Intraocular pressure measurement in keratoconus: a narrative review

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Corneal Disease Research

Background:

• Accurate intraocular pressure (IOP) measurement is critical for diagnosing and managing glaucoma.
• Keratoconus (KC) is a corneal disease causing thinning, irregular astigmatism, and altered biomechanics, complicating IOP assessment.
• Goldmann applanation tonometry (GAT) may underestimate IOP in KC patients due to corneal changes.

Purpose of the Study:

• To investigate accurate IOP measurement methods for patients with keratoconus (KC).
• To evaluate newer tonometry devices for improved IOP assessment in KC.
• To address the lack of manometric studies in KC patients regarding IOP measurement.

Main Methods:

• Evaluation of advanced tonometry devices: dynamic contour tonometry (DCT), ocular response analyzer (ORA), and corneal visualization scheimpflug technology (Corvis-ST).
• Comparison of IOP measurements obtained from these devices against traditional methods in KC patients.
• Assessment of how corneal biomechanics and central corneal thickness influence IOP readings in KC.

Main Results:

• Newer devices like DCT, ORA (corneal-compensated IOP - IOPcc), and Corvis-ST (biomechanical corrected IOP - bIOP) show potential to reduce inaccuracies in IOP measurements for KC.
• These advanced methods may better account for the unique biomechanical properties and thinning of the cornea in KC.
• IOP measurements obtained by different methods are not interchangeable in KC patients.

Conclusions:

• Consistent use of the same IOP measurement device is crucial for monitoring KC patients over time.
• Advanced tonometry devices offer promising alternatives for more accurate IOP assessment in keratoconus.
• Further research is needed to understand structural and functional changes in glaucoma suspects with KC.