Which Medical Conditions can Affect your Vision?

Whilst eyesight naturally changes as we age, many medical conditions — some affecting the eyes directly and others impacting the wider body — can interfere with vision. Understanding how different conditions affect eyesight can help with early detection, timely treatment and, in many cases, the prevention of permanent sight loss.

Medical Conditions Affecting the Whole Body

Diabetes

Diabetes increases the risk of cataracts and glaucoma. Fluctuating blood sugar levels can also cause temporary blurred vision. Effective diabetes management plays a key role in protecting eyesight.

People with can also develop diabetic retinopathy, which occurs when high blood sugar levels damage retinal blood vessels. Early stages may not cause symptoms, but advanced disease can lead to blurred vision, floaters and vision loss. Good blood sugar control and regular diabetic eye screening are essential for prevention.

High Blood Pressure (Hypertension)

High blood pressure can damage the blood vessels in the retina, a condition known as hypertensive retinopathy. This may cause vision changes, headaches or, in severe cases, sudden vision loss. Managing blood pressure is crucial for eye health as well as overall wellbeing.

Autoimmune Disorders

Autoimmune diseases occur when the immune system mistakenly attacks healthy tissue. Several can affect the eyes, including:

• Rheumatoid arthritis: Can cause dry eye syndrome or inflammation.

• Lupus: May affect retinal blood vessels.

• Multiple sclerosis (MS): Often associated with optic neuritis, causing blurred or lost vision and pain with eye movement.

Thyroid Disease

Overactive thyroid disease, particularly Graves’ disease, can cause thyroid eye disease. Symptoms include bulging eyes, dryness, double vision and, in severe cases, vision loss due to optic nerve compression.

Neurological Conditions and Vision

Stroke

A stroke can affect the parts of the brain responsible for vision, leading to partial vision loss, blind spots, double vision or difficulty recognising objects. Visual problems after a stroke may improve with rehabilitation, but some changes can be permanent.

Brain Tumours

Tumours affecting the brain or optic pathways can cause visual disturbances, including blurred vision, loss of peripheral vision or visual field defects. Early diagnosis can be critical in preventing long-term damage.

Migraines

Some people experience visual migraines or migraine aura, which may involve flashing lights, zigzag patterns or temporary vision loss. These symptoms are usually short-lived but can be alarming.

Infectious and Inflammatory Conditions

Eye Infections

Infections such as conjunctivitis (pink eye), keratitis or uveitis can cause redness, pain, light sensitivity and blurred vision. Prompt treatment is important to avoid complications.

Sexually Transmitted Infections

Conditions such as syphilis, herpes and HIV can affect the eyes if left untreated, potentially leading to inflammation and vision impairment.

Nutritional Deficiencies

Vitamin A Deficiency

Vitamin A is essential for good vision, particularly in low-light conditions. Deficiency can lead to night blindness and, in severe cases, permanent damage to the cornea. While rare in the UK, it can occur in people with absorption disorders or poor diets.

Medication-Related Effects

Medications

Some medications, including steroids, antimalarial drugs and certain antidepressants, can affect vision. Side effects may include blurred vision, dry eyes, cataracts and  increased eye pressure.

Protecting Your Vision

Many conditions that affect vision can be managed effectively if detected early. Steps to protect eye health include:

• Attending regular eye tests, even if vision seems fine

• Managing chronic conditions such as diabetes and hypertension

• Eating a balanced diet rich in vitamins and antioxidants

• Seeking prompt medical advice for sudden vision changes

Taking Care of Yourself

Vision problems are not always caused by ageing or eye strain alone. A wide range of medical conditions — from eye-specific diseases to systemic and neurological disorders — can affect eyesight in different ways. 

Being aware of these conditions, recognising early warning signs and prioritising regular eye care can make a significant difference in preserving vision and quality of life.