Tono-Pen Tonometer in Mouse Intraocular Pressure (IOP) Studies
Intraocular Pressure (IOP) is a vital indicator of ocular health. In glaucoma and other eye disease research, elevated IOP is a major contributor to vision damage. Mice are widely used as animal models in ophthalmology, including induced ocular hypertension, gene knockout, transgenic studies, and pharmacological testing. However, the small size and complex anatomy of the mouse eye make traditional invasive methods prone to tissue injury or data bias. Achieving non-invasive and accurate IOP measurement has long been a challenge.
In 2003, John Danias and colleagues published a study in Investigative Ophthalmology & Visual Science, validating the Tono-Pen Tonometer for mouse IOP measurement. Their experiments confirmed it as a reliable non-invasive tool, making it an excellent choice for laboratory use.
Study Design
The study assessed the accuracy of the Tono-Pen Tonometer in mice through two approaches:
- Ex vivo eyes: C57BL/6 mouse eyes were cannulated, with IOP set in 5 mmHg steps (10–45 mmHg). Measurements with the device were compared to manometer values.
- In vivo eyes: IOP was controlled with a vitreous micro-needle in live mice while readings were taken with the tonometer.
This design confirmed reliability in both isolated and live eye conditions.
Key Results
The measurements showed a strong correlation with true IOP:
- Ex vivo: y = 1.07x + 0.42 (R² = 0.99, P < 0.0001)
- In vivo: y = 0.87x + 2.17 (R² = 0.97, P < 0.0001)
These findings demonstrated that the tonometer was highly accurate in the 10–45 mmHg range, with variability of only about 13%. Despite the small structure of the mouse eye, it consistently produced stable and reliable readings.
Advantages in Research
The Tono-Pen Tonometer offers several strengths for mouse IOP measurement:
- High precision, closely matching invasive methods.
- Non-invasive, requiring only light corneal contact, often without anesthesia.
- Simple operation, portable and efficient.
- Versatility for glaucoma models, genetic research, and drug evaluation.
Conclusion
By combining ease of use with accuracy, the Tono-Pen Tonometer has become a valuable instrument for mouse IOP studies. Whether investigating glaucoma mechanisms or testing new ophthalmic therapies, researchers can rely on this device for dependable, non-invasive measurements.
Reference
Danias J, Kontiola AI, Friberg T, Grosskreutz CL. Method for the noninvasive measurement of intraocular pressure in mice. Invest Ophthalmol Vis Sci. 2003;44(6):2686–2689.
