Influence of medication on the eye: How medication works and can impair vision

Whether antibiotics, painkillers or the contraceptive pill – many of us regularly take medication without thinking about the possible side effects on our eyes. However, the active ingredients in these preparations can affect our eyesight, cause dryness or even cause serious eye problems. Did you know that some medications can increase intraocular pressure or cause blurred vision?

In this article, you will find out which medications cause eye problems, why this happens and what you should pay particular attention to. We give you an overview of typical preparations, explain the causes of side effects and show you when it is time to see an ophthalmologist.

How can a drug affect the eyes?

The active ingredients of many medications act on the eye by entering the eye tissue via the bloodstream or the mucous membranes. Medications that are administered directly into the eye – such as eye drops – pass through the cornea in order to take effect. In doing so, they can penetrate into the deeper layers of the eye and affect the optic nerve or the lens of the eye. Medications taken orally, such as ibuprofen or acetylsalicylic acid, can also enter the eye through the blood vessels and cause side effects such as increased intraocular pressure or burning eyes.

Vision and visual disorders: Which medications affect the eye?

If a medication regularly has side effects relating to the eyes or vision, this will also be noted in the package leaflet for the medication. If in doubt, you can read there whether the effect you are experiencing is normal or whether the medication may be responsible for the change you have noticed.

Antibiotics and their effects on eyes

Antibiotics are prescribed to fight bacterial infections in the body. They work by inhibiting the growth of bacteria or killing them completely. While they are vital in treating infections, they can also have side effects on the eyes.

Antibiotics are often used to treat:

• Respiratory tract infections (e.g. bronchitis, pneumonia)
• Urinary tract infections
• Skin and soft tissue infections
• Conjunctivitis (with a bacterial cause)

Antibiotics can be administered in tablet form, as an injection or locally as eye drops if the infection directly affects the eye.

Examples of commonly used antibiotics:

• Amoxicillin (against respiratory tract infections)
• Doxycycline (against acne and bacterial eye infections)
• Azithromycin (for ear infections and certain eye infections)
• Ciprofloxacin (against urinary tract infections and bacterial eye infections)

What effects do antibiotics have on the eyes?

Many antibiotics, especially those that are taken systemically (i.e. via the bloodstream), can affect the eyes as a side effect. The following eye problems frequently occur when taking antibiotics:

• Dry eyes: Some antibiotics, such as doxycycline, can reduce the flow of tears and lead to dry eyes.
• Blurred vision: This can occur if the active substance enters the eye via the bloodstream and affects visual acuity.
• Increased sensitivity to light: Certain antibiotics can increase the sensitivity of the eyes to light, which is particularly unpleasant outdoors or in artificial light.
• Allergic reactions: In rare cases, antibiotics can cause allergic reactions such as burning, redness or swelling around the eye.

Why do antibiotics cause side effects in the eye?

Antibiotics have a systemic effect and reach various organs, including the eyes, via the bloodstream. As the eyes are particularly sensitive to changes in the fluid balance and blood supply, this can lead to side effects such as dry eyes, irritated eyes or vision problems. In some cases, as with the direct application of antibiotic eye drops, these active ingredients can irritate the cornea and lead to visual disturbances.

Birth control pill

The contraceptive pill is a hormonal contraceptive that is mainly taken to prevent pregnancy. It works by changing the hormone balance in the body, preventing ovulation and affecting the lining of the uterus. However, taking these hormonal preparations can also have side effects on the eyes, as hormones play an important role in regulating many bodily functions, including tear production and fluid balance.

When is the contraceptive pill taken?

The contraceptive pill is taken for various reasons, including:

• Contraception
• Regulation of the menstrual cycle
• Relief from acne and skin problems
• Treatment of hormonal complaints such as endometriosis

Examples of common birth control pills:

• Ethinylestradiol/levonorgestrel (classic combination pill)
• Drospirenone/ethinylestradiol (for hormone-induced acne and PMS)
• Desogestrel (mini-pill without oestrogen)

What effects does the contraceptive pill have on the eyes?

The hormonal changes triggered by taking the pill can also have an effect on the eyes. Common side effects associated with the pill are

• Dry eyes: Hormonal changes affect tear production and can cause dry eyes. This often leads to symptoms such as burning eyes or a foreign body sensation.
• Blurred vision: The hormonal effect can slightly change the shape of the cornea, which can lead to temporary visual disturbances or blurred vision.
• Increased sensitivity to light: In some cases, the contraceptive pill can make your eyes more sensitive to bright light.
• Changes in contact lens tolerance: Women who wear contact lenses more frequently report intolerance and the feeling that the lenses fit less well, which can be attributed to hormonal changes and the resulting dryness of the eyes.

