How do you determine when to wean patients with idiopathic intracranial hypertension off of acetazolamide?

As a neuro-ophthalmologist, my greatest concern is vision-threatening papilledema in IIH. So if there is no papilledema, that threat should be resolved for the time being, right?

Not so fast. Accurate direct ophthalmoscopy has become an "optional" skill set for most neurologists. Subtle papilledema or post papilledema optic atrophy in IIH is not readily appreciated without a dilated fundus exam, and I speak from experience when I attest that the overwhelming majority of neurology residents/attendings in my academic neurology dept do not carry tropicamide or phenylephrine dilating drops (and many don't own/carry an ophthalmoscope).

Moving forward, it is better to light a single candle than curse the darkness, so consider consulting an ophtha...

I agree with the above answers.

There are a variety of factors that come into play to make this decision. The first metric I use is papilledema grade (not CSF pressure measurement as that varies).

1. If papilledema has resolved (grade 0) and the patient is asymptomatic with stable vision, I begin a slow taper. I counsel the patient not to gain weight (make and keep healthy lifestyle modifications) as that can trigger a relapse.
2. The IIH Treatment Trial showed that patients who had stable grade 1 papilledema did not have visual field worsening. There is probably an exception to this somewhere but in my practice, I have tapered many asymptomatic, visually stable patients with Frisen grade 1 edema off acetazolamide successfully. With grade 1 edema,...

I am not aware of any published articles that specifically address this question. However, if patients remain asymptomatic for 6-12 months, I would consider gradually tapering off medical therapy. I would define asymptomatic as having headaches occurring less frequently, such as less than 10 days per month, with resolved optic disk edema and a stable eye exam. If the eye exam remains stable, even if headaches occur more frequently, I would consider checking LP, and if the opening pressure is less than 20 cm/H2O, I would also consider tapering off medication. If headaches increase in frequency or severity, or if vision symptoms or the eye exam worsen with decreased acetazolamide dose, I would revert to the previous dose.

I do not have the necessary clinical experience, but would probably do so based on the patient's headache complaint and fundoscopic examination.