Subjects were randomized in three cohorts to receive ( @ ) a single eye-drop containing @ , @ , or @ g rhNGF ; ( @ ) a single ascending dose of rhNGF eye drops three times a day for @day ( total daily dose @ , @ , or @ g ) , or vehicle ; or ( @ ) a multiple ascending dose of rhNGF eye drops three times a day for @days ( total dose @ , @ , or @ g ) , or vehicle .