It’s hard to believe that something as serious as glaucoma in the eye can be treated by the use of eye drops and medications, and to a certain extent that is true when you consider the nature of the condition.
Glaucoma is a degeneration of the optic nerve that takes the information about an image seen by the eye that has been focussed on to the retina at the rear, and then transmits it to the brain for processing. If the optic nerve degenerates to such an extent that no information is sent then total vision loss is the result.
Once glaucoma has been diagnosed it is largely a matter of management rather than treatment to cure the condition. It is not possible to reverse any damage that the optic nerve has suffered.
What is the glaucoma management protocol?
The main objective is to lower intraocular pressure (IOP) of the eye.
Medication can be administered topically in the form of eye drops, or systemically taken orally or received by injection.
IOP will have increased due to a variety of reasons related to the aqueous humour within the eye not being able to drain away through the very fine mesh called the trabecular meshwork. Lowering and maintaining a stable IOP can stabilise any deterioration in the optic nerve.
The use of eye drops is an ideal mode of application of medication for lowering IOP and there are quite a few variants available, each with their particular suitability and inevitable side effects. It is often the case that if one variant produces a disturbing side effect a change can alleviate them without new effects being suffered.
Glaucoma Drugs and their functions:
Reduce the eye’s ability to produce aqueous humour – timolol, levobunolol
Contract the ciliary muscles and so tighten the meshwork, enabling more drainage – pilocarpine
Increase outflow of the aqueous humour fluid from the eye – latanaprost, travoprost
Both increase outflow AND reduce humour production – brimonidine, apraclonidine
Oral medication that reduces the eye’s ability to produce aqueous humour and thus decrease IOP – Diamox
Problems associated with eye drops and medications
Whilst studies into the effectiveness or otherwise of drugs taken in the form of eye drops or orally are frequently made, often no attempt is made to ensure that:
• Do patients obtain the necessary drugs in the first instance?
• Do patients continue to take the required dosage?
Glaucoma having a very slow development and with little or no symptoms for a patient to be overly concerned about can lead to apathy.
It has been found that up to 50% of patients did not obtain the prescribed medication, and 25% only took their medication once – that means only 25% took their medication as directed, a very apathetic approach indeed!
Compliance with glaucoma treatment is a huge problem, but so is careful selection of drugs so that they will have minimal side effects.
An example of this was a study done in Canada a few years ago looking at people that were being treated for glaucoma in a retirement hospital with the beta blocker, Timolol. A side effect of beta blockers is lethargy. When the patients were changed to a different glaucoma treatment, 30% of them were more energetic to the point that they were allowed to leave the hospital.
Careful selection of glaucoma drugs is essential to maximise effect and minimise potential side-effects.
It is thought by some that a change in diet may help in management.
For example caffeine increases IOP in those suffering from glaucoma, so a reduction in intake may be of benefit.
Studies in the past have concluded that marijuana has the effect of reducing IOP, however only to the same extent as conventional drugs. In some states of the USA as an example marijuana is legal as long as it is for medicinal purposes – glaucoma treatment being one of the indications.
Exercise has been shown to reduce intraocular pressure. Most people could eliminate the use of one lot of drops if they were to take up 4 brisk exercise sessions per week – unfortunately most people choose just to use the drops and not accept the health advantages of exercise.