, a repeat Holter test showed a sinus rhythm of 80 beats/min, without bradycardia.

Case 2

A 73 year old woman complained of...