How long are cosopt ( timolol and dorzolamide) eye drops effective for after each application?

[Cyclingalong]

I have narrow angle glaucoma , diagnosed around 12 years ago, have been on various eye drops for that time ( more added as my glaucoma progressed) and had laser iridotomy in both eyes 6 years ago. My pressures have never been over 21 and for the last few years have been around 12-14.

My glaucoma has steadily progressed over time, one eye has always been more affected than the other. I’ve been on cosopt preservative free drops twice daily for several years now and latanoprost preservative free drops once daily.

At my latest hospital appointment I saw an optometrist for my assessment and questioned the use of timolol drops at night as I have read that they can also affect blood pressure and as blood pressure is lower during sleep anyway there could be larger drops in blood pressure which could affect the circulation to the eyes and this could worsen glaucoma.

The optometrist said she always advises that the second dose of cosopt should be at tea time because of this possible effect. However she didn’t know what the actual duration of effective action of cosopt was so it got me wondering.

Are there any papers or good information on the duration of action of cosopt ( and other eye drops)? That is my main question.

I know many people stick to a strict 12 hour gap between twice daily drops, I tend to do 10.5 - 13 hours between twice daily drops depending on my shifts etc. If I am now told to have a 9-10 hour gap ( for a tea time dose) is this evidence based and is there then a gap in treatment before the morning dose ( and is this a concern or not).

A tea time dose of timolol drops could still affect my blood pressure during the early hours of the morning. As my glaucoma is steadily progressing should I question the second daily dose again next time I see my consultant?

Interested to hear the experience of others and what you have been advised. Very interested to be pointed in the direction of some accurate information about the duration of action of the different glaucoma eye drops after each application.

Thank you.

[Trish_GlaucomaUK Partner]

To find out this information, it would be best to contact the manufacturer Santen who produce Cosopt.

[Cyclingalong in reply to Trish_GlaucomaUK]

Thanks Trish. I’ve emailed them to ask. I can find some bits of information in paper abstracts and on Santen’s website and links and references they give but can’t access the actual papers to read. I’ll let everyone know what they say.

I’m still interested to hear what other people have been told and will ask my consultant more when I do see him - that seems to be every 2nd hospital check up over the last 12 + months.

[Cyclingalong in reply to Cyclingalong]

Santen replied to say they won’t give me the information, I need to speak to my consultant. I’ve done some more reading around of papers that are free access or abstracts of papers but I’ll wait to see what my consultant says for the latest thoughts and information.

[Alanthered]

I take Brinzolamide/Timolol twice a day. While I try to stick to 12-12 gaps it is not always practical. Like I need to put them in 9am Tuesday because I volunteer for a local conservation group & need to leave home by 9.15. For most evening doses this is not a problem. BUT from time to time I will be at a football match and not get homes until 10.40 ish. So my strategy has been to move the drops on by 20mins a session (9.20 pm, 9.40am etc), However last week I saw my overall consultant (though privately!) and asked his advice. He said 'that sounds like a lot of trouble!' You will be OK if you are an hour or two late occasionally. The effects of the drops don't fall off a cliff edge after 12 hrs!

[Cyclingalong in reply to Alanthered]

Thank you. That’s helpful to know. I’ll see what my consultant says next time I see him as well.