I take them through Poseray, and combine 6 'eye' textures/parts into one 'part'. Lacrimal, tear, pupil, iris, and another 2. Then just apply the eye texture to that. Good enough for not too close-ups, though with an added RT reflection it might well be quite good up close, never tried that. I combine lots more into 1 part, as some parts use the same map. Needs some figuring out.