The Tono-Pen. A manometric and clinical study

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Devices

Background:

• Intraocular pressure (IOP) measurement is crucial for glaucoma diagnosis and management.
• Existing tonometers have varying degrees of accuracy, reproducibility, and portability.
• A need exists for reliable, accurate, and user-friendly IOP measurement devices.

Purpose of the Study:

• To evaluate the accuracy and reproducibility of the Tono-Pen, a novel miniaturized digital tonometer.
• To compare the Tono-Pen's performance against established tonometry methods.
• To assess the clinical utility of the Tono-Pen in patients with normal corneas.

Main Methods:

• Laboratory evaluation using enucleated human eyes with an indwelling pressure transducer (manometric study).
• Clinical evaluation involving 100 eyes in 50 patients with normal corneas.
• Comparison of Tono-Pen results with MacKay-Marg tonometer, pneumotonometer, and Goldmann applanation tonometer.

Main Results:

• Good reproducibility was observed in both manometric (SD = 1.09) and clinical (SD = 1.21) studies.
• The Tono-Pen showed less mean error at high pressures in the manometric study compared to other devices.
• No statistically significant difference in IOP measurements was found between the Tono-Pen and Goldmann applanation tonometer within the 10-35 mm Hg range.

Conclusions:

• The Tono-Pen is a reliable and accurate device for measuring intraocular pressure.
• Its miniaturized, digital, and electronic nature makes it portable and easy to use.
• The Tono-Pen shows potential as a valuable tool in ophthalmic practice for IOP assessment.