(I am not a medical professional so use your own judgment and research skills.)
Maybe Anbesol or clove drops with saline in the eye? In theory it will confuse the parasite because it will be numb and unable to navigate or feed, and it will eventually die.
You will need to look into whether it is safe to use in the eye. A cursory search said Anbesol would be safe, possibly a mild irritant.
You might make a hot water infusion of clove powder in sterile saline eye rinse solution. Filter it through a coffee filter before use.
Or maybe a rinse with thuja or black walnut hull.
Something like this, maybe: Into a small cup put sterile saline eye rinse and a bit of tincture, fit the cup over the eye socket snuggly to prevent leaks, close the eye, tilt the head back, and open the eye allowing the rinse to cover the eye.
Frequently chewing on cedar leaves or black walnut hull might allow the active constituents to affect the eyes.
You may have not used the dewormer remedy long enough.
You should probably talk to someone more qualified in the natural health field.