What is the normal intraocular pressure range?

• A. 5-15 mmHg
• B. 20-30 mmHg
• C. 15-25 mmHg
• D. 10-21 mmHg

Answer: (D)

Normal intraocular pressure is the force exerted by the fluid inside the eye, balancing production of aqueous humor by the ciliary body with its drainage through the eye’s outflow pathways. In healthy eyes, this pressure typically falls within about 10 to 21 millimeters of mercury, with an average around 15 mmHg. Values consistently outside this range can signal issues: higher pressures (above about 21 mmHg) may indicate glaucoma risk, while unusually low pressures (below about 10 mmHg) can occur after surgery or with inflammation and may signal hypotony. Since measurements can be influenced by factors like corneal thickness and time of day, clinicians interpret IOP within the broader clinical context. Thus, the normal range is 10–21 mmHg.