Validation of the Barraquer tonometer for high intraocular pressure estimation

Area of Science:

• Ophthalmology
• Biomedical Engineering

Background:

• Accurate intraocular pressure (IOP) measurement is critical in ophthalmology.
• High IOP poses risks and requires precise monitoring during procedures like LASIK.
• Existing tonometry devices vary in accuracy, especially at elevated pressures.

Purpose of the Study:

• To compare the accuracy of the Tono-Pen XL and pneumatonometer for high IOP measurements in human eye bank eyes.
• To evaluate the validity of the Barraquer tonometer for high IOP assessment in an ex vivo model.

Main Methods:

• Human cadaver eyes were cannulated to monitor IOP in the anterior chamber and vitreous cavity.
• IOP measurements were taken using the Tono-Pen XL and pneumatonometer at 50, 65, and 90 mmHg.
• The Barraquer tonometer was used to assess high IOP, with readings recorded at specific corneal interface points.

Main Results:

• The Tono-Pen XL consistently underestimated IOP, particularly at higher levels.
• The pneumatonometer showed accuracy at 50 and 65 mmHg but underestimated IOP at 90 mmHg.
• The Barraquer tonometer accurately estimated high IOP, with minor variability between measurement points.

Conclusions:

• The Tono-Pen XL is unsuitable for assessing IOP levels encountered during LASIK flap creation in this ex vivo model.
• Pneumatonometers and Barraquer tonometers demonstrate accuracy for high IOP measurements.
• Pneumatonometer readings may underestimate IOP around 90 mmHg.