Why does the contraceptive pill cause eye problems?

Hormones such as oestrogen and progesterone, which are contained in the contraceptive pill, influence the fluid balance in the body, including the tear fluid. If the lacrimal glands are less active, the eyes may dry out. Hormonal fluctuations can also affect the cornea and other structures of the eye, which can cause visual disturbances.

In rare cases, taking the pill can lead to more serious eye problems such as an increase in intraocular pressure, which can increase the risk of glaucoma. If side effects such as blurred vision or dry eyes persist, it is advisable to consult an ophthalmologist and discuss taking the pill. In some cases, an alternative preparation with a different hormone composition can alleviate the symptoms.

Sildenafil (Viagra) and its effects

Sildenafil, the active ingredient in Viagra, is used to treat erectile dysfunction. It dilates the blood vessels to improve blood flow – including in the eye. However, this can lead to various side effects.

Common effects on the eyes are

• Increased sensitivity to light
• Blurred vision
• Blue cast in vision

These side effects occur because sildenafil also affects the blood supply to the optic nerve and the lens of the eye. In rare cases, this can lead to a serious impairment of vision, which is why a doctor or ophthalmologist should be consulted if symptoms recur.

Antihypertensives

Antihypertensives are used to treat high blood pressure, but can also have side effects on the eyes. As they regulate blood flow in the body, they also affect blood flow to the eye.

Examples of antihypertensive drugs:

• Amlodipine (calcium channel blocker)
• Ramipril (ACE inhibitor)
• Metoprolol (beta blocker)
• Valsartan (angiotensin II receptor blocker)
• Hydrochlorothiazide (diuretic)

These medications work in different ways to lower blood pressure but, as mentioned, can have side effects on the eyes that should be monitored.

Typical effects are

• Dry eyes due to reduced tear production
• Blurred vision
• In rare cases, an increase in intraocular pressure, which can increase the risk of glaucoma

Corticosteroids

Corticosteroids are used to treat inflammation and autoimmune diseases, but can also cause eye problems, especially with prolonged use.

Possible effects on the eyes:

• Increased intraocular pressure (risk of glaucoma)
• Cataract formation (cataract)
• Dry eyes and visual disturbances

One example of a commonly used corticosteroid is prednisolone. If you take corticosteroids over a longer period of time, regular eye examinations should be carried out to detect possible side effects at an early stage.

Psychotropic drugs

Psychotropic drugs are used to treat mental illnesses such as depression, anxiety disorders and bipolar disorders. They affect the central nervous system and can also have an effect on the eyes and vision due to their active ingredients.

When are psychotropic drugs taken?

Psychotropic drugs are prescribed for the treatment of:

• Depression (e.g. antidepressants)
• Anxiety and panic disorders
• Bipolar disorders
• Schizophrenia (e.g. antipsychotics)

Examples of frequently used psychotropic drugs:

• Amitriptyline (antidepressant)
• Citalopram (antidepressant)
• Olanzapine (antipsychotic)
• Diazepam (anxiolytic)

What effects do psychotropic drugs have on the eyes?

Psychotropic drugs can have various side effects on the eyes, depending on the active ingredient and dosage:

• Dry eyes: Many psychotropic drugs, such as antidepressants, reduce tear production and lead to dry eyes and a foreign body sensation.
• Blurred vision: This often occurs because psychotropic drugs can affect the eye muscles.
• Increased intraocular pressure: Some psychotropic drugs can increase intraocular pressure, which increases the risk of glaucoma.

Why do psychotropic drugs cause eye problems?

Psychotropic drugs have a systemic effect and influence many bodily functions, including the fluid balance and nerve control in the eye. Antidepressants from the group of tricyclic antidepressants or serotonin reuptake inhibitors (SSRIs) in particular can reduce the flow of tearsby blocking neurotransmitters, which leads to dry eyes. The eye muscles and the cornea can also be affected by the medication, leading to blurred vision.

Painkillers

Painkillers are used to relieve pain and inflammation, particularly in the case of headaches, joint pain or post-operative complaints. Although they are generally well tolerated, some painkillers can have side effects on the eyes.

When are painkillers taken?

Painkillers are often used for the following complaints:

• Headaches and migraines
• Joint pain and arthritis
• Postoperative pain
• Fever and inflammation

Examples of commonly used painkillers:

• Ibuprofen (non-steroidal anti-inflammatory drug)
• Paracetamol (analgesic and antipyretic agent)
• Acetylsalicylic acid (e.g. aspirin, also for blood thinning)
• Diclofenac (anti-inflammatory and pain-relieving)

What effects do painkillers have on the eyes?

