Introduction: Glaucoma used to be the most common cause for blindness in Iceland. As the incidence of glaucoma increases with age, the patients often have numerous comorbidities and use various medications. It is important to keep in mind interactions and side effects of glaucoma medications when deciding systemic medical treatment for these patients to ensure their safety and comfort. The goal of the study was to gather information about drug use of patients with severe glaucoma.

Methods: A retrospective study where data were collected from 100 consecutive patients who underwent a trabeculectomy as first glaucoma surgery at Landspitali National University Hospital of Iceland during 2013-2017. All systemic and ophthalmic medi­cations during 6 months before and after the surgery, medical diagnoses, age and gender of the patients were registered.

Results: Of all 100 patients, 87 used systemic medication, averaging 5.3 drugs/patient. Mean number of glaucoma medi­cation used was 3.0. Mean age at surgery was 75 years and 53 were women. The most common systemic drug class was anti- hypertensives, used by 57 patients where beta-blockers were the most common, used by 30 patients. Zopiclone was the most common single drug, used by 29 patients.

Conclusion: It is evident that patients with glaucoma take various drugs for systemic illness that can affect their glaucoma and have interactions with glaucoma drugs. It is urgent that healthcare providers keep this in mind when deciding on systemic treatment for patients with glaucoma, with regards to possible interactions with glaucoma drugs and the effect on patient's overall health.

Table I. The number of individuals who used each glaucoma medicine.

Table II. The number of individuals and their medical treatment.

Table III. The subclassification of the most common drug classes.

Table IV. The most common systemic diseases.

Tafla V. The most common side effects from glaucoma treatment.

Table VI. Interactions between glaucoma drugs and systemic medications.