Antihistamines causing angle closure

[eyedesire]

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Hey everyone,

Just wondering if anyone has thoughts on whether topical antihistamines can induce or precipitate acute angle-closure glaucoma in individuals predisposed with narrow angles?? Has anyone not prescribed antihistamines because the patient has narrow angles? or vice versa? Any input would be great, thanks 🙂

 

[Meibomian SxN]

Hey everyone,

Just wondering if anyone has thoughts on whether topical antihistamines can induce or precipitate acute angle-closure glaucoma in individuals predisposed with narrow angles?? Has anyone not prescribed antihistamines because the patient has narrow angles? or vice versa? Any input would be great, thanks 🙂

I've never heard of that relation.

 

[eyedesire]

Yeah, never heard of it until a pharmacist mentioned it to me. Then I looked further into it and found this in Bartlett and Jaanus text about topical anti-histamines: "because of the anticholinergic properties of the antihistamines can produce some degree of mydriasis, these drugs could potentially produce angle closure glaucoma in patients with narrow angles. The topical antihistamines are thsu contraindicated in patients with narrow anterior chamber angles"

Just wondering if this actually happens in real life???

 

[thiaeyemd]

I think what is referred to in that textbook is a theoretical risk. Diphenhydramine (Benadryl) has much greater anticholinergic properties as an Ethanolamine class antihistamine than the piperazine class (Zyrtec) etc.. Even the drops we use Patanol, Lastacraft, zatidor have minimal anticholinergic properties if any. The "contraindication" label is a technicality that sounds like something a Phd would write in a textbook but someone here can correct me if I am wrong, is not applied in clinical use when a narrow angle patient has ocular allergies. Most narrow angle patients are treated with peripheral iridotomies anyway so not a lot of them just walking around and also seeing an eye professional who is treating them for ocular allergies but not addressing the narrow angle.

 

[Tippytoe]

OTC allergy drops can definately induce pupil dilation in some people. I had a young lady that ran me in circles with a monocular mydriasis a few years ago. Right before sending her for neuroimaging, she finally admited to using Napcon-A (OTC). Pts do not think they are 'real' meds since they are not Rx'd.

So being the curious one that I am, I purchased a bottle myself and used it in one eye. On my green eyes, it dilated fairly well. Now I made sure I ask every such patient of OTC allergy use.

So in a predisposed person with very narrow angles (and there are many who have never had an eye exam so are undiagnosed), an angle closure is surely possible with these meds.