Medical systems, devices, and related methods

1. A method, comprising:

inflating a first balloon within an internal carotid artery so as to block antegrade flow of blood into an ophthalmic artery;

maintaining antegrade flow of blood in the internal carotid artery via a perfusion lumen in the first balloon; and

inserting a device into the ophthalmic artery via a lumen extending through a portion of the first balloon to a side opening in the first balloon, wherein the side opening in the first balloon is a radially outward side opening.

2. The method of claim 1 , further comprising inflating a second balloon distally of the ophthalmic artery.

3. The method of claim 2 , wherein the perfusion lumen extends through the second balloon, and wherein the maintaining antegrade flow of blood in the internal carotid artery includes maintaining antegrade flow of blood in the internal carotid artery via the perfusion lumen extending through the first balloon and the second balloon.

4. The method of claim 1 , further including:

inducing retrograde blood flow in the ophthalmic artery of the subject.

5. The method of claim 1 , wherein inflating the first balloon forms a seal against a wall of the internal carotid artery.

6. The method of claim 1 , further including positioning the first balloon within internal carotid artery over a guidewire via a guidewire lumen.

7. A method, comprising:

inflating a first balloon within an internal carotid artery of a subject proximal of an ophthalmic artery of the subject;

inflating a second balloon within the internal carotid artery distal of the ophthalmic artery;

impeding, via at least one of the inflating the first balloon or the inflating the second balloon, antegrade blood flow in the ophthalmic artery;

maintaining antegrade blood flow in the internal carotid artery of the subject via a perfusion lumen; and

inserting a device into the ophthalmic artery via a lumen extending through a portion of the first balloon to a side opening in the first balloon.

8. The method of claim 7 , further including:

inducing retrograde blood flow in the ophthalmic artery.

9. The method of claim 8 , further including:

passing the induced retrograde blood flow through a channel of the first balloon.

10. The method of claim 7 , wherein the passing the induced retrograde blood flow through the channel of the first balloon includes imparting negative pressure to the channel of the first balloon.

11. The method of claim 7 , further including distally advancing the second balloon relative to the first balloon via a shaft.

12. The method of claim 7 , further including adjusting a degree of expansion of the second balloon to increase a blood flow rate in the internal carotid artery.

13. The method of claim 7 , wherein the inflating the second balloon does not form a complete seal against a wall of the internal carotid artery.

14. A method, comprising:

positioning a balloon within an internal carotid artery, the balloon including an opening extending through a sidewall of the balloon, wherein the sidewall of the balloon is a radially outward sidewall of the balloon;

expanding the balloon so as to contact a wall of the internal carotid artery; and

aligning the opening of the balloon with an ophthalmic artery;

wherein the expanding the balloon includes adjusting a blood flow rate of the ophthalmic artery.

15. The method of claim 14 , further including permitting blood flow through the opening of the balloon.

16. The method of claim 15 , wherein permitting blood flow through the opening includes permitting induced retrograde blood from the ophthalmic artery, through the opening, to a location proximal of the balloon.

17. The method of claim 14 , further including fluidly coupling a region of the internal carotid artery proximal of the balloon with a region of the internal carotid artery distal of the balloon via a lumen disparate from the sidewall opening of the balloon.