Why does Itachi's/ Sasuke's eye bleed when they use Amaterasu?

[Yanks]

Title says all.

 

[Atalaya]

Cuz it's cool.

 

[Transcendence]

Chakra pressure in their optic nerves causes the blood to pour out.

 

[Prince Charles]

I mean flaming hot black fire is coming out your pupil?

 

[Revengedace]

Time of the Month

 

[Kirin Rei]

While they had MS, it was meant to depict the harm MS techniques caused the eye.

In EMS...
Kishi likes the Uchiha's and bleeding eyes are cool. :|

That's the only explanation I can come up with.

Seriously though, I think it just shows how much the eyes strain while performing MS/EMS techs. Nothing more, nothing less.

 

[ItachiStillSolos]

Just cuz '

 

[Moss]

It strains their eyes, obviously.

 

[Twisted007]

Drama effect U_U

 

[GiantShuriken]

The fire grazes the tear glands on its way out.

 

[Yanks]

Chakra pressure in their optic nerves causes the blood to pour out.

most logical reason today

 

[Flawž]

To make it look intense.

 

[Lord Naruto San]

It makem look badass i mean blood coming out your eye while you kickin ass

 

[Strict]

It strains their eyes, obviously.

Obviously not. It's for the cooler appearance.

 

[marksonm]

First of all, it is because of the pressure involved in bringing a flame technique from their eyes; which affect their optic nerve and causes it to bleed, also it is partly because their technique is from Yin (mental and spiritual) just like susanoo, so their eyes are the medium via which the spiritual technique comes into the physical world through the combination of Yin and Yang.