Central and peripheral intraocular pressure measured by a rebound tonometer

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Background:

• Intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
• Goldmann applanation tonometry (GT) is the gold standard, but rebound tonometry (IC) offers portability and ease of use.
• Understanding regional corneal variations in IC measurements is essential for accurate IOP assessment.

Purpose of the Study:

• To determine which corneal region yields IOP measurements closest to Goldmann applanation tonometry (GT) using the Icare rebound tonometer (IC).
• To identify key parameters for developing a predictive model for GT based on IC measurements.

Main Methods:

• 102 normal eyes underwent IC measurements at central (ICC), superior (ICS), inferior (ICI), temporal (ICT), and nasal (ICN) corneal regions.
• Differences between IC and GT were analyzed using Bland-Altman method.
• Stepwise multiple regression analysis was performed to predict GT using various ocular parameters and regional IC measurements.

Main Results:

• IC measurements were consistently higher than GT across all corneal regions.
• The central corneal region (ICC) exhibited the least bias, followed by the temporal region (ICT).
• A predictive formula was derived: GT = (0.445 × ICC) + (0.198 × ICN) + 3.022. ICT showed the highest correlation with GT when ICC was excluded.

Conclusions:

• Central corneal measurements (ICC) with IC are closest to GT.
• Incorporating nasal corneal measurements (ICN) enhances the prediction accuracy of GT.
• Temporal corneal measurements (ICT) serve as a reliable alternative when ICC is unavailable or unreliable due to ocular rigidity variations.