swollen eye... please help

Welcome to MFK!!!

The swollen eye (popeye) may be unrelated to the parasitic infestation and treatment. Aros can easily scratch their eyeson plastic plants, powerheads, etc. The result being a corneal abrasion that bacteria can enter. The majority of these infections are caused by gram-positive bacteria. An antibiotic such as erythromycin or tetracycline should clear the eye up. Lfs carry erythromycin in an aqueous solution called Maracyn.
As with all medications you buy. Be sure to check the expiration date since antibiotics lose potency after about 2 years. If you find a package with no expiration date, leave it alone, since it would be more than 5 years old (before mandatory dating)

Depends on the seriousness of the infection. And, the eye will usually look a bit worse, at the onset of treatment, before it looks better. Figure 24 to 48 hours for the medication to reach the bulk of the infection and another 48 to 72 hours before the majority of the swelling subsides.
I recommend treating in a quarantine tank. You can use totes from Walmart if you don't have another tank. The only filtration that can safely be used would be mechanical. Antibiotics have a habit of affecting bio-filters. Can't use chemical filters since these will absorb the medication. If you must treat in the main tank, perform a good 40-50% water change and gravel wash before starting treatment. This will remove large amounts of bacteria that can quickly rob medication from where it's most needed. Remove carbons/resins. If your aro is accustomed to taking prepared foods, stop offering live for the treatment duration. And, if possible, offer the fish medicated floating sticks/pellets. The meds won't interfere with the maracyn. But, the additional vitamins usually found in medicated foods will help boost the aro's immune system.