Well, how careless of you! Anyway, let's focus on our topic. From what I know, sperms are not poisonous and they would not make you blind. However, they would give rise to some minor problems such as irritation, burning eyes, and painful eyes. Thus, you have to take care of the mess before the feeling kills you. Just get some normal saline to flush your eyes and get some eye drops to deal with the rest.
If you get the bit of sperm in your eyes, you need to wash your eyes with clean water as soon as possible. Then you need to use the clean cloth to dry your eyes. It will not damage your eyes which you should take it relax. You need to use the eye drops to clear the eyes and make the eyes get comfortable. You should also have the rest for the eyes.
No, normally speaking it won't do harm to your eyes. All you need is to wash it with clean water.
Sperm is alkalescent. It changes the ph value of your eyes when it invades. It will stimulate the eyes to some extent. But the effect is too insignificant to notice.
If you really feel uncomfortable even after you have washed your eyes with water, you can have hot compress to feel better. Meanwhile, you need to blink more and drip some eye drops.