Sir,

We investigated anomalies in drug choice when prescribing new glaucoma drops in glaucoma clinics. A total of 1436 records were assessed for 6 months. Of these, 115 patients had a change in drop. An independent glaucoma consultant ophthalmologist categorised the drug choice into three using clearly defined criteria: no anomaly/error, anomaly, error.

An anomaly was defined as the prescription of two new drugs simultaneously, prescription of an additional drug without stopping current ineffective drug,1 prescription of a new drug without considering non-adherence,2 and prescription change to unorthodox drug frequency.3 An error was defined as the prescription of a contraindicated drug or a drug with a clearly documented previous adverse drug reaction. Benefit of doubt was given at all times (e.g., multiple changes in drops were considered to be reasonable practice where a pressure rise was an unacceptable risk).

We found that over three quarters of changes in medication had consultant or fellow involvement. Optometrists, registrars, and associate specialists, collectively, were responsible for less than a fifth (n=21) of changes in glaucoma drops.

There was a high standard of clinical practice in 92 (80%) cases. In one-fifth, therapeutic management was considered to be anomalous or erroneous: there were 15 anomalies in management (13%, 95% CI 7–19%) and 8 errors (7%, 95% CI 2–12%). Seven of these were prescribed a drug with a clearly documented previous adverse reaction and one patient was prescribed Timolol despite advice from their cardiologist to avoid beta blockers.

The following risk factors were examined: day of week, time of clinic, patients per clinician, presence of consultant, and staff grade. There was no correlation between these factors and the numbers of errors or anomalies occurring.

Errors are inevitable, however, the magnitude reported here is unacceptably high. The majority may be accounted for by a failure to fully examine hospital records, and changes are needed to assist the clinicians in busy clinics. Electronic records accompanied by decision support reduce errors in prescribing.4 We are currently working towards this. Another important step is to encourage shared decision making with patients. The results of the study are being introduced into the glaucoma service induction training.