Effective Pupil Dilatation With A Mixture Of 0.75% Tropicamide And 2.5% Phenylephrine: A Randomized Controlled Trial

摘要

Purpose: To compare the efficacy in pupil dilatation between a mixture containing 0.75% tropicamide and 2.5% phenylephrine and the alternate application of 1% tropicamide and 10% phenylephrine eye drops.Material and Methods : Patients requiring pupil dilatation were randomized to receive one drop of the mixture every 10 min for four times or our standard application of one drop of 1% tropicamide alternating with one drop of 10% phenylephrine every 10 min for two cycles. Pupil size was measured under bright light with the pupil gauge before, and every 5 min after initial application for 40 min. Application of the drops was discontinued once the pupil diameter reached 7 mm. Blood pressure and pulse rate were monitored every 15 min.Results: Of 40 patients (age 57.3±10.9 years, range 35-70 years), 22 were randomized into the mixture group and 18 into the alternate drug group. Baseline pupil sizes were 1.7±0.5 mm in the mixture group and 1.8±0.4 mm in the alternate drug group. The pupils were successfully dilated to 7 mm within 40 min in 17 patients of the mixture group compared to seven patients in the alternate drug group ( P =0.004, Log Rank test). The mean pupil sizes at 40 min were 6.6±0.8 and 6.0±0.9 mm in the mixture and alternate drug groups respectively ( P =0.050, t-test). Blood pressure and pulse rate were stable and similar in both groups.Conclusions: The mixture of 0.75% tropicamide and 2.5% phenylephrine is superior to our standard application of 1% tropicamide alternating with 10% phenylephrine. It provides faster and more successful pupil dilatation within 40 min. Introduction Pupil dilatation is mandatory for thorough indirect ophthalmoscopy. Drugs used to dilate the pupil include parasympatholytic and sympathomimetic agents. We routinely used 1% tropicamide and 10% phenylephrine in our patients for this purpose. The former was instilled followed by the latter 10 min later. This cycle was repeated 10 min after the first one. In case the pupil was not adequately dilated, another cycle of instillation was applied. Occasional adverse drug reactions have been reported with the usage of 10% phenylephrine, and consists of tachycardia, elevated blood pressure and stroke. (1) Sequencing of drugs in this alternate application routine was sometimes confusing in our busy hospital. To address these problems, we prepared a mixture containing 0.75% tropicamide and 2.5% phenylephrine to use as a mydriatric agent. This study evaluated the efficacy in pupil dilatation of this mixture compared to the alternate application of the separate drugs according to our standard practice. Materials and Methods This double-blind randomized controlled trial was approved by the institutional ethical committee. This study was conducted at the outpatient unit, Department of Ophthalmology, government medical college srinagar. Patients requiring pupil dilatation for indirect ophthalmoscopy were enrolled. Exclusion criteria included being younger than 20 years, the presence of posterior synechia, narrow angle or shallow anterior chamber, currently on any miotic drugs, past history of any ocular injuries or intraocular surgeries including laser treatment, current infectious eye diseases, and being diagnosed with arterial hypertension, cardiac diseases or angle closure glaucoma. All participants were informed about the details of the study before signing the consent. Their eyes were inspected to detect the excluding conditions. The sample size was calculated by Query Advisor program. A total number of 40 patients were required to verify that the time spent for pupil dilatation was different between groups by more than 10 min. Poor pupil dilatation is recognized in diabetic patients. The enrolled patients were therefore classified as diabetics or non-diabetics before being allocated to two groups by stratified block randomization. This measure distributed diabetic patients equally into each study group. Sequence of patient allocation was prepared by a c