Brief Answer:
A few days; not on the same day as the surgery, until a few days prior

Detailed Answer:
Hello sir and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. Most eye drops prescribed for glaucoma take effect within a few hours and the effect also does not last too long, requiring more than one application a day. Improvement depends on what your intra-ocular pressure is and how much correction is required with the help of medications. But I would say an improvement observed by the individual should be within a few days time itself.

Most glaucoma eye drops are used to shrink the pupils, while you need to have your pupils dilated for surgery. So your surgeon will advise you on which eye drops you need to use prior to the surgery, in most cases the eye drops prescribed prior to surgery are start about 1-2 hours before surgery, and in that case you should be able to use the usual glaucoma medications until a day before surgery at least.

I hope you find my response helpful. Please feel free to write back to me for any further clarifications, I am always here to help.

Best wishes.

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