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Glaucoma

Normal Eye Pressure Range: What Your Numbers Mean

Eye pressure (intraocular pressure) is measured in millimetres of mercury (mmHg). Most healthy eyes sit between about 10 and 21 mmHg. A single high reading is common and does not mean you have glaucoma — but it does mean your optic nerve should be checked properly.

  • Typical range: about 10–21 mmHg
  • Pressure varies through the day
  • Thicker or thinner corneas change the reading
  • Diagnosis depends on the optic nerve and visual field, not pressure alone

What your reading may mean

  • Under 21 mmHg — usually normal, but glaucoma can still occur
  • 21–30 mmHg — raised; needs optic nerve and field tests
  • Over 30 mmHg — high; usually treated promptly
  • A big difference between eyes — worth investigating

What happens next

An ophthalmologist will repeat the pressure and check whether it is affecting the optic nerve.

  • Repeat pressure measurement
  • Corneal thickness measurement
  • OCT scan of the optic nerve
  • Visual field test
  • Drops or SLT laser if treatment is needed

Keeping your eyes healthy

Glaucoma is usually painless until late, so regular checks matter.

  • Eye test every 1–2 years, yearly over 40 with family history
  • Use prescribed drops every day
  • Tell your optician about glaucoma in the family

When to seek urgent care

  • Sudden severe eye pain with headache or vomiting
  • Red eye with blurred vision and haloes around lights
  • These can be acute glaucoma — go to A&E immediately

Frequently asked questions

Book an assessment

Appointments with Ms Tahmina Pearsall are available across the UK, with urgent slots prioritised for sudden symptoms.

The £250 consultation fee is charged separately from any treatment or surgery.

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