Eye pressure fluctuation

About this calculator

Enter eye pressure readings from clinic visits or a home tonometer to see how much they vary, with a chart and table of the readings.

What you need

• Each eye pressure reading with its date and time
• Whether the readings are from clinic visits, a home tonometer or both

How it is calculated

Range = highest − lowest reading. Average = sum of readings ÷ number of readings. Sample standard deviation = √[Σ(reading − average)² ÷ (n − 1)], which needs at least two readings.

What the result can and cannot tell you

The range and the highest value depend on when readings were taken and on any unusual reading. How much day-to-day fluctuation adds to glaucoma risk on its own is still uncertain, so your eye doctor reads these numbers with your optic nerve and visual field results. Clinic and home tonometers can read differently, so summarize them separately.

References

1. The relationship between intraocular pressure and glaucoma: an evolving concept
2. Netra Eye Institute: Normal eye pressure range by age

Related

• Eye pressure reduction
• Ocular perfusion pressure
• Nerve fiber layer trend
• Eye pressure guide
• All eye calculators

For information only. These tools explain numbers and do not replace an eye examination or your eye doctor’s advice. Values you enter stay in your browser.