Intraocular pressure (IOP) is the fluid pressure inside the eye. It is a key factor in glaucoma development and the primary target of treatment. Understanding IOP is essential for every glaucoma patient.
What Is Normal IOP?
Normal IOP typically ranges from 10 to 21 mmHg, though what is 'normal' varies between individuals. Some people develop glaucoma damage at pressures below 21 mmHg (normal-tension glaucoma), while others tolerate pressures above 21 mmHg without damage (ocular hypertension). The goal of treatment is to reach a 'target pressure' that prevents further optic nerve damage for each individual patient.
How Is IOP Measured?
The gold standard for IOP measurement is Goldmann applanation tonometry, performed during a slit lamp exam with anesthetic eye drops. Non-contact tonometry (the 'air puff' test) is also commonly used for screening. Newer methods include rebound tonometry (iCare), which requires no drops. IOP can fluctuate throughout the day, so your doctor may recommend measurements at different times.
Factors Affecting IOP
IOP naturally fluctuates during the day, typically being highest in the early morning. Factors that can elevate IOP include certain body positions (lying flat), tight neckwear, straining (Valsalva maneuver), caffeine intake, and certain medications (corticosteroids). Corneal thickness also affects IOP readings — thicker corneas may overestimate pressure, while thinner corneas may underestimate it.
IOP and Treatment Goals
The primary goal of glaucoma treatment is to lower IOP to a level that prevents further optic nerve damage. Studies have shown that reducing IOP by 20–30% from baseline significantly reduces the risk of progression. Treatment options include eye drops, laser therapy, and surgery. Prof. Leshno will determine your target pressure based on your specific type of glaucoma, severity of damage, life expectancy, and risk factors.