Hi Trinni, Eye Bright can do the trick if there are some highlights within the eye to be brought out. Within Eye Bright, make sure you set Lighten to 100% Fade to 0 and that the Brush Size is correct, and then click on the eye a number of times.
If that doesn’t do the trick you can try Effects > Doodle (towards the end) to paint a small amount of light color (white or yellowy white) onto the eye. You can also play with the different settings such as Brush Size, Hardness and Fade to create an effect which looks realistic.