Summary of findings 2. Pharmacological treatment.

Pharmacological treatments (Gabapentin / Baclofen / 3,4‐DAP / 4‐AP) for people with acquired nystagmus
Participant or population: people with acquired nystagmus Setting: eye clinic Intervention: pharmacological treatment Comparison: placebo or other drugs
Comparison	Main findings	№ of participants (studies)	Certainty of the evidence (GRADE)
Gabapentin up to 900 mg/day) versus baclofen (up to 30 mg/day). Follow‐up 2 weeks	Gabapentin may work better than baclofen in improving ocular motility and reducing participant‐reported symptoms (oscillopsia). These effects may be different in pendular and jerk nystagmus but there was no formal subgroup analysis so it is unclear if the difference between the two types of nystagmus was a chance finding. Quality of life was not reported but ten participants with pendular nystagmus chose to continue treatment with gabapentin and one with baclofen. Two participants with jerk nystagmus chose to continue treatment with gabapentin and one with baclofen. Drug intolerance was reported in one person for gabapentin and four participants for baclofen. Increased ataxia was reported in three participants for gabapentin and two participants for baclofen.	21 (1 RCT)	⊕⊝⊝⊝ VERY LOW1
3,4‐DAP (20 mg, single dose) versus placebo. Assessments made 30 minutes after taking the drug or placebo	3,4‐DAP may reduce the mean peak slow‐phase velocity in people with downbeat nystagmus. In 10 of the 17 participants, mean peak slow‐phase velocity decreased by more than 50% and these 10 people reported having less oscillopsia. No significant adverse events were reported. Nine participants continued treatment. Three participants reported transient side effects of minor perioral/distal paraesthesia.	17 (1 RCT)	⊕⊝⊝⊝ VERY LOW1
4‐AP (10 mg, single dose) versus 3,4‐DAP (10 mg, single dose) Assessments made at 45 and 90 minutes after taking the drug	3,4 DAP and 4‐AP may reduce mean slow‐phase velocity in people with downbeat nystagmus. This effect may be stronger with 4‐AP. All participants reported mild paraesthesias with both medications.	8 (1 RCT)	⊕⊝⊝⊝ VERY LOW1
GRADE Working Group grades of evidence High‐certainty: We are very confident that the true effect lies close to that of the estimate of the effect Moderate‐certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low‐certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low‐certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

¹ Downgraded two levels for imprecision (due to small number of participants) and one level for serious risk of bias (cross‐over study with analysis that did not permit estimation of effect size).