Which of the following mydriatics has the shortest duration of action?

Ans. is 'd' i.e., Tropicamide Following table enumerates the salient features mydriatic durgs:Salient features of common cycloplegic and mydriatic drugsSI. NoName of the drugAge of the patient when indicatedDasage of instillationPeak effectTime of performing retinoscopyDuration of actionPeriod of postcycloplegic testTonus allowance1.Atropine sulphate (1% ointment)< 5 yearTDS x day2-3 days 4th day10-20 daysAfter 3 weeks of retinoscopyID2.Homatropine hydrobromide (2% drops)5-6 yearsOne drop every 10 min. for 6 times60-90 rainAfter 90 min. of instillation of first drop48-72 hoursAfter3days of retinoscopy0.5D3.Cyclopentolate hydrochloride (1% drops)8-20 yearsOne drop every 15 min. for 3 times80-90 minAfter 90 min. of instillation of first drop6-18 hoursAfter 3 days of retinoscopy0.75D4.Tropicamide (0.5%, 1% drops)Not used as cycloplegic for retinoscopy; used only as mydriaticOne drop every 15 min 15 3 to 4 times20-40 min.-4-6 hours--5.Phenyephrine (5%, 10% drops)Used only as mydriatic alone or in combination with tropicamideOne drop every 15 min. for 3 to 4 times30-40 min-4-6 hours--* Tropicamide has has the shortest duration of action of 4 - 6 hours.