From the Guidelines
Normal intraocular pressure (IOP) is typically considered to be 21 mmHg or less, as defined by the primary open-angle glaucoma suspect preferred practice pattern 1. This definition is based on the understanding that an IOP greater than 21 mmHg is often associated with an increased risk of developing glaucoma.
Key Points to Consider
- The normal range for IOP measured with a tonometer is generally between 10-21 mmHg 1.
- Goldmann applanation tonometry is considered the gold standard for IOP measurement, but other tonometers like the non-contact tonometer, Tono-Pen, or iCare rebound tonometer may also be used 1.
- IOP can fluctuate throughout the day, with readings often being highest in the early morning and lowest in the evening, so multiple measurements over time are recommended 1.
- Factors that can affect IOP readings include corneal thickness, corneal irregularities, and recent eye surgery 1.
Importance of Regular Monitoring
Regular IOP monitoring is essential for individuals at risk of developing glaucoma, including those with a family history of the condition, certain ethnic or racial backgrounds, or other risk factors 1. By monitoring IOP and maintaining it within the normal range, individuals can reduce their risk of developing glaucoma and related vision problems.
Considerations for Clinical Practice
In clinical practice, it is crucial to consider the individual's overall risk profile when interpreting IOP readings, as some people may be at higher risk for glaucoma despite having normal IOP 1. Additionally, clinicians should be aware of the potential for IOP to fluctuate and the importance of regular monitoring to ensure accurate assessments and effective management of glaucoma risk.
From the Research
Normal IOP Values
- Normal intraocular pressure (IOP) values range from 10 to 21 mmHg, with a mean of 15.5 mmHg +/- 2 standard deviations 2
- IOP values can be influenced by various factors, including patient position, central corneal thickness, corneal diameter and curvature, corneal rigidity, and corneal hydration state 2
Measurement of IOP
- Tonometry is the measurement of intraocular pressure (IOP) 2
- Goldmann applanation tonometry is considered the gold standard for intraocular pressure measurement 2
- Other methods of measuring IOP include noncontact tonometry, Tono-Pen, ICare tonometer, dynamic contour tonometry, and ocular response analyzer 2
IOP Reduction
- Latanoprost and timolol are commonly used to reduce IOP in patients with glaucoma or ocular hypertension 3, 4, 5, 6
- The IOP-lowering effects of latanoprost and timolol can vary depending on the individual patient and the specific formulation used 3, 4, 5, 6
- Latanoprost increases uveoscleral outflow, while timolol reduces aqueous flow 6