2.5% and 10% Phenylephrine for Mydriasis in Diabetic Patients with Darkly Pigmented Irides
Olan Suwan-apichon MD*, Tanapat Ratanapakorn MD*, Ronakorn Panjaphongse MD*, Suthasinee Sinawat MD*, Thuss Sanguansak MD*, Yosanan Yospaiboon MD*
Affiliation : * Department of Ophthalmology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
Objective : To compare the clinical efficacy and systemic side effects of 2.5% and 10% phenylephrine for mydriasis in diabetic
patient with darkly pigmented irides.
Material and Method: 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.
Results : 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.
Conclusion : 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 of significant vascular
disease and autonomic dysfunction and seem to be susceptible to severe adverse reaction of phenylephrine.
Keywords : Phenylephrine, Mydriasis, Diabetes
