Q: What do my eye drops actually do?
A: Eye drops used in the treatment of glaucoma work by reducing the intraocular pressure (IOP) within your eyes. There are several classes of drops, which have different mechanisms of action. Prostaglandins, such as latanoprost, travoprost and bimatoprost reduce IOP by increasing drainage outflow from the eye. Other drop classes reduce the formation of fluid within the eye – such as beta blockers (eg timolol), alpha agonists (eg brimonidine, apraclonidine) and carbonic anhydrase inhibitors (eg dorzolamide, brinzolamide).
Q: Why are there different preservatives in my eye drops? Why do some eye drops have no preservatives at all?
A: Eye drops used in the treatment of glaucoma typically come in bottles and last approximately 1 month once opened, and are then discarded. Preservatives in the solutions are important in preventing bacteria building up in the bottles after opening. The most common preservative, benzalkonium chloride, is very good at preventing bacterial growth, but can be harmful to the surface of the eye. In recent years some eye drops have been formulated with other, potentially gentler preservatives that seem to be just as effective at preventing bacterial growth. Still other eye drops have been formulated with no preservatives at all – these may be the gentlest form of glaucoma drops and may be suitable for sore, irritated eyes. The preservative-free eye drops are usually designed for single usage – they come in very small, clear plastic dispensers designed to be discarded after each drop administration – hence are only used on opening, when the solution is still sterile.
Q: The information says to discard my eye drop bottle 28 days after opening. I always have some left, why can’t I keep using it until it is empty?
A: On average, the preservatives in bottles of glaucoma medications are designed to safely prevent bacterial growth for 28 days. Hence using the bottle longer than is recommended by the manufacturer can potentially lead to solution degradation, less effective active ingredients and dangerous build-up of bacteria that can lead to infection of the surface of the eye.
Q: I use a product that comes in single use containers. Do I have to throw it out after one use if it holds more than I need for the day?
A: Single use containers generally have preservative free medication formulations within them. These are designed to be used once and then immediately discarded. If kept for a period after being opened, bacteria and other harmful micro-organisms could potentially grow in the solutions to dangerous levels. If reused after this period the micro-organisms in the solution could lead to a harmful infection of the surface of the eye.
Q: Do I need to keep my drops cool?
A: It is recommended to store eye drops refrigerated before opening the bottle. Once opened, the bottle can be kept at or below 25 degrees (room temperature), ensuring it is out of direct sunlight and not in a hot environment for prolonged periods, to avoid medication degradation. Consult your pharmacist if you have any concerns about how to store your medication or if your drops require refrigeration.
Q: Can I instil 2 drops to make sure it goes in?
A: Firstly, it is important that you follow the dosage as prescribed. If one drop has been prescribed there is no need for a second. Two drops will generally not cause your eyes harm, but will mean you run out of drops faster and spend more money on your treatment. One good tip is to get into the practice of closing your eye and lightly pressing the inside corner of your eye when the drop has gone in. This maximises the absorption of the drop by your eye and stops it from being washed away into your tear duct.
If you take more than one type of drop, you should leave 5 minutes between each type. It is preferable that the drop doesn’t make contact with your skin, but if it does, simply wipe it away.
If you are having trouble instilling your drops, click here for further information.
Q: I was told to use my eye drops every day and to make sure I did it at the same time each day. Why is that important?
A: The eye drops only work when they are being used – if you stop using them the eye pressure will increase again. Hence it is important to use them every day, otherwise the IOP will fluctuate. There is some evidence to suggest that fluctuations in IOP may be as harmful to the optic nerve as high IOP.
Using the drops at the same time each day prevents day-to-day fluctuations in 24 hour IOP pattern, however is not as important as using the drops every day. Getting into a fixed daily routine generally helps patients to remember to use the drops each day. If, on the occasional day, you are a little late with using the drops, it is better to use the drops late than not at all.
Q: I don't think my drops are making my vision any better.
A: At this point in time there is no cure for glaucoma. Fortunately though, for most people with glaucoma, taking the appropriate eye drop medication will preserve their vision and minimise the chance of further losses. This is why early detection, ensuring the medication is taken as prescribed and attending regular follow-up appointments is so important.
At these follow-up appointments the effectiveness of treatment is assessed by taking a reading of the pressure in your eye, examining the health of the eye structures and measuring how well you see from the centre of your vision all the way to the edge of your sight. If you are experiencing problems taking your medication or with their side effects then this should be discussed with your eye-care practitioner as there may be a more suitable medication or treatment option for you.
While new therapies to restore vision continue to be explored none have yet been proven to be effective. Glaucoma Australia and your care providers will continue to keep you updated on advances in treatments.
Q: Is it OK for my GP to renew my glaucoma eye drop prescription?
A: It is vital to continue to use your prescribed glaucoma eye drops every day. Erratic dosing can contribute to vision loss and may ultimately result in the need for more aggressive glaucoma interventions. In the event that you run out of your eye drops, repeat prescriptions can be obtained from your GP. However, only your ophthalmologist or optometrist is able to assess if the medication is still effective. For this reason regular assessments (as directed) with your eyecare professional remain critical in the management of your glaucoma. If you are not able to see your ophthalmologist before your prescription runs out you may be able to renew your prescription with your optometrist if they are therapeutically endorsed. Optometrists are also very familiar with glaucoma management and have equipment not available in GP practices to determine if your eye drops are still effective in controlling your glaucoma.
Q: Are generic glaucoma eye drops the same as brand named ones?
When an eye drop is researched and developed it is then released for sale by a company under its “brand name”. Once the patent protection for the drug has expired, other pharmaceutical companies may manufacture and sell the drop. Usually this drop is given its chemical name otherwise known as the “generic” name.
The generic version of a drug must contain the same active ingredient and be “bioequivalent”. This means that the same amount of active ingredient is absorbed by the body over the same period of time. The clinical effectiveness of generic medications is assumed to be similar to the branded product. Inactive ingredients such as preservatives and pH adjusters may be different in generic drops.
Generic drops may be more affordable for patients and are a safe and effective alternative to their branded counterparts. In conditions, such as glaucoma, patient compliance is important to prevent disease progression and cost of medication may impact this. Some studies have however suggested that the generic drop may not be the clinical equivalent even though it is the chemical equivalent. Patients who change from the branded to generic formulation should be closely monitored to ensure the desired therapeutic response has been reached.
Q: When travelling in a different timezone when should I instil my drops?
A: Like recovering from jet-lag, it is useful to have a period of adjustment for 24-48 hours and then change over to the new time zone for administering medications. For example – daily drops can be administered slightly later one day to get in the new time zone.
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