Changes in Eyesight: When to See a Doctor

Our vision supports almost everything we do, from reading and writing, to driving, recognising faces and navigating daily life. Up to 80% of all the impressions in life have been perceived through our vision and even the smallest of changes in eyesight can feel unsettling. Some changes are entirely normal, particularly with age. Others can signal something more serious.

Knowing the difference matters and recognising when to monitor a symptom and when to seek help can make a real difference to outcomes, particularly for conditions that progress quietly.

We caught up with Consultant Ophthalmic Surgeon, Mr Rohit Jolly, to find out the most common changes in vision, what may be causing them, and the signs that should prompt you to seek medical advice. Mr Jolly specialises in neuro-ophthalmology, cataracts, squint surgery and general ophthalmology for both adults and children.

Common Changes in Eyesight

It is very common for vision to change over time. Many people notice increasing difficulty with reading, focusing between distances or needing brighter light, particularly from their 40s onwards.

Common symptoms include:

• Blurred vision, either at distance or up close, and it may come and go
• Fluctuating vision, where clarity changes throughout the day
• Double vision in one or both eyes
• Sensitivity to light in everyday settings
• Difficulty focusing, especially when switching between screens and distance
• Dry, gritty or watering eyes
• Reduced night vision or difficulty in low light
• Seeing floaters, flashes or shadows
• Eye strain, particularly after prolonged screen use

Some of these can be explained by fatigue, dry eyes, or an uncorrected refractive error. However, persistent or worsening symptoms should not be ignored.

When to See a Doctor for your eye health

As a general rule, any sudden or persistent change in vision should be assessed.

You should seek medical advice urgently if you experience:

• Sudden loss or reduction of vision, particularly in one eye
• A shadow or “curtain” moving across your vision
• New flashes of light, especially with an increase in floaters
• Distortion, where straight lines appear bent or wavy
• Double vision with both eyes open that does not resolve
• Eye pain, redness or a pressure sensation
• Episodes of missing vision or blind spots

These symptoms can indicate serious conditions such as a retinal detachment, macular problems, optic nerve problems, or acute pressure problems associated with glaucoma, and in some cases may be linked to neurological or vascular causes. Early assessment is important.

Possible Causes of Vision Changes

There are many potential causes of changes in eyesight, ranging from common and easily corrected issues to more serious underlying conditions.

Refractive Errors
Short-sightedness (myopia), long-sightedness (hyperopia), and astigmatism are among the most common causes of blurred vision. These can change over time and are typically managed with glasses or contact lenses.

Presbyopia
An age-related reduction in the eye’s ability to focus on near objects, usually becoming noticeable in our 40s.

Cataracts
Cataracts is a gradual clouding and hardening of the eye’s lens, leading to blurred vision, glare, and reduced contrast sensitivity.

Macular Degeneration
A condition affecting central vision, often making tasks like reading, appreciating details or recognising faces more difficult.

Glaucoma
A group of conditions associated with optic nerve damage, often linked to raised intraocular pressure, that result in loss of vision. Glaucoma can progress without obvious symptoms in early stages.

Diabetic Eye Disease
High blood sugar levels can damage retinal blood vessels, leading to fluctuating or blurred vision from bleeding into the structures of the back of the eye and, in advanced cases, vision loss. Find out more common diabetic eye problems.

Hypertension (High Blood Pressure)
High blood pressure can affect the blood vessels in the eye and, in some cases, the optic nerve.

Eye Inflammation or Infection
Conditions such as conjunctivitis or uveitis may cause redness, discomfort, watering and discharge as well as light sensitivity.

Why Early Diagnosis For Eye Conditions Matters

Many eye conditions develop gradually and without pain. By the time symptoms become noticeable, some degree of damage may already have occurred.

Early assessment allows for:

• Detection of conditions before significant vision loss
• Timely treatment or monitoring
• Identification of associations with wider health conditions such as diabetes, hypertension or even thyroid related concerns
• Accurate updates to vision correction where needed

If you have a family history of eye disease or underlying health conditions, regular eye examinations are particularly important.

What Happens During an Eye Exam?

A comprehensive eye examination looks at both how well you see and the health of your eyes. The examination may also look at how the rest of the nerves (cranial nerves) supplying the face and head work.

This may include:

• Visual acuity testing (which measures how clearly you can see at different distances)
• Refraction to assess for glasses or contact lenses
• Measurement of intraocular pressure (which can check for signs of glaucoma)
• Visual field testing
• Examination of all segments of the eyes, with focus on the cornea, lens, retina and optic nerve

These tests are straightforward and provide valuable information about both ocular and general health.

Looking After Your Eyes Day to Day

Simple habits can support long-term eye health:

• Attend regular eye examinations, even if your vision feels stable
• Use appropriate lighting when reading or working
• Take regular breaks from screens (for example, the 20-20-20 rule)
• Wear appropriate UV protection outdoors
• Avoid rubbing your eyes
• Monitor and act on any new or changing symptoms

Private Eye Care at St John & St Elizabeth Hospital

At St John & St Elizabeth Hospital, we offer a full complement of private ophthalmology services for patients experiencing changes in vision, for all age groups. Based in St John’s Wood, we see patients from the neighbouring North London area but also further across the London sector.

Our eye service includes:

• Prompt access to appointments, including same day where possible
• Assessment by experienced Consultant Ophthalmologists
• On-site diagnostics and tailored treatment plans
• Continuity of care where ongoing monitoring is needed

Get in touch to book an appointment

Final Thoughts From An Eye Expert

Not all changes in eyesight are serious, but some do require prompt attention.

Sudden vision loss, distortion, flashes of light or visual change associated with pain should always be treated as urgent. More gradual symptoms, such as progressive blurring of vision or increasing sensitivity to light, will warrant assessment if they persist, but no so much in an emergency setting.

If you are unsure, it is always safer to have your eyes checked. Early diagnosis remains one of the most effective ways to protect your vision and safeguard your wellbeing and future.