Complex sentence: Significant envenomations (as with all snakebites, the amount of venom injected is highly variable and unpredictable) can produce vision abnormalities and difficulty swallowing and speaking; in severe cases, skeletal muscle weakness can lead to difficulty breathing and even respiratory failure.
Split into simpler sentences: Significant envenomations (as with all snakebites, the quantity of venom injected is highly variable and unpredictable) can produce vision abnormalities and difficulty swallowing and speaking. In severe cases, skeletal muscle weakness can lead to difficulty breathing and even respiratory failure.