Efficacy of temporary lower punctal occlusion in enhancing pupil dilation after 1% tropicamide instillation

Background: Pupil dilatation is essential for complete fundoscopic examinations and some eye surgeries. Whether temporary punctual occlusion will enhance the magnitude of pupillary dilation is not known.

Objectives: We measured the pupil diameter after one drop of 1% tropicamide instillation with and without temporary punctal occlusion at 0 and 30 min in the same patient.

Methods: Ninety-eight eyes from 49 patients at the Department of Ophthalmology, King Chulalongkorn Memorial Hospital were randomized into temporary punctal occlusion group (group 1) and simple closure group (group 2) after instillation one drop of 1% tropicamide in both eyes. Pupil diameters were photographed and measured before starting the drop and again 30 minutes later for each patient.

Results: At 30 minutes the mean pupil sizes of group 1 and group 2 were 3.92±1.53 mm and 3.83±1.43 mm, respectively. The mean difference of pupillary dilatation in group 1 was 2.75±1.94 mm whereas group 2 was 3.19±1.77 mm. The difference between the two group was statistically significant but not clinically important (p = 0.001) (95%CI (-0.69)-(-0.18)).

Conclusions: Temporary punctal occlusion could enhance pupil dilation after one drop of 1% tropicamide instillation within 30 minutes. The degree of dilatation was not clinically important. Additional doses of 1% tropicamide or combination preparation will be required for clinically adequate mydriasis.