2.5% and 10% phenylephrine for mydriasis in diabetic patients with darkly pigmented irides

To compare the clinical efficacy and systemic side effects of2.5% and 10%phenylephrinefor mydriasis in diabetic patient with darkly pigmented irides.

A prospective randomized double-blind controlled trial was conducted. One hundred diabetic patients were randomly allocated into 2.5% and 10% phenylephrine groups by block randomization. Pupil diameter, blood pressure and heart rate were measured before and after eye drop instillations.

The mean pupil diameters after instillation in the right eye were 7.05 +/- 0.71 mm (2.5% phenylephrine group) and 7.40 +/- 0.72 mm (10% phenylephrine group, p = 0.02) and in the left eye were 7.05 +/- 0.72 mm (2.5% phenylephrine group) and 7.39 +/- 0.72 mm (10% phenylephrine group, p = 0.02). There was no clinically significant difference in mean heart rate, mean systolic and diastolic blood pressure.

In diabetic patients with darkly pigmented irides, 10% phenylephrine is more effective than 2.5% phenylephrine with statistical significance. The authors recommend a single dose of 10% phenyleprine for mydriasis in these patients. However the lower concentration is recommended for use in those who exhibit a higher prevalence ofsignificant vascular disease and autonomic dysfunction and seem to be susceptible to severe adverse reaction of phenylephrine.