Subjects were randomized in three cohorts to receive ( 1 ) a single eye-drop containing 0.0175 , 0.175 , or 0.7 g rhNGF ; ( 2 ) a single ascending dose of rhNGF eye drops three times a day for 1day ( total daily dose 2.1 , 6.3 , or 18.9 g ) , or vehicle ; or ( 3 ) a multiple ascending dose of rhNGF eye drops three times a day for 5days ( total dose 10.5 , 31.5 , or 94.5 g ) , or vehicle .