Fig. 6. Directed nerve sprouting as a function of time and distance from the wound (EF strength). The polarization index of nerve sprouting angles was calculated for new sprouts from intact nerves. From 16 to 24 hours, new sprouts oriented significantly with time (compare 16 and 24 hour control PI values, P<0.01). In control corneas, new sprouts within 0-250 µm of wound edge were oriented more perpendicularly than those at 250 µm-1 mm, where the EF strength drops off (P<0.01 for 16 hours; P<0.05 for 24 hours). At 16 hours, all four drugs that increased the EF (PGE2, aminophylline, AgNO₃ and ascorbic acid) enhanced perpendicular orientation up to twofold (compare 16 hour control PI with 16 hour PGE2 and aminophylline PI values, both P<0.01). At 24 hours, reducing EF with ouabain or furosemide significantly reduced nerve orientation (compare 24 hour control PI with 24 hour ouabain or furosemide PI values, P<0.01 or P<0.05 respectively), and this was more obvious at 0-250 µm (compare 24 hour ouabain 0-250 µm PI with 250 µm-1 mm PI, P<0.05). Tubocurare and neomycin also significantly reduced nerve orientation (compare 24 hour control PI with 24 hour tubocurare and neomycin PI values, P<0.05 and 0.01, respectively).