Glaucoma drops are highly effective in reducing high eye pressure and have huge advances in their formulation and combination treatments. This means that the drops are kinder to the eyes than ever before, but there will always be people in whom even preservative free drops make their eyes red.
If you have just started using drops, then we expect the eyes to be moderately red for the first 14-16 days. The active drug in the drops can make the blood vessels on the surface of the eye dilate. This does not mean that you are allergic to them. I always tell patients this when starting with glaucoma drops. If you understand that the initially increased redness is part of the drug’s effectiveness and is likely to dissipate after two weeks, you are more likely to carry on taking it and not be alarmed. If you do not know this, it might tempt you to stop a drop that is highly effective, in the misunderstanding that you are allergic to it.
Allergic reactions to the drops
Most prolonged redness when using glaucoma drops is due to sensitivity to the preservatives in the bottle. These substances help to ensure that the medication bottle remains free from harmful bacteria for the 28 days that the bottle can be used for and ensures that the environment within the bottle remains stable to keep the active drug at its peak performance. The main glaucoma drug that causes the true allergy is brimonidine (also known as Alphagan). This is a highly effective glaucoma drop but approximately 15% of the patients is allergic to it and it usually takes 3 months till the allergy is noted. Alphagan can be prescribed with other drops such as Timolol as a combination therapy (Combigan), and this seems to reduce the rate of allergy.
We are very lucky now that the drop manufacturers have listened to patients’ and glaucoma specialists’ feedback about preserved drops meaning that we now have preservative free versions of most glaucoma drop treatments. This has been a game changer for patients who are sensitive to the preservative. They no longer need to struggle on with a drop that, although effective, makes their eyes red and sore every day.
Ms Crawley has a particular interest in preservative free drops and has been involved in clinical trials looking at tolerability, effectiveness and red eye in patients taking life-long glaucoma drop treatment. It is usually possible to find a treatment regime that minimises eye redness. If you find that your glaucoma drops sting and make your eyes red and uncomfortable, we are there for you to discuss the alternatives. We need to make lifelong glaucoma drop treatment as easy and as comfortable as possible.