People often don't realise this – but many prescription drugs and some over-the-counter and herbal remedies have potential to cause adverse side-effects to the eyes.
However, the risks can be managed, says Specsavers Rotorua optometrist, Celeste Raisbeck: "The effects of medications of all descriptions on the eyes can range from minor issues, such as temporary blurred vision, to more serious problems or permanent damage.
"When starting to take a new medication or treatment, it's advisable to check it out with your optometrist, especially if you have an existing eye condition, or history of one in your family," she says.
Steroids, a family of drugs commonly prescribed for a range of ailments including rashes, allergies, and arthritis, have been known to cause new ocular issues or worsen a pre-existing diagnosis if taken alongside conditions such as glaucoma or cataracts.
Glaucoma causes damage to the optic nerve connecting the eye to the brain, often resulting in the gradual loss of peripheral vision. Cataracts are very common and typically cause blurred vision. If left untreated, cataracts will compromise vision, with an operation needed to remove them.
"It is advisable to tell your optometrist before you start steroid treatments," says Raisbeck. "We may recommend more frequent eye checks to see whether the steroids are having an impact on your vision. Eye problems may well be temporary and not serious, but it's important to get checked out earlier rather than later."
Dry eye syndrome is another common side-effect of many medications and occurs when your eyes' tear film is insufficient. The tell-tale signs are a gritty feeling that gets worse during the day and eyelids that may be sticky when waking up. Patients may also report very red, painful or watery eyes and sensitivity to light.
Raisbeck says any change in vision clarity, or the onset of pain, is a sign to get your eyes checked as soon as possible.
"It's important to keep your eyes lubricated so they can protect against infections and clear away debris from the surface of your eyes. Tears play a crucial role in eye health and dry eye, if left untreated, can lead to serious complications.
"The good news is that often eye drops can relieve symptoms quickly and no further treatment is necessary."
Eye twitching is a sensation that affects many people, often for no apparent reason. Research has shown that eye twitching is often caused by lifestyle factors including a lack of sleep, stress or dehydration – but has also been linked to certain medications.
"If the spasms are worrying you and are getting worse, it's best to get your eyes checked by your optometrist," says Raisbeck. "There could be another underlying reason for the twitching."
All Specsavers stores have the technology to identify and treat a raft of eye issues, including those that may result as a side-effect of medication. This includes hospital-grade technology to help optometrists detect sight-threatening eye conditions, early through an advanced 3D scan of the back of the eye.