In healthy eyes, fluid (aqueous humour) drains away through the trabecular meshwork. In angle closure, the iris moves forward and blocks this drainage, causing the pressure to rise and potentially leading to vision loss.
A laser peripheral iridotomy creates a tiny hole in the outer part of the iris using a laser beam. This gives the fluid a permanent escape route and pushes the iris back, opening the drainage channels again. Aqueous humour is not the same as tears, so your tears will not be affected.
During the procedure you will sit with your chin resting on the laser machine, similar to the microscope used in clinic. A special contact lens is placed on the front of your eye to keep it still and focus the laser. You will see bright flashes of light and hear clicking sounds. The treatment usually takes about 15 minutes and is generally painless, though you may feel slight discomfort.
Afterwards your vision may be slightly blurred for a few hours, so you should not drive home. You can otherwise resume normal activities straight away. Anti-inflammatory drops will be given, and your eye pressure will be checked about an hour later before you go home with any prescriptions and a follow-up appointment.