Dorzolamide

Lowering the pressure inside the eye

Dorzolamide belongs to the carbonic anhydrase inhibitor group of eye medicines. It slows an enzyme found in the ciliary body, the tissue layer behind the iris that makes the clear fluid filling the front of the eye. With that enzyme slowed, the eye produces less of the fluid, and the pressure inside falls. Glaucoma and ocular hypertension — pressure inside the eye that is higher than it should be — are the conditions treated this way. Pressure that stays high damages the optic nerve over the years, which is why the drops go in every day rather than now and then. They hold the pressure down; they do not cure glaucoma, and stopping them lets it climb again.

Trusopt or Cosopt: which bottle?

Two dorzolamide bottles are sold here. Trusopt holds dorzolamide 2% on its own. Cosopt pairs dorzolamide 2% with timolol 0.5%; timolol is a beta-blocker that also reduces fluid production, through a different receptor, so the two ingredients press on pressure from two directions in a single bottle. Trusopt is normally put in three times a day, while Cosopt, because timolol lasts longer, goes in twice. Which one suits depends on how much the pressure needs to come down. Both belong to the Eye Care range.

Putting the drops in

Start with clean hands. Tip the head back, draw the lower lid away from the eye to make a small gap, and let one drop fall into it, keeping the nozzle clear of lashes and skin. Shut the eye softly for a minute or two, then press gently on the inner corner, beside the nose, for around a minute: that keeps the medicine on the eye and reduces the bitter taste it leaves at the back of the throat. Where two different eye medicines are used, leave ten minutes between them; if one eye needs more than one drop of dorzolamide, wait five minutes between drops. Soft contact lenses come out before the drop and go back in at least fifteen minutes afterwards.

Storing the bottle

Keep the bottle standing up, the cap on, somewhere cool and out of direct light, and put it where children cannot reach it.

Side effects and interactions

The drop often stings or burns for a moment, and a bitter taste follows. Sensitivity to bright light, nausea and vomiting are also reported. Less often the eyes turn itchy, red, watery or swollen, or feel dry, and a skin rash can appear. Swelling of the face or throat, or trouble breathing, after a dose needs urgent treatment. A small amount of dorzolamide reaches the bloodstream, and acetazolamide tablets, which act on the same enzyme throughout the body, add to its effect. Other eye medicines can be used alongside, spaced as described above.