Name of the drug Age of the patient when indicated Duration of instillation Peak effect Time of performing retinoscopy Duration of action Period of post cycloplegic test Tonus allowance Atropine Sulphate < 5years TDS x 3days 2-3 days 4th day 10-20days After 3weeks of retinoscopy 1D Homatropine hydrobromide 5-8years one drop/10min/6times 60-90min After 90min of instillation of first drop 48-72hrs After 3 days of retinoscopy 0.5D Cyclopentolate HCL 8-20years One drop/15min/3times 80-90min After 90min of instillation of first drop 6-18hrs After 3 days of retinoscopy 0.5D Tropicamide Used only as a mydriatic not cycloplegic for retinoscopy One drop/15min/3-4 times 20-40min ----- 4-6hrs ----- ----- Phenylephrine Used only as a mydriatic alone or in combination with tropicamide One drop/15min/3-4 times 30-40min ----- 4-6hrs ---- ---- Reference : Khurana comprehensive ophthalmology; 4th ed; Pg: 550 table 23.1