Ambient is 3% in the above examples.  I turned it way down assuming it would defeat the purpose of IBL.  If it were left at 20% the first image could not be so dark.  I actually worried that turning it way down might have been the problem with the eyes, but it has minor effect.  An indirect or spotlight catches the eyes much more strongly.

Klebnor

Lotus 123 ~ S-Render ~ OS/2 WARP ~ IBM 8088 / 4.77 Mhz ~ Hercules Ultima graphics, Hitachi 10 MB HDD, 64K RAM, 12 in diagonal CRT Monitor (16 colors / 60 Hz refresh rate), 240 Watt PS, Dual 1.44 MB Floppies, 2 button mouse input device.  Beige horizontal case.  I don't display my unit.