In rare cases, painkillers can cause side effects on the eyes, especially if taken for long periods or in high doses:

• Dry eyes: Some painkillers such as ibuprofen can impair the flow of tears and lead to dry eyes.
• Blurred vision: Painkillers such as acetylsalicylic acid can in rare cases lead to temporary visual disturbances or blurred vision.
• Bleeding in the eye: Painkillers with a blood-thinning effect, such as acetylsalicylic acid, can increase the risk of bleeding in the eye, especially in people with pre-existing eye problems.

Why do painkillers cause eye problems?

Painkillers affect the body in many ways, particularly through their anti-inflammatory or blood-thinning effects. With long-term use, some painkillers can change the blood flow to the eyeor affect tear production, which can leadto dry eyes and, in rare cases, visual disturbances. Painkillers such as ibuprofen or diclofenac can also slightlyirritate the corneain sensitive people.

Eye drops: medication that acts directly on the eye

Eye drops are a common form of treatment for various eye problems, as they deliver the active ingredient directly into the eye and have a targeted effect. They are used to treat inflammation, infections, glaucoma and dry eyes. Despite their localized application, eye drops can have various side effects.

What types of eye drops are there?

There are many different types of eye drops, depending on the intended use:

• Antibiotic eye drops: for the treatment of bacterial eye infections, such as ciprofloxacin or ofloxacin
• Anti-inflammatory eye drops: contain corticosteroids such as prednisolone to reduce inflammation
• Antiglaucoma eye drops: to reduce intraocular pressure, such as latanoprost or timolol
• Artificial tears: for the treatment of dry eyes
• Antiallergic eye drops: e.g. olopatadine to alleviate allergic reactions in the eye

What side effects can eye drops have?

Although eye drops act directly on the eye and are often better tolerated than systemic medication, they can still cause side effects:

• Irritation and burning: Many eye drops, especially those with preservatives, can cause a burning sensation in the eye.
• Dry eyes: Some eye drops can reduce tear production, which can lead to dry eyes with prolonged use.
• Blurred vision: Blurred vision may occur temporarily shortly after application, especially with eye drops containing oily or viscous ingredients.
• Increased intraocular pressure: Eye drops containing corticosteroids such as prednisolone can increase intraocular pressure and increase the risk of glaucoma if used over a longer period of time.
• Allergic reactions: Some people react to certain ingredients in eye drops, which can lead to redness, swelling or itching.

When to see an ophthalmologist or stop taking medication?

It is always advisable to take possible side effects of medication seriously, especially if they affect the eye. As the eyes are a very sensitive organ, even slight discomfort, such as dry eyes or visual disturbances, can be an indication of the body’s reaction to the medication. But when should you see an ophthalmologist or stop taking a medication?

Typical signs for which you should consult an ophthalmologist:

• Persistent visual disturbances: If you notice blurred vision, blurred vision or reduced visual acuity after taking or using a medicine for a prolonged period of time.
• Strong sensitivity to light: If the eye suddenly reacts excessively sensitively to light, this is a warning signal.
• Dry eyes that do not improve despite treatment: Unpleasant symptoms such as burning eyes or a foreign body sensation that are not alleviated by eye drops or artificial tears.
• Eye pressure or pain: A feeling of pressure behind the eyes or even pain could indicate increased intraocular pressure or other serious problems.
• Redness and swelling: Redness or swelling of the eye that occurs suddenly and does not subside could be an indication of an allergic reaction or a more serious eye condition.
• Bleeding in the eye: In rare cases, bleeding in the eye can occur, particularly with painkillers with a blood-thinning effect such as acetylsalicylic acid.

Discontinuing medication – when should you be careful?

The unauthorized discontinuation of medication should always be discussed with the attending physician. In many cases, there are alternatives that have fewer side effects for the eyes, or adjusting the dosage may be sufficient. It is important to work with a treating doctor or ophthalmologist to find out whether the side effects are actually caused by the medication or whether there may be an underlying eye condition.

Why is early clarification important?

• Early detection of eye diseases: Some medications can exacerbate side effects if a condition such as glaucoma or cataracts already exists. An early visit to the ophthalmologist can help to diagnose such diseases before they progress.
• Alternative preparations: If the medication affects the eyes too much, the doctor may be able to prescribe an alternative preparation that has fewer side effects.
• Prevention of worsening: Untreated side effects, such as dry eyes or increased intraocular pressure, can lead to permanent damage to the eye in the long term if they are not treated in time.

If in doubt, it is better to see an ophthalmologist once more to avoid serious complications and to take appropriate measures at an early stage.