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Intraocular Pressure Measurement (Tonometry)

Intraocular pressure measurement (tonometry) — determining eye pressure for glaucoma screening and follow-up.

Measurement of intraocular pressure with a device. It is a basic diagnostic method used in glaucoma diagnosis, screening and treatment follow-up.

Indication

  • Screening during routine eye examinations in individuals over 40 years old
  • Follow-up in individuals with a family history of glaucoma
  • Measurement in people with risk factors such as high myopia, diabetes or cortisone use
  • Monitoring treatment response in patients diagnosed with glaucoma
  • Evaluation in complaints such as eye pain, headache, vision loss or seeing halos
  • Intraocular pressure check before and after eye surgery

Preparation

  • If contact lenses are worn, they should be removed before the examination
  • A tight collar or tie is loosened (pressure on the neck may affect the measurement)
  • For Goldmann tonometry, a topical anesthetic drop and fluorescein dye are instilled into the eye
  • Previous intraocular pressure records, if any, are reported to the physician

How it's performed

  1. The patient is seated in front of a slit-lamp biomicroscope, with chin and forehead supported
  2. In Goldmann applanation tonometry, a topical anesthetic drop and fluorescein are instilled in the eye
  3. A fine-tipped probe gently touches the eye surface to measure intraocular pressure
  4. In non-contact (air-puff) tonometry, the measurement is taken with a brief puff of air
  5. Generally, both eyes are measured separately and the procedure is completed within 1-2 minutes
  6. The result is recorded in mmHg; with the Goldmann method, 21 mmHg is accepted as the upper limit

Post-procedure

  • After the measurement, mild short-term burning or blurred vision may occur and resolves quickly
  • The eye should not be rubbed until the anesthetic effect wears off (about 20-30 minutes)
  • If a high value is detected, visual field testing, OCT and fundus examination are planned
  • In glaucoma follow-up, the measurement interval is determined by the physician (usually every 3-6 months)

Risks

  • Transient corneal epithelial scratch (rarely with Goldmann tonometry)
  • Transient irritation or allergic reaction to the anesthetic drop
  • Risk of measurement values deviating from the actual value in people with very thin or thick corneas
  • If an eye infection is present, the measurement is postponed; otherwise there is a transmission risk

FAQ

Is intraocular pressure measurement painful?

No. After the anesthetic drop, only a slight pressure sensation is felt at the moment of probe contact, without pain. With the air-puff method, only a short breeze is felt.

My intraocular pressure is high; do I definitely have glaucoma?

No. High intraocular pressure is an important risk factor for glaucoma but does not establish the diagnosis on its own. Evaluation is made together with visual field testing, optic nerve examination and OCT.

How often should the measurement be repeated?

In healthy adults over 40, every 1-2 years; in those with risk factors, once a year; in patients with diagnosed glaucoma, generally every 3-6 months according to the physician's recommendation.